Cooling after gear swap
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Joined: Jul 2019
Posts: 9
Cooling after gear swap
I've got a 3.23 posi in my 73 442 and do a fair amount of highway driving. It's turning close to 3,000 rpm at 75 mph which is enough engine noise for me on extended trips.
I agree with the others if you do alot of highway driving I would not put 3.42's in your car. I'd stick with a 3.23 or a 3.08 gear ratio. If your goal is more performance and most of your driving is city streets and rarely highway, then go with the 3.42 gears.
I agree with the others if you do alot of highway driving I would not put 3.42's in your car. I'd stick with a 3.23 or a 3.08 gear ratio. If your goal is more performance and most of your driving is city streets and rarely highway, then go with the 3.42 gears.
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Joined: Jul 2019
Posts: 9
3000 RPMs
any issues with overheating at 3000 RPMs? I just put 3.55’s in my 72 442 but when i get on the freeway & hit 3000 rpms at 60 mph the temp goes up pretty fast 220-230? Then as i putt around town no problem staying at 180 which im running a 180 stat.. also i have a 3 core aluminum radiator with flexalite 410 dual fans.. it’s driving me crazy.. thanks. 👍
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Joined: Feb 2013
Posts: 15,394
From: Phoenix, AZ
So what you're experiencing is the engine is making more heat than the cooling system can remove. You need to either reduce the heat generated by the engine or increase the heat dissipation of the cooling system, whether that means a larger / more efficient radiator, more air flow, or more coolant flow.
Things to look at:
- Ensure you have a correct shroud.
- Make sure the radiator surrounds are intact to direct air flow across the radiator.
- The dual electric fans may be restricting air flow at highway speed.
- Get rid of any underdrive pulleys, if you have them.
- Ensure the ignition timing is correct.
There may be some other things that I missed and if so, hopefully someone else will point them out.
Things to look at:
- Ensure you have a correct shroud.
- Make sure the radiator surrounds are intact to direct air flow across the radiator.
- The dual electric fans may be restricting air flow at highway speed.
- Get rid of any underdrive pulleys, if you have them.
- Ensure the ignition timing is correct.
There may be some other things that I missed and if so, hopefully someone else will point them out.
Last edited by Fun71; Jul 31, 2019 at 09:17 PM.
Thread Starter
Registered User
Joined: Jul 2019
Posts: 9
3000 rpms
So what you're experiencing is the engine is making more heat than the cooling system can remove. You need to either reduce the heat generated by the engine or increase the heat dissipation of the cooling system, whether that means a larger / more efficient radiator, more air flow, or more coolant flow.
Things to look at:
- Ensure you have a correct shroud.
- Make sure the radiator surrounds are intact to direct air flow across the radiator.
- The dual electric fans may be restricting air flow at highway speed.
- Get rid of any underdrive pulleys, if you have them.
- Ensure the ignition timing is correct.
There may be some other things that I missed and if so, hopefully someone else will point them out.
Things to look at:
- Ensure you have a correct shroud.
- Make sure the radiator surrounds are intact to direct air flow across the radiator.
- The dual electric fans may be restricting air flow at highway speed.
- Get rid of any underdrive pulleys, if you have them.
- Ensure the ignition timing is correct.
There may be some other things that I missed and if so, hopefully someone else will point them out.
Old(s) Fart
Joined: Mar 2007
Posts: 50,768
From: Northern VA
I moved your question to it's own post rather than resurrecting and hijacking a marginally related thread from five years ago. You're likely to get better answers when the thread title is pertinent to your question. Good luck.
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Joined: Jul 2019
Posts: 9
Out of Line, Everytime😉
Joined: Dec 2006
Posts: 10,082
From: Melville, Saskatchewan
I found the Champion 3 core in my G body wasn't big enough for my 403, especially towing, saw similar 230 degree temps with the boat behind. Same thing dropped to 180 around town. At speed you shouldn't even need a fan. Do what Fun71 suggests, dams in place and go back to the shroud and clutch fan. It sounds like the rad is too small.
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Joined: Jul 2006
Posts: 1,826
From: Richfield, Oh
timing
Your timing could also be causing the issue and Fuel delivery - Since you are not overheating on short runs which means your hitting the accelerator pump all the time giving extra fuel to air ratio and engine at 40to 50 MPH has less efficiency... The more RPM is moving more air and the carb might be on the lean side and the ignition might be bumped too much.
Check those two things also.
Do you use VACCUUM advance or none?
What is your full advance at 3000 RPM or does it even fully advance at 3000 RPM or higher?
Jim
Check those two things also.
Do you use VACCUUM advance or none?
What is your full advance at 3000 RPM or does it even fully advance at 3000 RPM or higher?
Jim
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