Aftermarket Intake Manifold

[Bobert0670]

Ok all, I have searched and searched and seem to be able to find only 1 company that makes a intake manifold for my AMC 258 i6 / 4.2l . Offenhauser makes a 6257DP and a 5999DP the only difference I can see is that one says 360 degree. Has anyone here used either one? What do you think about them? If this info is somewhere else on this board I could not find it! Thanks for any input.

 

[IOPort51]

I think Clifford performance makes one. You want to run a 4 bbl.??

Ok all, I have searched and searched and seem to be able to find only 1 company that makes a intake manifold for my AMC 258 i6 / 4.2l . Offenhauser makes a 6257DP and a 5999DP the only difference I can see is that one says 360 degree. Has anyone here used either one? What do you think about them? If this info is somewhere else on this board I could not find it! Thanks for any input.

 

[elwood blues]

I think Clifford performance makes one. You want to run a 4 bbl.??

The 6257 is for 1981 and newer AMC 258 i6 / 4.2l 's, the 5999 is for 1980 and older AMC 232 i6 /AMC 258 i6 / 4.2l 's. Like IO said, there is also Clifford Perormance, but, their intakes do not have provisions for an EGR valve or a power steering pump...

Here's some websites;

Phethean Racing Products - Offenhauser

Clifford Performance: Jeep & AMC Cars

 

[oldthunder]

I've got an Offy on my '78 with a Holley 390. Works perfectly, that carb really wakes up a AMC 258 i6 / 4.2l . You can put an adapter on it and run a 2 bbl. I recently pulled off the 2nd set of rotten headers in 10 years and went back with a stock exhaust manifold with no performance change. I had to dremel off some casting boogars on the new manifold and the Offy matched up perfectly. Note if you have power brakes this might not fit.

 

[Bobert0670]

Thanks for the info guys, I have a 1980 model but I have found that it was actually made in 79. I think I will go with the Offy because I have power steering, although no power brakes. The main reason I am wanting to go aftermarket is
a. I cant find a OEM replacement
b. More power is always better
c. My original manifolds are so rusted together I am not sure I could get them apart without damaging them.
d. 4bbl is well 2 more!

Thanks again.

 

[caveman]

I bought a clifford performance intake for my high port head and wouldn't buy from them again. It took 9 weeks for them to get it to me after prepaying for it and it was very poor quality workmanship. They don't do any of the work themself anymore. they farm it all out.

 

[terenhelfer]

i also had a question regarding the offenhauser intake. i have an 83 CJ7 and was able to get the 5999 manifold that was intended for pre 1980. does anyone know if it will still fit the head? assuming i will have to change the exhaust manifold and have no erg applications. thanks

 

[Jimbos76cj]

Thanks for the info guys, I have a 1980 model but I have found that it was actually made in 79. I think I will go with the Offy because I have power steering, although no power brakes. The main reason I am wanting to go aftermarket is
a. I cant find a OEM replacement
b. More power is always better
c. My original manifolds are so rusted together I am not sure I could get them apart without damaging them.
They should come apart pretty easy. Sincethey are not bolted together there should be no problem
d. 4bbl is well 2 more!
While you math skills are fantastic 2 more is not always better on a stock AMC 258 i6 / 4.2l . A stock AMC 258 i6 / 4.2l only needs between 4-500 crm. There seems to be a split down the middle between people loving the 390 or 470 holley's The other cheaper option is an adapter and motor craft 2100 woth the 1.08 venturi's.

Thanks again.

Ive run the 2100 with good success.