Intake Manifold Crack

[Woodie1]

I changed the carb on our 39 this afternoon & found a crack in the carb mounting surface. Not knowing the inner structure of the manifold, do you think this could be a problem? I'm thinking not.

[5851a]

Almost looks like a witness mark from a gasket for lack of a better explanation. Nice looking harness and wire harness btw.

[Woodie1]

Thanks. It is a crack. I sanded the surface after scraping the old gasket off. I can feel it with my fingers.

[Russ/40]

Not an issue.

[Jack E/NJ]

You call that a crack? This is a crack.

[Woodie1]

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You're right Jack. A little bondo will take care of that crack.

[deuce lover]

A quick check with a vacuum gauge will verify if its an issue.

[Terry,OH]

The other side of the crack is the exhaust port. Exhaust is circulated through the intake to warm the intake and the fuel that flows through. 39 intake should not be too hard to find.

[AnthonyG]

Not an issue X2. Several reasons it’s not. The crack doesn’t break out at the fuel intake ports or the edge of seating surface, so even if it does enter the surface deep enough to break into exhaust as Terry,OH speaks of the carb gasket will seal. If your a belt and suspenders guy like me, I’d put a thin layer of high temp RTV on it & install / tighten gasket & carb while wet & let cure. No potential for any leakage of exhaust or vacuum & an invisible fix.

[Wat-0]

You might try the wicking Loctite like is used for weld porosity.

LOCTITE® Letter Grade AA(089)Wicking Grade High Strength Threadlocker is used to lock and seal fine threaded nuts, bolts, and studs in a wide variety of applications . It is also used to seal porosity in welds, castings, cracks and powdered metal parts.

[TJ]

Originally Posted by AnthonyG

Not an issue X2. Several reasons it’s not. The crack doesn’t break out at the fuel intake ports or the edge of seating surface, so even if it does enter the surface deep enough to break into exhaust as Terry,OH speaks of the carb gasket will seal. If your a belt and suspenders guy like me, I’d put a thin layer of high temp RTV on it & install / tighten gasket & carb while wet & let cure. No potential for any leakage of exhaust or vacuum & an invisible fix.

I would not use RTV anywhere around a carb or where gas may leak.That stuff turns to "snot" when it comers in contact with fuel

[aussie merc]

very gently drill the ends of the crack this will stop it running 1/16 th is plenty then either weld it shut or fill with metal putty or just leave it alone until it becomes a nuisance