I have a 58mm throttle body and I am aware that i have to port the stock manifold before installing it, however, I can get a great deal on an LT4 manifold and was not sure if it would bolt right up. It would be much easier to port a manifold that does not have to be taken of the car if it would be a swap that needed no modifications. Thanks

 

The runners wont meet up with the LT1 heads without some serious machining.

 

The LT4 manifold will not work on the LT1. The ports are slightly taller and don't line up with the LT1 heads right.

Sorry

 

werd

 

Actually, there is very little difference at all in the runners/port size on a STOCK LT4 intake, compared to the STOCK LT1 intake. The intake runners on the LT4 head are "raised roof" (0.100" taller), but strangely enough the LT4 intake ports are not the same shape as the LT4 head ports. There is more "meat" on the top of the LT4 intake runner to allow it to be ported to match the LT4 heads, and in fact the LT4 intake MUST be substantially reworked to support ported LT4 heads. So.... "port mismatch" is not the problem when putting an LT4 intake on an LT1 head.

What is a problem is an interference between the LT4 intake and the valve cover support rail on the LT1 heads. One or the other has to be machined to allow the two to be bolted together.

Ofcourse the LT4 intake would need the throttle bores opened up to 58mm just like the LT1 intake... so I'm not sure you would really be saving any work by trying to put the LT4 intake on the LT1 heads..... actually you would be making more work than simply pulling the LT1 intake and having it opened up to 58mm.