Can't figure what's going on with my truck - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Cochise · 05-27-2012, 03:31 PM

1970 Chevy C-10 with 350/350 out of a '72 Cheyenne. I was having trouble starting my truck back after it ran for awhile. My mechanic who works at the dealership I work walked me through the motor install and told me it was either the starter or the HEI distributor shaft may be stuck. I took the wires off the cap, looked below the rotor bug and decided since it moved freely that it was the starter. After I replaced the starter I put everything back the way I had it and would turn over fast, but wouldn't start. I pulled the cap back off and noticed that I pointed the rotor at number 1, but for points, so I went to TDC, raised dist shaft and pointed at number 1 for HEI, put it all together and I either get a huge backfire (at midnight) or I get fire through carb. I have checked the firing order 8 times to be sure and clockwise.
1. I am not positive that the 3 pin wire on the Dist is plugged all the way in, could that be?
2. What else could it be?
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GASoline71 · 05-27-2012, 03:36 PM

Backfire through the carb is timing. A valve is still open during a combustion cycle. You need to find TDC again, and set your rotor to point either straight ahead or at the #1 cylinder... it really doesn't matter as long as the #1 plug terminal on the cap is relative to where you set your pointer.

Gary

Cochise · 05-27-2012, 04:05 PM

Do I have to bump it, or can I manually move it?
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snacks · 05-27-2012, 04:08 PM

what he said find tdc ,where the rotor is pointing is 1 start from there as long as your not 180 out rotor should be in the 3 4 or 5 oclock position,

Cochise · 05-27-2012, 04:31 PM

It sounds like from what everybody is saying that I have done everything right, except maybe I AM 180 out. I didn't bump to TDC, I just turned it to TDC by turning it by hand, could that be it?
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Mcnasty · 05-27-2012, 04:54 PM

Make darn sure you're TDC on compression stroke on #1 cylinder!!! You can do this by putting your finger firmly over the spark plug hole to create a seal then rotate the motor by hand. Listen for the "hiss". Start from there.

Cochise · 05-27-2012, 05:01 PM

Yep, did that too, still didn't work, but I'll try to do it again tonight
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Cochise · 05-27-2012, 10:48 PM

Thank you very much for your help....by turning it by hand I wasn't able to really hear the pssh, even by turning it by hand with a ratchet. I had my wife bump it and it ended up pointing at 1 o'clock I moved it and reset it and he fired up after a little walking around with the timing....now I can sleep
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GASoline71 · 05-28-2012, 09:20 AM

Good deal. Sounds like you were possibly bringing it up on the exhaust stroke. Now that she's on the compression stroke... all is good.

Gary

ChevLoRay · 05-28-2012, 11:16 AM

Don't know about your engine, but remember the harmonic balancer has a rubber piece between the inner and outer parts....and, that the outer ring can shift over the years and what you think is TDC according to the timing marks, is actually off. Some engines are more prone to this than others, it seems. I'm not saying yours has such a problem, but there may be someone here who is new and didn't know that fact.

Those of us who grew up with points and condensor ignition systems have forgotten about some of the "finer points" that we learned at the time. OBDII is a wonderful thing, but some old school learning is still good.

I've seen people blame the carb for your problem, and then spend money that they didn't need to when the issue was as simple as yours was.

05-27-2012, 04:05 PM	#3
Cochise Junior Member Join Date: Apr 2006 Location: Rogers, AR Posts: 298	Re: Can't figure what's going on with my truck Do I have to bump it, or can I manually move it? Posted via Mobile Device

05-27-2012, 04:08 PM	#4
snacks Registered User Join Date: Jan 2009 Location: rocklin california Posts: 142	Re: Can't figure what's going on with my truck what he said find tdc ,where the rotor is pointing is 1 start from there as long as your not 180 out rotor should be in the 3 4 or 5 oclock position,

05-27-2012, 04:31 PM	#5
Cochise Junior Member Join Date: Apr 2006 Location: Rogers, AR Posts: 298	Re: Can't figure what's going on with my truck It sounds like from what everybody is saying that I have done everything right, except maybe I AM 180 out. I didn't bump to TDC, I just turned it to TDC by turning it by hand, could that be it? Posted via Mobile Device

05-27-2012, 04:54 PM	#6
Mcnasty Registered User Join Date: Mar 2011 Location: Maple Ridge B.C. Posts: 5	Re: Can't figure what's going on with my truck Make darn sure you're TDC on compression stroke on #1 cylinder!!! You can do this by putting your finger firmly over the spark plug hole to create a seal then rotate the motor by hand. Listen for the "hiss". Start from there.

05-27-2012, 05:01 PM	#7
Cochise Junior Member Join Date: Apr 2006 Location: Rogers, AR Posts: 298	Re: Can't figure what's going on with my truck Yep, did that too, still didn't work, but I'll try to do it again tonight Posted via Mobile Device

05-27-2012, 03:31 PM	#1
Cochise Junior Member Join Date: Apr 2006 Location: Rogers, AR Posts: 298	Can't figure what's going on with my truck 1970 Chevy C-10 with 350/350 out of a '72 Cheyenne. I was having trouble starting my truck back after it ran for awhile. My mechanic who works at the dealership I work walked me through the motor install and told me it was either the starter or the HEI distributor shaft may be stuck. I took the wires off the cap, looked below the rotor bug and decided since it moved freely that it was the starter. After I replaced the starter I put everything back the way I had it and would turn over fast, but wouldn't start. I pulled the cap back off and noticed that I pointed the rotor at number 1, but for points, so I went to TDC, raised dist shaft and pointed at number 1 for HEI, put it all together and I either get a huge backfire (at midnight) or I get fire through carb. I have checked the firing order 8 times to be sure and clockwise. 1. I am not positive that the 3 pin wire on the Dist is plugged all the way in, could that be? 2. What else could it be? Posted via Mobile Device

05-27-2012, 10:48 PM	#8
Cochise Junior Member Join Date: Apr 2006 Location: Rogers, AR Posts: 298	Re: Can't figure what's going on with my truck Thank you very much for your help....by turning it by hand I wasn't able to really hear the pssh, even by turning it by hand with a ratchet. I had my wife bump it and it ended up pointing at 1 o'clock I moved it and reset it and he fired up after a little walking around with the timing....now I can sleep Posted via Mobile Device

05-28-2012, 11:16 AM	#10
ChevLoRay Old Skool Club Join Date: Jun 2001 Location: Benton, AR "The Heart of Arkansas" Posts: 10,880	Re: Can't figure what's going on with my truck Don't know about your engine, but remember the harmonic balancer has a rubber piece between the inner and outer parts....and, that the outer ring can shift over the years and what you think is TDC according to the timing marks, is actually off. Some engines are more prone to this than others, it seems. I'm not saying yours has such a problem, but there may be someone here who is new and didn't know that fact. Those of us who grew up with points and condensor ignition systems have forgotten about some of the "finer points" that we learned at the time. OBDII is a wonderful thing, but some old school learning is still good. I've seen people blame the carb for your problem, and then spend money that they didn't need to when the issue was as simple as yours was. __________________ Member Nr. 2770 '96 GMC Sportside; 4.3/SLT - Daily driven....constantly needs washed. '69 C-10 SWB; 350/TH400 - in limbo The older I get, the better I was.



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