engine backfires & shudders ?
 

Summertime Tucson is HOT !
My temp gauge reads 200+ degrees late in the day at freeway driving & the engine will occasionally backfire thru the carb.
30K miles on a Chevy 350 crate engine, Edelbrock intake & 4-bbl carb, headers with dual exhaust, no cat or emission controls, fresh rebuilt 700R4 A/T. 5-year old replacement HD radiator 4-row with a recent flush, 160 degree thermostat & flowmaster water pump. Runs great in the mornings 180 degrees using the A/C unit. Problem is driving home; ambient temp 100-110 degrees, freeway cruising in OD 1800 RPM doing 65 MPH, running the A/C unit, it is another HOT damn summer day & I am not pushing it, the engine starts to overheat, etc . . .

Likely it's the carburetor that is running too lean, increasing the engine heat. Might be you need a new distributor cap and rotor too.

Q: why are you running a 160 F thermostat? I wouldn't run less the 180-185F in a vehicle, else you won't get as clean a burn.

Cripes, with a four row radiator you shouldnt have any overheating problems at all. What year and make is your Chevrolet?

Summertime Tucson is HOT !
My temp gauge reads 200+ degrees late in the day at freeway driving & the engine will occasionally backfire thru the carb.
30K miles on a Chevy 350 crate engine, Edelbrock intake & 4-bbl carb, headers with dual exhaust, no cat or emission controls, fresh rebuilt 700R4 A/T. 5-year old replacement HD radiator 4-row with a recent flush, 160 degree thermostat & flowmaster water pump. Runs great in the mornings 180 degrees using the A/C unit. Problem is driving home; ambient temp 100-110 degrees, freeway cruising in OD 1800 RPM doing 65 MPH, running the A/C unit, it is another HOT damn summer day & I am not pushing it, the engine starts to overheat, etc . . .

Backfire through the carb is ignition . When did this start after the new engine? Edelbrocks are great carb, you might look at the fuel line routing. Make sure that it isn't routing around a heat source such as exhaust.

The engine has 30K miles on it now. The carb & intake are both Edelbrock Performer & installed new about 2 years ago. I just rerouted the fuel line & fuel filter within the engine bay a week ago,also replaced the fuel filter before the electric fuel pump mounted to the frame near the rear relocated fuel tank. The engine starts up & runs fine in the AM. Problems start in the late day, I am sure the Southern Arizona heat and subsequent engine heat build up is the main problem. It has been averaging 105 degrees for weeks now. I have ordered a replacement Edelbrock electric fuel pump & regulator, insulation for fuel line, distributor cap & rotor. Stay Tuned . . .