Starting issues after reaching operating temperature

[Bubba Aaron]

I have a 68 c10 with a 400 sbc. It's runs 11:1 compression with Keith black pistons. It has a edelbrock performer rpm top end. 850 speed demon carb and a complete MSD 6AL ignition. I run a electric water pump and fan and just recently had a 18 circuit wiring harness installed. As well as a new hi torque mini starter. My issue is after I start my pickup and it get to operating teperature and turn it off it won't start untill it cools. It does this untill my battery drains. I just had my alternator checked and it passed. I was told not to ground my battery to my aluminum heads so I moved the ground to the frame and i still have the same issue? Thx for any advice anyone can give.
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[68gmsee]

First, welcome to the site...

I'm assuming here that when it does run you have no issues with it until it gets up to operating temp.

Since I'm not familiar with any carb but quadrajets the first thing to check is the choke, if you have one, to make sure it opens up completely when warmed up.

Next is to check inside the carb throat to see if it is flooding. Check with a flashlight and see if you can detect any dripping or a strong gas smell. You should notice black to dark gray smoke on startup out the tailpipe.

Check the battery cables at the end connections to make sure they're clean and if they're old, replace them. They corrode internally at the connection and it's not visible because of the insulation.

Check the battery posts with a vdc meter for 13.5 to 14.5 volts give or take. Mine checks out at about 13.8 volts when idling.

The only other thing that's a possibility is if the piston rings were not gapped correctly and expanding when engine is warm seizing the engine until it cools and they contract again. I've seen this only once but it can happen.

[southern parts]

check your timing too

[Bubba Aaron]

The piston ring issue sounds like a possibility. Because shortly after getting my engine built I was getting oil spitting out my dip stick. So when I took it to a mechanic other than the one who put the engine together to do a compression test I was loseing compression anywhere from ten to twenty five percent compression per cylinder. So when I took it back to the mechanic who built it he reved the engine and poured automatic transmission fluid into The carb while reving it. After doing so the blow by stopped and oil stopped coming out the oil dipstick. could this hAve caused the ring gap to expand? Also the timing is at 14 degrees advanced if I remember correctly.
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[68gmsee]

Originally Posted by Bubba Aaron

..... could this hAve caused the ring gap to expand? Also the timing is at 14 degrees advanced if I remember correctly.
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No. What he probably did is seat the rings in. Some recommend driving at different speeds and revving the engine several times while driving to introduce raw fuel into the cylinder walls. This removes the residual oil or dilutes it so the rings can seat quicker. The revving and adding tranny fluid does the same thing.

Play with the timing some. Maybe move it to 8 or 10 degrees btdc. Also check the vacuum advance to make sure it's working (you can use mouth suction) then hook it up to manifold vacuum if it's on ported vacuum.

[Bubba Aaron]

It doesn't die on me. But when I shut it off there is no squeak but it does stay on for a second or two when the ignition is off an it sounds like pressure being released.
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[Chevyman680063]

I had a similar issue with mine several months back and it turns out it was a hot start problem. The heat from the motor/intake was boiling the gas in the carb. I had to wait several minutes until it cooled down before it would start. I put a carb spacer on and it fixed the problem.

[hjewell2]

I dare say it is heat soak after you shut it off. try a 160* T-stat if you do not have one in already. 14* to 16* initail is normal for spicy motor what is the LSA and duration for the cam Maybe you can back it off tad. I myself never worry about initail I check for total advance 36*@ 3000 rpm. Does it crank over or does it ring the flywheel and not rollover when at this heat soak period. my LT1 motor is 11-1/2 with pop up pistons. when it hits the
90* mark its gets cranky (LOL) I know to let it set for an hour before restarting. At the racetrack I use fans to cool the engine bay between runs. Hope this helps.

[68gmsee]

Originally Posted by Bubba Aaron

It doesn't die on me. But when I shut it off there is no squeak but it does stay on for a second or two when the ignition is off an it sounds like pressure being released.
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Sorry, I was responding to another post on the squeak and inserted into this one by mistake.

I have heard of what Chevyman mentioned on some carbs. It may be worth a shot.

[Bubba Aaron]

Hjewelle it's doesn't crank over once it's warmed up. The electric fans turn on and run at full power. But it doesn't crank over
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[hjewell2]

Originally Posted by Bubba Aaron

Hjewelle it's doesn't crank over once it's warmed up. The electric fans turn on and run at full power. But it doesn't crank over
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I bet when it does not crank the temp is saying 210* 220* with analog temp gauge. Two things I check first, Starter then T-stat, New Mexico I would use a 160* T-stat 400 chevy does not like heat. A starter will heat soak as well and cause the dead battery sound.

[Bubba Aaron]

Hjewelle thx I'll change the therm. Cuz I just put a hi torque starter in it a few weeks ago. I'll keep you posted. Thx again!!!
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[CC69Rat]

Assuming it has headers on it? Do you have a heat shield on your starter .. or is the header pipe really close to the starter solenoid? Sounds like heat soak to me. (starter problems)

I usually run a big block high tourqe starter on high compression motors.

So when you turn the key it doesn't even grunt like it's trying to turn over it sounds like ?? .. if it tried to start up like it wasn't getting any fire then I would think carb or vapor lock / boiling in the bowls.

[Bubba Aaron]

So if it is heat soak on the starter won't a 160* therm help with that
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[CC69Rat]

I wouldnt think so. If the header is close to the solenoid that tube can reach 1000 degrees or more. Ots essentially cooking the solenoid. As it cools it fires off again.

You could also try to fab up an aluminum heat shield for it, just something to keep that crazy hot header tube off or at least away from the starter. I had a 69 camaro with this very same problem and the heat shield took care of it.
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[Bubba Aaron]

Would a header and exhaust wrap work?
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[kwmech]

Put the ground cable back on the engine. Get a 2 ga. cable and put it as close to the starter as you can. Also put a 2 ga. pos cable on the starter lug. Another possibility is the purple wire for the cranking, the eyelet over time has a tendency to attract oil from leaking valve covers and such. Another thing is the quality of the battery and the CCAs

[CC69Rat]

Post up a picture of the exhaust tubes as the run down by the starter. Pass side of course.. just to see how close it is..

Yes header wrap might help too..

Not saying this is the problem but definitely a possibility. Speaking from experience
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[SS Tim]

Originally Posted by kwmech

Put the ground cable back on the engine. Get a 2 ga. cable and put it as close to the starter as you can. Also put a 2 ga. pos cable on the starter lug. Another possibility is the purple wire for the cranking, the eyelet over time has a tendency to attract oil from leaking valve covers and such. Another thing is the quality of the battery and the CCAs

That is where I'd start. If you grounded the battery cable to the frame and not the head you may have a weak ground path for the starter. Running a ground cable from your frame ground point to the starter can really help.

[Bubba Aaron]

Well I wrapped the solinoid with a thermo shield and that didn't work. N I don't think it's vapor lock or I'm assuming. Cuz the engine doesn't even turn over once it turns of. I'm thinking the rings are seizing the engine. But what if I get the rings changed and the problem persists.
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[SS Tim]

If the motor had a mechanical issue the starter would try to do something. A solid soleniod clunk but nothing turns. Have you tried hot cranking with the headlights on? If the starter is stalling they would go out.

[Stevo427]

Starter like above or I'd check the timing.

[68gmsee]

Originally Posted by Bubba Aaron

Well I wrapped the solinoid with a thermo shield and that didn't work. N I don't think it's vapor lock or I'm assuming. Cuz the engine doesn't even turn over once it turns of. I'm thinking the rings are seizing the engine. But what if I get the rings changed and the problem persists.
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Okay, what if you don't turn it off? Does it stay running?

If I understand you correctly, the engine isn't even trying to turn over once you turn it off. In other words if you have someone try to start it, you don't hear a click or anything that sounds like the starter is at least making an effort to turn the engine. Right?

[CC69Rat]

Does it have an HEI in it? maybe that resister wire?

[Bubba Aaron]

Correct 68 gmsee. Like the starter ales a half turn n that's it then just clicks after that
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