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Discussion Starter · #1 ·
It is an original 350 in a '70 GMC pickup with a sm465 stick (if that matters any).
Only mod: Has an HEI ignition.

I moved the idle down to 700 rpm
Moved the timing back from 8 to 4 degrees
Adjusted the carb again
and it still does it. <IMG SRC="smilies/mad.gif" border="0">

Could the timing mechanisms (little arms w/ weights and springs) in the distributor be getting stuck? <IMG SRC="smilies/confused.gif" border="0">

It is an HEI and the problem seems to have slowly gotten worse over the past 2 months.

Any ideas?
 

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WHEN YOU CUT OFF THE KEY NO MORE POWER IS GETTING TO THE DISTRIBUTOR...THATS WHAT TURNS OFF THE ENGINE.....SO IT HAS NOTHING TO DO WITH TIMING OR SPARK..

TRY RUNNING 92 OCTANE FRON DIFF..CO...
CHEVRON 76 ECT ECT.....

MY CRUZAH WILL DIESEL WITH 89 BUT NOT WITH 92...

THE FUEL IS COMBUSTING FROM THE COMPRESSION AND OR HEAT....AND MAKING THE ENGINE RUN ON...

HOPE ANY OF THIS HELPS
 

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Could be a lot of reasons. First of all you did change the timing so that is good. Could be a result of the engine running hot too often. ie bad thermostat,clogged radiator or malfunctioning water pump. Could also be you have carbon build-up on the pistons. To clear this run the engine at high RPMs for a period of time ( freeway driving ) and that should blow it out. The fuel thing is also a good possibility.
 

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Originally posted by 71RCKCRZR RYAN COELHO:
<STRONG>WHEN YOU CUT OFF THE KEY NO MORE POWER IS GETTING TO THE DISTRIBUTOR...THATS WHAT TURNS OFF THE ENGINE.....SO IT HAS NOTHING TO DO WITH TIMING OR SPARK..

TRY RUNNING 92 OCTANE FRON DIFF..CO...
CHEVRON 76 ECT ECT.....

MY CRUZAH WILL DIESEL WITH 89 BUT NOT WITH 92...

THE FUEL IS COMBUSTING FROM THE COMPRESSION AND OR HEAT....AND MAKING THE ENGINE RUN ON...

HOPE ANY OF THIS HELPS</STRONG>
is there any reason you are yelling
<IMG SRC="smilies/flipoff.gif" border="0">
 

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Originally posted by Brent (aka)borton:
<STRONG>
Originally posted by 71RCKCRZR RYAN COELHO:
[qb]WHEN YOU CUT OFF THE KEY NO MORE POWER IS GETTING TO THE DISTRIBUTOR...THATS WHAT TURNS OFF THE ENGINE.....SO IT HAS NOTHING TO DO WITH TIMING OR SPARK..

TRY RUNNING 92 OCTANE FRON DIFF..CO...
CHEVRON 76 ECT ECT.....

MY CRUZAH WILL DIESEL WITH 89 BUT NOT WITH 92...

THE FUEL IS COMBUSTING FROM THE COMPRESSION AND OR HEAT....AND MAKING THE ENGINE RUN ON...

HOPE ANY OF THIS HELPS</STRONG>
is there any reason you are yelling
<IMG SRC="smilies/flipoff.gif" border="0">[/QB]

I DIDNT KNOW YOU COULD YELL WITH A KEYBOARD
<IMG SRC="smilies/biggrin.gif" border="0"> <IMG SRC="smilies/biggrin.gif" border="0">
 

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Originally posted by 71RCKCRZR RYAN COELHO:
<STRONG>
I DIDNT KNOW YOU COULD YELL WITH A KEYBOARD
<IMG SRC="smilies/biggrin.gif" border="0"> <IMG SRC="smilies/biggrin.gif" border="0"></STRONG>
Well then, this must be your lucky day, cause you just learned something new.
 

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If it's loaded with carbon it can glow hot enough to fire the fuel, run it up to about 1500-2000 rpm and pour 1/2 a beer bottle full of clean water in the carb slowly, to blast out the carbon.

make sure the vaccuum advance is hooked up above the throttle plates, and that the weights and springs are free.
 

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Discussion Starter · #9 ·
Thanks for the input. The thing barely ever even gets warm so it isn't overheating.

However, the carbon buildup could be extreme since I only drive it 7 miles each way to work and back and it barely gets warm. Also, the previous owner bought it NEW when he was 55 years old so it really has been driven by a grampa almost its entire "life" <IMG SRC="smilies/biggrin.gif" border="0">

I'll try to spray some electrical parts cleaner on the weights and springs in the ignition but I'm guessing it is the carbon buildup or low octane gas that I run.

It didn't do it the first 8 months I drove it...just over the last two it got gradually worse. <IMG SRC="smilies/frown.gif" border="0">

I may try the higher octane even though I hate to pay any more for gas than I have to...I guess it is worth a try.

Thanks again for the input.

BTW Jimmy76fj40, when I shut it off in gear I have to keep my foot on the brake pedal cause the thing will keep lunging forward <IMG SRC="smilies/frown.gif" border="0">
 

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Discussion Starter · #10 ·
Sooo...if I get a little more carbon buildup in there can I just run diesel? <IMG SRC="smilies/biggrin.gif" border="0"> <IMG SRC="smilies/jester.gif" border="0">

The carbon could act as a glow plug <IMG SRC="smilies/biggrin.gif" border="0">
 

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Did you check the timing with the vacume addvance disconnected?The timming for a 70 with a 4 speed is TDC and when you get up into the HEI years it is 8DegBefore.I run my CHevys at 12DegBefore but I am at 5500FT.Also Dieseling can be caused by a lean mix in the carb.Try richening it up a little.I like to get rid of carbon by pulling the PCV from the valve cover and sucking 2 caps full of ATF through.A cap from a quart of oil works.Do this when running and brings the revs up a little to keep from dying.It will smoke for a little bit ,Just let it idle untill it quits.Blazin <IMG SRC="smilies/biggrin.gif" border="0"> <IMG SRC="smilies/usa.gif" border="0">
 

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Originally posted by blazin:
<STRONG>Did you check the timing with the vacume addvance disconnected?The timming for a 70 with a 4 speed is TDC and when you get up into the HEI years it is 8DegBefore.I run my CHevys at 12DegBefore but I am at 5500FT.Also Dieseling can be caused by a lean mix in the carb.Try richening it up a little.I like to get rid of carbon by pulling the PCV from the valve cover and sucking 2 caps full of ATF through.A cap from a quart of oil works.Do this when running and brings the revs up a little to keep from dying.It will smoke for a little bit ,Just let it idle untill it quits.Blazin <IMG SRC="smilies/biggrin.gif" border="0"> <IMG SRC="smilies/usa.gif" border="0"></STRONG>
NOT TO BE A BUNGHOLE BUT THE TIMING HAS NOTHING TO DO WITH IT....WHEN THE KEY TURNS OFF SO DOES THE IGNITION DISTRIBUTOR ECTECT..

THE TRANNY FLUID IS AN AWSOME IDEA...ALTHOUGH I WOULD POUR IT INSIDE THE CARB AT A DESCENT RPM.... BECAUSE THE FLUID HAS A DETURGENT IN IT AND WILL CLEAN THE VALVES YOUR BEST BET IS THE GAS...

WHEN I TURN MY CRUZAH OFF I SLOWLY LET THE CLUTCH OUT UNTIL THE RPMS GO DOWN A LITTLE THEN TURN THE KEY OFF..DO IT WITH MY CAMARO TOO
 

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Originally posted by Tankota:
<STRONG>It is an original 350 in a '70 GMC pickup with a sm465 stick (if that matters any).
Only mod: Has an HEI ignition.

I moved the idle down to 700 rpm
Moved the timing back from 8 to 4 degrees
Adjusted the carb again
and it still does it. <IMG SRC="smilies/mad.gif" border="0">

Could the timing mechanisms (little arms w/ weights and springs) in the distributor be getting stuck? <IMG SRC="smilies/confused.gif" border="0">

It is an HEI and the problem seems to have slowly gotten worse over the past 2 months.

Any ideas?</STRONG>
if you wanna quit dieselin, fix the carb. old quadrajunk carbs tend to not close all the way and they diesel. fix it to shut completely and it'll quit. if it don't , do the cold water thing with the engine warm.if that don't work, shut it off in gear. but i've had several do it and the carb was always the problem.
 

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NOT TO BE A BUNGHOLE BUT THE TIMING HAS NOTHING TO DO WITH IT....WHEN THE KEY TURNS OFF SO DOES THE IGNITION DISTRIBUTOR ECTECT..

THE TRANNY FLUID IS AN AWSOME IDEA...ALTHOUGH I WOULD POUR IT INSIDE THE CARB AT A DESCENT RPM.... BECAUSE THE FLUID HAS A DETURGENT IN IT AND WILL CLEAN THE VALVES YOUR BEST BET IS THE GAS...

WHEN I TURN MY CRUZAH OFF I SLOWLY LET THE CLUTCH OUT UNTIL THE RPMS GO DOWN A LITTLE THEN TURN THE KEY OFF..DO IT WITH MY CAMARO TOO
Come awn man. Someone already said something to you. Turn off the damn caps <IMG SRC="smilies/flipoff.gif" border="0">
 

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Originally posted by dirtrod:
<STRONG>If it's loaded with carbon it can glow hot enough to fire the fuel, run it up to about 1500-2000 rpm and pour 1/2 a beer bottle full of clean water in the carb slowly, to blast out the carbon.
.</STRONG>
Can't you bend shit by putting water into your combustion chambers? Or is that with a shit load of water at the same time?

Thanks,
Milan
 

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Discussion Starter · #17 ·
Doh! I forgot to unhook the vacuum advance when I checked the timing. When I recover from my injury (quad brake pedal made a 1" hole in my leg <IMG SRC="smilies/crybaby2.gif" border="0"> ) and its not raining I'll go check it again.

Thanks for all the input <IMG SRC="smilies/smile.gif" border="0">

Interesting note: The dieseling has not happened the last two days I drove to work... <IMG SRC="smilies/confused.gif" border="0">

The carb was just rebuilt by a professional (I very rarely ever pay anyone to work on any of my vehicles...this was the first time in about 6 years).
 

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Discussion Starter · #18 ·
Hey Wheelinjp...yah, you've got my machined 350 block hanging in your garage...don't you <IMG SRC="smilies/biggrin.gif" border="0">
 

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Originally posted by Tankota:
<STRONG>Doh! I forgot to unhook the vacuum advance when I checked the timing. When I recover from my injury (quad brake pedal made a 1" hole in my leg <IMG SRC="smilies/crybaby2.gif" border="0"> ) and its not raining I'll go check it again.

Thanks for all the input <IMG SRC="smilies/smile.gif" border="0">

Interesting note: The dieseling has not happened the last two days I drove to work... <IMG SRC="smilies/confused.gif" border="0">

The carb was just rebuilt by a professional (I very rarely ever pay anyone to work on any of my vehicles...this was the first time in about 6 years).</STRONG>

Last time I had that problem it was solved by going to higher octane gas.
 

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Yeah I got something hangin for you. Hey Dave what rpm do you have that $100.00 dollar truck set at? With a manual it should be around 600 to 700 rpms at idle, and if the idle is too high that will make it diesel.I was thinking of the 3 other vehicles I have had dieseling prob. and I am pretty sure it was a carb prob. Call the shop that just built that and ask them. It is strange that its an intermitent problem. Did you run fuel dryer through yet this year?
 
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