I'm working on my bosses 70 Chevelle, healthy 350, worked over iron heads, Edelbrock rpm intake, 9.5 comp, unknown cam ( sounds like 280 or so), 3/4 length coated headers, custom serpentine belt setup, 4 core aluminum rad, all new hoses (spring in lower hose), new heater core, 5000 cfm electric fans with controller.
I did not assemble long block, it was built by previous owner 10+ years ago and has sat for last 5 completely dry.
Now for the issue........
Rev'd up to 1200rpm or running down the road it holds a solid 180, never moves, right at the thermostat temp no matter how hard I run it. At or near idle the temp fluctuates 40 degrees and does it really quickly. It will hold 180 for anywhere from 10 seconds to 1 minute then it will go from 180 to 220 in 5-6 seconds then will drop back to 180 after 10-15 seconds, it just bounces all over the place. rev it back up to 1200 and it will settle back to 180 after 15 seconds or so.
The temp at sending unit mounted in the top of intake on drivers side matches what the mechanical gauge reads (verified with infrared thermometer).
I'm positive there is no air in system, picked up nose of car 5 feet with tow truck and ran for 30+ min.
So far I've gone thru 4 thermostats, 2 different brands, 2 were stock style, 2 are high flow.
Pulled the new PRW high flow WP and verified it is a reverse rotation (visually looked at veins then hooked it to a drill).
I flushed block back and forth into a container and no sediment.
Flushed the new 4 core rad back and forth verifying no flow issues.
Flushed new heater core both ways.
It doesn't lose coolant, no bubbles in radiator.
Idling exhaust tube temps are 240-260 at all cylinders, but the drivers side head is 40+ degrees hotter than the same point on the passenger side head measuring on the intake side of both.
Verified timing marks and set advance at 12 idle 34 all in.
idle is not running lean and is not overly rich either.
lower rad hose temp is 140-150 while temp swings are happening so rad is cooling enough.
I called Eddies Motorsport, the manufacture of the serp system, they haven't had anything like this reported. Tech guy was very helpful and knowledgeable, but we are left scratching our heads.
I'm pretty confident that this is a flow issue in the drivers side head, but am a loss as to how to fix. I just ordered a new WP from a different manufacture, maybe the PRW doesn't flow evenly?
Anything you guys can think of that I may have missed.
I did not assemble long block, it was built by previous owner 10+ years ago and has sat for last 5 completely dry.
Now for the issue........
Rev'd up to 1200rpm or running down the road it holds a solid 180, never moves, right at the thermostat temp no matter how hard I run it. At or near idle the temp fluctuates 40 degrees and does it really quickly. It will hold 180 for anywhere from 10 seconds to 1 minute then it will go from 180 to 220 in 5-6 seconds then will drop back to 180 after 10-15 seconds, it just bounces all over the place. rev it back up to 1200 and it will settle back to 180 after 15 seconds or so.
The temp at sending unit mounted in the top of intake on drivers side matches what the mechanical gauge reads (verified with infrared thermometer).
I'm positive there is no air in system, picked up nose of car 5 feet with tow truck and ran for 30+ min.
So far I've gone thru 4 thermostats, 2 different brands, 2 were stock style, 2 are high flow.
Pulled the new PRW high flow WP and verified it is a reverse rotation (visually looked at veins then hooked it to a drill).
I flushed block back and forth into a container and no sediment.
Flushed the new 4 core rad back and forth verifying no flow issues.
Flushed new heater core both ways.
It doesn't lose coolant, no bubbles in radiator.
Idling exhaust tube temps are 240-260 at all cylinders, but the drivers side head is 40+ degrees hotter than the same point on the passenger side head measuring on the intake side of both.
Verified timing marks and set advance at 12 idle 34 all in.
idle is not running lean and is not overly rich either.
lower rad hose temp is 140-150 while temp swings are happening so rad is cooling enough.
I called Eddies Motorsport, the manufacture of the serp system, they haven't had anything like this reported. Tech guy was very helpful and knowledgeable, but we are left scratching our heads.
I'm pretty confident that this is a flow issue in the drivers side head, but am a loss as to how to fix. I just ordered a new WP from a different manufacture, maybe the PRW doesn't flow evenly?
Anything you guys can think of that I may have missed.
