LS to AMC rocker conversion
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Category: The Garage
Forum Name: AMC V8 Engine Repair and Modifications
Forum Description: AMC-made V8 engine mechanical, ignition and fuel from basic repair to high-perf modifications
URL: https://theamcforum.com/forum/forum_posts.asp?TID=58303
Printed Date: Apr/16/2024 at 2:05pm
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Topic: LS to AMC rocker conversion
Posted By: jcisworthy
Subject: LS to AMC rocker conversion
Date Posted: Mar/07/2014 at 3:19pm
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I am looking into using the LS factory 1.7 ratio rockers on the AMC style bridge heads. So far it looks like an easy conversion. The spacing on a stock LS rocker shim per pair of valves is identical to AMC bridges so all you have to do is cut the LS factory rocker spacer in 4 pieces to make them fit and replace the LS 8mm bolts with a 5/16 course grade 8 cap screw and small washer. The advantages are, more lift LS rockers are 1.7 ratio, less weight over the valve if you are running a roller tip rocker, cheap, free to 50 dollars used, roller fulcrum good to .600 lift as is, easily upgraded with a Comp cams trunion kit for lifts above .600, very strong, no need for guide plates or drilling and taping for studs. I will keep you posted but it is going to be a little while before I have time to mock it up on an engine.
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Replies:
Posted By: 1greasygt
Date Posted: Mar/07/2014 at 3:49pm
| And I will be watching. Thanks. |
Posted By: Ken_Parkman
Date Posted: Mar/07/2014 at 3:58pm
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Fantastic info - THANKS! |
Posted By: jcisworthy
Date Posted: Mar/07/2014 at 5:07pm
| No problem, I thought it was pretty cool when I looked at it. Makes the bridge style heads a lot more desirable real quick. |
Posted By: Slate
Date Posted: Mar/07/2014 at 5:08pm
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It's AMC heaven if it works out. Cheap and effective. Thanks for sharing whatever comes. S
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Posted By: jcisworthy
Date Posted: Mar/07/2014 at 5:37pm
| Oh its going to happen, geometry is too close not to do it. If anyone has something together that they cam mock up sooner than I can, do it! Also opens possibilities to use offset 1.8 rockers on the intake off an LS 7 set up. I have look at the offset on them thought I think the offset is in the wrong direction, may not work. |
Posted By: 232jav3sp
Date Posted: Mar/07/2014 at 6:42pm
| heck yeah! Keep us updated! Been kicking around the idea of using the stock iron heads on the 360 I have from a Wagoneer. Just having a hard time justifying the Edel heads. But, I'm a long way off from that... |
Posted By: Traveller
Date Posted: Mar/07/2014 at 6:50pm
| Worthy idea. They don't break often at all, and they're available cheap for sure. |
Posted By: A0M797X112187
Date Posted: Mar/07/2014 at 6:50pm
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Subscribing..... ------------- -D Payne AMO 2834 ( Expired ) NAMDRA 3770 
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Posted By: 74Bubblefender
Date Posted: Mar/07/2014 at 7:11pm
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Make sure they clear the spring and youll probably need to open up the pushrod hole quite a bit. ------------- We are just about to forge new AMC V8 crankshafts.. please check here http://www.bulltear.com/forums/showthread.php?19564 |
Posted By: Rebel Machine
Date Posted: Mar/07/2014 at 7:14pm
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Very interesting! -Steve- |
Posted By: Buzzman72
Date Posted: Mar/07/2014 at 8:08pm
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Apparently the factory LS rocker arms MAY have a problem with shedding needles from the stock needle bearings. But Comp Cams has a trunnion upgrade kit, so that might salvage the project. http://tech.corvettecentral.com/2012/04/retro-ls-build-rocker-arm-upgrade/" rel="nofollow - http://tech.corvettecentral.com/2012/04/retro-ls-build-rocker-arm-upgrade/ Just wanna go into this with eyes wide open. ------------- Buzzman72...void where prohibited, your mileage may vary, objects in mirror may be closer than they appear, and alcohol may intensify any side effects. |
Posted By: Mopar_guy
Date Posted: Mar/07/2014 at 8:19pm
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What's the OEM application for these? I'm putting my 304 back together next week and if I can some of these, I can mock them up and take some pics to see how they fit.
-------------  " http://theamcforum.com/forum/hemilina_topic95889.html" rel="nofollow - Hemilina " My 1973, 5.7 Hemi swapped Javelin |
Posted By: jcisworthy
Date Posted: Mar/07/2014 at 8:35pm
| Not exactly sure of the years I will check and get back to you tomorrow. Very broad application of LS engines in various vehicles used the same set up so there are tons out there with better info. |
Posted By: jcisworthy
Date Posted: Mar/07/2014 at 8:50pm
| Some info here http://www.superchevy.com/technical/engines_drivetrain/cams_heads_valvetrain/sucp_1209_budget_ls_rocker_upgrade/ |
Posted By: jcisworthy
Date Posted: Mar/07/2014 at 10:15pm
| The 2012 Copo Camaro at school had 150 passes on stock rockers with a little over 200 seat and 600 open spring pressures, no issues. They are upgraded with the Comp trunnion kit now. |
Posted By: RASelkirk
Date Posted: Mar/08/2014 at 8:18pm
Any LS Gen III engine from '97 thru '08 with cathedral port heads. On these heads, the intake and exhaust rockers are interchangeable and have 1.7:1 ratio. . When the LS Gen IV engines went to the rectangular port heads, the intake rockers were offset 0.180" with the ratio staying at 1.7:1. The only LS engine that came with 1.8:1 rockers was the LS7 with it's proprietary heads and offset intake rockers. Russ ------------- '63 American 220 Sedan (under re-construction) |
Mopar_guy wrote:Posted By: Mopar_guy
Date Posted: Mar/09/2014 at 7:13am
Not knowing Chevy's much, what vehicles are they in? If I go to the auto parts store, what application do I ask for? ------------- " http://theamcforum.com/forum/hemilina_topic95889.html" rel="nofollow - Hemilina " My 1973, 5.7 Hemi swapped Javelin |
Posted By: jcisworthy
Date Posted: Mar/09/2014 at 8:08am
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If you go used anything with an LS 1, LS 2 and LS 6 in it in the range of years listed above are the same. L92, LS3, LS9 use the same rockers on the exhaust, intakes are different. If you are going for new I would go right to GM and get them. Part numbers for rockers are 10214664 and the stands are 12552203. The rocker stands are 3.74 each, 2 required and the rockers are 11.21 each 16 required of course. These are prices I found on line using part numbers from my GM performance catalog, check with your local dealer. Get the 5/16 course thread cap screws at any local hardware store for about a dollar each, I will check the length later. The GM part numbers above are for LS1, LS2 and LS6 intake and exhaust 1.7 ratio straight design. You know will need to set up geometry using these, dont you? Looks like around 200 dollars for everything, rockers, stands, bolts, plus tax using the prices above, used should be less than half of that. I have seen them on Ebay for around 50 dollars used.
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Posted By: Rebel Machine
Date Posted: Mar/09/2014 at 10:11am
I wonder if the saddles you showed below would accept a stud mounted performance rocker arm. Probably have to sleeve the arm's pivot to take up the bolt diameter difference but if it worked you could use a roller tip if you wanted. -Steve- ****UPDATE**** I see there are already bridged roller tip rockers. The mount above would be nice to eliminate guide plates. http://www.summitracing.com/parts/scc-scp1097bl/overview/make/american-motors" rel="nofollow - http://www.summitracing.com/parts/scc-scp1097bl/overview/make/american-motors -Steve- |
Posted By: RASelkirk
Date Posted: Mar/10/2014 at 6:22pm
Pretty much anything from a '97 Vette up thru 2007 (to be sure) GTO or truck. If you have a doubt, you can check application crossover on RockAuto.com. No problem with used stock rockers as long as they weren't used with an aftermarket cam. The "stock on stock" rockers on cam last forever. The problem arose when people went to extreme lobe profiles with insufficient springs which tended to blow out the trunnion bearing needles (which were not encapsulated from the factory). As alluded to in a previous post, Comp Cams (among others) has a trunnion upgrade with encapsulated bearings. The latest on that is, Comp was sending cheap sheetmetal Chicom circlips which were falling out and allowing the bearings to walk. It's always something... Russ ------------- '63 American 220 Sedan (under re-construction) |
Posted By: Mopar_guy
Date Posted: Mar/10/2014 at 6:42pm
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OK, thanks for the info. A co-worker has a buddy that does a lot with LS engines so he's going to try and get me some to try out. I'll be putting the heads back on my engine later this week so if I can get some rockers I can check out the fit and geometry to see if they'll work. I'll keep you posted. ------------- " http://theamcforum.com/forum/hemilina_topic95889.html" rel="nofollow - Hemilina " My 1973, 5.7 Hemi swapped Javelin |
Posted By: jcisworthy
Date Posted: Mar/10/2014 at 7:42pm
| Going to mock it up tomorrow a 401 complete short block came in to school today so I can bolt a head on it and see how things line up. I will post results tomorrow night. |
Posted By: 232jav3sp
Date Posted: Mar/10/2014 at 8:04pm
| Yes please do! |
Posted By: M+M
Date Posted: Mar/11/2014 at 8:21am
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Nice JC.... Sending you a pm..... ;) ------------- M+M Performance Heads & Machine https://www.facebook.com/pages/MM-Performance-Heads-and-Machine/209556499235670?ref=hl |
Posted By: White70JavelinSST
Date Posted: Mar/11/2014 at 8:39am
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Just getting on the notification list for this subject. Very interesting and thanks for sharing the idea with us JC.
It's good of ole man GM to inadvertently make parts for us AMC guys.
I'll be watching for updates.
Armand ------------- 70 Javelin SST, second owner, purchased 1972 |
Posted By: Hurst390
Date Posted: Mar/11/2014 at 12:05pm
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I like the idea of a another avenue you have explored here...a little more lift and a better rocker cheap...but in the end... wouldn't milling the bosses for guideplates and tapping them for studs be better in the long run? Then any cam and spring combo would be usable.... I'm guessing your still gonna have to shim or mill those stands right? Thanks for the time and pics! ------------- SC/Hurst Rambler 11.62 120 100% Street Legal |
Posted By: jcisworthy
Date Posted: Mar/11/2014 at 4:02pm
Mocked up a 401 with stock bridge bosses and stock valves, hydrolic cam probably stock but not sure what is in it. Using an 8" long push rod the lash adjustment was at 1/2 turn preload when torqued. Geometry looked pretty good, not quite as good as stock but these are 1.7 rockers also. It was close enough where I would not be afraid to run it hard on a daily basis. 3/8 pushrod stayed centered in the through hole in the head throughout the sweep, very happy with how it all looked. Has clearance on retainer also.      
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Posted By: jcisworthy
Date Posted: Mar/11/2014 at 4:07pm
| With a cam any bigger than .500 lift I would upgrade to the Comp trunnion kit to be safe. .500 lift with a 1.6 is .531 lift with a 1.7. I have read where these go to .600 without mods but probably better to be safe than sorry. The trunnion on these stock has a stop built in as you can see in the pictures the upgrade does not it can rotate 360 degrees. |
Posted By: jcisworthy
Date Posted: Mar/11/2014 at 5:29pm
| I found my Comp Cams adjustable push rods which are more accurate then what I used today. I will check it again tomorrow, I think it may come out with a different length maybe 7.950. What I used today is an adjustable push rod where you have to measure it with calipers after it is adjusted. 7.950 is more popular than 8.000. Of course each application will have to be checked separately to be sure. Get one or two Comp Cams 7703-1's to check your engine. |
Posted By: Mopar_guy
Date Posted: Mar/11/2014 at 6:34pm
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Looks good! Since these will work, I might buy a set and put them in since they're pretty cheap.Thanks again for posting this!
------------- " http://theamcforum.com/forum/hemilina_topic95889.html" rel="nofollow - Hemilina " My 1973, 5.7 Hemi swapped Javelin |
Posted By: RASelkirk
Date Posted: Mar/11/2014 at 6:53pm
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There's a guy a couple hours from me (in Waco) occasionally selling used rocker sets, among other J/Y parts, on E-Bay. Search for username bding44, I saw he had a set the other day for $27.50. The trunnion upgrade runs ~ $135, but pay close attention to the retainer rings. If they're sheetmetal, you can buy some quality US-made rings for around $10 for 32 from http://www.allensfasteners.com/" rel="nofollow - Allen's Fasteners . They also happen have the absolute best price on anything from ARP... Russ ------------- '63 American 220 Sedan (under re-construction) |
Posted By: jcisworthy
Date Posted: Mar/11/2014 at 7:15pm
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Plus pushrods. If it turns out something less than 8" will work they will be cheaper. http://www.ebay.com/itm/390786309638?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649
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Posted By: jcisworthy
Date Posted: Mar/12/2014 at 2:51pm
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Checked the geometry with the Comp Cams adjustable pushrods today and it looks like with a 7.950 long pushrod the lifter preload is about 1/8 turn, with an 8.000 pushrod it is between 1/2 and 3/4 preload. I found a push rod that measures 7.963 long, 3/8 diameter fits 1988-95 GM 231 cid with roller cam, cost is about 2 dollars each. Preload should be around 1/4 range with it. GM part number on the pushrod is 25532501 Also, I was told today that the school's 2012 Copo Camaro came from the factory with 630-640 lift range with factory needle bearing rockers no trunnion upgrade and ran 150 passes with over 200 seat pressure and over 600# open no issues, so these rockers should hold up well in most any engine and even better with a trunnion upgrade. What I said earlier about cams around .500 lift may not be accurate, possibly up to .600 without a trunnion upgrade. That would be .637 lift at the valve with these 1.7 rockers.
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Posted By: tsanchez
Date Posted: Mar/12/2014 at 2:55pm
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Need to check geometry, not if its centered but because its not a roller it needs to rock across valve without scrubbing or it will destroy vale tips ------------- http://s192.photobucket.com/user/antonsan/media/jav1_zps87a70dce.jpg.html" rel="nofollow"> 
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Posted By: jcisworthy
Date Posted: Mar/12/2014 at 3:11pm
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Rocker starts just below center and sweeps further below center then back. About .150 distance or so. I checked it against the factory bridge and it was similar only little lower on the valve. Everyone who runs this absolutely needs to check their combination. What I listed above may/should work with a stock of close to stock set up and maybe others I dont know. What ever the case, it looks like a pushrod length change in whatever you are running may be the only change needed to bolt on and run LS rockers on a bridge head.
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Posted By: tsanchez
Date Posted: Mar/12/2014 at 3:47pm
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It should start from the intake side and roll across and at max lift be on the exhaust side, it cannot act like a roller and come back. Just a note on stock ls1 the casting mark near the tip is right at 90 degrees from valve stem which means from the pics you posted you would need to mill the head to get the rocker lower for it to work at all and then you would need to install ls style small spring retainers to clear rocker. ------------- http://s192.photobucket.com/user/antonsan/media/jav1_zps87a70dce.jpg.html" rel="nofollow">
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Posted By: jcisworthy
Date Posted: Mar/12/2014 at 4:20pm
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I checked this set up on a used 401 flat tappet hydraulic cam and the factory bridge. On the same engine and they left the same mark on the valve only a little lower with the LS rockers and the rocker does not hit the stock AMC retainer at any point with about .040 clearance at the closest point, eyeballing it.
I dont think there will be any issues running this set up as a bolt on but I may be wrong. |
Posted By: jcisworthy
Date Posted: Mar/12/2014 at 4:32pm
| Bottom line is everyone needs to check their own set up. |
Posted By: jcisworthy
Date Posted: Mar/13/2014 at 11:15am
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Couple things to watch out for on the rockers. First, as rocker opens valve make sure the head of the cap screw does not contact the rib in the rocker. Second, make sure the stop in the rocker does not bottom out throughout the lift range. I am going to try to mock up enough of an engine this weekend and check geometry closer I had very little time when I checked it on the 401 and it is now apart.
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Posted By: jcisworthy
Date Posted: Mar/17/2014 at 12:44pm
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Mocked up a cam in a 401 block today geometry was different than the other one last week. The bosses will need to be milled to get correct geometry or longer valves. Took a picture of an LS1 head with rocker sitting on it and you can see where GM sets it. Note the position of the stop, they set it so the travel goes from stop to stop, almost, for max lift potential. Other picture is AMC heads last week, you can see it is close to GM but not quite the starting point, should run fine with the pushrod I listed in previous comment and .530 lift or less with the 1.7 LS ratio factored in. If if you get something similar to that and the sweep on the valve is good this will work. It is a viable option to machining for studs and the parts that go with that but not a bolt on in all or possibly no cases. I am going to build an engine with this set up and will detail what was done but it will be a couple months before I can get to it.  
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Posted By: FuzzFace2
Date Posted: Mar/18/2014 at 9:28am
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Could you use lash caps to raise the valve tip?
I found this thru Google http://www.speedtalk.com/forum/viewtopic.php?f=1&t=14729" rel="nofollow - http://www.speedtalk.com/forum/viewtopic.php?f=1&t=14729
Looks like you could use caps I just dont know how thick you can get them in?
I wonder how much HP they add to say a stock motor because of the extra lift going from 1.6 to 1.7? The old VW type 1 motor you could get hi lift rockers to up HP and why I ask.
Dave ---- ------------- TSM = Technical Service Manual 75 Gremlin X v8 for sale 70 Javelin 360/auto drag car 70 Javelin 360/T5 Street car |
Posted By: jcisworthy
Date Posted: Mar/18/2014 at 1:26pm
| Yes, lash caps can be used also. |
Posted By: Mopar_guy
Date Posted: Mar/19/2014 at 4:52pm
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I thought about machining the supports down instead of the head. The valve caps are a good idea as well.
------------- " http://theamcforum.com/forum/hemilina_topic95889.html" rel="nofollow - Hemilina " My 1973, 5.7 Hemi swapped Javelin |
Posted By: jcisworthy
Date Posted: Mar/19/2014 at 5:53pm
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I would not machine the spacers down it will compromise them, they are only about .100 thick to begin with. The first engine I checked would have been on the money with an .080 lash cap on it but even without it and medium lift I am confident it would have ran fine even if used hard. Lash caps would be nice to monitor the wear and protect the valves as long as there is enough valve stem above the retainer to use them. Dont think it would have been an issue with the stock valves but it needs to be checked like everything else.
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Posted By: jcisworthy
Date Posted: Apr/16/2014 at 8:59pm
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Found these on ebay, interesting. Spacing should be a bolt on for bridged heads. Building a 401 now, think I may try a set. Just swap out their 8mm cap screws for 5/16 http://www.ebay.com/itm/CHEVY-LS-1-8-NON-ADJUSTABLE-STAINLESS-STEEL-ROLLER-ROCKERS-PEDESTALS-BOLTS-/171299229786?pt=Motors_Car_Truck_Parts_Accessories&hash=item27e23ad05a&vxp=mtr
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Posted By: jcisworthy
Date Posted: Apr/16/2014 at 9:06pm
| There is an adjustable version also, look basically the same. That is what I will try. |
Posted By: superstingray77
Date Posted: Apr/17/2014 at 3:41pm
| Ill be following this I have to order rockers for my 401 build. The heads are done already (were bridged 1990 360 heads) I had them machined and re-worked for screw in studs and plates. Will the 1.8 geometry work out? |
Posted By: jcisworthy
Date Posted: Apr/17/2014 at 6:14pm
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Every engine has to be checked but the set up above is for a bridge head without screw in stud mods, stock 5/15 threaded holes. The bolts above will be 8mm so 5/16 cap screws will be needed to bolt them down. The 1.8's will need something for sure, highly unlikely they are a bolt on or close enough to run it bolt on. Longer valve, different length pushrod of both needed to get geometry. I will let you how it works out on the engine I am working on.
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Posted By: adeleon
Date Posted: Feb/26/2015 at 5:50pm
| Any updates on this? |
Posted By: jcisworthy
Date Posted: Feb/26/2015 at 8:02pm
The combination had .100 longer than stock valves. I needed .060 shims for geometry under the rocker stands with appropriate pushrod lengths for preload and everything ran perfect. 
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Posted By: Slate
Date Posted: Feb/26/2015 at 10:42pm
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If stock valves were used what would be different about the install? Steve
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Posted By: jcisworthy
Date Posted: Feb/27/2015 at 4:51am
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Shorter push rods and you may not need to shim the stands. I think with stock length valve it is a bolt on set up with a longer pushrod. It would have to be mocked up and checked as well as retainer to rocker arm clearance.
Stock spring diameters should clear the rocker by a safe distance but it needs to be checked. |
Posted By: SCarolinaAMX
Date Posted: Feb/27/2015 at 10:48am
| Amazing results! Thanks for sharing! |
Posted By: SCarolinaAMX
Date Posted: Feb/27/2015 at 10:50am
| PM sent. |
Posted By: Slate
Date Posted: Feb/27/2015 at 12:16pm
From what you have tested out and are saying that would be the route to go for novices, and I'm one of 'em. Got a low mile bridge rocker 401 that this application might be just the ticket for. Thanks for your innovation and sharing your experiences. Steve |
Posted By: 73hornut
Date Posted: Feb/27/2015 at 6:19pm
------------- 71 Javelin 74 Gremlin 79 Spirit AMX Rogue Valley Rumblers Like Us on FB https://www.facebook.com/groups/1602825606650796" rel="nofollow - https://www.facebook.com/groups/1602825606650796 |
Posted By: jcisworthy
Date Posted: Feb/27/2015 at 7:34pm
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I said shorter push rods and meant to say shorter valves and you may not need to shim the stands. With the LS set up and bridge rockers for that matter the geometry is set by moving the stand whether it is up, down, back or forward. The pushrod length sets preload on the lifter. |
Posted By: Mopar_guy
Date Posted: Feb/27/2015 at 8:39pm
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Anybody look into Mopar Magnum rockers? They look so close and are 1.6 ratio and have a pedestal too.
------------- " http://theamcforum.com/forum/hemilina_topic95889.html" rel="nofollow - Hemilina " My 1973, 5.7 Hemi swapped Javelin |
Posted By: xspiriment
Date Posted: Feb/27/2015 at 9:55pm
| This conversion gave me interest in trying it on a six 4.0 head. I asked in the six cylinder engine mod section but had little response. Any thoughts of it working on a 4.0L ??? |
Posted By: 73hornut
Date Posted: Feb/27/2015 at 10:27pm
------------- 71 Javelin 74 Gremlin 79 Spirit AMX Rogue Valley Rumblers Like Us on FB https://www.facebook.com/groups/1602825606650796" rel="nofollow - https://www.facebook.com/groups/1602825606650796 |
Posted By: Hurst390
Date Posted: Feb/28/2015 at 11:33am
------------- SC/Hurst Rambler 11.62 120 100% Street Legal |
Posted By: jcisworthy
Date Posted: Feb/28/2015 at 12:11pm
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The LS rockers use an 8mm bolt where I used 5/16 cap screws to screw into the existing AMC thread on the bridge heads. There is not much room to make the hole in the LS rockers larger, 3/8 maybe on the high side. A lot depends on the thread size in the 4.0 heads and the valve guide spacing. If the spacing is between 1.900-1.930 center to center and the threads are 5/16 there is a good chance the LS valvetrain may work.
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Posted By: amc67rogue
Date Posted: Feb/28/2015 at 12:25pm
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All Gen.2 & 3 v8 199 thru 258 4.0 have the same valve spacing. IIRC the Gen 1 250-327 is the same as Gen 2 & 3. ------------- Keith Coggins 67Rogue X code |
Posted By: xspiriment
Date Posted: Feb/28/2015 at 2:56pm
Thanks for the replies for the 4.0. The 4.0 uses the same bridged rocker assy as the v-8 so i think it will work. i have to try this when i work on a 4.6 stroker in my future. To many projects right now. 
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Posted By: Aljav
Date Posted: Mar/01/2015 at 9:58am
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If memory serves me right the 6 rocker arm has very different dimension than the 290-401 rocker arms, ------------- 69 AMX 9.86 132 mph 71 JAV/AMX and 69 Javelin, .. NAMDRA member #1106 |
Posted By: gschuld
Date Posted: Nov/24/2016 at 10:02am
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Any updates on this? George |
Posted By: 5spdwagon
Date Posted: Dec/21/2018 at 3:25am
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I bet this is a awesome upgrade for the ones who have the talent to make it happen
------------- Real hot rods have 3 pedals |
Posted By: Brad
Date Posted: Dec/21/2018 at 1:02pm
Thanks for your posts on this. Do you think these would work ok? Any idea if the stock valve covers will still fit? https://www.jegs.com/i/Speedmaster/746/PCE261.1091/10002/-1" rel="nofollow - https://www.jegs.com/i/Speedmaster/746/PCE261.1092/10002/-1 After asking customer support at Jegs, these are adjustable? 1.7 ratio
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Posted By: jcisworthy
Date Posted: Dec/21/2018 at 1:26pm
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I have switched to the style in the link for bridge heads https://www.ebay.com/itm/Chevy-GM-LS1-LS6-1-7-Ratio-Aluminum-Shaft-Rocker-Arms-Set-with-Hardware/291950958737?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649" rel="nofollow - https://www.ebay.com/itm/Chevy-GM-LS1-LS6-1-7-Ratio-Aluminum-Shaft-Rocker-Arms-Set-with-Hardware/291950958737?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649 I may do a thread on what it takes to use them when the 304 I am building goes together ------------- Specializing in dyno services, engine building, and cylinder head porting rbjracing.com Phone Number 518-915-3203 |
Posted By: Brad
Date Posted: Dec/21/2018 at 1:34pm
| Thanks for the reply, I edited my post after Jegs comfirmed the part # I edited is adjustable. I scored a 401 but haven't pulled it appart yet . I bought a rusted out parts car 73 Javelin that the owner "says" has a brand new not rebuilt 401 that was installed by a AMC dealership in 1978 . It's "supposed to" have less than 5000 miles on it? I assumed it will have bridged rockers? If its as reported , plan is to do a cam swap, roller rockers and go? But we all know what "assume" stands for lol |
Posted By: Sonic Silver
Date Posted: Dec/21/2018 at 1:40pm
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Posted By: Brad
Date Posted: Dec/21/2018 at 1:44pm
Why did you switch to the style in your link? Was there an issue with the LS rockers in pairs style? Thanks for passing along your experiences, saves us all time and money
 |
Posted By: White70JavelinSST
Date Posted: Dec/21/2018 at 2:17pm
Curious, do the rocker bosses require machining for this conversion? and, Could this conversion be made adaptable to a 291 head? Are the rocker bosses spaced the same from bridged to rocker stud heads? I understand the 5/16 to, crap can't remember, is it 7/16 or 3/8 boss on a 291 will cause a bit of a stir....
------------- 70 Javelin SST, second owner, purchased 1972 |
Posted By: jcisworthy
Date Posted: Dec/21/2018 at 3:33pm
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I had a case where they did not fit under stock covers and another where they did. With a thick, 5/16 I think, valve cover gasket SCE offers I beleive they would have fit. We ended up using aftermarket covers. I will mock up on the 304 heads and see if they fit with factory covers. I did mill .030 off the pedistals just to even them up. I do not have the rockers yet but should in a week or so. Looking at the shaft support rail, it looks like the factory slots for the 8mm bolts can be opened up and used with 7/16 screw in stud heads. Button head bolts would have to be used to clear the rocker body. I did the measurements using 7/16 button head bolt online dimensions a while ago and the button heads would have worked The stands have to be cut in four separate sections and used in pairs because they are obviously different than LS in its entirety. The slots need to be milled .060 beyond the factory length to the left as mounted on the head also for proper rocker to valve stem alignment. That is with the factory 8mm to 5/16 setup. I did not have issues with the other rockers but lately they seem to be only available in 1.8 ratio and the other setup is more rigid so I use them now. ------------- Specializing in dyno services, engine building, and cylinder head porting rbjracing.com Phone Number 518-915-3203 |
Posted By: JolleyGreenSST
Date Posted: Dec/28/2018 at 5:47pm
Any possibility of a how to with pics or maybe even a YouTube video? I'm in the process of rebuilding my 401 and I would love to go with the stock LS rockers from a junkyard 5.3 and ebay has the comp cams trunnion kit for $65! What would I need to do to make this work with my 502 bridges heads? ------------- "God is good all the time and all the time God is good!" |
Posted By: klvn8r
Date Posted: Jan/03/2019 at 6:41pm
| Russ, are you near DFW, or south of Waco? |
Posted By: 5spdwagon
Date Posted: Jan/06/2019 at 5:22am
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Can’t this be done on a set of eddy heads or does this require a lot of set up and machining to make work?
------------- Real hot rods have 3 pedals |
Posted By: EVF_Sportabout
Date Posted: Feb/24/2019 at 5:26pm
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John are the 304 heads you mention the ones that went on my engine? Did you ever do a thread on the setup?
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Posted By: jcisworthy
Date Posted: Feb/25/2019 at 6:59pm
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I did not do a thread. I will try to start one on the next engine I use them on ------------- Specializing in dyno services, engine building, and cylinder head porting rbjracing.com Phone Number 518-915-3203 |
Posted By: flejl
Date Posted: Feb/21/2022 at 6:58am
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This is very interesting! From what I have read, the following steps are needed: 1. buy a set up used, not abused factory LS rockers and mounts. 2. Cut the mounts to allow bolting a pain to the AMC bridged heads using 5/16" grade 8 cap head screws. 3. Check rocker geometry (could use some more details on this). 4 Should be bolt in upgrade for cams with in the .500 lift range. Any/all updates or corrections will be greatly appreciated. Thank You |
Posted By: Kreep
Date Posted: Feb/21/2022 at 7:32am
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That should work, assuming your heads have bridge rockers and not the pivot ball type. What I found is the AMC trunion to valve distance is slightly longer than on an LS. The trunion boss is also a little higher which makes it tough to get "correct" rocker geometry. I ended up milling down the LS pedestals. When jcisworthy installed a cam in the .600 range he had to shim the pedestals partway back up to keep the tip on the valve stem. In my opinion, there are two really good ways to do this. First, install taller Pontiac valves (.100ish or better .200ish taller) and run factory rockers with upgraded trunion bearings. Second, use aftermarket LS rockers with a roller tip. I believe these have the same effect as a taller valve. Obviously this is the better path in your case. The reason for taller valves or roller tips is that will correct the geometry. Also, there is about a 10 degree angle between the valve stem and trunion boss. The higher you go the closer they get together which makes up for the shorter LS rocker.
------------- 1982 Jeep CJ-7 http://theamcforum.com/forum/basically-stock-cj7_topic106501.html https://irate4x4.com/threads/basically-stock-cj-7-update.383765/ |
Posted By: flejl
Date Posted: Feb/22/2022 at 9:10am
| Will the stack LS rockers or aftermarket LS roller rockers fit under the factory AMC stamped steel valve covers? |
Posted By: Kreep
Date Posted: Feb/22/2022 at 9:31am
Easily. ------------- 1982 Jeep CJ-7 http://theamcforum.com/forum/basically-stock-cj7_topic106501.html https://irate4x4.com/threads/basically-stock-cj-7-update.383765/ |
Posted By: bobsterfl
Date Posted: Feb/25/2022 at 7:39pm
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FWIW, I have a full set of LS rockers and "stands" listed in the for sale section if anyone is interested. ------------- Bobsterfl 1970 BBO Javelin 390 - Torqueflight |
Posted By: Chisam
Date Posted: Feb/26/2022 at 1:14am
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Not all LS rockers fit easily under Factory valve covers. I was told by the engine builder they would as I had Factory valve covers chromed and did talk to him about this. They did not. I had to have spacers made to use the valve covers for my 69 Ambassador. ------------- 1968 AMX 390 4SP |
Posted By: Chisam
Date Posted: Feb/26/2022 at 1:24am
------------- 1968 AMX 390 4SP |
Posted By: Kreep
Date Posted: Feb/26/2022 at 7:45am
I stand corrected. Which aftermarket rockers are you using? ------------- 1982 Jeep CJ-7 http://theamcforum.com/forum/basically-stock-cj7_topic106501.html https://irate4x4.com/threads/basically-stock-cj-7-update.383765/ |
Posted By: nitro-express
Date Posted: Jan/20/2024 at 5:57pm
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I am in the process of cobbling together a 304 or perhaps a 401. I have head issues, and the LS rocker arm swap sounds interesting. I am having a bit of a search issue, I could only find one reference to the spacing between valves on a stock AMC V8 head and it lists the space to be 1.950 CL of intake valve to CL of exhaust valve. This is probably the same as the rocker stud spacing. On an LS I found the 2.115" spacing listed for an LS3. I have a set of Ford 351W heads and the rockers are good on it, I may use those, but the LS idea does appeal to me as well. I was also searching for a 1:5 ratio rocker to tame down a fairly wild cam I have. n-e
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Posted By: PHAT69AMX
Date Posted: Jan/20/2024 at 7:39pm
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Is it really cheaper than just buying Harland Sharp AMC Roller Rockers? -------------  Link to a http://www.youtube.com/watch?v=MySiKQsmWxU" rel="nofollow - Short YouTube Burnout Video |
Posted By: Kreep
Date Posted: Jan/21/2024 at 5:40pm
LS3 has one offset rocker. LS1, LS2 and LS6 are the right ones for this swap. But these rockers are 1.7:1 so that's the wrong direction to tame your cam. ------------- 1982 Jeep CJ-7 http://theamcforum.com/forum/basically-stock-cj7_topic106501.html https://irate4x4.com/threads/basically-stock-cj-7-update.383765/ |
Posted By: Have2SC's
Date Posted: Jan/21/2024 at 7:08pm
------------- 1971 SC360 Hornet 4 speed 1970 Javelin 390 4 speed "Base Model" 1967 Rambler 220 X code 343 4 speed |
Posted By: mbwicz
Date Posted: Jan/22/2024 at 7:56am
I think when this thread was started there weren't commonly available roller rockers for bridge rocker AMC heads. The last couple of years Harland Sharp (and maybe others) have come out with rockers that are compatible. Your point is valid, though. Mike ------------- 1970 AMX, one step forward, one step back. Both steps cost time and money. |
Posted By: BBO UK
Date Posted: Jan/22/2024 at 8:11am
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Harland sharp now offer shaft rockers for both bridged and studed AMC heads, talk to Mike Luke ( POS#1 ) not as cheap as this Chevy LS fix, but purpose built for our heads. |
Posted By: Kreep
Date Posted: Jan/22/2024 at 9:10am
Maybe. A set of Summit Racing house rockers with upgraded trunions is $260. Add $25 for stands. So yes, $285 is less than $625 for the Harland Sharp rockers. But in my opinion it only makes sense if you are replacing the valves with something 0.1 to 0.2" taller to correct the geometry. There are other advantages. The LS rocker arms are lighter over the valve, have a 1.7:1 ratio, and the slipper shoe is more reliable than a roller tip. ------------- 1982 Jeep CJ-7 http://theamcforum.com/forum/basically-stock-cj7_topic106501.html https://irate4x4.com/threads/basically-stock-cj-7-update.383765/ |
Posted By: PHAT69AMX
Date Posted: Jan/22/2024 at 7:22pm
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Was thinking individual stud AMC HS Roller Rockers. ------------- Link to a http://www.youtube.com/watch?v=MySiKQsmWxU" rel="nofollow - Short YouTube Burnout Video |
Posted By: BBO UK
Date Posted: Jan/23/2024 at 11:05am
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Individual stud AMC HS Roller Rockers, would be an easier replacement, but cost more than the LS rockers. The shaft system is good but expensive, but its nice to have it available for those that can use it. When John started this thread 10 years ago the choise was more limited and we were gratefull that he took the time to figure out how to use something cheap and high performance for our engines.
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