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Hole in exhaust x-over

buick430

Regular Contributor
Hey guys running the boat today trying to get full power and I blew a pinhole in the intake manifold right in the bottom of the cavity the thermostatic choke would be if I had one. I plan on dremeling the entire cavity clean, then filling with JB weld. Any suggestions or thoughts, other that replacing the manifold? Ive used JB weld on exhaust cross overs on big block buicks with success.

Thanks, will
 
Not sure that alone will last. I'd try a piece of metal AND the J B Weld held by screws (drill and tap the manifold).

Jeff
 
It was pretty easy, Sounded like an exhaust leak. I heard it when i moored up. Lifted the hatches an just felt around. I will pull the carb and get some pictures this weekend.
 
I would rather block the exhaust passages all together if I pull the intake.

will

Will,
Good idea if you are going to run the quarter mile at the strip. Maybe not so good for marine engine economy.
Blocking the heat crossover would result in longer warm up time and use more fuel.

I'll 2nd Jeff's fix.
 
Chrysler got it right in early big blocks. When the thermostat is closed, water is routed under the carb and then back to the pump. The flow to the intake is closed off once the t-stat opens.

Unlike a car there is no heat riser in a boat, so the exhaust crossover in the intake does little to help warm up.
 
Excellent point! (Wish I had thought of that....)

The only reason I can think of why NOT to plug that sucker up is IF you're NOT running an electric choke--it needs the heat to open the older types. ack in my racing days, we used to pour molten lead in there to block 'em off.

Jeff
 
Yea I have done it on a couple street daily driven cars that I honestly noticed no difference (even a performance gain!). My carter carbs dont even have choke plates or linkage installed, Not cold enough in southern california! I will try the screw and JB weld. I reall dont want to pull the intake either way.

will
 
FWIW ask your parts guy for a propane intake gasket set. it will be already blocked off:

Top propane
bottom gas
$(KGrHqVHJBEE7)2UUkWUBPF0Nokg2w~~60_58.JPG
 
update, I filled the entire cavity with JB weld. So far so good. I have % hours on the repair at heavy load all looks well.
 
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