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How do I replace the choke tube in the rh exhaust manifold of a 1960 vette manifold. Bought this manifold off ebay and the tube is already out on the underside of the manifold and actually bent inside the manifold. I'm thinking I may need to drill it out! What size drill bit? Is it pressed into the manifold or screwed in - I am thinking pressed in but how do you stop it from blowing past the tube.
Also, Will need to re-tap all of the holes, what size taps and what type of thread for the manifold to exhaust pipe and for the gen bracket to the manifold?
How do I replace the choke tube in the rh exhaust manifold of a 1960 vette manifold. Bought this manifold off ebay and the tube is already out on the underside of the manifold and actually bent inside the manifold. I'm thinking I may need to drill it out! What size drill bit? Is it pressed into the manifold or screwed in - I am thinking pressed in but how do you stop it from blowing past the tube.
Also, Will need to re-tap all of the holes, what size taps and what type of thread for the manifold to exhaust pipe and for the gen bracket to the manifold?
Thanks in advance
The clean air tube is simply pressed into the manifold. I've replaced several. Most of the vendors sell them.
They are usually "staked" at either end. If yours is rusted/broken inside, simply cut it in the manifold and pull it out of either end. OR, often one end is flared. Look at the opposite end, relieve the staking, and pull/wiggle it out.
Putting the new one in is easy. Just slide/tap it in place and stake down each end.
How do I replace the choke tube in the rh exhaust manifold of a 1960 vette manifold. Bought this manifold off ebay and the tube is already out on the underside of the manifold and actually bent inside the manifold. I'm thinking I may need to drill it out! What size drill bit? Is it pressed into the manifold or screwed in - I am thinking pressed in but how do you stop it from blowing past the tube.
Also, Will need to re-tap all of the holes, what size taps and what type of thread for the manifold to exhaust pipe and for the gen bracket to the manifold?
Thanks in advance
Should have explained a bit better. I see you're "Down Under".
It's called a clean air tube. That's where you'll find it listed in the catalogs.
The exhaust gasses heat the air within that tube, and supply clean, hot air to the choke, enabling it to function properly.
IF it has holes or is broken, exhaust gasses get into the choke, gumming it up. AND, of course, lets not forget about the exhaust leaks either.
It's a really simple job.
MIke has given you the thread sizes. You can retap them, or if you need to repair/restore them, you can use a helicoil to restore the threads.
The upper and lower holes in the manifold for the heat riser tube are different sizes. Thus, the new tube only goes in from one direction.
SOME replacement tubes are correctly sized on each end, and some are not.
The clean air tube is installed from the bottom, and is staked at the bottom to retain it; drive it out from the top, replace from the bottom, and stake it in place.
The holes in the outlet flange for the studs that retain the exhaust pipes are 3/8"-16.
Thanks very much, had already worked out the 3/8 BSW but to look at would have sworn the exhaust holes were the same. Now have the 5/16 BSW tap as well and am ready to go - when I can find the time!
The tube drives out from top to bottom - each end of the hot air tube is expanded so it can only go in and come out one way - installs from the bottom.
The top end is expanded to 5/16" OD and the bottom is expanded larger to ~ .351" on my GM NOS tube
There are no 5/16" threads on an exhaust manifold - the exhaust pipe stud holes are 3/8" and the generator mtg bracket holes are most likely 7/16" (at least they are on my 2 1/2" manifolds)
I read the posts here but still have questions. I bought "replacement" manifolds from Corvette America. As you can see in the pictures, the tube in the right side manifold is cut off at both the top and bottom of the manifold. Should they look like this or is it broken? How do I connect these parts to the pipe? Does it need to be removed or replaced? How to I get it out, just tap it thru?
Thanks for any advise.
Last edited by Mikey Hawks; 04-08-2015 at 07:39 PM.
As stated in some of the replies, the tube sits slightly inside the manifold and there is a seperate tube that goes from the top of the manifold to the carburetor that just poshes into the tube in the manifold. I don't know about the bottom extension that goes back to the carbi ... my 1960 Vette does not have this and there is nowhere for it to go on the barbs either. It is possible that the extension is cut off and equally possible that someone tried to put it in from the top and got it stuck or it has a home made pipe in it. If the extension piece has been cut off you might be able to extract it or you might be able to expand the inside diameter of the hole with a drill to the same size as the extension.
Being a 327ci it must be a 62 and younger car?? I'm guessing and perhaps the carbi is a Carter CFB or something else of which I'm not familiar with. There are guys on the forum with 100 time more experience and knowledge than me, I'm sure one will chime in nd give you a hand.
Apart from that I'm all out of ideas.
Regards
Mick
Originally Posted by Mikey Hawks
I read the posts here but still have questions. I bought "replacement" manifolds from Corvette America. As you can see in the pictures, the tube in the right side manifold is cut off at both the top and bottom of the manifold. Should they look like this or is it broken? How do I connect these parts to the pipe? Does it need to be removed or replaced? How to I get it out, just tap it thru?
Should have realized this info might be important. 1964, 327 - 300hp, with a Carter AFB carb. Thanks, Mick. I'm going to try to extract it and see what happens. I may end up contacting Corvette America for their tech advise since they sold me all the parts in question.
When replacing the choke tube, is there an easy way to get the old one out without disconnecting the lower exhaust or removing the manifold? i.e. can it be driven or pulled out?
And from reading this thread, I gather that the new tube is installed from the bottom and staked in place. How do you stake it?
When replacing the choke tube, is there an easy way to get the old one out without disconnecting the lower exhaust or removing the manifold? i.e. can it be driven or pulled out?
And from reading this thread, I gather that the new tube is installed from the bottom and staked in place. How do you stake it?
I recently replaced mine. Got it from Long Island Corvette. Take a machine screw with a slightly smaller diameter than the choke tube & about 2" long. Place it over the top of the tube and tap it until it's free, (about 1/2" or so). Then you can grab it from the bottom and pull it out providing you have enough clearance. If you don't have the clearance, do it from the bottom up. It's only held in the manifold and the top and bottom. The center is hollow. Replacing it is just the opposite and it should be friction held, no fasteners. Hope this helps.
I'd like to jump up that thread with a question concerning the function: Is it correct that all the time the engine is running air flows thru the Heat Tube?
I wonder about that on my 64 because that hot air heats up the carb which is pretty warm anyway.
The tube passes air warmed by the exhaust manifold as it flows through the tube and NOT the hot combustion exhaust gasses. The warm air goes into the choke housing through the bakelite cover and not directly to the carb. It is not that big a concern to 'heating up the carb' if you are thinking about 'hot soak' issues. Other factors supersede this bit of warm air.
12-20-2010, 02:51 AM
Choke tube replacement - in manifold???
