I have a 1988 4.3 V6 Cobra. It was originally equipped with the OMC one piece V6 manifolds which have long since become no longer available. In ‘17 I had to do a top end engine overhaul (re-manufactured cylinder heads etc) and was also due for new exhaust since in salt water you should replace every 5-7 years due to corrosion. I started researching the parts needed for this...I bought aftermarket Barr Marine manifolds and elbows; and needed to buy Volvo Penta 90* aluminum exhaust pipes that adapt the 4” elbow exit to the 3.5” Y pipe, including the Volvo Penta hoses which fit the old OMC Y pipe perfectly. Keep in mind that from 1994-1998 OMC and Volvo had a joint venture and they used many if not all of the same parts. So all the VP stuff which is still available should fit the OMC engine of the same model year. Some parts listed as OMC as unavailable are still available from VP. What’s confusing me is that the 3.5” inner diameter hoses should fit your Y pipe. Can you post up pix of what you have? Later on when I’m on my desktop I can check the VP parts #s I used.
after perusing several VP parts diagrams I have found 2 numbers for those lower hoses:
385741, replaced by 3863450
the OMC #s for your year are the same except it does not say replaced by 3863450
In either case it should not matter, the Y pipe diameter is 3.5".
here's my conversion....if you look at parts diagrams there is one difference, the aluminum 90* pipe that connects the upper hoses from the exhaust elbow to the lower hoses changed, the later model pipe (what I used) is a made with a steeper angle, which I believe was needed when they went to the Vortec engines, (1996) which due to camshaft specs had a tendency to pull water back up the exhaust than the pre-Vortec (which is probably what you have, you can tell by the # of bolts that hold down the intake, for the pre-Vortec it is 12 bolts, for Vortec it is 8 bolts. They also added a pair of one way check valves in the elbows to prevent vacuum in the exhaust from pulling water back up. But with the pre-vortec engines these are not needed.
https://www.dropbox.com/s/3a527i10hyq24 ... n.jpg?dl=0Just thought of something...I used the VP hoses for upper (from the exhaust elbow 4" to the aluminum elbow, then from the bottom of the alu elbow 3.5" to the Y pipe) and lower hoses and they were marked as far as which way they go on that aluminum elbow, I can't recall of both the upper and lower hoses are marked that way, but for sure the upper hoses were. Right now the boat is covered up for winter still so can't check. The upper hoses had a pictogram showing which end goes on the side with the aluminum 90* elbow.
After fitting everything up it all fit right, no leaks, used it for a month last year before it got too late in the season....
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