C2 Carb and Fan Shroud Question

[Michael S.]

1. 1967 L79 carb List 3814 makes a high pitched whistling sound only at normal operating temp, but especially when backing out of the throttle. Vacuum leak ? If I need a rebuild, any suggestions for shops? Are the kits hard to find ?
2. Anyone have a picture of the L79 fan shroud ? I think I have the proper one but it is hard to tell with the assembly manual.
3. Last one for now- I have a non original AIR System. It has a different routing and a different diverter valve- attached to the pump itself. Any suggestions for a source for the proper system ?

Thanks in advance for your help.

[Peter J.]

Re: C2 Carb and Fan Shroud Question

Mike I have a correct Holley on my 66 L79 with the same problem. Whistle loud enough to hear over side pipe exhaust. Mine starts after engine is up to temp too. This carb was no problem for over two years after I bought it restored and still works fine except for the whistle. I used propane to try to find a leak but no luck.
I posted a question about this problem and a member suggested I use two gaskets between the carb body and base (worked for him). I plan on giving his fix a try. Hope somebody has answer before I tear in to the carb.

[Craig S.]

Re: C2 Carb and Fan Shroud Question

Mike - I am assuming since you have a 3814 the large vacuum port on the passenger side of the throttle plate is plugged or connected to the diverter valve. Also, the correct diverter valves on the 66/67 are different in design that the later 68up diverter valves. You may be having an issue with the carb and the diverter valve design. I have a 67 L79 A.I.R. car that I managed to get a complete original system with the pipes, hoses, diverter valve, brackets, pump, etc from Cranes Corvettes in San Diego. He has quite a bit of the smog stuff. Anohter place to check out there is Americas Finest Corvettes, also in San Diego. I know Bill Hodell used to be involved in the smog stuff too, but I had heard he no longer is into these items.

Hold on to your wallet as all the unique parts for 66/67 will run a real bundle....don't wince if it hits $2000 for the system.....Craig

[Kieran A.]

Re: C2 Carb and Fan Shroud Question

Mike, my 1967 L-79 also had an extremely loud whistle when the engine was up to operating temperature. This made it difficult to diagnose because any procedure that cooled the carberator or the intake manifold would eliminate the source of the problem(ie. spraying the gasket areas with carberator cleaner to teporarily seal the vacuum leak) because of the cooling effect of the spray. Just when the problem seemed to go away a long run would cause the intake manifold to heat up and the whistle would return. I went as far as to replace the throttle plate at the base of the carberator suspecting that it had been warped by the over tightening of the four hold down nuts. This worked for a while but I suspect the real culprit was that the carberator studs were pulled up from the intake manifold and the gasket cold not compensate for this warpage at high temperatures. Rather than pull the intake,I placed two caberator to intake gaskets and never had another problem with vacuum leakage from this area again. Regards,Kieran #11373