62 250hp/327 clean air tube
Is there supposed to be one on this motor and if so where does it connect at each end? I looked at a car over the weekend that had one and was connected at a left rear carb stud and the other end was hanging down by the right exhaust manifold. If not connected would it cause the heat riser in the right exhaust to flutter?
-
-
Re: 62 250hp/327 clean air tube
Hi John,
You kind'a got 2 issues going here. The "clean air tube" refers to the choke hot air supply system. A steel tube goes from the choke cover to the RH exhaust manifold. An inner tube passes through the manifold extracting heat from the exhaust which travels to the coke coil. Beneath the exhaust manifold, a fitting assembly connects to the tube running through the exhaust manifold, comes up and, with a rubber hose, connects to the carburetor at a vacuum source, usually on the RH side of the carb.
This system basically provides clean exhaust heated air to the choke coil & mechanism to tell it what to do.
The "hollow" rear carb stud is usually a source for the windshield washer/wiper coordinator vacuum. Not sure, but maybe also used for AT vacuum. Never had a AT, so a little foggy here.
Anyway, hope this is of some basic help. Of course, the AIM & other reference books are worthy of reading.
And to answer a specific question, I don't believe the situation you describe would ever cause the exhaust heat riser to "flutter."
Best, Dennis -
Re: 62 250hp/327 clean air tube
I believe the rubber hose from the tube at the bottom of the exhaust manifold would connect to a clean air source, not a vacuum source at the carb within the air filter. Thus the name; "clean air tube". The choke housing has a vacuum draw port in it to pull the heated air through the clean air system. It is only about 1.5 to 2.5 "hg, but is enough to make the system work. If the heated air is not of a temp to make the choke coil move enough, one can either insulate the tube or pinch it with a vice grips near the manifold to restrict the air flow further and allow it to heat up more. The only other alternative is to back off on the choke adjustment to ensure it is full open when the engine is full warm.
The clean air system really has nothing to do directly with the heat riser butterfly other than the butterfly being closed during engine warmup may contribute to the heat on the pinched tube within the manifold.
Stu foxComment
-
Re: 62 250hp/327 clean air tube
The choke tube is a metal tube that fits into the exhaust manifold and draws air through the tube which goes through the exhaust manifold and is open at the bottom end. It is connected to the choke housing on the carb.
The hot air tube is a metal tube with a bracket which attacheds to the front center exhaust manifold bolt on the passenger side. It is close to the exhaust manifold and picks up heat from the manifold. At the top of the tube is a rubber hose which connects to a tube on the top flange of the carburetor which in turn sucks hot air into the carb.
I know the sustem is used on the 1962 AFB carbs but I am not sure of any other applications.Comment
-
Re: 62 250hp/327 clean air tube
Bruce;
Perhaps the 62 is different than the 63, but on the 63 it is a closed loop system;
Air is drawn from the AFB carb secondary air horn (clean air), down through the rubber hose to the "hot air tube" which in turn connects to the bottom end of the heat tube in the exhaust manifold. The choke tube then connects from the top end of the heat tube to the choke housing. The slight vacuum draw on the choke tube pulls air through the entire system from the carb air horn on. If your hot air tube does not connect to the heat tube in the manifold, then why would you need it to connect to the carb air horn? Suggest you look at your 62 system again and I think you will find it matches my description or it is not connected to function properly.
Stu FoxComment
-
Re: 62 250hp/327 clean air tube
Stu,
Attached are some pictures of the choke tube and the hot air tube on my 340 HP 62 Corvette. Both systems, the choke and the hot air tube work as I described.
I have also attached pictures of a hot air tube with the rubber hose.
The hot air tube is open at both ends and gets the heat which comes off the exhaust manifold. As you know the choke tube is inside the exhaust manifold and gets it heat by pulling air through the hot tube. Both systems are open to the air.
I don't know how a 63 setup works but I would think it's similar. Actually the Paragon catalog shows it to be the same as the 62 setup (picture attached).
Stu,
I stand corrected , the clean air tube does connect to the bottom of the choke tube as you described.
Bruce BComment
-
Re: 62 250hp/327 clean air tube
Bruce;
Your pictures show exactly what I have described. The hot air tube (#4001), with the rubber hose attached shown in your pictures, is supposed to be installed so that the end with the curve inserts in the bottom of the manifold tube (below the exhaust manifold). The choke tube inserts into the top of the manifold tube. Guess we are just talking symantics here.
Stu FoxComment
-
Re: 62 250hp/327 clean air tube
Actually, the '62 system is similar to the '63 but differs in one major respect, in that the clean air feed is via a tube in the carburetor air horn rather than a nipple in the air cleaner. The system and the intent, to keep dirt from entering the choke housing is the same.Bill Clupper #618Comment
-
Re: 62 250hp/327 clean air tube
William;
The 63 does use the tube to the air horn on the AFB, not the air cleaner. They probably started that with the 62 due to the fancy air cleaners they used, then continued on to the 63. Mind you, I'm talking L-76 here as I do not know what the Air Cleaner is like on an L-75. I believe, all AFB's used on the 62 and 63 Vettes have the tube in the secondary part of the air horn for the clean air tube. Can't say for sure on the 64 and beyond.
Stu FoxComment
-
Re: 62 250hp/327 clean air tube
You are correct, I was thinking Holley and Chrome air cleaners.Bill Clupper #618Comment
Comment