Canary94GT

I finally bolted on my new exhaust manifold, only to find that my old choke tube does not fit into the small hole on the top of the exhaust manifold.

I thought about sanding down the tube, but there is not a whole lot to sand. I could also drill out the hole on the manifold, but I would get metal shavings inside the exhaust.

Did choke tube sizes for inline-sixes change over the years? What should I do?

coda618

Is this an oem-used exhaust manifold? If so, it is likely that the old choke tube tip from the original car that it was in rusted and is still in the whole and that is why yours wont fit. Had a similar problem with my manifold. I tried to drill it out but wound up stapping the drill bit in the whol and wound up welding a stid to the drill bit, then heated the manifold, put a vice grip on the stud and bange it our. If the old tip is in there, you will have to pry it, or drill it out somehow. Your best bet might be to remove the plug at the bottom (where the inlet tube plugs in) and then push the broke tip out of the top from the inside. You will likely have to heat the manifold up alot in a vice then bang out the plug with a hammer and chissel. You will find a steel filter in the manifold that should be removed and cleaned thouroughly as well.

If it is a new manifold, I am at a loss.

Hope that makes sense. Keep in mind my point of reference is a 289. Your system may be set up a little different, but I would think it is pretty much the same principal.
Good luck.

Canary94GT

I purchased it as a new manifold from CJ Pony Parts, but it has been welded and looks like its manufactured. I talked to them about it and they said it should have never gone out, so they refunded the money since I was already committed to using this manifold. But it's been beadblasted before and I am pretty sure I didn't see a piece of old tube in there.

So it won't harm anything to drill through and get shavings in the exhaust system (or possibly the head)?

1slow67

Just take the manifold back off and then drill it.

Canary94GT

I really rather not remove the manifold since my machinist surfaced the head and manifold and installed a gasket and torqued it down pretty well. :\

1slow67

I was watching some show on Speed and they recommended greasing up the bit so the shavings would stick in the grease instead of falling down in the manifold.

Canary94GT

Hmm thats a good idea, would probably make it easier to drill also.

But I found out by looking at my old manifold that the choke tube hole is not open to the exhaust, it is just a hole that runs through the manifold and gets heated up with the engine (hence why it is also called a heat riser).

So I went ahead and drilled it through and then vacuumed out the hole and the old choke tube slipped in fine. Now I am excited

coda618

You have air being pulled back into the carb. I don't think I would drill with the manifold in. I would remoe, unplug the bottom for access and make sure you get all the shavings out. My .02.

Canary94GT

A little late, but all that happens is heat rises. It is not being sucked in hard enough to my knowledge to be able to carry metal chunks up the skinny tube.

coda618

At least blow it out with compressed air. Blow from the bottom to the top. There is some suction...though I agree not much.

Good luck.