77 258 4.2 intake manifold conversion

[CJ777]

I have a 77 I-6 AMC 258 i6 / 4.2l AMC 258 i6 / 4.2l and have did the motorcraft 2bbl 2100 upgrade and still have the 1 bbl intake with the proper base adapter and gaskets, but I'd like to find a 2 bbl intake that will work with it.
Anyone know which intake manifold that will work with my stoock exhaust manifold and mate up with everything else?

Thanks

 

[elwood blues]

I have a 77 I-6 AMC 258 i6 / 4.2l AMC 258 i6 / 4.2l and have did the motorcraft 2bbl 2100 upgrade and still have the 1 bbl intake with the proper base adapter and gaskets, but I'd like to find a 2 bbl intake that will work with it.
Anyone know which intake manifold that will work with my stoock exhaust manifold and mate up with everything else?

Thanks

Yes I do. I did that exact thing, I had a stock single barrel intake and I upgraded it to a two barrel. Any 1964 to 1979 AMC 2 barrel intake will work. There was a redesign in 1980 and the manifolds changed. So, nothing 1980 or newer will work with your stock exhaust manifold.

Here's the big thing, you're going to have to find a used one, I've never found anyone that makes aftermarket new ones.

 

[elwood blues]

Just thought of something else. You will still need an adapter for the MC2100, AMC used Rochester carburetors, and the MC2100 is a standard Holley size. You pick get an adapter plate from Summit, Jegs or wherever.

Trans-Dapt Performance Products 2086 - Trans-Dapt Performance Carburetor Adapters - Overview - SummitRacing.com

 

[CJ777]

Thanks Elwood.
When you remove the stock intake from the stock exhaust, they are bolted together, are they inconnected? meanining is there a port from the intake to the exhaust?

 

[elwood blues]

No, there's no port or anything that connects the two, just the four bolts. In the manuals I have it said to remove them from the engine together, then seperate them once they are out of the engine bay.

 

[CJ777]

That's a useful bit of info.. I tried removing them separately and ended up sheering off onf the inner of the four bolts. I was planning on replacing my gaskets, then just stopped there and put everything back together. It's what got me thinking of upgrading since i have to take everything off just fix an exhaust leak.
I also realized that it seems i have to remove the radiator just to slide out the smog pump mounting bolt to remove the pump and gain access to everthing else.

 

[elwood blues]

I also realized that it seems i have to remove the radiator just to slide out the smog pump mounting bolt to remove the pump and gain access to everthing else.

You shouldn't have to, I removed all of that stuff, smog pump, intake/exhaust manifolds, etc without removing the radiator. It's tight and you have to work around the fan, and sometimes move the fan a rotation of two to get it out of the way, but it's doable without reomoving the radiator.

 

[CJ777]

I'll give a shot once i find an intake and exhaust.
Thanks

 

[CJ777]

Did you notice any performance gain fomr the two barrel intake?

 

[elwood blues]

Did you notice any performance gain fomr the two barrel intake?

I did the MC2100 upgrade at the same time I swapped manifolds. I noticed a substantial gain in power, it was well worth the time and money.