I removed the intake manifold from the engine and during inspection found hairline cracks coming off of the exhaust crossover ports. Is this a problem and should I do anything about it? Should they be sealed?

 

I think that should be addressed and can. Without correcting the crack exhaust gases will seep into the crankcase under the intake and make the whole crankcase environment more dirty, hareder job for the oil to keep it all clean.

 

You likely aren't getting anything measurable through that hairline crack.
Each piston ring has a .016-.020 gap that allows exhaust gasses into the crankcase & that isn't a concern.
It will plug itself with carbon anyway.

As for the crack, there is a chance it will continue to spread.
Without welding repair, you also could drill the end of the crack with a small drill bit & tap it for a 1/16" NPT plug to stop it from continuing.
No one will see it from the bottom anyway.

 

What about drilling it, then filling with high temp epoxy?

 

I wouldn't try to use epoxy to fix it. If you're going to repair the crack then do it right and have it welded.

 

Is this just basic aluminum welding or is there something else I need to aware of? I would have to get a welder to do it.

 

Have a pro aluminum welder stitch it up. Good time to check the sealing surface for flatness.
Consider blocking off the crossover all together, Have the welder tack in the aluminum plugs on both sides shy of the seal surface.
This will eliminate the problem from recurring and reduce the heat wick of the carb.

Depending on what style of choke it will need to be readjusted for optimal operation with the cooler intake,

WINS:
1. no more hot start issues.
2. longer life out of the carb, cooler carb.
2. crack will not recur.
3. slight performance gain.
4..no more discoloration (or paint burn off on a painted intake)

 

The crossover was blocked off 32 years ago when the engine was rebuilt. There is an electric choke. I don't know when the cracks occured. This is the first time since I've owned the car that the intake was taken out.

 

If it were mine, I would drill the small hole at the end of the crack. Then I would clean the crack and hole off to fresh metal and seal it with JB Weld. Then I would reinstall it and not worry about it. May not be the best thing but is what I would do.

 

That would be the simplest thing to do. Have you done this yourself? The thing about welding is that I'm concerned it may cause more damage in addition to the existing cracks. You know, lots of heat on a relatively thin walled object. If the exhaust heat caused the cracks then what will the heat from welding do? I'm not an expert with welding so maybe this is nothing to worry about.

 

Personally I would scope the crossover and make sure the crack goes through to the crossover before doing anything.

 

If the crossovers are closed, don’t worry about it.

 

I would suggest stop drilling, gouging and laying a proper bead to prevent further damage and future headaches. If you can’t source a good welder locally, pm me. I know a guy..😉

 

Stacking dimes...thats what Im talking about. Nice metal work.

 

Yeah, you can just drill a small hole at each end just to stop it from continuing to spread. I wouldn't epoxy it, but that's just because I have a bad habit of using epoxy poorly, and if that ever falls out then it'll cause a real mess. Right now that crack really isn't a big deal since the crossover is sealed.
Welding that is pretty straight forward, but the aluminum will be very very dirty. The welder will need a lot of patience as oil and junk will continue to come out of the pores. I had to fix up some casting voids after porting on a used intake and it was time consuming. There's plenty of meat there - that is not what a welder would call thin.

 

Cleaning up the heads' mating surfaces I saw that the exhaust crossover port is plugged as well. So the hot gas is not even getting into the manifold. I'm am considering just leaving it alone given that there is no risk of vacuum or coolant leaks.