Can a change in the timing cause an increase in engine temp. I change my Distributor and the vacuum advance doesn't seem to be working on the new distributor. Engine is running hotter. Could this be caused by the non-working vacuum advance or did the thermostate start sticking? Thanks.
Can change in timing advance cause a temp increase
Jim_66SS
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Can a change in the timing cause an increase in engine temp. I change my Distributor and the vacuum advance doesn't seem to be working on the new distributor. Engine is running hotter. Could this be caused by the non-working vacuum advance or did the thermostate start sticking? Thanks.
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The Timing can cause the engine to run hotter..
Timing set at 8 deg adv with vac can disconnected. Then hooked up and it stayed at 8 Deg.???? Guess I might have got stuck on an original cannister for my 66. Is there anyway to check why the vac cannister doesn't work? Thanks.
James,yes retarded timing will make a motor run hotter.
1st thing,if your runng an aftermarket cam of any kind 8 deg base timing is way too retarded by 8-10 deg,you need at least 16-18 deg base timing so try that.
Also make sure you have the vac adv attached to full intake vacuum and not ported for full intake vacuum all the time.
If vac adv still doesnt wortk after verifying thats ok then you need to take a vacuum reading at oidle and then get a vac adv thats fully activated at approx 2" below the lowest idle vacuum reaind to ensure its always fully activated with motor running to ensure a stable idle.
Also,when you adv the base timing by 8-10 deg that will inc the idle speed which will likely activate the mech adv in the dist.
So when you idle it back down after adv the timing recheck the base timing to ensure its still at 16-18 deg and if not tweak the base timing iuntill its at 16-18 deg.
also ensure total isntr over 38 tops & if thats the case then you need to adj/recurve the mech adv for approx 20 deg all in by 2800 ish rpms.
Then 16-18 deg base + 20 deg mech in dist = approx 36-38 total.
Good luck.
Scott
1st thing,if your runng an aftermarket cam of any kind 8 deg base timing is way too retarded by 8-10 deg,you need at least 16-18 deg base timing so try that.
Also make sure you have the vac adv attached to full intake vacuum and not ported for full intake vacuum all the time.
If vac adv still doesnt wortk after verifying thats ok then you need to take a vacuum reading at oidle and then get a vac adv thats fully activated at approx 2" below the lowest idle vacuum reaind to ensure its always fully activated with motor running to ensure a stable idle.
Also,when you adv the base timing by 8-10 deg that will inc the idle speed which will likely activate the mech adv in the dist.
So when you idle it back down after adv the timing recheck the base timing to ensure its still at 16-18 deg and if not tweak the base timing iuntill its at 16-18 deg.
also ensure total isntr over 38 tops & if thats the case then you need to adj/recurve the mech adv for approx 20 deg all in by 2800 ish rpms.
Then 16-18 deg base + 20 deg mech in dist = approx 36-38 total.
Good luck.
Scott
Almost positive the cam is the original cam that came with the66 396/360HP. Car ran fine, and right at 185 degrees in 90 degree heat last summer. Initial timing was set at 8 deg adv and when I hooked up vac can it increase the timming. I am not sure how far the timming was advanced., the #'s on the cannister were 502 and 14. Mechanical advance of the original distributor varied up to 15 deg @ 5000 rpms accoriding to my book. Total timing seem to be around 36 degrees at the balancer when I ran the rpms up to near 5000 rpms.
Mechanical on the distributor is suppose to be 15 deg at distributor, which I think is 30 deg at the balancer, is that right? This winter all I did was replace the vacuum cannister with what was suppose to be an original vacuum can for the 66 396/360 hp engine. The numbers being 360 12.
After the engine ran hot, I check the timming and it was at 8 degrees and when I hooked up the vacuum can it did not increase,????. I pulled the distributor cap and there didn't seem to be a problem with how the distributor functioned. Thermostate seemed to kick in at 185 degree. So I thought maybe something was wrong with the vac can and this caused it to heat up. What do you think?
Vacuum advance is connected to the throttle plate on an original 360 hp 3419 holley carb as it came from the factory.
Not sure what a Mity-vac is or how to use it. Maybe there was a leak in the hose from the vac can to the carb. I think the vac is suppose to pull 12 degrees of advance at 14" of vacuum according to the book. So when I have initial timing set at 8 and hook up the vacuum advance with idle at around 700 rps, Should I get a reading of 20 or 32 degrees at the balancer?
Thanks everyone.
Outside temp is in the 50's again in MN, wo will have to wait for warmer weather.
Mechanical on the distributor is suppose to be 15 deg at distributor, which I think is 30 deg at the balancer, is that right? This winter all I did was replace the vacuum cannister with what was suppose to be an original vacuum can for the 66 396/360 hp engine. The numbers being 360 12.
After the engine ran hot, I check the timming and it was at 8 degrees and when I hooked up the vacuum can it did not increase,????. I pulled the distributor cap and there didn't seem to be a problem with how the distributor functioned. Thermostate seemed to kick in at 185 degree. So I thought maybe something was wrong with the vac can and this caused it to heat up. What do you think?
Vacuum advance is connected to the throttle plate on an original 360 hp 3419 holley carb as it came from the factory.
Not sure what a Mity-vac is or how to use it. Maybe there was a leak in the hose from the vac can to the carb. I think the vac is suppose to pull 12 degrees of advance at 14" of vacuum according to the book. So when I have initial timing set at 8 and hook up the vacuum advance with idle at around 700 rps, Should I get a reading of 20 or 32 degrees at the balancer?
Thanks everyone.
Outside temp is in the 50's again in MN, wo will have to wait for warmer weather.
Ok,then the 8 deg base should be ok since it ran ok temp wise last yr at that same base timing setting.
But i will say this,your motor seems to be very sensitive to timing temp wise but it should not be that sensitive to no vac adv unless you do in fact have a mild perf cam . Then in that case whats likely happening is with base timing at only 8 deg & needs to be approx 16-18 deg thats 8 to 10 deg retarded making the motor much more sensitive to loosing some timing from a non workng vac adv at idle/lower enoigne speeds. Now with the vac adv not working that took away at least 10 more deg timing if not more like 15+ & along with the retartded base timing that would definately make it run considerably hotter. But if you were for ex running 16-18 deg base timing the motor would have still lost the timing at idle from the non working vac adv but it would still have 18 deg base timing insted of only 8 being 8-10 deg more retartded making the motor more sensitive to loosing the vac adv at idle which is what makes me think you have an aftermarket cam in your motor.
Think about this,just about nobody/no engine builder buys a stock GM way over priced cam for a rbld. 999 out of 1,000 of these muscle car motors that were rblt in the past 15-20+ yrs got an aftermakret crane(in the past prior to going out of buisness)/comp/lunati/etc cam and i think your motor very likely has an aftermarket perf cam and you dont know it. Most people/engine rebuilders use the term loosly "i put a stock cam or stock type cam in the motor" when rblt but its just about never a true original stock GM replacement cam & even mild aftermarket perf cams need approx 16-18 deg base timing for best results/perf. Maybe once in a while it could be a blueprint cam from crane in the past but comps repl cams for muscle car motors state in the catalog that they are a little hotter for better perf with more duration & tighter LSA's and of those that i have installed they all neede approx 16-18 deg base timing too.
But if you get the correct vac adv hooke to full int vacuum the additionaltiming from tha will likely get the motor temps back down a few deg.
Well,enough of that.
Mighty vac is a hand held/operated vacuum pump that has a gauge on it which you can monitor to see at what vacuum lvl the vac adv starts to activate.
You need to take an idle vacuum reading and then simply get a vac adv thats full activated at approx 2" below the lowest idle vacuum to ensure its always full activated for stable idle & lowe speed engine operation.
If the vac adv on you old dist is of the same design and did work ok then maybe you could simply sawap it to your new dist .
Also,if it still runs hotter then it did last yr after getting vac adv working properly then try a new t-stat,they can go bad & or get partially stuck (not opening fully) at any time esp when sitting in off season for 3,4,5, months of non use then firing up the motor for the new cruise season .
Scott
But i will say this,your motor seems to be very sensitive to timing temp wise but it should not be that sensitive to no vac adv unless you do in fact have a mild perf cam . Then in that case whats likely happening is with base timing at only 8 deg & needs to be approx 16-18 deg thats 8 to 10 deg retarded making the motor much more sensitive to loosing some timing from a non workng vac adv at idle/lower enoigne speeds. Now with the vac adv not working that took away at least 10 more deg timing if not more like 15+ & along with the retartded base timing that would definately make it run considerably hotter. But if you were for ex running 16-18 deg base timing the motor would have still lost the timing at idle from the non working vac adv but it would still have 18 deg base timing insted of only 8 being 8-10 deg more retartded making the motor more sensitive to loosing the vac adv at idle which is what makes me think you have an aftermarket cam in your motor.
Think about this,just about nobody/no engine builder buys a stock GM way over priced cam for a rbld. 999 out of 1,000 of these muscle car motors that were rblt in the past 15-20+ yrs got an aftermakret crane(in the past prior to going out of buisness)/comp/lunati/etc cam and i think your motor very likely has an aftermarket perf cam and you dont know it. Most people/engine rebuilders use the term loosly "i put a stock cam or stock type cam in the motor" when rblt but its just about never a true original stock GM replacement cam & even mild aftermarket perf cams need approx 16-18 deg base timing for best results/perf. Maybe once in a while it could be a blueprint cam from crane in the past but comps repl cams for muscle car motors state in the catalog that they are a little hotter for better perf with more duration & tighter LSA's and of those that i have installed they all neede approx 16-18 deg base timing too.
But if you get the correct vac adv hooke to full int vacuum the additionaltiming from tha will likely get the motor temps back down a few deg.
Well,enough of that.
Mighty vac is a hand held/operated vacuum pump that has a gauge on it which you can monitor to see at what vacuum lvl the vac adv starts to activate.
You need to take an idle vacuum reading and then simply get a vac adv thats full activated at approx 2" below the lowest idle vacuum to ensure its always full activated for stable idle & lowe speed engine operation.
If the vac adv on you old dist is of the same design and did work ok then maybe you could simply sawap it to your new dist .
Also,if it still runs hotter then it did last yr after getting vac adv working properly then try a new t-stat,they can go bad & or get partially stuck (not opening fully) at any time esp when sitting in off season for 3,4,5, months of non use then firing up the motor for the new cruise season .
Scott
Thanks for the help Scott.
I will have to check into the T-Stat more thoughly. I put in a new Stewart Warner High Flow last spring. Maybe it was sticking. I will have to see if a friend has a mity vac. I was told by a previous owner that he did what appeared to be the 1st rebuild the engine in 79 or 80, and reused the cam that was in the car. I check the lift and it was within a couple of .001th of what the book said the 66 cam had, so thought it likley original to block.
When it warms up here again in MN I will be able to check things out.
I will have to check into the T-Stat more thoughly. I put in a new Stewart Warner High Flow last spring. Maybe it was sticking. I will have to see if a friend has a mity vac. I was told by a previous owner that he did what appeared to be the 1st rebuild the engine in 79 or 80, and reused the cam that was in the car. I check the lift and it was within a couple of .001th of what the book said the 66 cam had, so thought it likley original to block.
When it warms up here again in MN I will be able to check things out.
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