Just canibalize a parts carb. Junkyard, swap meet, Ebay. But once open you may as well rebuild the whole thing anyway.
Carb issue
- Thread starter Jorge1958
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Before tearing down the carb, I'd make sure it wasn't something else. Carb rebuilding can be tricky, especially if that wasn't your problem. Does it do it with the A/C on? Or off? Or on level ground or up/down hill? Only when warmed up or only cold? Or both? Has the dwell for the mixture control solenoid been checked? Check EVERY vacuum line for cracks/looseness/leaks. I'd also check for any ECM codes, so if you have a scan tool for OBD1 type ECMs, do it. You may have an intermittent problem.
If you use a carb cleaner, or water, or propane method to chase down your leaks (or the off-chance if you know of someone who has a whamodyne smoke generator for this purpose), be CAREFUL and ensure you unplug the mixture control solenoid or TPS to keep the emission system in open loop mode. This will essentially lock your fuel mixture to default and the computer won't adjust it. Otherwise the computer will compensate for the carb cleaner, etc., and you won't necessarily get a change in idle when you do hit a vacuum leak. There's likely a whole bunch of you tube videos out there to help find out how to do it. It's actually cheap to do, just takes time. AND you need to be careful if using flammable stuff. A lot of people I know, and I've used it too, is a hand held propane torch with a piece of small diameter tubing adapted to the outlet valve and use it as a snooper to poke around all the suspected leak areas. Crack open the valve slightly and when the idle speeds up if you go over a suspected area, double check it again to make sure idle changes when the propane gets sucked in.
Personally, I'd investigate further. I was only pointing out that there was a hot high idle issue with at least SOME 86 Montes with the 305 and 4bbl carbs during manufacture. Doesn't mean yours has this issue. If yours varies in rpm, I'd check elsewhere first before tearing into anything. Mine went high and stayed there. I had to blip the throttle a lot of times to get it idle to come down where it should be. But idle was either high or normal, it didn't vary. So your issue may not be the same.
I am unfamiliar with Monte Carlo SS fuel tank venting so I don't know if they use a canister control valve (CCV) system like Olds V8s did. Sometimes, the vacuum controlled CCV diaphragm, due to age, etc., will crack and leak air. And that kind of leak is hard to find. And on an Olds V8, it's a PITA to replace due to all the crap in the way.
If you use a carb cleaner, or water, or propane method to chase down your leaks (or the off-chance if you know of someone who has a whamodyne smoke generator for this purpose), be CAREFUL and ensure you unplug the mixture control solenoid or TPS to keep the emission system in open loop mode. This will essentially lock your fuel mixture to default and the computer won't adjust it. Otherwise the computer will compensate for the carb cleaner, etc., and you won't necessarily get a change in idle when you do hit a vacuum leak. There's likely a whole bunch of you tube videos out there to help find out how to do it. It's actually cheap to do, just takes time. AND you need to be careful if using flammable stuff. A lot of people I know, and I've used it too, is a hand held propane torch with a piece of small diameter tubing adapted to the outlet valve and use it as a snooper to poke around all the suspected leak areas. Crack open the valve slightly and when the idle speeds up if you go over a suspected area, double check it again to make sure idle changes when the propane gets sucked in.
Personally, I'd investigate further. I was only pointing out that there was a hot high idle issue with at least SOME 86 Montes with the 305 and 4bbl carbs during manufacture. Doesn't mean yours has this issue. If yours varies in rpm, I'd check elsewhere first before tearing into anything. Mine went high and stayed there. I had to blip the throttle a lot of times to get it idle to come down where it should be. But idle was either high or normal, it didn't vary. So your issue may not be the same.
I am unfamiliar with Monte Carlo SS fuel tank venting so I don't know if they use a canister control valve (CCV) system like Olds V8s did. Sometimes, the vacuum controlled CCV diaphragm, due to age, etc., will crack and leak air. And that kind of leak is hard to find. And on an Olds V8, it's a PITA to replace due to all the crap in the way.
Thanks for all the info. Im gonna do alot more checking before i tear into the carb. The car runs so good i have a hard time thinking its anything to big. I will keep you posted on what i may find.
So i went thru all the vac hoses. All looked good but i changed them all out anyway. Havent had any issues today. Seems to be doing fine. But its an intermittent problem. It really runs good. We'll c how it goes. It sure is a fun car to drive. Thanks for your help folks
Good to hear. Sometimes it's a simple fix, other times it's not. Keep an eye open for any more issues. If nothing else it's peace of mind that you get knowing all your vacuum hoses are new!
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