Converting old log style to new center style manifolds

[Boatbuck]

1974 Glastron/Carlson cv-18ss has Ford 302, 200hp, with Glastron FL 818 log style manifolds and risers exhausting into the "Y" and out the OMC 280 sterndrive. It's time to replace the manifolds and risers. As you may know, they just don't make them anymore. I want to convert to the center riser type manifold, having a hard time figuring out which model or SKU or part number would work. I have been on many forums, on many manufacturer's web sites, made many phone calls and still at a loss. Any help would be appreciated.

 

[jimmbo]

Has Mercrusier or Volvo used the 302 the past 30 yrs? If so, they might have a newer style Manifold. Of course everything downstream would need adaptation as well

 

[froggy1150]

Mine are Barr Marine. I would call them and see if they have complete kits. The water passages are Larger than the stock ones so they don't plug as fast

 

[Bondo]

Ayuh,.... Welcome Aboard,.... The problem yer gonna have is tryin' to marry up the outlets to that stringer drive outlets,.....

Volvo had 280 drives,.... OMC used Stringer drives,..... Not the same,....

 

[Redrig]

OMC Manifold conversion - Ford

Hello all, My 302 Manifolds have been getting worse and worse to the point that I am shocked my engine has not hydrolocked. So over the last year or so I have been putting the pieces together to do this conversion, I was able to piece this together for about half of what I have seen the "kits"...

forums.iboats.com

That thread may help . I had to go through this a few years ago

But I had the OMC log manifolds and an electric shift stringer

 

[Boatbuck]

Ayuh,.... Welcome Aboard,.... The problem yer gonna have is tryin' to marry up the outlets to that stringer drive outlets,.....

Volvo had 280 drives,.... OMC used Stringer drives,..... Not the same,....

Thank you for the welcome.
I stand corrected, it was/is a Volvo out drive. I don't know why I keep thinking OMC 280, sorry for the confusion.
Marry'ing up to the block also could be an issue (old 302 vs newer 302, same bolt pattern?), getting clearance under the engine cover (I saw a draft image showing height is about 15" up from center line of the exhaust ports to top of center riser). It appears there are a number of rubber boots to connect the riser to the "Y" tube, just hard to tell which one(s) would work. None of the boot images online show dimensions.
I am letting the exhaust bolts soak with WD40, sprayed on periodically, while I figure old how to proceed.

 

[Boatbuck]

Has Mercrusier or Volvo used the 302 the past 30 yrs? If so, they might have a newer style Manifold. Of course everything downstream would need adaptation as well

I am checking that out, could be changes to the bolt pattern and size of the exhaust ports I suppose?

 

[Boatbuck]

Mine are Barr Marine. I would call them and see if they have complete kits. The water passages are Larger than the stock ones so they don't plug as fast

I did see Barr Marine as a prospect supplier, will double check them out. I did find this site. Seems like it would work.

Exhaust Manifold Kit for Mercruiser Ford 302 5.0L, 351 5.8L V8, Inboard - Outboard [BPIMANMERFRDI-O] - $1,495.00 : ebasicpower.com, Marine Engine Parts | Fishing Tackle | Basic Power Industries

ebasicpower.com Exhaust Manifold Kit for Mercruiser Ford 302 5.0L, 351 5.8L V8, Inboard - Outboard [BPIMANMERFRDI-O] - Complete Exhaust Manifold Kit Converts older log style manifolds to center rise design. Fits older Mercruiser (Ford) Small Block V8 Inboard/Outboards Includes:

bpi.ebasicpower.com

 

[Boatbuck]

OMC Manifold conversion - Ford

Hello all, My 302 Manifolds have been getting worse and worse to the point that I am shocked my engine has not hydrolocked. So over the last year or so I have been putting the pieces together to do this conversion, I was able to piece this together for about half of what I have seen the "kits"...

forums.iboats.com

That thread may help . I had to go through this a few years ago

But I had the OMC log manifolds and an electric shift stringer

Yeah, helpful post. My exhaust have 2 bolts per exhaust port, I probably need to stick with the 2 bolt design. Thank you.

 

[Mihali]

1974 Glastron/Carlson cv-18ss has Ford 302, 200hp, with Glastron FL 818 log style manifolds and risers exhausting into the "Y" and out the OMC 280 sterndrive. It's time to replace the manifolds and risers. As you may know, they just don't make them anymore. I want to convert to the center riser type manifold, having a hard time figuring out which model or SKU or part number would work. I have been on many forums, on many manufacturer's web sites, made many phone calls and still at a loss. Any help would be appreciated.

It can be done, Like this. I did it.

 

[Mihali]

Has Mercrusier or Volvo used the 302 the past 30 yrs? If so, they might have a newer style Manifold. Of course everything downstream would need adaptation as well