Intake manifold

[Karlomora]

I have a 1988 omc cobra, 4.3 liters and I need to replace my manifolds. Would like to know wich is a good brand name. The one that I have is OMC 9842222. Thank for your help.

 

[Lou C]

do a search on my member name...I replaced those one piece units with Barr aftermatket + Volvo Penta parts to mate them to the OMC Y pipe....

 

[Bondo]

I have a 1988 omc cobra, 4.3 liters and I need to replace my manifolds. Would like to know wich is a good brand name. The one that I have is OMC 9842222. Thank for your help.

Ayuh,..... Welcome Aboard,..... Intake,..?? or exhaust,..??

 

[Lou C]

That part # is for the exhaust manifold. Once in a while you can find those units on eBay but they are all used & old, might be ok for a few years but who knows. The better plan if you’re going to keep the boat is to convert it to the later style exhaust. You can buy a conversion kit from GLM but their quality is spotty. I used Barr Marine aftermarket for the manifolds & VP exhaust 90* down pipes & hoses. The VP stuff can be found used on eBay & those parts usually don’t rot out even in salt water. The Barr elbows mated perfect to the VP hoses it all fit perfect on the OMC Y pipe. No leaks no problems!

 

[Lou C]

updated 2 piece exhaust on 1988 OMC 4.3

 

[Don't Panic!]

I went the cheaper route than Lou and used the full GLM kit.

The manifold/risers appear fine, though I can obviously only see the outside. I had no fit/leak issues, though I did deburr with a flat file followed by some 220 grit on a square metal bar to clean up the mating surfaces prior to install. There was considerable overspray on both the manifold and riser mating surfaces, but they seemed flat.

I used Permatex Aviation Sealant on the riser junction gasket. I love that stuff. I'd never heard of it before last year, now I use it on everything lol.

As an FYI, the new setup is taller and wider than the OEM batwings, and I had minor clearance issues. It's a tighter fit under the doghouse, and the new risers and rear elbows run noticeably hotter than the batwings did.

 

[Lou C]

That seems to be a difference between the GLM and Barr exhaust because the Barr set up runs about the same temp as the batwings did. Both idled at approx 95-100*F depending on where you measured it, and the hottest they ever get is about 125-135*F after coming off plane. The starboard side being slightly hotter.

 

[Karlomora]

Thank you for your reply.
Well I took both exhaust manifold, they look good, just dirty, give them a nice clean up specially in the batting holes, also I replaced the flappers, one was missing, installing all new hoses and thermostat. Now just need to know what is the torque to apply for the nuts on the exhaust manifold. Thank you.

 

[Lou C]

about 25 ft lbs.

 

[Karlomora]

Is any order how to apply the torque. Thank you for your help.

 

[Lou C]

for the exhaust manifolds....I'd start with the inner bolts torque em to like 10-15 ft lbs then do the outer ones, then come back to the inner bolts and bring em up to 25. They don't really need much to seal the exhaust manifold gasket.

 

[Karlomora]

Thank you Sir. Almost there.

 

[Renken2000Classic]

I went the cheaper route than Lou and used the full GLM kit.

The manifold/risers appear fine, though I can obviously only see the outside. I had no fit/leak issues, though I did deburr with a flat file followed by some 220 grit on a square metal bar to clean up the mating surfaces prior to install. There was considerable overspray on both the manifold and riser mating surfaces, but they seemed flat.

I used Permatex Aviation Sealant on the riser junction gasket. I love that stuff. I'd never heard of it before last year, now I use it on everything lol.

As an FYI, the new setup is taller and wider than the OEM batwings, and I had minor clearance issues. It's a tighter fit under the doghouse, and the new risers and rear elbows run noticeably hotter than the batwings did.

I did too. Don't remember using any sealant though. Began seeing fine cracks in the rubber sooner than seemed like should have.

There was a pinhole leak in one of the manifolds, but by the time I got a replacement from GLM, it had sealed itself; prob with rust.

Also had to trim a little of the boat's fiberglass to get them to fit.