The Stovebolt Site Forums The Shop Area Engine Shop 292 exhaust manifold

I just got my large bore 292 exhaust manifold back from the welding shop with a could not fix note on it. Once it was cleaned up it had a spider web of cracks in addition to the big one I took it in for. It was the large (2 3/8 i.d.) exhaust used on the larger trucks with the straight down drop and a 3 bolt flange. I am wondering if anyone knows of a source for a new or used but not cracked large bore 292 exhaust or if folks who are using the smaller (same as a 250 ex manifold are happy with the way the motor exhales. I can get any number of the smaller bore exhausts with a 30 degree sweep to the rear so that is an option but it seems like bigger is better?

New ones are on Ebay all the time- - - -they're listed for John Deere combines that run Chevy 292's. Not that expensive, BTW!
Jerry

Jerry, question above of interest to me as well. Any big drawbacks with using the 250 manifold on the 292? I will not be asking for increased performance. Just regular joe driving.

The port openings of the 292 are the same as the 250 since they both use the same head, so from port opening to exhaust exiting the manifold would be the only change area. I would bet side by side, the manifolds are the same except the outlet diameter. I am sure there was reason for the larger pipe diameter, but for everyday driving, I real doubt you would see any difference.
It would be a good test for someone to try.

Thanks joe. Jerry had previously mentioned to me that the manifold fits the 230,250,292 series. Glad to understand that it will not be noticed by my driving style.

The light duty 292 engines, 10-30 series used an exhaust manifold like the 230-250. The medium duty trucks, 40-60 series used the manifold with the larger opening that pointed straight down. It had no heat riser provisions. 292 engines are hard on ex. manifolds if driven hard. They crack & warp all the time.
George

The heat most likely had something to do with the size. The harder the engines worked, the more heat they made, so a larger opening would expel the exhaust that much quicker.

All good to know. I had plan to use the existing 250 manifold during my upgrade to the 292 - which I look forward to, except to the the comments on mpg. I guess the 2nd kid will not get to go to college.

I'm late to the party here- - - -been on the road for a while! Ditto to all the above. The big outlet port and no heat riser is beneficial under heavy load, high RPM conditions when the engine needs to breathe freely. Unless you're spending lots of time at full throttle in the lower gears, the 250 manifold should work well. Another bit of trivia- - - -dyno tests tend to prove that too much exhaust pipe (like split manifolds and duals) actually reduces low-end torque. Maybe the engineers who designed the stock exhaust systems weren't dummies after all!

Speaking of exhaust heat- - - -Try running a big motorhome up a long, steep hill with the engine cover removed sometime. A Dodge 440 or a Chevy 454 will have the exhaust manifolds glowing cherry red and popping like popcorn!
Jerry

Cracks on the 292 exhaust manifolds was so common and next impossible to repair, Borla made stainless hedders, found on mostly UPS trucks. Next 292 I get will give them a try.

Check on old F Gleaner Combines . The 292 six was a motor option on a lot of them verses the Diesel engine. I found a used heavy duty starter off one and it whirled the ole 292 in my truck better than ever.