engine quits when put in gear

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WarEagle
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engine quits when put in gear

Post by WarEagle »

So, my motor wants to quit when I put the C4 into gear. She idles good, vacuum is steady at 22", but when I put her into R or D she likes to quit.

What would be the top 3-4 reasons why this would happen? I can usually fix it, but I have trouble diagnosing!!

Thanks,
1972 F100 300 cid straight 6
2009 F150 4.6L Super Crew
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HIO Silver
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Re: engine quits when put in gear

Post by HIO Silver »

... a disconnected vacuum line somewhere.
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WarEagle
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Re: engine quits when put in gear

Post by WarEagle »

HIO Silver wrote:... a disconnected vacuum line somewhere.
I checked both vac lines - one to the automatic tranny and the other goes to the valve cover. Is the 'breather line' to the valve cover really necessary or should I just cap that vac port on the intake and get breather caps? What would the result be if I capped it off and how does it affect the tuning?
1972 F100 300 cid straight 6
2009 F150 4.6L Super Crew
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Re: engine quits when put in gear

Post by Jacksdad »

Could still be a vacuum leak.
Do you have a tach to gauge where your idle speed is at now? Maybe try raising it slightly to see if it helps.
1971 DRW F350 cab and chassis with an Open Road motorhome conversion, Dana 70, 352 (originally 390)/C6, PS, power front discs, and 159" w/b.
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WarEagle
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Re: engine quits when put in gear

Post by WarEagle »

Jacksdad wrote:Could still be a vacuum leak.
Do you have a tach to gauge where your idle speed is at now? Maybe try raising it slightly to see if it helps.
I just tried that, thanks. I raised the idle with the manual choke to 850 rpm and it still died. I tried it with a wide open choke and it still died.

I also tried the vacuum leak trick of spraying carb cleaner at the base of the carb and all intake runners, but no change in rpm. All hoses seem to be connected and clamps are tight.
1972 F100 300 cid straight 6
2009 F150 4.6L Super Crew
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Re: engine quits when put in gear

Post by tnlprt »

Power brakes?
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Re: engine quits when put in gear

Post by WarEagle »

tnlprt wrote:Power brakes?
nope
1972 F100 300 cid straight 6
2009 F150 4.6L Super Crew
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Re: engine quits when put in gear

Post by WarEagle »

***UPDATE***

I read the post from '302 Engine Stalls Post by KU4WW » Tue Mar 14, 2017 4:10 pm ' and thought about it. My Holley 450 cfm carb was rebuilt but it was several years ago, and has not seen much action since. I picked up a Holley Street Avenger 600 cfm 4bbl, bolted it on, and that was the problem!! I still have to fine tune it, but what a difference! The old one must have had varnish buildup or a vac leak somewhere.

Thanks for the suggestions. Hope this helps someone else someday.
1972 F100 300 cid straight 6
2009 F150 4.6L Super Crew
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Re: engine quits when put in gear

Post by colnago »

WarEagle wrote:Is the 'breather line' to the valve cover really necessary or should I just cap that vac port on the intake and get breather caps?
In my case, I had to run the PCV line to the intake/carb (I don't have breather lines on my valve covers). Without it, I was getting condensation build-up in my crankcase. My oil filler is just a breather cap, so I only have a single line for recirculation. This is on a 352, by the way.

Joseph
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Re: engine quits when put in gear

Post by jzjames »

Is the motor (compression) tired and crapped out?
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Re: engine quits when put in gear

Post by tnlprt »

Set the timing with the vacuum advance hose disconnected and plugged
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Re: engine quits when put in gear

Post by WarEagle »

jzjames wrote:Is the motor (compression) tired and crapped out?
No, the compression is great at 160 to 170. Freshly rebuilt.
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Re: engine quits when put in gear

Post by WarEagle »

tnlprt wrote:Set the timing with the vacuum advance hose disconnected and plugged
I did this also. One other thing I checked was the vac advance spring in the vac adv canister. I put a slightly stiffer spring in there to decrease the amount of advance, and that helped when under WOT. It was advancing too far before.
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Re: engine quits when put in gear

Post by tnlprt »

WarEagle wrote:
tnlprt wrote:Set the timing with the vacuum advance hose disconnected and plugged
I did this also. One other thing I checked was the vac advance spring in the vac adv canister. I put a slightly stiffer spring in there to decrease the amount of advance, and that helped when under WOT. It was advancing too far before.
A stiffer spring only slows the rate of advance down .

The distributor has built in stops to limit the amount of mechanical advance
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