They are completely different engines. A couple of major obvious things: chevy's have a stamped steel timing cover and a water pump that is separated from the block while pontiacs have a cast aluminum cover with the water pump integral (like a Ford), pontiacs have a valley pan with the intake floating over the top while the Chevy intake covers the valley, the pontiac distributor turns the opposite way, the pontiac engine is a lot wider, hence the engine offset to the passenger side in the bird.
The starters are also mounted on different sides. Passenger side for Chevy - Drivers side for Pontiac.
2012 Mustang Boss 302 #1918, Competition Orange. FGF replacement 2006 Mustang V6 Pony, Vista Blue. Factory ordered. 2019 BMW X3 (Titled to the wife, but I'm always driving it for her. So I'm claiming it) Old projects, gone but not forgotten: 1967 FB 400, original CA car. After 22 years of work, trashed by the guy who was supposed to paint it. I had to sell it. 1980 Turbo Trans Am 1970 Mustang fastback, 351C 4Bbl, auto 1988 Mustang GT, 5 speed 1983 F-150 4x4, built 302 1994 Chevy K2500 HD 4x4, 454 TBI
...and of course, the bell housing is "B-O-P" (Buick, Olds, Pontiac) bolt pattern, so a chev motor reqrs a chev tranny bell housing. I think BOP distributors rotate CCW while Chevs rotate CW too (correct me if I'm wrong on that one) so different distrib caps, firing order too I believe...basically, like previous posts said, completely different animals....not that you couldnt adapt a chev 350 to work, but by the time you mod everything (motor mounts are different too I think) you're prolly into it more than just finding the right Poncho motor... BTW, I have had awesome reliability from all the Poncho's (maybe 10-12?) I've owned over the years, mostly 400's, but only ever had one major mechanical failure (dropped a valve)
As it turns out, almost all V-8's have the same 1-8-4-3-6-5-7-2 firing order, even most Fords if you use the GM style cylinder numbering system. I think the 5.0 (late 302) has a different order.
Some of the cam grinders are coming out with a revised firing order to get rid of the 5-7 pairing. This apparently does a few things but the most beneficial is the elimination of a damaging crossfire between the two plug wires - #5 fires, leaks to #7 45 degrees too early and detonation can result.
There's also a basic difference in the intake manifold. Chevy uses the intake manifold to seal the lifter valley. Pontiac does not. This causes the chevy to always run hotter intake charges than the Pontiac.
In essence, there are two basic firing orders for standard "90 degree" V-8 motors. Then, there are what are known as 180 degree V-8 motors. These don't sound right at all.
