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Wanted: Advice on 258 build-up |
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Javelin Dan 
AMC Apprentice 
Joined: Aug/02/2014 Location: Akron, OH. Status: Offline Points: 52 |
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 Topic: Wanted: Advice on 258 build-upPosted: Aug/02/2014 at 8:21pm |
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Greetings all - new member, first time
poster. I own a '69 Javelin and I have a penchant for inline sixes. I
previously posted over at the AMC Forum - much good info there, but
not much love for the "six in a row won't go" crowd. I
cruised around this forum and saw some good stuff here and was hoping
for a little feed-back. 5.) Is it worth the time and hassle to
use the reverse flow 4-liter water pump? I would need the complete
pulley set wouldn't I? Would it put the fan closer to the radiator?
(already a problem). |
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tached_out
AMC Nut 
Joined: Feb/08/2008 Location: Vancouver, BC Status: Offline Points: 328 |
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Posted: Aug/03/2014 at 2:49am |
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Hi Dan, Welcome. I like your plan. I don't think you are far off (if at all) on your HP goal. Sounds like you are going to have a fun ride when you are done. That combo should also put you deep into the 13 second bracket and very close to 100 mph.
A 500 cfm carb isn't going to be bad for driving around with, but I think a 600 or larger will get you down the track a little quicker. I'll take a stab at your questions (and then take a few stabs from the other members). 1.) Yes. 2.) No, in my opinion. There are sellers of new HEI type distributors and last time I checked they were around $80. 3.) Yes, all the time. You just have to make room for the locating dowel to fit the intake where it has to sit. A round file works well for this. You may also have to make slightly different shaped hold down washers. Although the intake ports on the early 4L are closer to where the 258's are, it's probably easier to fit a 258 style intake Offenhauser on the `91 and later head. The injector relief on yours may be hard to cover with the flange around the intake runner. 4.) No. 5.) Yes and yes if you want to run a serpentine belt. If you'd like to run a "V" belt, I would look for all the pulleys and brackets from a later `70s to early `80s engine. That way you can have a Delco alternator on the passenger side and your power steering pump on the driver's side. The `81 and up engine used an aluminum standard rotation water pump. I've just finished building a somewhat similar engine. It's going in the car this weekend. I hope to be breaking in the cam in the next few days. I'm very interested to see how yours turns out.
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amchornet1970
AMC Addicted
Joined: Feb/22/2012 Location: Oshkosh, Wis. Status: Offline Points: 516 |
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Posted: Aug/03/2014 at 7:33am |
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Hello Dan and I see you have been busy! I see Tached_out has got all you questions answered already. The only big differance with the 4.0 water pump is that it turns the opposite direction due to the serp. belt. you can use the water pump off the 258 with the v belts with no big deal. The only thing I could think of is to make up a custom intake and go with two or three carbs. just to get the carbs. closer to cylinders 1-2 and 5-6. But that really wouldn’t be that big of a deal anyways.
Oh yes and the power steering pump brckt. might have to me modified to fit onto the intake. I believe its just a small cut to make a hole longer. Very nice build! I am planing on a stoker build myself for my 76 hornet but right now am installing a 4.0 motor with the mpfi system into my 85 eagle. That has a comp. cam with .462 and .485 lift |
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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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Javelin Dan
AMC Apprentice
Joined: Aug/02/2014 Location: Akron, OH. Status: Offline Points: 52 |
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Posted: Aug/03/2014 at 9:00pm |
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tached_out & amchornet1970 -
Thanks for the response and the support! I purposely kept out a lot of detail in the interest of brevity. The original 232 has a Crane cam of similar specs, but is somewhat lazy because of low cranking compression due to the original pistons and combustion chambers. I'm looking for somewhere around 9:1 - 9.5:1 compression with this new set-up. I already am using an Offy intake with a 390 cfm Holley. Don't think it's enough as my brother has used both a 600 Edelbrock and currently a 600 Street demon on his Buick 3.8 V-6 (milder Edelbrock cam) with no ill effects. Maybe I will consider a 600 over a 500... I've already converted to a Delco 1-wire alternator. Got a local shop who clued me in to the correct housing (used on mail trucks?) that doesn't need to have the holes hogged out. Bolted right up and gives me 90 amps of trouble free power. I have to buy an intake no matter what. I want to sell the old motor as a running package. I can get an Offy at Summit (virtually in my own back yard - how cool is that?) for around $300. I can get one from Clifford to fit the 4-liter head but would probably be $400 or more with the carb plate and shipping. The Clifford is a single plane, the Offy is a dual plane, but says in the blurb not for automatics. Anyone want to weigh in on this? Any clarification on the distributor thing? What brand? Where? I'm running the original with a Pertronix kit on the old motor. Never a lick of trouble. FYI, I added an MSD-6AL to this combo and saw absolutely no change or improvement of any kind. Don't know what that means... The sandman's beating me to death so I'll quit ranting for now. You don't know what a pleasure it is to communicate with people that actually get what I'm doing without saying "Why don't you just put a 401 in it?" Keep the input coming! Thanks again. |
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tached_out
AMC Nut
Joined: Feb/08/2008 Location: Vancouver, BC Status: Offline Points: 328 |
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Posted: Aug/04/2014 at 1:59am |
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The Clifford intake is for a high port, or later `91 and up 4L. It's also the more expensive of your options. I would recommend the Offy open plenum for `81 and up 258 and make it fit. I have never liked their dual ports for any application.
Not for automatics simply means there is no provision for the kickdown linkage to attach. You will have to get creative.
Here is a supplier for an HEI. http://www.skipwhiteperformance.com/detail.aspx?Item=6511-CL You can find them for more at Summit and for less at Amazon. They're all over the internet. It's a personal choice kind of thing. There's no need to change from what you run now if it's working for you. I just like the idea of brand new parts for cheap. |
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uncljohn
AMC Addicted
Joined: Jan/03/2013 Location: Peoria AZ Status: Offline Points: 5394 |
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Posted: Aug/04/2014 at 5:18am |
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The I-6 is more or less a fun engine to build I have found. As a firm believer in Smoky Yunick's
http://www.smokeyyunick.com/ Philosophy that an engine is an air pump and if you can get it to pump more air it will run faster and no where in there does is specify the engine configuration I had previously built a leaning tower of power and terrorized the by ways with it. But fast forward to a different era requiring something that ran well AND could pass smog at the same time I used a 258 that had been massaged to give a little over 9:1 compression to be compatible with the available premium 91 octane fuel and then added an Iskenderian 256-Supercam and a MOPAR retrofit kit for the MPFI, a modified 904 with a 2200 rpm stall torque converter. A single exhaust tube type header with a hiflow catalytic converter and a 16 inch glass pack. Those being the major mods it has run well now for about 50,000 miles and develops an estimated 180HP. I have a 232 on the stands that I will massage for about 9:1 compression and then use a bit more of an Iskenderian cam and an available Offenhauser intake with a 400 cfm Carter AFB and by using a LOKAR or a Jeep cable operated automatic transmission kit use another 904 or I have a 5 speed from a Merkur that I can use. That engine is slated to go into a T-bucket street roadster. Dressed up for a night on the town, the engine always run well and draws comments at local cruise nights. |
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70 390 5spd Donohue
74 Hornet In restoration 76 Hornet, 5.7L Mercury Marine Power 80 Fuel Injected I6 Spirit 74 232 I-6, 4bbl, 270HL Isky Cam |
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1986cj7
AMC Apprentice
Joined: Sep/14/2013 Location: missouri Status: Offline Points: 36 |
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Posted: Aug/04/2014 at 10:32am |
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I am bye far an expert but what I'm doing with my build is using a 96 4.0l head dual plane offy intake cheap ss header from summit an ATP challenge y header. Putting 1.94 Chevy intake and 1.50 exhaust valves into the head. Balancing the rotating assembly. A comp cam 68-231-4. I know the comp cam isn't favored to much because of high lift. HEI distributor and topping it off with a 600 cfm holley 4bbl. Which I think may be to big a carb. But will see how it flows on the bench.
Edited by 1986cj7 - Aug/04/2014 at 10:35am |
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farna
Supporter of TheAMCForum 
Moderator Lost Dealership Project Joined: Jul/08/2007 Location: South Carolina Status: Offline Points: 19672 |
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Posted: Aug/04/2014 at 10:50am |
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Best head is a 91-96 4.0L head. Use the factory exhaust or a Borla header and the Offy dual plane intake -- for a street car. If you're building a drag car the Clifford or Offy single planes are better. The single plane is great for high rpm running, but the DP will give better low and mid range performance. The DP has to be a little more restrictive at high rpm, but not much, and the higher charge velocity probably makes up for it.
I prefer a 500 cfm carb (the 467 cfm Holley Truck Avenger is a great choice), but many have been successfully running a 600 cfm carb on a built-up six. You need a good cam.I usually recommend the Isky 256 Supercam or 256/262 for street performance, but you might want to use the 262 Supercam. I don't like the Comp Xtreme cams because the high lift requires different springs, and the Comp springs are really stiff -- you'd need to run a high pressure additive with today's oil or an off-road oil. Even diesel oil doesn't have enough! Crane makes an AMC six spring that is right on the edge of being too stiff for normal oil. Diesel oil would be fine with it, regular oil should be if you don't drive real hard. If you want a Comp Xtreme cam use the Crane springs, or Comp will reduce lift so you can use something like the Mopar Performance springs (just enough over stock to work at high rpm, but not so much you need oil additives or off-road oil after break-in). The only affect is that you lose about 500 rpm off the upper range of the cam. I prefer to use the Duraspark distributors with the TFI upgrade, but if you have to buy a distributor anyway the HEI units are probably the most economical way to go. Performance wise they are equal. There have been problems with the Motorcraft control boxes though. There are instructions on the web to replace it with an HEI ignition module, which is more durable as long as its on something to sink heat off (mount on something large and metal, inner fender is fine). |
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Frank Swygert
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farna
Supporter of TheAMCForum
Moderator Lost Dealership Project Joined: Jul/08/2007 Location: South Carolina Status: Offline Points: 19672 |
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Posted: Aug/04/2014 at 10:53am |
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The last 4.0L head made (99-06) is arguably the best street car head. It has the smallest ports, but they are much better shaped and produce the best low and mid range power. They start to fall off at 4000 rpm though. Under 4000 they produce a bit better power than the larger port older heads. Since you've mentioned max power you probably want something that will run up to 5000-6000 rpm.
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Frank Swygert
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Bart R. Orlans
AMC Nut
Joined: Mar/28/2010 Location: New Jersey Status: Offline Points: 489 |
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Posted: Aug/04/2014 at 12:45pm |
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Speaking of six cylinder build ups, I thought it would be fun to share this old article from back in the day. Yes, it deals with an inferior Ford 200, but it makes for interesting reading and shows what is possible with these engines, even back in the '60s.
http://www.classicinlines.com/HA1.asp |
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Bart R. Orlans
They call me daddy at home |
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