New Exhaust Manifolds for OMC 4.3

[ACausey]

Hi All,
It looks like I need new exhaust manifolds for my 1988 OMC 4.3L. I have seen a few different conversion kits out there. I'm leaning toward the GLM 58994 kit. My question...

Does anyone have any experience with these or advice on the best choice?

Thanks!
Andy

 

[HT32BSX115]

Re: New Exhaust Manifolds for OMC 4.3

Hi Andy,

Welcome to IBOATS!

That kit is probably the one I would choose.....

I do seem to remember that some GLM riser-manifold surfaces have been known to not be perfectly flat.....That is what I have read right here from people that have experienced that sort of problem.

This is of course anecdotal info. NOT my experience. I would however inspect VERY carefully the mating surfaces of both the riser/elbows and manifolds to verify that they are indeed FLAT and true. If they're not, either get them machined flat or get them replaced..........if you buy them locally, you can take them back to whomever you bought them from and be "covered"

If you buy them online or mail-order, (and there's a problem) you're sort of stuck with shipping hassles, time spent sending them back and forth and arguing with the merchant.

One member here just sent his to a machine shop and had them run a couple of passes with a vertical milling machine to clean up the surfaces.....

(My neighbor has a REALLY nice mill that I can use when ever I want!)

Good luck,


Rick

 

[ACausey]

Re: New Exhaust Manifolds for OMC 4.3

Thanks Rick! Not sure I want to have to re-mill brand new parts, but I guess you get what you pay for. Anyone try the Osco manifolds?

Andy

 

[Joshua Nichols]

Re: New Exhaust Manifolds for OMC 4.3

Thanks Rick! Not sure I want to have to re-mill brand new parts, but I guess you get what you pay for. Anyone try the Osco manifolds?

Andy

I installed a Osco set over the winter.. Been pretty good so far.. No leaks.. Parts where packaged well.. I found mine brand new from ebay for 800 bucks..

Painted em up gray.. Look pretty good...

I was looking to install the GLM stuff too, but some nightmare stories on here.. People complaining about the China junk.. All this made me go with the built in the USA stuff..

 

[HT32BSX115]

Re: New Exhaust Manifolds for OMC 4.3

All this made me go with the built in the USA stuff..

Yeah.....I might probably do the same thing......

 

[Lou C]

Re: New Exhaust Manifolds for OMC 4.3

Back when I replaced the original bat wings on my 88 in 2004, I saw the price starting to go up on www.dougrussell.com and I decided to buy another set. They sat in my garage till now and now I am replacing the set I put on in 04 so that turned out to be a good decision. Here in salt if you get 6-7 years out of manifolds that's considered good.
I'd go with OCSCO instead of GLM if I had to choose. I like the one piece units because there is no gasket to leak but they are expensive to cast no doubt and to check them for clogging you have to take them completely off, no separate riser to remove.

 

[Stanp1]

Re: New Exhaust Manifolds for OMC 4.3

I bought the osco conversion 7 years ago and used them in salt water. No problems. I just put new gaskets on the risers. Had to use a power washer to blow out the rust chucks that got stuck in the top of the riser. Needless to say, I had to buy a new gasket again. They run cool. but this is it. there will be new ones put on next season.

I have considered using Merc manifold and risers and add a wet exhaust hose to adapt to the y pipe. The cost of OMC replacements is too high. I wonder if anyone has done a merc conversion on the exhaust manifolds to replace the OMC version. It can't be that difficult.