[lust4speed]

Originally Posted by steve25

Fact!
Above 30 mph no car needs a operating fan

Actually I have several cars that need the fan at highway speeds because of a high pressure area under the engine compartment. This blockage is enough to pretty much equal out the flow through the radiator. Not unusual for my 67 GTO to have the clutch fan engage to maintain coolant temp on a hot day buzzing down the freeway.


I always wanted to try a home made air dam positioned back from the front bumper a little to redirect the majority of airflow from under the car. This would make a low pressure area that would allow easier airflow through the radiator. GM started adding air dams on quite a few of their cars in the mid-70's.

[Formulajones]

Originally Posted by tjs72lemans

I wondered if the timing could be an issue with long slow uphill climbs. I do have the TCS disconnected.
The radiator is filled about an inch below top. I didn't notice any spit out in the past few runs after shut down. I would've noticed that in the garage for sure. But, it may be still trying to find that sweet spot in the level.
I do not have the frame horn seals. I do have the lower radiator core support air dam though.
I'm not sure what my total advance is. I do know it was set on the dyno with 12 initial.
I really need to check and make sure my vac advance is functioning. It's a new cheap HEI, but seems to work well otherwise.
Overflow hose is connected and tight. I've checked the coolant level a few times in the last runs and it seems to be close to an inch below top. That's about where I filled it with 50/50 anti freeze premix when engine was installed.
This sender/gauge from Bosch is mechanical, so I can only assume these are calibrated and tested to read correctly since the line and gauge stay connected at assembly. My temp gun does read about the same.
During rebuild, I initially bought a 160 thermostat and switched it to a 180 due to the talk on this site about running too cool. Maybe with it running hotter than the 180 thermostat, I should consider going to a 160.

My hunch is that since you disconnected the TCS, your vacuum advance is not working. Most cars by this time ran the vacuum advance through a transmission control spark, where it would only add the additional timing when the transmission was in high gear or reverse. So if you have everything hooked up the way the factory intended, and then disconnected the TCS, that effectively kills the vacuum advance for the engine.

I usually just bypass the vacuum advance from the TCS so I have the additional timing in all gears all the time with these setups. Smog police don't like it but it's a pretty easy switch back and forth if you have to go through that sort of thing.

[steve25]

I agree that those pre 68 cars had a need for better less leakage rad shrouds then what they where made with.

[tjs72lemans]

I have the TCS on the intake, but just bypassed it as you have done.

[Schurkey]

Originally Posted by tjs72lemans

Timing at dyno session at initial at 12 degrees. After market HEI, advance not checked.

You need to verify the amount of centrifugal AND vacuum advance; and what RPM and vacuum level that advance is "in".

Originally Posted by tjs72lemans

Stock carb rebuilt/tuned by Cliff.

As long as the idle mixture screws are adjusted properly, and you have appropriate fuel pressure, it's just about guaranteed to have enough fuel to not be running lean.

Originally Posted by tjs72lemans

The stock fan definately moves the air.

Are you comparing it to a fan clutch that's actually engaged? Lots of clutch fans "seem" to move a lot of air...and then the clutch engages and Dorothy and Toto fly past you.

Modern fan clutches don't engage until the engine is somewhere around 200 degrees, maybe more. So there may be some benefit to adjusting the fan clutch engagement as said previously.

Originally Posted by tjs72lemans

It never puked, just seemed warmer than I was expecting. I figured it may be tight and running warmer, but does a good job with temps in the 90's through town.
I figured this 30 degree angle hill to top of bluff would be good for some break in runs up and down. But, found it doesn't like that right now.

IF (big IF) the gauge is accurate, 220 is a long way from hot enough to cause damage if there's no boilover and no detonation.

GM doesn't turn on the electric fan until 220.

The "HOT" light doesn't turn on until 240--265 degrees, depending on sending unit and location.




For fook's sake DO NOT put in a 160 thermostat with a hole drilled in it. IF (big IF) your thermostat is defective, get another 180 or 195, and don't drill any bigass holes in it. The only time the drilled hole is an advantage is when you're filling the cooling system after servicing it; and a .040 hole bleeds air just as well as a .125 hole or two. Filled properly, you don't need a hole at all, which is why most thermostats don't have one installed at the Thermostat Factory.

[Schurkey]

Originally Posted by lust4speed

I always wanted to try a home made air dam positioned back from the front bumper a little to redirect the majority of airflow from under the car. This would make a low pressure area that would allow easier airflow through the radiator. GM started adding air dams on quite a few of their cars in the mid-70's.

No. At least, not exactly. Put the air dam directly under the radiator support.

High-pressure air in front of the radiator, low-pressure air behind. Encourages air flow through the rad.

[Cliff R]

You mentioned clearancing the water pump, is it a new pump? Does it have a stamped steel or cast iron impeller on it?.......

[tjs72lemans]

New pump and is cast iron.
The clutch fan must be engaged while idling, because it moves a lot of air even when car is cold and first started. Not sure if it blows any more with it at a high temp.
I have read another post with someone's numbers on thermostats and opening temps. It seems the 180 (as I have), operate around 12 degrees hotter. I used a number of 195 in my thread, but it does seem a bit less than that as I peak at the gage. It could very well be 192 or 193. So, I assume it operates as it should.