Just built 355 overheating!

Frankenchevy · Jul 1, 2020

Bear in mind, vortec heads don’t want as much timing as other first gen heads. They mix more efficiently and the flame front travels faster. Depending on your gearing, your freeway cruise will be near 2500rpm. If your setting at a low load, freeway speed (base timing + high vacuum advance + centrifugal advance) keep your feelers on for pinging.

Not sure how sophisticated tbi era knock sensors are or if they’re even a thing in that era...

1987 GMC Jimmy · Jul 1, 2020

The ESC circuit is pretty good at quickly catching knocks and adapting. I say quickly, but that concedes that a baud rate of 160 is quick. It’s quaint, but I like it.

Respectfully, I think electric fans and seven core radiators are a deflective solution that allow the problem to remain. If it was a motor out of a WWII plane I could see it, but that’s not the case here. I think we need to take a step back, take a shot of your preferred spirit, and every variable presented here needs to be considered. The first thing I thought of was also the backwards rotation water pump or something hinky in the assembly. I’d revisit all the suggestions named here because they’re all viable.

redneck_reed78 · Jul 3, 2020

Update on the temp problem, two sending unit in a row were bad, or the guage. Verified with a heat gun. But my potential timing issue still remains, so I will have to work on that tomorrow. Thanks.

AZ-520 · Jul 6, 2020

I got a .060 over SBC with 454 radiator and it runs fine even in Tucson AZ 110 summer day. I would ditch TBI and toss in HEI and carb. I also like to use those old analog temp gauge and oil pressure on the engine direct to the block for an extra reference to the dash gauges.

https://www.summitracing.com/search...e-gauges/part-type/gauges-analog?fr=part-type

https://www.summitracing.com/parts/bkc-21-0077

potent rodent · Jul 6, 2020

i think u need to look at your timing all gen 1 small blocks run around 34 to 36 total timing, thats one of your over heating problems , the next is get u a thermostat in it , coolant is going through the system to fast to cool it down . how mutch total timing are u running?. do u have a shroud , what shape is your rad in .

Just built 355 overheating!

Frankenchevy

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1987 GMC Jimmy

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