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tbonebanjo
10-20-2009, 07:00 AM
Greetings. I am fairly new to the forum and have already found much help on this site. Thanks, S1-V8!
My own private hell is an 85 S-10 355/350 w/650 holley. The truck will not idle after the choke opens. If I hold it mostly closed (about 1/4" opening at the plate) it runs fine, sounds fairly smooth. As soon as I let it open it dies. I took it out on the street and it ran fine once I got above 3000 or so, I was going sideways down the street, so it seems to have plenty of power (maybe after getting into the secondaries), but when I let off the gas it died. I thought it might be a head gasket, but there is no steam coming out the exhaust. Now I'm thinking it might be a vacuum leak? The previous owner installed the intake manifold, and I'm thinking he skimped out on gaskets (he only used silicone on the thermostat housing). I'd hate to crack the engine open just to find out I needed to adjust the floats on the carb or something. Any ideas would be greatly appreciated.

Carl

STIpend
10-20-2009, 07:39 AM
Sounds like the idle circuit in the carb is not working or the idle screws need adjustment.

oncearacer52
10-20-2009, 08:06 AM
Maybe a leak at carb base or intake. Can you hold your hands over the top of the carb and shut off the air. If so and it still runs then you got a leak.

manyfire
10-20-2009, 10:41 AM
Maybe a leak at carb base or intake. Can you hold your hands over the top of the carb and shut off the air. If so and it still runs then you got a leak.
I would also check around the intake manifold, if you don't set those rubber pieces on the front and back of the motor right they will leak every time, it could be drawing air inside the manifold at the gaskets if they weren't installed right, if you aren't comfortable with the work he did I would pull it and reinstall, it is only about 60-100 bucks and a half days work and will let you inspect the top-end of the motor, change the oil and a coolant swap. It would drive me crazy not knowing if the work was done right.
JMO

truckmec67
10-20-2009, 01:27 PM
spray some wd40 around the intake & carb, if the engines revs up u got a leak, this way u can pinpoint the leak, as for as the rubbers go on the end of the intake i would use silicone instead

Melonhead
10-20-2009, 02:18 PM
WD40 is non flammable now...

manyfire
10-20-2009, 03:04 PM
WD40 is non flammable now...
figures they would screw it up