Underdrive pulleys and overheating?

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Thanatos340

Thanatos340

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Anyone here using aftermarket under-drive billet pulleys and if so did this cause over heating problems for you?

I have a 1969 340, 11:1, 508 lift cam, Nicely worked J heads, making right at 400hp. Running a 7 Blade Fan and fairly stout custom radiator that uses a HD Truck core and stock plastic shroud. Never had overheatng problems with this set up when it was in my 76 duster. Kept a nice 185 consistently.

I moved this entire set-up to my 73 Duster (Engine, Radiator, Fan and shroud), Only thing I changed was to go to Billet Pulleys (Under drive) (These - http://www.cvfracing.com/Chrysler-Small-Block-Pulley-Kit-ALT-p/scre1kit.htm ) and a HV water pump. Now it wants to run at 220+ when cruising around town (Maybe even higher but when it gets that hot, I take it home. Only putting a few miles on it at a time before it starts getting too hot).

What I am really wondering is if I change to an Aluminum 3 row radiator, would it solve this problem or should I just scrap those pretty pulleys that are not spinning that fan (And water pump) as fast?
 
Put your old stuff that worked back on. Problem solved.
I read all of the cooling threads and 9 times out of 10, the cooling problem is an owner trying to reinvent the wheel.

My engine is much like yours. A bit more radical actually.

I could start it and let it idle on a 100 degree day until it ran out of gas and it wouldn't overheat.

My cooling system is 100% stock 68, 340 stuff except for the $30 NAPA stock replacement water pump.
 
I just pulled the underdrive pulley off my big block stroker. It acted fine on the highway, but would start to overheat as soon as you got into any stop and go traffic. On the weekend I went to the race trck and the car idled for about 15 minutes waiting in line, and it never moved over 1/2 on the factory gauge. My best run was within 1/2 a tenth of the last time I raced with the underdrive pulley.
 
I was just looking through the cooling section to see if anyone had this similar problem as mine. But, my pulley set up is a trutrac billet specialties one. It is not under driven, but came with and edelbrock high volume pump. Well since the kit came with that pump, I took my factory one off and installed the whole kit. Well I was over heating like mad, and when I got on the high way it would not want to cool down still. It should of been obvious what the problem was, but I had changed heads, upped the cam timing, and a few other things all at the same time so I had no clue why it was overheating. Well after dealing with it for a long time now and even getting a new radiator. I tested a crossed the upper and lower radiator hoses and it was less than 10 degrees drop in temp with 2 12" fans running at full blast. So just last weekend I got a wild hair up my butt, and desided to swap back to the factory style pump to see if that would help, but still kept the serpentine set up on it. That was a tough task as the factory style one dose not have even bolt hole bosses, and I had to grind them to make it fit. But, with the factory pump back on, it now cools like it did before I put the pullies on, and I can cruise around town again. With the HV pump it was a race to make it to the high way. My guess is that it flowed to fast for the radiator to pull enough heat out of the coolant.
 
I wouldn't mess around with under drive pulleys on our kinda cars. They work better for stock type stuff trying to get a touch more torque. They usually cause cooling problems on already warm running V8s. I would leave them alone.
 
I ealizr this is an old thread. But i have the same tru trc setup on my 73 duster 360 /400 hp crate. I started with a champion aluminum 3 or 4 core radiator
And the champion shroud with two 12” spal fans for a total of 2600 cfm.
It overheated like crazy!!! I mean it wanted to climb to 240. It was bad i even tried clower hose coolant restrictors of different sizes and no better . So i decided to put on a set of ford contour fans. It fits the core nice and i used a seal as well , dakota digital fan controller
The radiator and fan ar so thick i had to machine the nose of the water pump pulley doen to the bolt holes. And it still touches the fan shroud. Anyway. These fans have cooled 700 hp big blocks without issue. It still ran hot this summer. Not as bad. Now that its winter time. I can take it out on a cruise and it will run at 190. As soon as i come to a stop it starts to climb to 210 or higher. Mind u i have a trans cooler and an ac condensor ( ac is not working yet). But honestly i think it may very well be a the tru trac. I had the same setup on a 61 F-100 with a 521 scj 600 hp crate motor. And i had the 1800 dollar be cool 1000 hp cooling module. And it did the same damn thing. At a light it would just start climbing in temp to the point i would ger back to my shop and shut it daown and it would diesel. Anyway i sold the truck without the motor. I took the tru trac off and sold the 521. I now have it ona 380 hp 460 in a 66 f100 4x4. But i did use a stock water pump. I havent tried it yet but hope that ome is better. Im just about ready to ditch the 3k dollar pretty *** fromt accesories and just throw a regular belt setup and pulley setup on it. Idk if the tru trac is underdrive for the waterpump or what but it sucked on both vehicles. I now have the same setup for my gtx with 540 hemi and i hope it doesent iverheat when finished. Idk. I havent found the solution yet.
 
panheadchuck said:
I ealizr this is an old thread. But i have the same tru trc setup on my 73 duster 360 /400 hp crate. I started with a champion aluminum 3 or 4 core radiator
And the champion shroud with two 12” spal fans for a total of 2600 cfm.
It overheated like crazy!!! I mean it wanted to climb to 240. It was bad i even tried clower hose coolant restrictors of different sizes and no better . So i decided to put on a set of ford contour fans. It fits the core nice and i used a seal as well , dakota digital fan controller
The radiator and fan ar so thick i had to machine the nose of the water pump pulley doen to the bolt holes. And it still touches the fan shroud. Anyway. These fans have cooled 700 hp big blocks without issue. It still ran hot this summer. Not as bad. Now that its winter time. I can take it out on a cruise and it will run at 190. As soon as i come to a stop it starts to climb to 210 or higher. Mind u i have a trans cooler and an ac condensor ( ac is not working yet). But honestly i think it may very well be a the tru trac. I had the same setup on a 61 F-100 with a 521 scj 600 hp crate motor. And i had the 1800 dollar be cool 1000 hp cooling module. And it did the same damn thing. At a light it would just start climbing in temp to the point i would ger back to my shop and shut it daown and it would diesel. Anyway i sold the truck without the motor. I took the tru trac off and sold the 521. I now have it ona 380 hp 460 in a 66 f100 4x4. But i did use a stock water pump. I havent tried it yet but hope that ome is better. Im just about ready to ditch the 3k dollar pretty *** fromt accesories and just throw a regular belt setup and pulley setup on it. Idk if the tru trac is underdrive for the waterpump or what but it sucked on both vehicles. I now have the same setup for my gtx with 540 hemi and i hope it doesent iverheat when finished. Idk. I havent found the solution yet.
Click to expand...

If, the lower pulley is smaller , ur under driven, most aftermarket set ups are that way that I`ve seen-------not good for any big h.p. unless on a race car. jmo
 
70 340 swinger. I run a cvf racing early 67 aluminum crank pulley with 70 water pump pulley to align belt with anti super damper thicker. The pulley is a little smaller, champion 3 core clutch fan no shroud washer in place of stat 580 hp 410 Stroker doesn’t go over 180 on hottest days. I’m happy with it!
 
The whole deal with under drive is simple. It assumes you will be roaring around most of the time with the engine at high RPM
 
famous bob said:
If, the lower pulley is smaller , ur under driven, most aftermarket set ups are that way that I`ve seen-------not good for any big h.p. unless on a race car. jmo
Click to expand...
yes i contacted CVF they are 1.2 overdriven
 
panheadchuck said:
I ealizr this is an old thread. But i have the same tru trc setup on my 73 duster 360 /400 hp crate. I started with a champion aluminum 3 or 4 core radiator
And the champion shroud with two 12” spal fans for a total of 2600 cfm.
It overheated like crazy!!! I mean it wanted to climb to 240. It was bad i even tried clower hose coolant restrictors of different sizes and no better . So i decided to put on a set of ford contour fans. It fits the core nice and i used a seal as well , dakota digital fan controller
The radiator and fan ar so thick i had to machine the nose of the water pump pulley doen to the bolt holes. And it still touches the fan shroud. Anyway. These fans have cooled 700 hp big blocks without issue. It still ran hot this summer. Not as bad. Now that its winter time. I can take it out on a cruise and it will run at 190. As soon as i come to a stop it starts to climb to 210 or higher. Mind u i have a trans cooler and an ac condensor ( ac is not working yet). But honestly i think it may very well be a the tru trac. I had the same setup on a 61 F-100 with a 521 scj 600 hp crate motor. And i had the 1800 dollar be cool 1000 hp cooling module. And it did the same damn thing. At a light it would just start climbing in temp to the point i would ger back to my shop and shut it daown and it would diesel. Anyway i sold the truck without the motor. I took the tru trac off and sold the 521. I now have it ona 380 hp 460 in a 66 f100 4x4. But i did use a stock water pump. I havent tried it yet but hope that ome is better. Im just about ready to ditch the 3k dollar pretty *** fromt accesories and just throw a regular belt setup and pulley setup on it. Idk if the tru trac is underdrive for the waterpump or what but it sucked on both vehicles. I now have the same setup for my gtx with 540 hemi and i hope it doesent iverheat when finished. Idk. I havent found the solution yet.
Click to expand...

I have pretty much the same setup as your Tru Trac and 12” spal fans, but the fans are the thick paddle style ones with no shroud, and I have nothing but problems with over heating also.
 
Overheating can be a huge issue with high horsepower motors . You can solve this problem but you must be persistant and take it one step at a time . I would start by doing the least expensive item first and then working your way up from there . I would start with a high flow water pump along with a high flow thermostat . If that helps even a little you're on the right track . Next I would try different diameter water pump pulleys . I would suggest larger diameter to start . If a larger one helps go larger until it doesn't cool better . Next I would go up on the fan diameter . If that helps , you are gaining on it . small victories will get you there . IMO electric fans are o.k. as long as your electrical system can handle the load otherwise stick to the mechanical stuff . Go get'm
 
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