I run an ancient 7 blade stainless flex fan with stock pulleys. I also use a stock 4 core radiator. No A/C though. But it stays cool. Just did 2500 miles with it cross country. But I also think I'm a little further from the edge of detonation than you are even though I have 11.4 compression ratio. I can crank in more timing.

One thing I've learned is that there is usually little value in *cleaning/rodding* an old radiator. Yes it gets the tubes flowing, but the real issue is the *insulation* that has built up inside the tubes like a thin coating. It's very common and coolants react to heat in various ways...but usually they create a coating at hot spots that only makes things worse. I see it all the time in the diesel world. Recoring a stock radiator gets good heat transfer again through the tubes..just as the new Dewitt's is going to do.

JIM

 

Hey JIM,

What method do you use to limit a vacuum advance?

Example, I get about 16-17* out of my vac advance at 1500-3000 ish.... I would to limit that vac advance to about 7-8* max....or cut it in half per say.....without welding on the track, can I just use a small nut/bolt combo screwed in the track to stop the vac adv arm on the pick up?

 

Crane sells a stepped limiter plate or you can make one from sheetmetal.

http://cranecams.com/pdf/254g.pdf

 

thanks for the link!

Not sure if that will work with an MSD 8572 or not though..... I will pop the cap off this weekend and take a looky....for some reason I thought it was just a track on the VA and the arm from the diaphragm slid in it pulling on the p/u coil....I figured I could rig something up...maybe not.

 

TEST DAY #5......90*, 60% humidity



Changes made:
Everything the same as last test except I set the locked timing at 32*, I made a vacuum advance limiting plate and limited my total timing to 36.5* at 3000 rpms....so basically 4.5* worth of vacuum.



Test:
Not quite as hot as last week's test...about 2-3* cooler ambient temps. I drove the exact same 30 mile test route keeping the rpms around 2950-3000rpms.... Car ran 190-191* the entire time....I mean the gauge was stuck at 191* max.....exiting the freeway and idling in town it went to 195* but I am betting it would have started to cool down some after the initial heat soak from the highway drive cooled down..



Deductions:
The car definetly likes the extra 4-5* of timing at part throttle, makes it snappier around town, runs a little smoother down low and knocked off an average of 4-5* in water temp....(depending on ambient air). No noticeable pinging around town with the AC on and vac adv hooked up, straight 93 pump gas.



So the last thing I am going to do to reduce temps is installed the Dewitts AL radiator....Hopefully it will knock another 10* off of this thing to give me some room for when its REALLY hot.....We average about 97* here in the summer and often times break 101-102* so....I need a little more cooling.... When I put the new radiator in, I am going to run 2- gallons of Prestone anti freeze, 3 gals of distilled water and try to put the thermostat back in and see what it does.....If it runs hotter, I will put the thermostat back out....also may add another water wetter but only if needed as that makes a nasty mess of the coolant.

 

Alan, what gauge are you using to get those precise temp readings? Do you have an aftermarket gauge? I know the stock gauge does not read precise temps. Or do you have a Temp IR gun your using? Look forward to hearing about the Dewitts install/results. Its 100 degrees here today....

 

Rob,

I have this gauge right here tucked up behind my console...


The sender is in the intake. I still have the factory gauge hooked up with the sender in the driverside head. They are only 2* apart at 210*....verified with IR gun also.

 

Ya know aircooled aircraft engines have cowl flaps to control the hot air getting out. And who really knows what the airflow is out (or in) under the car? I'm curious if running without the hood on would increase flow enough to make a difference in traffic. Hey what the heck were louvers invented for in the first place?

Nice effort ajrothm,
cardo0

 

OK... good idea. I think I may do that. I did notice you had a sending unit in your intake while looking at your build pics from a while back.

 

That’s why I posted this earlier.

Old VW engines had the flaps too.
A lot of BB guys have solved cooling issues by venting their hoods.

Check these pics
http://forums.corvetteforum.com/1574006192-post6.html

 

Sorry noonie, didn't mean to take from your good suggestion. Must have skimmed right over your post.
cardo0

 

Maybe he needed to be reminded

No problem ever. Glad you reminded me about the air flaps, been a long time since I fooled with those.

 

Im not sure abought this but a friend told me his son has a big cube SB was running to hot to suit him, so he ran a hose from the back of the intake manifold to the front of it on both sides and it cooled down the engine temp quite a bit dint say how much. but as the story goes i have sence found out that the newer vetts, well not so new now have what thay call reverse flow basickly the same thing hopeing someone will try this to see if it works, Id like to know if this works. Interwsting. firstvett69

 

First this is a great post.

Living in Houston I was at my wits end with this **** to be frank.

I had similiar issues. New shroud, DeWitts Radiator etc..... much of the same testing. To be honest I never resolved the issue!

Now the motor is being rebuilt; that might help? I figure I will be back at square one. I want to remove the Stewart Warner high flow pump and go back stock. I did not see any improvement at all; I know it "should" work physics right, but it does not seem to help at all.

I was so frustrated that I wanted to sell the car; seriously. I could not drive for several months of the year in Texas.

As a back up instead of selling the car that I like I have bought a back up old car .... an old air cooled Porsche ... maybe not real smart in Houston

 

Test Day 6......88*

Changes made:
Installed Dewitts radiator, all new seals(again), reinstalled my 160* thermostat, no water wetter..... Just 2 gals Prestone AF and 4 gals or so of distilled water. Timing still at 32* locked and 36.5* with vac advance.

Test:
Finished the radiator install sooner then I thought, I was very careful to seal up every gap/hole I could find between the shroud and radiator. Left my house with it at 160* and got to the freeway with it at 170*, AC ON... Got on the freeway, ran it up to 3000rpms and it started COOLING DOWN... Got down to 165*....stayed at 165* for 15 miles or so running 70+.....I sped up to 80mph and it stayed at 165*.....I slowed down to 60 mph, punched it a couple times...168-170*..... Running 60-65 mph it stayed around 168-170*.....speed back up to 70 mph and it stayed at 165-167*. Ran the 15 miles back home, it held this temp, exit the freeway and running through town at 30-35mph it was around 170-175*.... Stopped at the house, left it idling in the driveway with the AC on for about 15-20 mins and it was at 195* but it seemed to be stable there.....AC blowing 45*. I didn't drive it again to see if it cooled down at speed but I am sure it would.


Deductions:
NOW its not as hot as my usual testing....Normally it is 92* when I test so its 4* cooler out now but the difference in highway temps is atleast 20* drop with the Dewitts radiator. I haven't really tested it much in town yet either but I assume its gonna run 195* or less in town with the AC, probably in the 180s if I am moving at all...

So at this point, I am done with it.....Unless for some reason it starts to get really hot in town, I am gonna call it good. We will see when our temps go up another 10-12* ambient though....for now, I am happy with it.... 650hp BB with AC running <170*.....can't beat that with a stick....

Fingers crossed....

 

Couple pics of the installed Dewitts and massive seals....

 

i think the next step is to replace the iron heads with Aluminum
better cooling , less prone to pinging , 70lbs less. i think you need all of these

i'm astonished by the cleaness of your motor and engine bay...never been able to have mine like your

 

Great write up and nice pics! Glad everything worked out for you

 

Yes that is true....I would take all of those but....I would have to spend some BUX to get heads that would match what my small port ovals flow.....especially at low lift...I do have my eye on those AFR 290 Ovals but....I am afraid I wound't gain much power, especially for the $2500 they would cost me.....Probably not worth spending the money but......Someday maybe...

 

I'm starting to think that it might be my aluminum heads that put my cooling system over the edge. Aluminum heads conduct much more heat into the coolant, which means the radiator must reject much more heat into the environment. If yours is just now capable of doing the job, will aluminum heads put you back into trouble?

Just food for thought. I may be ordering one of those aluminum radiators once I can save up $550, and that's no easy task.