Exhaust riser adapter / spacer question
 

Since I am building a redheaded stepchild with twin small block Chrysler engines I know I am swimming up stream, but here goes.

I am planning on running Barr center rise manifolds on my motors, but would like to make adapter plates / spacers to install Mercury or EMI stainless risers. If I make solid plates 1" thick, will they gewt enough cooling from being bolted to the manifold and risers which will be cooled? Barr uses adapters to run their risers that have water passages, but if I run water passages they will trap air and not allow water flow which will not be of any help at all. My last resort will be to just run the Barr risers and adjust my cam specs accordingly. Thanks in advance Murf

https://bpi.ebasicpower.com/mm5/grap.../BAR534002.jpg
https://bpi.ebasicpower.com/mm5/grap.../BAR534005.jpg
http://www.cobemarine.com/images/P/barr-25.jpg

If I understand this correctly, your spacers will not have the cooling passage but will adapt the bolt pattern from the Barr manifold to the Gil riser (assuming they're not the same)? The spacers will be exposed to water on the bottom side via the water passages in the manifold. I'd think this should be sufficient. The gil riser has a relatively thick flange (not 1" though) that doesn't burn up for lack of water flow.

How do you plan to route the water from the manifold to the riser?

Ryan

Yes, that is exactly what I meant. As for the water connection, the top of the manifold has two 1/2" threaded bungs. I am going to run a hose from there to the riser like most Mercruiser / aftermarket applications

http://i184.photobucket.com/albums/x...pseu4kgoth.jpg

I would be worried about where they meet and thermal expansion. A solid block is not going to cool and will heat and hold that temp while the rest of the manifold will be cooled by water.

That is my concern

No it won't. Heat doesn't 'hold' anywhere. Heat flows from hot areas to cold areas.

I would prefer a pass through water passage setup like the wide band spacers available. He effectively wants a dry stack connection where water flows up from the bottom of the manifold, dead heads against the bottom of the spacer/adapter, then flows around through a bypass hose to the top side of the elbow and out the exhaust. The spacer/adapter will be sandwiched by two water cooled parts (manifold and elbow) and those two items will draw heat out from the spacer.

If you get a chance run the setup on a test stand and you should see if it works. I believe it would be fine.

You are 100 % correct in what I'm trying to accomplish, I'm just concerned the cooled manifold and riser won't draw enough heat away from the spacer.

I hear what you are saying Trash but I will just add that the main issue with cast manifolds is they leak at the risers and is one reason Merc went with a dry joint for the 496. Being he is using Chryslers I know his options are extremely limited and to be honest I would try what he is asking. I would just try to keep it as small as possible and maybe a use a little copper RTV and a bad ass gasket.

I may be totally wrong here , but it looks like you are going to have a pocket of trapped air from the base of the threaded hole , leaving the top inch or so of the manifold uncooled.

That is how the ran them in closed cooling systems, a blank gasket with no cooling holes, the plumb the raw water to the risers.