View Full Version : Replacement exhaust manifold

Jeff S
01-24-2011, 12:54 PM
Upon disassembly, it became evident my old log style manifolds have reached the end of their life span with issues far beyond leaking gaskets. That said, I've decided to replace them with more modern centerise manifolds for my 1969 302HM/Volvo application-- 2 questions:

Anyone have a preference on replacement manifolds-- if so why?
Also, I've seen some with one 1 bolt per cylinder flanges others with 2 bolts per cylinder-- can either be used?

01-24-2011, 01:42 PM
Center rise is a good move, the engine will run slightly better. I have been in the boating biz quite awhile and do like Osco better than the others.

Jeff S
01-24-2011, 08:19 PM
Thanks MOP, I was leaning towards the Osco manifolds too but I'm concerned about the single bolt per flange configuration-- mine is 2 bolts per flange. I really hate to give up the classic look of the log mainifolds especially since the prior owner had given them a really cool looking yellow powder coating. They're just too far gone inside and at the rear flanges to salvage. I do have 2 risers in good condition if anyone is interested-- would need a light grinding on the flange to remove some pitting.

01-25-2011, 02:14 PM
Don't worry about the bolts you don't need the doubles with the cast iron, I never had any exhaust leakage in the three years I owned the boat.

01-25-2011, 10:39 PM
You need to check out Barr Marine manifolds, they offer them in cast iron or aluminum, long before Osco did.
FM-1-83 (Iron Center Riser Manifold)
FM-1-92 (Alum Center Riser Manifold)
Risers in 3" or 4" ID Hose
I was Dir of Mfg there for a little over 12 years, that ended about 11 years ago. I still have contacts there, PM me if you need assistance.

Gary S
01-26-2011, 12:14 AM
Jeff,if your risers are like these I would be interested.Thanks Gary


Jeff S
01-26-2011, 11:31 AM
Knots2u: Thanks for the advice-- I went with a Barr maniford and riser set for carburated 302/351 engine.

Gary S: Mine are the Hardin style.

Gary S
01-26-2011, 08:04 PM
Thanks anyway Jeff.