High idle

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Jul 9, 2008 | 11:54 AM

Ford150/428/dud

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High idle

1979 F150, 351M/c6
The problem I have is it idles a little bit high.

I recently swapped in a 4bbl intake non egr performer 400/rebuilt autolite 4100 1.12 venturi, and a 3 way timing set.

I have checked for vacume leaks everywhere with a little bit of LP and a small hose to direct it, and I have none.

I cant adjust the idle mixture screws i can turn them in and out makes no difference.

I have moved the dizzy all over and the only spot it runns good with power, causes it to diesel when turned off.

Im about to use it as a boat anchor and find a 4bt.

Any suggestions?????

Thanks

NIck

Jul 9, 2008 | 06:32 PM

ibleedblue1385

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From: Parma, MI

Carb not jetted right? It sounds more like a vaccum leak, but you said you checked it.

Try using starting fluid when you check for leaks.

Jul 9, 2008 | 07:53 PM

ctubutis

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From: Denver Metro Area, CO

I believe the original Throttle Kicker device was in place to let the carb fully close when the
engine was shut off in order to ensure it stops running (doesn't diesel).

But my first suspicion is the carb; you should not be able to turn the idle mixture adjustment
screws all the way in with there being no difference in how the engine idles. Something is
wrong there.

-ct

Jul 9, 2008 | 10:12 PM

Ford150/428/dud

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This carb was on a running 428 before I rebuilt it. It really does seem like a vacume leak, because the idle mix screws do not change anything.

I put a gasket under the air cleaner stud, and got the secondary opening a previous problem i figured out. I also switched the coil, and pickup coil in the dizzy related wiring.

I will definatly try to use some starting fluid to check for leaks.

With Egr removed has anyone ever had their dizzy recurved??

Throttle kicker do you have a pic?????

Thanks
NIck

Jul 9, 2008 | 10:29 PM

ctubutis

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Posts: 22,415

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From: Denver Metro Area, CO

Quote:

Originally Posted by Ford150/428/dud

This carb was on a running 428 before I rebuilt it. It really does seem like a vacume leak, because the idle mix screws do not change anything.

Well, in my experience, vacuum leak or not, fully closing the two idle adjustment
screws will result in the engine dying. I've created intentional vacuum leaks and fiddled
with my carb to no end in order to pass the emissions tests.

Quote:

With Egr removed has anyone ever had their dizzy recurved??

I believe recurving the distributor is necessary only if your engine is run by a computer.
But I'm not entirely positive on this, it's just a random bit of info I picked up over time.

Quote:

Throttle kicker do you have a pic?????

eBay Motors: FORD THROTTLE KICKER FOR TWO BARREL CARBURATOR (item 120180014847 end time Jul-31-08 15:59:42 PDT)

-ct

Jul 9, 2008 | 10:43 PM

Ford150/428/dud

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OK I understand what you are talking about.

I was fiddling around with my carb some more and I can close the secondary shaft a little and it idles down just a hair still not low enough, when the secondarys open back up it doesnt close all of the way. It must be sticking internally like the butterflys. When I close the shaft and turn off the key it still diesels.

I dont have any starting fluid so ill try that tommorrow when i pickup a can.

Thanks

nick

Jul 10, 2008 | 09:22 AM

beartracks

Lead Driver

Joined: Nov 2000

Posts: 6,635

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From: Albuquerque

The secondaries normally don't close tight. If they did they might stick. You might have a vacuum leak on the underneath sideof the manifold, along the bottom of the runners. Do you have any oil leaks/burning?