It's also going on a 99% stock '78 corvette, which according to the specs for the carb, had an astronomically high high idle of 1600rpm, so I'd say I got it dialed in as much as I could.
Quadrajet intake gasket is wet, erratic high idle.
- Thread starter MrSony
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Mr.Sony-If he really worked there- and presumably got a discount- why is he even wasting your time? I'll tell you why- because he sees rebuilt carb after rebuilt carb come back in with problems. I once had a '68 Pontiac 350 2 barrel and the carb flooded something awful. Being young and stupid I just went and got an off the shelf rebuilt- which flooded something awful. 4 carbs later I gave up. I opened my factory manual and learned how to rebuild a carb. I never looked back.
I'd like to see those specs that say the idle should be at 1600 rpm. There is something wrong is you can't get the idle under 1000 rpm.
I've seen that video. WhoSaidTyler is a great channel. Here is a picture of the 4 page packet, thing that Quadrajetparts.com includes in every rebuild kit they sell detailing the specs of whatever qjet you may be working on. Has stuff from 1975 to 1978 for Chevy, Caddy, BOP and GMC. Look at the leftmost side, where the "77" is. Chevrolet & GMC Truck 350" Eng. Carb is 17057204. First column after that is float level, then pump rod location, pump rod, bench setting for fast idle, Choke rod, air valve rod, vacuum break front (where applicable), vacuum break rear (where applicable), Air Valve Spring Turns, unloader, and Fast Idle RPM. H/S is the high step of the fast idle cam, 2/S is the second step. L/S is Low Step, P is Park, N is Neutral.
you are missing the top of the chart that tells you what the column is....that 1600 is for a cold rpm, not an idle in park after it's hit operating temperature...and just because that is the spec if you can't turn it down then there is something wrong with the carb.
I have to agree with Steve. The 1600 H/S cold is fine. I set all mine at 1500 fast idle cold. If I let it warm up that same setting gets it up to 2000 rpm. But 1000 rpm hot idle is not right. Remember- those specs on that sheet are beginning points. The hardware settings like float height and vacuum break you can go with. But I find that I usually need to start with about 4 or 5 turns out on the idle mixture screws. Once hot, I turn them in and play with the curb idle screw until I get the highest vacuum reading at the lowest rpm. That is assuming the initial timing is correct and vacuum advance is not interfering. On a healthy motor you should be able to get it down so low it stalls. Something is artificially keeping the idle speed too high. Usually that means a vacuum leak or something physically keeping the throttle open. I have even seen that caused by the wrong carb-to-manifold gasket.
I listed what all the columns were. And I've said it initially was 1400rpm cold idle and it wouldn't idle down. Fixed that, now the high idle is properly set at 1400 (I thought 1600 was a tad high, but that's just me), and it idles in park at 900-1000 when warm. That was on a 305 though, not the 350 the carb was meant for. The gasket that I used was the really thick open gasket that doesn't have the holes in the middle for each blade, just a big open hole. I could've turned it down more, but it was futile to do so as his engine is different than mine. I solved the fuel seeping issue and the sticking fast idle, that's all I needed to do. It's his job to set it and tune it right to his engine. I got it to idle in park at 1000 rpm, that doesn't mean that's as low as it will go.
II had it as low as 900 warm in park, and it ran it's best on the 305 that way. But again, what the owner of the carb must to do make it run right on his 350, is different than the settings I had to make it run well on the 305. I set it where I know it would run decent as soon as he got it. It's his job to figure it out and tune it precisely to his and his engine's liking.
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