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'64 Valiant Conv V8
'72 Scamp /6 4bbl
'79 Adventurer SE

Backpressure isn't what the problem is. Loss of scavenging can result in pumping losses when too large an exhaust is installed.
Free flowing exhaust can have the effect of leaning the engine out. It should be fairly minimal though. If it wasn't overheating before, it's doubtful that increasing to the 2-1/4" exhaust would be the culprit.

Did you recurve the ignition when you changed to the 4bbl? Too little, or too much advance can contribute to overheating. What is your base timing? What is your mechanical advance, all in, and at what rpm?

What are the other changes you speak of?

CJ

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Part of Tyrde-Browne Racing

You mentioned you had over heating problems before the exhaust change.....
The 2.25" pipe shouldn't do it.
What muffler are using?

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

Ceej Thanks for the help. I have other posts re: timing. I have determined thru them that the advance is OK now that the diaphragm has been replaced and upgraded to a 10X. I'm at 50BTDC at 3K RPM both mech and vac. Idle is 20 BTDC; 2K is 40 BTDC both mech only and with vac; 3K is 40BTDC with only mech.

I have replaced the cap and changed the radiator to an resevoir contained overflow system. (Should help things but who knows what else was disturbed.)

I have removed the A/C condenser since there were no other A/C components. (also should help cooling)

I straightened the bent fan blades (still more help.)

I may have just missed it getting hot before since there wasn't much freeway driving. The weird thing is the temp guage says its getting up to 245 degrees, but the radiator was boelow 190 with a digital touch thermometer. There wasn't even any bubbling in the resevoir. Maybe I just need a new temp guage? I plan to get a gun thermometer and retest.

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'64 Valiant Conv V8
'72 Scamp /6 4bbl
'79 Adventurer SE

Agressive Ted. I have a Flowmaster 40.

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'64 Valiant Conv V8
'72 Scamp /6 4bbl
'79 Adventurer SE

Try replacing the temp sender. If it was overheated once, it may be damaged.
It's a cheap fix.....to get the gauge reading correctly again.

2.25" exhaust and FM40 is not going to make the engine over heat....it will help it run more efficiently. I ran that combo for several years with out problems.

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

The radiator was the problem. Seemed that is could keep the car cool at street speeds but not at highway. I used the '74 radiator and built a sheet metal piece to close off the 1" gap in the shroud. The '74 cores are an inch taller than the '72. Thanks for everyone's help.

SS

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'64 Valiant Conv V8
'72 Scamp /6 4bbl
'79 Adventurer SE