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Does change adv curve, engine run hotter?

1538 Views 8 Replies 4 Participants Last post by  Jim_66SS
I put in lighter springs so that the distributor advance comes in sooner. Now the car seems to run about 23* hotter. This is on a stock 66 396/360hp. Is this normal? Thanks.
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with orgional springs total didn't come all in until about 5000 rpms, so total was never all in. with lighter spring total is all in around 3500 rpms, so when running at 2800 on the hwy there is now more advance. The more advance is what I was thinking was causing the higher temps.

So Hank, what your are saying is that running more advance at 2800 rpms should not cause more heat. Thanks.
Thanks Scott. Just got the spring kit a few weeks ago and installed it then. Had the car out yesterday for about 100 miles and it ran at about 190 degrees, guessing by looking at the old temp guage (thermostate is 185). Mostly hwy traffic; but some in town and outside temp was about 70 degrees.

Yes, not sure about the cam; but best guess is a stock gm cam from 1970 CE 402/350hp short block , which is bored 30 over. Stock 1966 702 heads and stock1966 holley intake, stock 1966 water pump, stock harrison radiator, and stock 1966 holley carb. Don't know about the pistons; I imagine they were replaced when the engine was bored in 1980. Compression is even @ around 180 per cylinder.

I am running a factory SB clutch fan from the 60's which sits about 1/4" further inside the fan shroud than origional. But I think it is OK.

I don't think I gave the car a good enough test the first time I ran it this spring. Just a short trip around town and when I parked the car and shut off the engine, I measured the engine temp with an infrared guagae and it red about 208 for the block and heads. Will have to test the car some more.

I tested two sets of the springs that came in the mr. gasket kit. By Using a mark on the balancer that was 1/10 the circumferance from the 0 mark. Silver was all in at about 3000, gold was all in at about 3600, and black I guest assumed was the stiffest spring and didn't test it. With My original springs total was all in at about 5000. I deceided to use the silver spring. It looked like the distributor was adding about 30* at the balancer. ( The 66 chassis manual I have says to set initial at 4* and the distributor mechanical is 0* at 900, 14* at 1275, 19* at 1600 and 30* at 5000)

I set the inital timing at 10*.

I think the vacuum cannister adds about 14*at idle. Origional specs says 0* at 7" and 12* at 12". Car idles at about 12" and when crusing at around 2600 rpms reads at about 17".

I rarely drive the car over 4000-4500 rpm. Usually at around 2700 rpms on the hwy.

If the distributor adds 30* as it seems should I set the initial at 6*? That would give a total of 36* plus the vacuum advance which I think is around 14*. Or is it OK to leave inital timing at 10*? Also seems like you are suggesting I use the lighter springs, so total come in sooner. I generally use 91 or 92 octane fuel, since that is what is available here in MN. I did order some of the supreme 130 today and plan to try that. Also have some of the Crane breakin lube that you suggested to add to the oil. THANKS.
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Thanks for all you help Scott. I did try the initial at 16*, it ran at idle; but really pinged when accelerating. Think I will drive the car and check the temp with the infared temp guage, then change to the lighter springs and check the temp. When I talked to the former owner who rebuilt the engine in the early 80's, he thought he only bored it and did a valve job; but that was trying to remember back 25 yrs.
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