Topic: rebuilt carb, whistling sound and idling high and small pops/backfires
in Forum: C3 Fuel, Emission Control, and Exhaust Systems
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so some updates. when i put te carb back on after rebuild, i used the gasket. apparently the spacers have a rubber gasket, and the regular gasket i put on messed with things. i pulled it off, cleaned it, and put it back on without the paper gasket. no more air issues!
She started right up again, couple of quick revs and got it to stay steady. once it warmed up, i played with tuning. seems i cant get it to idle under 1100-1200rpm no matter what i do. it runs smooth and no more popping, but i turned the idle screw all the way out, and played with the idle mixture screws. they are at 2.5 turns out, and almost seem like they will fall out. it seems to idle faster with them all the way in. i'll play some more, but i would think it should slow the idle when i turn them in. otherwise, it seems to running great, at 1100-1200rpm. so i've made some progress!
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On my Holley 4150, there is a small set screw that holds the secondary butterflies slightly open at idle. If it is holding them open to far, then it is hard to get it to idle down. It is underneath on the pax side.
yeah, that would have been helpful! haha! so you are the winner! i backed that off a bit, and then played with the idle screws, they are now at 1.5 out. oddly, it seems like when i turn them in, the idle gets faster... i did read about a smog version(or something like that) that would follow this. either way, its idling at 8-900rpm and fairly smooth. it never was the smoothest thing, plus i was a kid when i drove it before and never really thought much more than "is it running? yes, then drive!"
if i drop it to 600-650rpm, it really feels like it is going to die. i've read that where it should be, but under 800 and i'll be on the gas pedal to keep it running.
getting tires this week, going to get it on the road!
Thank you to everyone for your help! every little piece of information helped and now i can say i have rebuilt a carb, and the car actually ran afterwards! haha!
so i got new tires, and took her for a spin last night, in the dark because no plates yet! i live next to a small school, so i just pulled out of the driveway, in to the school parking lot, went around once or twice, then back home. i need some more carb work! did well out of the driveway, a little sputtering up the small hill to the school. literally 50 yards to the parking lot. ok in the parking lot, but when i pulled back into my driveway, the idle went down and i stalled. started right back up, but the idle was obviously lower, down to 500. had to do a 50 point turn to get her back into the garage past my other cars, stalled every time i stopped. idle is way lower now. i did let it warm up before i drove it.
it was nice to at least get her on the road after so many years. though i was worried the whole time and it was only 50 yards!
forgive me, for this may be a really stupid question/comment...would i need to set it after rebuilding a carb? it was running fine before all this crap went down(fuel line rotten, then pump went bad, then rebuilt carb). i did take the distributor cap off once to check the position of the points, but it wen back on at the exact same place.
Few different things.
1. You always want to verify the three things that make a motor run: Fire,Fuel & Air
2. Timing can need to be readjusted after a carb rebuild, it mat have been set to over or under compensate for a carbs poor performance.
3. If the car ran good before what was the need to rebuild the carb?
4. If very well could be the carb not set up properly. Do you have anyone that is in your neck of the woods that knows anything about old school motors if so it may be a huge benefit for you to ask.
5. Recheck everything on the rebuild. I have had new power valves in the carb be bad.
Here is a PDF that might help you,
I will help you all I can from here.
Good Luck
You may have plugged a vacuum leak with that screw you put on the carb. If that is the case, then you will need to recheck your timing.
On a side note, you may be using ported vacuum instead of manifold vacuum. I've switched to manifold vacuum and have my LT-1 timed at 16* BTDC.
On a side note, you may be using ported vacuum instead of manifold vacuum. I've switched to manifold vacuum and have my LT-1 timed at 16* BTDC.
in Forum: C3 Fuel, Emission Control, and Exhaust Systems
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