Horsepower for 69Z 302 w/#140 cam

[Lynn]

I guess everyone has an opinion on this. I helped a buddy install a 140 cam in his 68 Z in 1970. I also ran a 140 cam in a Z engine with headers for a while in the 80's, so of course, now I am an expert, right? Maybe not. In the 1970 install, we didn't know squat about recurving (and I mean me and my buddy; obviously there were a lot of guys that could do that, but we were oblivious). That 68 didn't idle very well, and didn't run that well until 3600 rpm. With headers and no resonators, it ran like stink after that. Watched him take it to 8,000 rpm repeatedly without a failure. All we did was put one weak advance spring in, leave the other one, and put her back together, then play with timing until it would scream. Stock vac advance can, all hooked up like the factory had it. in my 80's build, the distributor was correctly recurved, but I was unaware of a low vac option for the vac advance, but did know enough to hook it to manifold instead of "ported spark" like the factory did.

Anyway, here is my take based on those experiences, AND some additional facts I have learned since.

1. 1980's build, idling at 1,000 rpm, I never had idle issues using 4053 carb. Power brakes were never starved for vac.
2. Much as I like Mike, and hope this engine is everything he wants, I don't see this being much of an improvement over the 30 30 cam if using manifolds instead of headers.
3. Several knowledgeable guys have insisted the chambered exhaust actually flows WORSE than the stock exhaust. It just makes more noise. I have no hard data to back it up, as I am only an "internet expert" on this. If it is true, then chambered after manifolds just makes things worse. If it can't breath, the cam isn't going to work.
4. Scott asked about 4053 carb and 480 distributor. Both can be used, but the distributor must be recurved and a different vac can (B26) used. Timing all in by 3000, limited to 24 to 26 degrees (at the crank) of centrifugal and about 8 to 10 more vac. Hook vac advance to MANIFOLD vacuum. Start out with initial timing at 8 to 10 <span style="font-weight: bold">without</span> the vac advanced hooked up, again at the crank. With the distributor set up like that you may not even need to re-jet the carb, but then again, you may. You won't know until you get it set up.