1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

6k idle after rebuild

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Old Nov 21, 2020 | 05:46 PM
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6k idle after rebuild

Rebuilding the engine went alright I hope, but now I have another question. Why does it idle at 6k right after start up? I haven't left it running for longer than 3 seconds because dear God I just spent a week putting everything back together and over $1000 worth of parts, too scared to risk having to do it all over again. Anyways, I did the rats nest delete and rebuilt carb, and then rebuilt engine so I have no idea what it could be. I made SURE the holes were plugged up so I doubt it's from the delete. Tommorow I'm gonna check all the bolts that hold the carb together and to the engine to make sure they're snug. I made sure the idle screw isn't far out (maybe like a turn and a half away from being lightly seated). But is there anything else I should check while I'm at it? Did it do much damage??(4 starts in all, all shorter than 3 seconds)
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Old Nov 21, 2020 | 10:28 PM
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The idle should be about 6 turns out from lightly seated, and the mix should be 3 or so
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Old Nov 21, 2020 | 10:34 PM
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Originally Posted by LEGALIZECHEY
The idle should be about 6 turns out from lightly seated, and the mix should be 3 or so
well that might explain it. When I rebuilt the carb the manual about 2 1/2 turns out, and some guy told me the further out the screw is, the more gas is going in, therefore the faster the idle so after I screwed it in to about one turn.
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Old Nov 21, 2020 | 10:38 PM
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More gas doesn't necessarily mean a faster idle , you also need air . But yeah 6k is way to high and you shouldn't be placing a newly built engine anywhere near that for more than a couple seconds if at all
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Old Nov 21, 2020 | 10:41 PM
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Originally Posted by Frogman
More gas doesn't necessarily mean a faster idle , you also need air . But yeah 6k is way to high and you shouldn't be placing a newly built engine anywhere near that for more than a couple seconds if at all
that's just what the guy said. He said more fuel is going in and in theory that means faster. And yea its probably not too healthy haha
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Old Nov 21, 2020 | 10:43 PM
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Originally Posted by el_ghapo
well that might explain it. When I rebuilt the carb the manual about 2 1/2 turns out, and some guy told me the further out the screw is, the more gas is going in, therefore the faster the idle so after I screwed it in to about one turn.
No sir. Your idle screw is adjusting how open the butterflies are at rest (or idle). It is on the right side of the carb, under the throttle linkage. The mixture screw is in the middle of the carb on the throttle body, and it's adjustment controls how much fuel is mixed with air going through the carb. Both will need to be adjusted and they can only be adjusted so much before the other needs attention.

here's a carb manual http://foxed.ca/rx7manual/manuals/ma...01979-1985.pdf
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Old Nov 21, 2020 | 11:55 PM
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at that high of an idle i would check if the throttle or choke linkages are binding up on something or possibly a return spring is missing or broken.
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Old Nov 21, 2020 | 11:57 PM
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Originally Posted by diabolical1
at that high of an idle i would check if the throttle or choke linkages are binding up on something or possibly a return spring is missing or broken.
both linkages are in good shape, haven't checked return spring yet but when I put the carb back together, not a single part was left over and it worked before just fine
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Old Nov 22, 2020 | 12:08 AM
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From: FL
check the manifold for cracks or a major vacuum leak.
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Old Nov 22, 2020 | 12:09 AM
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Originally Posted by diabolical1
check the manifold for cracks or a major vacuum leak.
no cracks, but it might not be snug on there. I'm gonna check tommorow
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Old Nov 22, 2020 | 09:50 AM
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My best guess is vacuum leak. If your lower intake manifold isn't snug to the block, or the carb to intake manifold isn't mated and has a gap, that'll cause a high idle too. Since you did the emissions removal, double-check your vacuum lines on the carb and manifold to make sure you capped off all the ports. Brake booster line is a bit one, and make sure that you have it connected to the intake manifold too.

Good luck and let us know how it goes.
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Old Nov 22, 2020 | 09:51 AM
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From: ND
Originally Posted by turbogslse
My best guess is vacuum leak. If your lower intake manifold isn't snug to the block, or the carb to intake manifold isn't mated and has a gap, that'll cause a high idle too. Since you did the emissions removal, double-check your vacuum lines on the carb and manifold to make sure you capped off all the ports. Brake booster line is a bit one, and make sure that you have it connected to the intake manifold too.

Good luck and let us know how it goes.
Will do, thanks for the help
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Old Nov 22, 2020 | 09:58 AM
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I second the vacuum leak if it is not the carburetors fault. I missed a big hole on my mani when I removed the rat's nest. Look behind the brake booster tube, that little vent hole caused me some big issues, and it was a really simple, kinda stupid mistake on my part
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Old Nov 22, 2020 | 02:43 PM
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lol. the funny thing is that that is exactly the spot i was thinking about when i thought of the major vacuum leak.
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