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Exhaust Manifold replacement Options for 1990 74L Merc

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darin_jordan

New member
"OK, I've done a lot of re

"OK, I've done a lot of research on this, and it appears that both GLM and HGE sell both Cast and Aluminum replacements. I've read discussions that some have had issues and others haven't, but none of these really specified whether or not there is an issue with going to the aluminum versions themselves...

If I'm reading things correctly, my options are these for both manifolds and risers:

CAST:

Barr
Osco
GLM
HGE
Sierra??

Aluminum:
GLM
HGE
Barr
???

Are there any other options out there I should consider.

I'm kind of a "Do it once, do it right" kind of guy, So I'd like to get the best option I can afford...

I'd be interested in hearing experiences with Aluminum vs. Cast? Also, Barr vs. Osco vs. HGE, vs. GLM???

Would like to get the right parts... any help would be appreciated...

Thanks,

Darin Jordan
Renton, WA"
 
Stick w/OEM. I bought a new o

Stick w/OEM. I bought a new one on eBay for $85 last year. He had two and offered both for the same price. Boy was I dumb; didn't take the offer.
 
"If you see anything other tha

"If you see anything other than pure fresh water, I'd stay away from aluminum exhaust parts. Maybe ok for the manifold but the chemistry isn't good for the elbow.

Barr and Osco have been around for a time and have proven track records. I think I did mine right by getting the barr parts ceramic-coated (before mercruiser offered it).

I've seen good and bad castings from GLM; i wouldn't spend my money on them."
 
There apparently isn't any

There apparently isn't any such thing as "OEM" Mercruiser for these... their manifolds are made by someone else... not sure who.
 
makomark:

Is the ceramic co

makomark:

Is the ceramic coating on the inside/outside of the manifolds? Where could I get my 2 yr old manifolds done; a header shop?
 
"Guy:

The ceramic coated se

"Guy:

The ceramic coated set was done on the outside, just like it would have been painted in black.

Mine were done by a guy that worked in the "speed shop" - aka hot rod shop. I'd imagine a header builder would know where to get it done, too.

Only "warning" - and remember this is on my big blocks - the bottom, thin part of all the ports are now white vs the original black. I imagine the rust will start poking thru soon but not yet.

Also, we did the other engine's manifolds in alumin-coat (sp?) Then had them sprayed. Still in pretty good shape but not as good as the ceramic pair. don't know whether it is the material, the applicator, or the prep work but the ceramic appears to be the superior coating."
 
"Darin:

You're "rig

"Darin:

You're "right" about Merc contracting out the manifold castings. The contract used to flow to barr and osco but went out of country in the 90's, at least that's my understanding. Not surprising as many blocks are cast in Mexico nowadays. the saving grace was they used a quality control inspector that understood the product...hope that hasn't changed."
 
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