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Discussion Starter · #1 ·
I was heading towards a Wal-mart on a back road when some rice rocket thought that he could get away with going 15 or 20 mph in a 55. So I down shifted and laided into it. The car backfired three or four times real quick then idled up. The car would come back down under 2000 rpm !!! I thought that somehow maybe my linkage got suck, but that wasnt it. I was burning points, yes points, I'm a student, so i put a ballast resisitor in to cut the volts down to 6. So I was wondering maybe, because this was my third set of points and I didnt want to change them again, maybe these points are toasted also? Would that cause it. And how do I bring the idle down? I advanced it an incrediable amount just so I woundnt cause hot spots on my drums. But then it wont start. I understand the starting thing, but not the high idleing. I have a 4160 holley 650 w/ vacuum secondaries, an edelbrock performer manifold, and a .440 equal lift cam in my 327. I also have a 2400 stall converter too. I was hopeing that someone out there goes, " Ya I remember when my 66 did that and all you have to do is...." The only plus side is, if you want to call it that because it is entirely expected, is I left that four banger that is producing 92 whole horsepower at peak, behind me! Thanks Gil
 

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Possibly jumped timing or point gap way off causing timing to advance? Blown power valve in Holley? Four barrel butterflies slightly held open?
 

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Discussion Starter · #6 ·
hi, just read your guys replies. Its not the power valve, I have a saver in it. The timing chain and sprockets are new so i dont think that is the problem. I can check the secondaries. Thanks guys, if you think of anything else, let me know. Gil
 

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yep,
check the secondarys to make sure they close all the way to the stop.also check the breaker plate that it does not shift to much from wear,or if your advance is sticking.also check the linkage to the secondaries,could be hangin up!now.you did sinch down that distibutor,I thought so.hope this helps 67RAT member #199
 

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To Bill T:
I saw a tool in the Jegs catalog last night for check the power valve for ruptured diaphragms. It was $20.

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"...it costs what now?" Lev
Team Chevelle Member #590
70 Malibu
350/300hp
Soon to be 396/325hp
 

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Burt,
If the throttle is closing all the way, you must have a BIG vacuum leak somewhere. If it backfired, did it blow the hose, or plug, off the back fitting on your Holley ? I forgot to plug it once on a new motor and had the same results, very high idle. It could also have blown out the carb base gasket. Same result. Check around, I bet you will find a vacuum leak.

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Bill Koustenis
Advanced Automotive Machine
Waldorf Md

1971 Heavy Chevy - original owner
Team Chevelle #100
 

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I have never seen a blown power valve cause a high idle, usually makes the engine run real rich off idle, stumbles & hesitates. I agree with BillK, vacuum leak someplace, dont rule out an internal intake manifold gasket failure into the lifter valley if all else fails. just pull off one of the breathers & the pvc valve if equipped & check for vacuum at the valve cover with your hand while running, should be none.

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http://msnhomepages.talkcity.com/yosemitedr/quintillis/index.html
 

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I had a Quadrajet carburetor backfire on me one time and it bent one of the butterflies. Try looking down the throttle bores of the carburetor with a bright light if one is bent every so slightly it will cause a high idle even when linkage appears to look right.
 

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Discussion Starter · #12 ·
Hey Sprinter, that's helpful. I did check the secondaries and the linkage on the side that controls the butterflies seems to have a kind of a hitch in it. Its not as smooth as I would imagine it would be. Should I pull the carb off and look? And what should I look for? Thanks for your time, -Gil
 

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burt,
If you think your secondary butterflys are hanging,try to close them while the motor is running by pushing down on the end of the butterfly shaft on the secondarys.pushing it towards the closed position,also the ajustment on the butterfly stop could be to high,this would make it run like you are slightly on the accel peddle.there is alot of good things to check in this post,give em all a look ,and you should be able to pinpiont it.--good luck--67RAT member #199
 

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Burt, Your actual linkage is probably OK! Its not the problem. The butterflies themselves tend to warp when you pop-back through the carb. I replaced the blades on the shaft and that cured the high idle problem.
 
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