1979 C3 Air Cleaner Assembly - plumbing

stuclark · September 03, 2014, 06:22:34 PM

I have '79 C3 with L48 engine but the standard twin snorkel air cleaner assembly. The picture is not my engine bay, but shows the assembly I mean. my question is..on the underside there is a small diameter vacuum line that goes onto the engine or somewhere to get a vacuum from. The 2 air intake valves for the exhaust hot air input are in place and work. But this one hose has broken off somewhere and I cannot find where it goes? I cannot hear leaking vacuum. Does anyone have a standard '79 with this configuration that can tell me where this goes?

sirfixalot · September 03, 2014, 08:36:36 PM

Will have a look tomorrow arvo

Vettech · September 03, 2014, 09:08:42 PM

Mine is a 78 but I think they are sameish. One hose goes from the top (hot air valve as per the pic) under to the thermostat, then a second hose goes down to a port on the base of the Quady. I can't remember which side and I can't look as I'll wake up all the mice and chickens. You may not hear anything as people remove these thinking they get better performance, (COS) this device ensures the engine comes up to temp quickly by drawing air from over the manifold, once hot the thermostat switches out. You may find carby port capped or plugged. Having said all that if you don't have the hot tube and the manifold heat stove cover - then its a fait au comple.

Vettech · September 03, 2014, 09:27:32 PM

Yes I think it is at the front of the carby (Quady) below the choke feed pipe - Oh and did you know that the Quady has a little itsy bitsy fuel filter in the carby at the fuel pipe entry port. You need two spanners be carefull not to twist the pipe. Have fun. (Please remember that I'm using knowledge of a 78 but they should be the same or close.)

sabre · September 06, 2014, 10:15:37 AM

Unless it changed between 78 & 79, the pictured air cleaner is from an L82. The L48 had a single inlet. I came across this in the assembly manuals when I was putting my anniversary model back to factory.
This doesn't answer your question but might help if you start looking for vacuum diagrams.

MY081 · September 06, 2014, 03:38:07 PM

Hi there sabre great to have you back on line and out of jail (bet the food is much better back home ) Please dont start building any trailers or corvettes for a day or two Lol Ray n Joy.

Vettech · September 06, 2014, 05:49:33 PM

Sabre - you are correct - but the two hot air valves need vac from the port in the base of the carburetor.

sabre · September 07, 2014, 06:16:57 AM

Quote from: MY081 on September 06, 2014, 03:38:07 PM
Hi there sabre great to have you back on line and out of jail (bet the food is much better back home ) Please dont start building any trailers or corvettes for a day or two Lol Ray n Joy.

Thanks MY081. Nice to be out. Not much chance of starting anything new, no driving for 6 weeks or heaving lifting for 3 months.

Quote from: Vettech on September 06, 2014, 05:49:33 PM
Sabre - you are correct - but the two hot air valves need vac from the port in the base of the carburetor.

Manual for '78 shows the pickup at front left carb base. On the Excalibur (305) hose goes from the carb port, thru a temp valve mounted under the air cleaner, then to a "Y" connector which feeds to both diverter valves.

stuclark - Note that these are rarely connected in Australia. The air preheater is primarily for sub zero operation, but if disconnected it is necessary to block the port in the base to prevent vac leaks.
The picture you originally posted shows the flex couplings and original ducts are missing. This is also common as they wear, are a pain to reconnect and crowd the engine bay; however these are more important in Aust as they attempt to get cool air into the carby rather than preheated air from behind the radiator. There's a huge debate over whether the restriction provided by the ducting or the increased air inlet temperature loses more power, but all agree cool air into the aircleaner is a good idea. I'm sure you'll get lots of varied opinions on this.
Good luck!

Vettech · September 08, 2014, 06:53:13 PM

Ahhhh Sabre good to read your home and on the forum - not on C3's - but we saw two of those Stutts Bearcat thingo's at the Port Show - a white one like yours and a ratty looking blue one. Pity you weren't there - I would reckon your white one would have cleaned up the prize easily. And the guy actually knew you. Sorry I don't remember his name - he wasn't a vette owner....