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Old 07-20-2002, 07:24 PM
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Post Stalling when in Gear

Why does this car stall when I throught it in gear?

Hear is my half baked theory... The vacuum signal to the GM350 trans is currently coming fom the intake manifold, like the brake booster. So when the car goes into gear it immediately has full vacuum signal and does some sort of stalling thinga ma bob and it kills the motor.

Should the vacuum come from the carb like the distributor advance signal so that the trans slowly builds that stalling thinga ma bob.

Well, what do ya think? Oh, could someone explain how the trns vacuum signal works.

Thanks,
Jim
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Old 07-21-2002, 03:59 AM
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The trans. vacuum source is correct. Your stalling problem is a result of the transmission drawing horsepower and loss of engine idle curb speed when it is put into gear.

If raising the curb idle speed (adjust in drive) doesn't stop it or the higher idle speed causes it to jerk into gear, you will need to mount an idle compensator (available OEM, Holley or Edelbrock) to raise and/or lower the idle RPM when in gear and to prevent dieseling when shut down. This will also act as a dashpot so that when letting off the fuel at say a sudden stop will also not cause the engine to stall.
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Old 07-21-2002, 02:08 PM
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What size cam and stall converter do you have??
I remember someone w/ a .560lift 265@.050 cam w/ a stock converter had to do neutral starts just to move it.
Do you have a very large cam and stock converter or small converter??
The tranny vac is OK it comes off the intake.
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Old 07-22-2002, 05:09 PM
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This is a 1967 327ci sbc with a stock cam and convertor. I have also been fighting a timing problem. I have verified TDC by using a piston stop, making two points, and then taking the center. The timing tab mark and balancer mark are right on. I have also verified that the distributors rotor is pointing directly at the #1 post when the motor is at TDC. I just rebuilt the distributor (Long story). I now have reliable spark. The car simply wont start unless I set timing to 40deg BTDC. If I try to run with 40deg of timing I get a lot of pinging and detonation. Once its started, I've tried sneaking up on 12deg BTDC but it wont have any of that. It just stalls out. If I try at 30deg BTDC it will sometimes start, but when I try to give it a test drive I get the stalling condition which originated this posting. Should I just richen up the fuel mixture and just run it at 40deg? Is 40deg unreasonable?

Could sticky or really leaky valves be an issue or do I need to tear the front of my engine down to check the timing chain & gears? Is there a way to check this by watching the valve train at TDC? do I need to let the lifters pump up before this can be checked?

I ready and willing to try anything.
HELP ME PLEASE.

<img src="confused.gif" border="0">
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Old 07-22-2002, 05:54 PM
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Let me ask another question. Can an engine start & run with the distributor installed 180deg backwards?

The crank shaft rotates 4 times for every 1 of the cam shaft (basic 4 stroke motor stuff) so if I want ot change the distributors installation I would need to bring the engine to TDC, remove the distributor, rotate the crank shaft 1 full revolution and then re-install the distributor. (right??)

But, again, will an engine even run if its 180deg out? Mine does currently start, but only if I really advance it. I can't go much past 45deg BTDC or the motor wont hardly crank (locked up)

Please help me out here. There are several other people posting with the same problem right now.

Thanks,
Jim

[ July 22, 2002: Message edited by: 54 Chevy ]</p>
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Old 07-23-2002, 05:13 AM
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YES THE MOTOR CAN START AT 180 OUT IF YOU MOVE THE DIST. AROUND ENOUGH BUT IT WILL RUN LIKE CRAP. ARE YOU SURE THE FIRING ORDER IS CORRECT. IT SHOULD BE 1-8-4-3-6-5-7-2 IN A CLOCKWISE DIRECTION. I WOULD CHECK THIS FOR SURE. THE EASIEST WAY I KNOW TO MAKE SURE YOU ARE ON TDC OF THE COMPRESSION STROKE IS TO TAKE THE #1 PLUG OUT AND PUT YOUR FINGER ON THE HOLE, SPIN THE MOTOR OVER AND WHEN YOU FEEL THE COMPRESSION PUSH YOUR FINGER OFF AND THE TIMING MARK IS NEAR TDC YOU ARE THERE. AT THIS POINT MAKE SURE THE ROTOR IS POINTING TO #1 IF ITS POINTING TO #6 THEN YOU ARE 180 OUT. HOPE THIS HELPS.. SCOTT
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Old 07-23-2002, 05:23 AM
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[quote]Is there a way to check this by watching the valve train at TDC?<hr></blockquote>

The easiest way to check timing chain stretch is to put No. 1 on TDC and the balancer on 0 degrees. Move the balancer in reverse rotation by wrench, noting when the distributor rotor begins to move. Read the marks on the balancer. This will give a quick indication of wear.

It sounds as though cam timing (chain/gears) is off or there is something wrong in the distributor advance curve.

[ July 23, 2002: Message edited by: KULTULZ ]</p>
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