Exhaust system on a base engine '63

[Gary B.]

[Kent S.]

Re: Exhaust system on a base engine '63

Yes, the 250 HP motor used 2" exhaust. I have a complete almost new CC system that I had to replace with the correct 2 1/2" for the 300 HP motor.

[Gary B.]

Re: Exhaust system on a base engine '63

Kent,

And for the 250HP engine, the exhaust manifolds were also 2.0"?

Gary

[Kent S.]

Re: Exhaust system on a base engine '63

Yes - 2" manifolds.

[Gene M.]

Re: Exhaust system on a base engine '63

Gary,
yes the base 63-65 250 horse used 2". I seem to recall the 250 & possibly 300 horse with automatic transmission got the 2" pipes too up to 65. Not sure on the 300 HP base automatics after that. Maybe John Hinckley can chime in.

[Kent S.]

Re: Exhaust system on a base engine '63

True - in '63 the 300 HP with Powerglide also had the 2" exhaust. Kind of strange to think the 2' vs. 2 1/2" exhaust had zero affect on horsepower???

[Joe L.]

Re: Exhaust system on a base engine '63


Gary------


No 1962-82 Corvette ever used 2.25" exhaust pipes.

The following used 2-1/2" outlet manifolds:

1962-65 with 300 HP and manual transmission, 340, 350, 360, 365, and 375 HP engines. No other 1955-79 small blocks ever used 2-1/2" outlet manifolds;

All 1965-74 big blocks

The following used 2-1/2" exhaust pipes:

1963-65 with 300 HP and manual transmission, 340, 350, 360, 365, and 375 HP.

1966-67 all with manual transmission

1965-67 all big block

[Gary B.]

Re: Exhaust system on a base engine '63

Thanks all. And when measuring exhaust pipe diameter, does one measure the ID or the OD?

Gary

[Joe L.]

Re: Exhaust system on a base engine '63

Gary,
yes the base 63-65 250 horse used 2". I seem to recall the 250 & possibly 300 horse with automatic transmission got the 2" pipes too up to 65. Not sure on the 300 HP base automatics after that. Maybe John Hinckley can chime in.

Gene------


No Corvette small block before 1962 and after 1965 used 2-1/2" exhaust manifolds.

[Duke W.]

Re: Exhaust system on a base engine '63

Thanks all. And when measuring exhaust pipe diameter, does one measure the ID or the OD?

Gary

Nominal pipe diameter is based on the OD, and wall thickness is typically about .060".

The 2.5" system would likely not improve the in-car performance of the 327/250 because the '62-64 versions had what were essentially 283 heads and inlet manifold with small ports and valves, so inlet flow was restricted. The '65 version has 461 heads, but retained the small port manifold. Go figure!

For a given muffler, smaller pipes will usually yield a quieter exhaust note, so that was probably the reason why the 2.0" manifolds and pipes were used on 327/300s with Powerglide. It's reasonable to assume that this combination would be favored by those who are more interested in a "luxury sports car" than a "performance sports car".

Duke

[Gene M.]

Re: Exhaust system on a base engine '63

Gene------


No Corvette small block before 1962 and after 1965 used 2-1/2" exhaust manifolds.

Yes, well known fact, we were just talking about the pipes not manifolds.

[Gary B.]

Re: Exhaust system on a base engine '63

Thanks again to everyone for the info.

Gary

[Joe L.]

Re: Exhaust system on a base engine '63

Yes, well known fact, we were just talking about the pipes not manifolds.

Gene------


If you look to the original question, it was in regards to BOTH exhaust pipe size and manifold outlet size.