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Performance Advice Needed |
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amchornet1970 
AMC Addicted 
Joined: Feb/22/2012 Location: Oshkosh, Wis. Status: Offline Points: 516 |
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 Posted: Dec/21/2020 at 8:52pm |
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Try this on for size https://youtu.be/YWcZMjA7ZgQ
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Joe
1976 hornet sedan 258 4.0 head mpfi 1985 Eagle sedan 1993 grand jeep Np242 http://s12.photobucket.com/user/amchornet/profile/ |
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farna
Supporter of TheAMCForum 
Moderator Lost Dealership Project Joined: Jul/08/2007 Location: South Carolina Status: Offline Points: 19676 |
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Posted: Dec/22/2020 at 6:43am |
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Great race motor, not practical for the street. But you can still use some of those tricks in a street build...
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Frank Swygert
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amcenthusiast
AMC Addicted
Joined: Jul/02/2012 Location: SW Atlanta GA Status: Offline Points: 1778 |
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Posted: Dec/22/2020 at 10:32am |
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Carb swap candidate: best bang for buck mod on this engine hands down. Which immediately becomes a 'carb guru' question -requiring a modified carburetor to work right on your engine. Easiest thing to do is find a stock 2bbl set up and go from there. The 258 is already a stroker engine: -already has high piston speed Don't re-engineer it -keep the stock 5000 rpm red line. You could dump a thousand $ into the valve train only to get 10 hp. (IMO get a rear sway bar instead; way better bang-for-buck mod on street driven car) Use Enginetech zinc phosphate coated lifters only -do not use new uncoated lifters 320 grit finish hone with moly coated rings -don't use 'super anti-friction oil' to seat your rings! (doesn't make sense on second thought) Put a new two row aluminum radiator on it. Edited by amcenthusiast - Dec/22/2020 at 12:10pm |
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443 XRV8 Gremlin YouTube video: https://www.youtube.com/watch?reload=9&v=2DmFOKRuzUc
XRV8 Race Parts website: http://amcramblermarlin.1colony.com/ |
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tomj
AMC Addicted
Joined: Jan/27/2010 Location: earth Status: Offline Points: 7544 |
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Posted: Dec/22/2020 at 10:11pm |
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Yowza, amcenthusiast, you nailed that one down in one succinct post!
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1960 Rambler Super two-door wagon, OHV auto
1961 Roadster American, 195.6 OHV, T5 http://www.ramblerLore.com |
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amcfool1
AMC Addicted
Joined: Jun/18/2011 Location: roanoke va Status: Offline Points: 1075 |
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Posted: Dec/22/2020 at 11:06pm |
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hi, another option, though not cheap, is the Holley Sniper BBD. You will need the 2 barrel intake manifold for this. I just did this on a 77 Hornet AMX, 258, manual trans. (Modern Driveline T5).
Just for some background, this 258 is not stock. I did the hotrodding 101 thing, cam, Lunati "Voodoo", intake, stock AMC from an 82 Eagle, with matching exhaust manifold and a 2" exhaust, and gears, stock were 2:73, now is 3:54 with Eaton TruTrac diff, in stock AMC 15 axle. (that is a story in itself!) The engine is +.030, has SBC valves w/new positive seals, Harlan Sharp roller rockers, Cloyes True Roller chain, and a couple more things I forget right now. Also new Champion aluminum radiator w/Eagle thermal clutch fan. Ok, I went from a stock, rebuilt, Carter BBD, car ran ok. Next tried a MC2150, also rebuilt, car ran better. Next, got "Economic Stimulus" checque, so decided to economically stimulate! Bought the Sniper BBD. Car runs like WOW!!!! MUCH better, totally woke that thing up. I finally feel I'm getting my moneys worth for all that engine work. I'm inadvertently chirping tires now, thing feels like a small V8. As for the fuel supply, Holley sells an intank module with no return line required for the Jeep CJ tank. Fits the Hornet and works with stock fuel gauge. We had to bend the float arm some. Reading is not perfect, 3/4 when full, but I can live with that until I pull the tank again to fiddle with it some more. So, long story short, I highly recommend the Holley Sniper BBD. Thanks and good luck to all, gz
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george z
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amcfool1
AMC Addicted
Joined: Jun/18/2011 Location: roanoke va Status: Offline Points: 1075 |
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Posted: Dec/23/2020 at 10:29am |
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hi, amcenthusiast, my car (77 Hornet AMX) does not have a rear sway bar, how/why would this help a street driven car? My goal is a nice healthy cruiser, I'm not going racing.
thanks, gz
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george z
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Gremmy
AMC Fan 
Joined: Dec/09/2020 Location: 70719 Status: Offline Points: 14 |
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Posted: Feb/25/2021 at 5:03pm |
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It's been a while and I have totally changed directions. I wound up buying a good running 258 out of a jeep a guy was LS swapping for 300 bucks.
So now I guess I have gone from being performance minded to cheap minded:-). My question is now about intake and exhaust manifolds. The 78 jeep had a 2 barrel intake. Don't know if that is factory or not. Should I go through all the pain of changing by kick down and throttle linkage to keep the 2 barrel or is it not worth it? Is there a way to post pictures on here? Thanks
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Pdok
Supporter of TheAMCForum
Joined: Apr/03/2011 Location: Alabama Status: Offline Points: 1025 |
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Posted: Feb/25/2021 at 8:37pm |
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Unless you go with the factory carb your chassis came with, I'm not sure what swap options you'd have that wouldn't also require some linkage fab work. Probably somebody else knows. The factory 2-bbl carbs are as good as they need to be, probably just a rebuild to make it work.
Not gonna lie, getting the trans linkage properly adjusted isn't trivial with a DIY linkage. It isn't super hard if you're careful to get the travel set right, but for the couple that I did on my Gremlin, the throttle part was way easier. When I swapped to the motorcraft carb, I went with the Lokar 904/727 cable, which was pretty easy to install, and adjusted easily, considering I luckily had the right bell crank throw distance already. Whatever you do, don't drive it around without the trans linkage hooked up, or you'll be hunting for a trans too.
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76 Grem X 258/904,4.0 head/MPFI, Comp X250H cam, Hughes springs, Clifford header, serpentine swap.
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FSJunkie
AMC Addicted
Joined: Jan/09/2011 Location: Flagstaff, AZ Status: Offline Points: 4742 |
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Posted: Feb/26/2021 at 2:05am |
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A two barrel Carter BBD carburetor became an option on the 258 around 1977 in Jeeps and AMC cars alike. It became standard around 1979.
I've owned both 232's and 258's, and both with one barrel and two barrel carburetors. I never noticed the 258's being noticeably faster or the two barrel carburetors adding noticeably more performance. Differences in vehicle weight, gearing, and tune mattered more. I own a low compression 1v 232 that blows the doors off the heavier cars with high compression 258 2v's.... I've never had drivability or starting problems with any of those Carter carburetors. YF, WCD, or BBD. They've all been easy to maintain, good runners that don't complain. The BBD has a tiny float bowl that goes dry in only a few days of sitting but that's about it. There's no reliability edge to any of them. I am partial to the YF though. I love it's elegant simplicity that is so effective at the same time. |
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1955 Packard
1966 Marlin 1972 Wagoneer 1973 Ambassador 1977 Hornet 1982 Concord D/L 1984 Eagle Limited |
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tomj
AMC Addicted
Joined: Jan/27/2010 Location: earth Status: Offline Points: 7544 |
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Posted: Feb/26/2021 at 10:09pm |
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I'm with FSJunkie on carbs. In good condition they're great carbs. Good condition is key, watch for worn throttle shafts and pitted bores.
There's nothing magical about expensive aftermarket carburetors, though they are more tunable. But it means you need to invest a substantial effort in tuning them, boxes of jets, A/F meter, etc. But you can tune and tweak a YF as easily (as hard, whatever). Still need the tools and persistence. But by reading plugs you can juggle main jet(s) or drill them out and get it so close it doesn't matter. Buy a spare jet for when you drill it out too large. $5 from Mike's Carburetors. Rear sway bars are useless -- except for turning corners quickly without heavy understeer. |
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1960 Rambler Super two-door wagon, OHV auto
1961 Roadster American, 195.6 OHV, T5 http://www.ramblerLore.com |
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