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Hi all, I am doing a smoke test on my 78 L82. Is there good method to seal off the carburetor? I tried wrapping duct tape around the horn but that did not work very well. I left the tape on and reinstalled the air cleaner which helped seal it lot more but not completely. Is there a better way.
Hi all, I am doing a smoke test on my 78 L82. Is there good method to seal off the carburetor? I tried wrapping duct tape around the horn but that did not work very well. I left the tape on and reinstalled the air cleaner which helped seal it lot more but not completely. Is there a better way.
5 days ago you were doing a tuneup. How did that turn into a smoke test?
I am injecting smoke into the intake manifold looking for any leaks. I have also sprayed carb cleaner around the perimeter.. So far I have not found any leaks. But as air takes the path of least resistance I questioning my test as the smoke comes out the throttle ports of the carb.
I don't think the throttle plates are air tight when closed, are they?
I will try some rags that sounds simple enough.
Yes , I am in the process or replacing the spark plug wires, distribution cap and rotor. Those parts are quite old and this is a normal maintenance process that should be done.
Why am I doing this? My engine runs horribly rich or lean. I have also had some carb work done as well as timing.
I am just trying to do a lot of the tests that have been suggested in other posts here.
I just decided that I will start an new retitled thread and describe each step I have taken: timing, carb, vacuum hoses etc.
I appreciate all the help and ideas you more experienced guys have and are giving me.
The throttle ports have some small clearance, but you shouldn't feel significant 'play' when you try to "shake" them. Most carb plates do not use bushings, and the bores will wear larger and eventually cause some leakage of vacuum. If your smoke is under pressure, you will find all possible sources of air leakage. You should work on those that seem to leak the most, first. If you get down to where the carb throttle shafts are in question, start the engine with a vacuum gauge plumbed to 'manifold' vacuum. Once warmed up, read the gauge when idling. Then, while running, put some PlayDoh or clay around the joint of the carb base and throttle shafts, sealing off that leakage. Read the vacuum gauge again. If you didn't gain more than 1 in. Hg., the leakage probably isn't worth the repair effort....YET.
I don't know what carb you have, but most carb parts supply outlets have bushing kits for tightening up the fit to the shafts. If the leakage is significant, you should consider the bushing fix.
I usually stuff some rags down the carb if I'm smoking an engine. I love using the smoke machine to track down vacuum leaks. It's crazy how effective it is at showing leaks.
I had some thin Plexiglas that I made a plate with. I used door weather stripping to seal it and used a spacer and carb stud to hold it down. Worked great. I even made my own smoke machine.
Here is a video of the only small leak I found on my Holley Sniper 2 throttle body troubleshooting what I thought was a vacuum leak during installation. Holley said this was normal to leak at the throttle blade shafts a little. I even sent it back to Holley (warranty) and they checked it out and found nothing wrong. I ended up replacing my dual plane intake to a single plane. I never did find a leak.
close carburetor for smoke test
