DeWitts Radiator
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Drifting
Joined: Jun 2000
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From: Southern NJ
C2 of Year Finalist (stock) 2019
DeWitts Radiator
Just ordered a new DeWitts radiator for my 66 BB. Ordered 1239066M. I am hoping this solves my temp problems sitting in traffic. The sale is pretty good as it brought the price down a lot.
Last edited by JL66REDCPE; Feb 8, 2017 at 08:09 AM.
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Not only the radiator, but carb jetting and vacuum advance can play a part in your issue. What are your timing numbers, and is the vacuum working properly? 
Dennis
Dennis
Melting Slicks
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From: Bornem
Thread Starter
Drifting
Joined: Jun 2000
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From: Southern NJ
C2 of Year Finalist (stock) 2019
Car is not running lean and the timing is set correctly, not by the shop manual however correct, I think it is running 14 degrees advance at idle with vac hose disconnected and plugged.. The vacuum can is working properly. It is a VC1810 and I tested it with a vacuum gage. It is running with ported vacuum. Also fan clutch seems to be working ok as well - not a K&B but from Paragon. I use 100% avgas.
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Drifting
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From: Southern NJ
C2 of Year Finalist (stock) 2019
Le Mans Master
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Thanks for the response.
Car is not running lean and the timing is set correctly, not by the shop manual however correct, I think it is running 14 degrees advance at idle with vac hose disconnected and plugged.. The vacuum can is working properly. It is a VC1810 and I tested it with a vacuum gage. It is running with ported vacuum. Also fan clutch seems to be working ok as well - not a K&B but from Paragon. I use 100% avgas.
Car is not running lean and the timing is set correctly, not by the shop manual however correct, I think it is running 14 degrees advance at idle with vac hose disconnected and plugged.. The vacuum can is working properly. It is a VC1810 and I tested it with a vacuum gage. It is running with ported vacuum. Also fan clutch seems to be working ok as well - not a K&B but from Paragon. I use 100% avgas.
https://www.paragoncorvette.com/p-36...utch-unit.aspx
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Assuming it's a '66 L-72 that's why it's running hot in low speed traffic. Converting from the OE ported vacuum advance to full time will likely solve the problem. You can do a test by buying a couple of feet of 1/8" vacuum hose and a tee. Remove the existing choke vacuum break hose and make a new harness with one port routed to the VAC. Go through the idle speed mixture adjustment procedure after you make the change. Assuming it's a OE L-72 cam, shoot for about 900 idle speed, which should yield about 14" manifold vacuum.
You can also modify the carb base by plugging one hole and drilling another to move the VAC signal port above below the throttle valve, which makes the mod invisible.
There's a good chance you don't need a new radiator.
Duke
You can also modify the carb base by plugging one hole and drilling another to move the VAC signal port above below the throttle valve, which makes the mod invisible.
There's a good chance you don't need a new radiator.
Duke
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Drifting
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From: Carmel CA
The Dewitt radiator is a quality product and that might solve your problem. If not, try adding the restricted bypass fitting to your water pump. It makes the water stay in the radiator a little longer and the engine runs cooler. My 67 L68 would get a little hot in stop and go driving on hot days. I tack welded a washer inside my hose fitting and I was amazed at the difference. The restricted fittings claim to lower water temp by 10 degrees and I believe it.
Doc
Doc
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St. Jude Donor '07
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Drifting
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From: Southern NJ
C2 of Year Finalist (stock) 2019
Assuming it's a '66 L-72 that's why it's running hot in low speed traffic. Converting from the OE ported vacuum advance to full time will likely solve the problem. You can do a test by buying a couple of feet of 1/8" vacuum hose and a tee. Remove the existing choke vacuum break hose and make a new harness with one port routed to the VAC. Go through the idle speed mixture adjustment procedure after you make the change. Assuming it's a OE L-72 cam, shoot for about 900 idle speed, which should yield about 14" manifold vacuum.
You can also modify the carb base by plugging one hole and drilling another to move the VAC signal port above below the throttle valve, which makes the mod invisible.
There's a good chance you don't need a new radiator.
Duke
You can also modify the carb base by plugging one hole and drilling another to move the VAC signal port above below the throttle valve, which makes the mod invisible.
There's a good chance you don't need a new radiator.
Duke
Duke - I doubt if you will remember this -- I tried this exact modification and believe it or not, the car ran hotter !!!! I know this is hard to believe and I could not believe it either. I attributed it to the modification leaning out the engine. The radiator was re-cored about 25 years ago however it only has 5500 miles on it.
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From: Inverness FL
St. Jude Donor '07
Duke - I doubt if you will remember this -- I tried this exact modification and believe it or not, the car ran hotter !!!! I know this is hard to believe and I could not believe it either. I attributed it to the modification leaning out the engine. The radiator was re-cored about 25 years ago however it only has 5500 miles on it.
Bill