Join Date: Mar 2010
Location: Carson City, Nv
Re: 351W in 69 1/2 Mav
74s are easier since the shock/spring towers seem to be just a little wider. Several things I've learned is the trans crossmember on 71+ Mav/Comets work with the exhaust better. 70 only had a 6 cyl and that's an issue. The holes in the trans tunnel aren't drilled for a double hump crossmember. (well they are now).
Another big issue is Headers from the same manufacturer can be different. Collector length and angle is different at times.
Hard part is some work and some don't.
I did this swap 20 years ago with a 72 and didn't have some of the header problems I've had. I notched the shock towers, actually more then needed for the headers, but it does make working on them the spark plugs etc much easier. Especially when you put the headers on and off 5 times for the pass side and 10 for the driver's. I got real good at putting them in with a few moves and in about 5 minutes.
I could write a tech article on what I've learned about header prep and installation. Lots of little tricks that make or break you. Amazing the welds, especially inside the collectors when you start checking them.
The 2 1/4" exhaust system I bought from Summit Racing, which I work about 1 mile away from. It's good quality and mandel bends make it work well.
Last edited by dacofaII; 01-04-2014 at 08:04 AM.