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Old 03-13-2019, 05:22 AM   #1
tino0217
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71 C10 dying after five minute cruise

Recently I did a compression check on my 71 C10 small block it checked out fine shortly after that the timing is all whacked might have the firing order wrong rectified that problem and had to redo the timing now the truck is getting hot after about 10 minute drive sometimes I can go 20 minutes in the neighborhood getting as high as 40 miles an hour next day I can go two and a half miles and it bogs out like it's too hot or it's flooding replace the radiator put in a new water pump change the thermostat put in and Electric fuel pump and it's still doing the same thing bottom hose is cold cold oh and I put in a new heater core but currently the heater is not connected I'm waiting on some parts any ideas would be greatly appreciated because this is driving me nuts and this is my daily it's even starting to Boggle my mechanic
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Old 03-13-2019, 08:55 AM   #2
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Re: 71 C10 dying after five minute cruise

Some questions that come to mind that might help figure out whats going on.

Was everything fine before you checked the compression?

What do you have your timing set at? Base, all in, all in RPM, vacuum. Manifold or ported vacuum?

When you say hot, is the gauge pegged? My gauge reads about 3/4 with a 195 thermostat. Have you verified the temperature or the block / head using an infrared thermometer / temp gun?

How is the electric fuel pump run? Is it inline with the old mechanical pump, or did you bypass it? All new hoses? Did you check the sock and any other fuel filters? Did you verify the flow of the old mechanical pump, or the new electric one?

What carburetor do you have?

Points or HEI?

How did the plugs look when you pulled them?



It wounds like whatever it is, is getting worse. Coil, HEI module, and fuel pump are 3 things that tend to run fine cold, then get worse when the engine heats up when they are failing.

I've heard some aftermarket carburetors are sensitive to heat, but I don't know 2 and a half miles would be enough to do that.

Another thought is that you are running lean. The choke gets you rich enough to run fine, then when it comes off, you are too lean.

If the ignition is too far retarded, it will run better with the rich mixture, then worse with the proper mixture with the choke off. The rich mixture ignites faster. Retarded ignition is also said to lead to overheating.
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Old 03-13-2019, 01:26 PM   #3
D.PASSMORE
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Re: 71 C10 dying after five minute cruise

Combustible engine runs on fire and gas. So, you should try and eliminated one of the two. It might be easier to zero in on the problem.

My first thought is that if it has a HEI, check ignition module, see if the engine is firing after it dies.

Good start...
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Old 03-13-2019, 09:51 PM   #4
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Re: 71 C10 dying after five minute cruise

You might want to learn what this dot . thing means as well as upper case letters begin sentences. That said, you need a new mechanic if you've randomly replaced all those parts. Incorrect timing is rumored to cause things to get hot, as is a lean condition, but I'd think it would happen more slowly.
Bogs out like it's too hot? Go get an aftermarket temp gauge from the nearest parts store and find out what the temp is.
Engine swap? As I recall serpentine systems, and/or some old 90s LT1 water pumps ran backwards. Might see if the water pump turns the right way.
Definitely recheck the the distributor to plug wire locations since that was changed. Also understand on an SBC, the driver's side is 1357 and pass is 2468.
Try spending an hour searching the internet with a question like why is my 350 overheating.
Good luck.
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Old 03-15-2019, 09:05 AM   #5
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Re: 71 C10 dying after five minute cruise

Quote:
Originally Posted by franken View Post
That said, you need a new mechanic if you've randomly replaced all those parts.
100% agree. Randomly replacing parts without troubleshooting seems to lead to even more questions as you don't know if the new part introduced any new issues. Don't introduce a change until you are 90%+ sure that part is the issue.

Also sounds like OP is tackling 2 issues at once, overheating and bogging. Take it 1 at a time. Deal with the overheating first as you can do that with the engine idling, then tackle the drivability issue.
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Old 03-15-2019, 10:37 AM   #6
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Re: 71 C10 dying after five minute cruise

These old engines are just about as simple as it gets , Throwing new parts at it looking for the miracle fix doesn't work . It's not your fuel pump the old mechanical one worked for 50 years , Sounds like your timing is set too far advanced (causing heat build up ) and watch this video another member just posted with his stalling and no power issue , Your problem could be as easy as replacing the fuel pick up tube sock in the gas tank . it doesn't matter that his is a 6 and yours is a V8 the systems work the same .


Post some pictures of the engine .

https://www.youtube.com/watch?v=D8EW...ature=youtu.be

Read his thread .

http://67-72chevytrucks.com/vboard/s...d.php?t=779051
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Old 03-18-2019, 04:12 AM   #7
tino0217
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Re: 71 C10 dying after five minute cruise

Turned out to be a couple of things. The glass filter was plugged and the modulator was shot. I ended up putting on a new electronic fuel pump, not to crazy how it sounds somtimes but it supposed to be safer. The things i did replace were needed, heater core leaking as well as the water pump. I picked up a rebuilt radiator for $20 so it wasn't all bad. My peace of mind is a lil bit more at ease as this is my daily. Thanks for your input much appreciated God bless
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