Headers

[Dan77CJ7]

Those of you who have headers on a AMC 258 i6 / 4.2l do notice performance gains?

Thinking about pulling the trigger..

 

[Torxhead]

I don't have them on my CJ, but have on other vehicles. My gripe is the underhood heat. I have talked to other people about them with the AMC 258 i6 / 4.2l and they do like them along with a mild performance gain. Borla seems to work good.

 

[Heavychevy]

Years ago it was told by header manufacturers that you gained between 10 and 20 hp with headers. Don't know if this so. With a AMC 304 , headers and a 4 barrel carb, it makes the old 74 want to kick up its heels.

 

[Lumpy Grits]

The under-hood heat issue is real.
LG

 

[jp360cj]

FWIW, I have headers on my 360. I'm going to swap over to stock manifolds for several reasons, including the ever-leaking gaskets and heat. (also because I want to ditch the side pipes and already have the manifolds).

 

[PistolDave]

Just adding headers without also upgrading the carb, intake, cam, and doing things like increasing compression will likely make little if any difference. To anyone that says their low compression AMC 258 i6 / 4.2l made a lot more power after doing nothing but adding headers, I say show me the before and after dyno sheets proving this. Peoples seat of the pants "butt-dynos" are notoriously inaccurate.

A buddy of mine switched to headers from cast manifolds without changing any other parts on a 68 nova with a GM 290hp crate 350. The car made 11 more hp on the next dyno pull. Anecdotal I know, but this was on a mild performance engine and it made very little difference. I believe the difference on a AMC 258 i6 / 4.2l would be unmeasurable.

Even if adding headers to a AMC 258 i6 / 4.2l added 20 more magical horsepower, it still wouldn't be worth it to deal with the leaks and the heat. Just my opinion.

 

[mtnwhlr]