Minor engine upgrade question

[InfidelOffroad]

Looking to buy headers, intake manifold, and valve cover any suggestions?

Headers, I was told that the engine in my CJ7 is actually a AMC 258 i6 / 4.2l swap out of a YJ. Will this matter for what headers I get? I have been looking to get this:
PaceSetter Headers 70-1135 - SummitRacing.com

Intake Manifold, I just want something that I can later used when I upgrade to this:
Howell Fuel Injection Conversion TBI Kit (Offroad) HOW-JP258

Valve Cover, currently have the plastic one that leaks like a sieve. Any suggestions for a good aluminum after market?

 

[Torxhead]

Those headers seem to be for all 258s, so it sounds like a good bet, just get one for a CJ. There will be a bit more underhood heat with headers, so you will have to deal with that. The Howell fuel injection conversion, is designed for the oem intake manifolds. You might want to go thru the instruction manual for the kit located on their website. The oem plastic valve cover has been a problem for a lot of guys, but they both have to be installed correctly, maybe someone will reccomend one for you. Mine has been in the closet for the past 15 years or so.

 

[MattandOrange]

I've only used clifford performance for some adapter bolt sleeves when I did a 4.0 head swap, but I've heard good things about them. Same thing with Offenhauser.

Clifford Performance :: Make 6 = 8

 

[sheddiggs]

Junk yard '81 aluminum intake w/ matching exhaust. (It's 2bbl). MC2100 carb 1.08. CRT HEI dist. Cheap and done!

 

[CJim7]

One thing you should be warned about. On many engines the addition of headers improves performance sometimes dramatically. The AMC 258 i6 / 4.2l has very poor flow because of the design and internal restriction. A substantial increase in performance wont be recognized with the addition of a header....until some headwork is done, whether it's porting and polishing or swapping out to a better flowing 4.0 head.

That's not to scare you away from it, just wanted to give you a heads-up in case you were expecting a big performance difference.

On another note, upgrading your ignition system is a great performance enhancer. Whether it's a Chevy HEI, Ford TFI, or one of the many aftermarket kits out there.

 

[johnnyreb]

I agree with cjslim7, do the ignition upgrade. But I got the head off a 1997 4.0. It flows better that a AMC 258 i6 / 4.2l and has smaller combustion chamber so displacement is boosted. It also came with a factory header. Then i'll mod an 81 AMC 258 i6 / 4.2l aluminum intake to fit.
Oh yeah I also ported and polished the new head ports.

 

[InfidelOffroad]

On another note, upgrading your ignition system is a great performance enhancer. Whether it's a Chevy HEI, Ford TFI, or one of the many aftermarket kits out there.

Already have an HEI distributor.

As for the 4.0 head. I decided that the gains are not worth the effort. Going with a better intake. Then getting a good exhaust manifold and matching it to the head. A lot less time and still substantial gains. I'm going to run it for a while with the carb. Wait until I actually have an issue with it (if I ever do that is) before switching over to any sort of EFI.

 

[johnnyreb]

well one of the guys did a write up on dyno results before and after a head swap. He got a 35 hp gain. I plan to continue to run a carb even after the swap. AMC 258 i6 / 4.2l heads just don't flow well.

 

[mtnwhlr]

I think instead of going to the trouble of doing a 4.0 head swap I'm going to swap the whole 4.0 HO because then you get EFI and then maybe down the road building a 4.0 stroker.

 

[johnnyreb]

I like the 4.0 stroker. Just swap in a AMC 258 i6 / 4.2l crank into a 4.0. For me the choice was simple. Help a buddy swap a blown motor, take blown motor home, remove head and scrap rest. So the price was right. I have no intentions of going with efi. I fact I want to sell the complete intake.

 

[InfidelOffroad]

Plan as of right now is to get:
http://www.summitracing.com/parts/ofy-5999dp/overview/
and run it with a smaller Holley.

That allows me to get w.e headers I want.