The Valaint runs smooth and strong since the recent rebuild....but it runs hot. This is not a thermostat or rad problem.

I raised the CR to 9.25:1 added a Comp 264 cam and Chev valves,(172/150) radiused the combustion chambers, bored 40 over.

I changed the vacuum advance to a 5r ,,,thinking about less mech advance.

I wonder about the water pump I used, Are they all the same?


Is my CR too high for regular?

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Yeah....Im the one who destroyed this rare, vintage automobile.....

Whenever I've rebuilt an engine they have always run hotter for a little while because the motor is still real tight. I imagine after a couple thousand miles it oughta start running cooler.

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70 Dart, 360, 727

1960-model water pumps were different for 170 (3-1/4" impeller) vs. 225 (3-1/2" impeller). For 1961 and later, the 3-1/2" impeller was used on all slants. So unless you happened upon a NOS 1960 170 pump, no, it's probably not the pump.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Someone recently was telling me about a water pump with a plastic impeller, which broke loose from the shaft and stopped pumping. I think all the replacement water pumps are steel or bronze now.

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I've been calling it as i see it for my entire life and that's not about to change. Take it or leave it.

The original impellers were cast iron, then after a few years a phenolic impeller with a cast iron insert was phased in. These work fine for many decades and miles, but yeah, eventually the phenolic part can slip on its cast iron hub. Never seen a bronze impeller on a passenger car slant water pump (only marine); since the '70s just about all the replacements have had a regular stamped-steel impeller.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

sandy, i know it seems dumb but check the bypass hose from the head to the waterpump (the one that takes care of pressure buildup relief when thermostat is closed)

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Juan Ignacio Caino

Please use e-mail button istead of PM'ing. I do log in sometimes but I'll be answering quicker thru e-mail.

I know it's stupid to suggest but you have a real guage in the proper location? How hot are you talking 190,200,210?

I have the same old stock gayuge in the stock location. The guage is fine,,,the rad is fine. What has changed is the motor has been rebuilt. The car cooled fine before the rebuild. The WP was changed at the time of the rebuild. We are talking hot enough at 70 mph....bt too hot on grades(and Man do we have grades here) The rad boils.

I wonder if the CR is too high for regular fuel.

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Yeah....Im the one who destroyed this rare, vintage automobile.....

Seems like the motor might still be tight as others said. 9.25:1 should not be too much for pump gas. Have you tried premium to see if there's a diff? Total mech advance should be 30 deg MAX.

Are you driving faster up those grades? My 64 Dart with all it's motor mods was fine on a 3-core OEM rodded-out rad out of a 63 V wagon, but got hot on serious road course duty. A universal Afco or Griffin radiator is an inexpensive and wonderful thing...

Lou

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Home of Slant6-powered fun machines since 1988

Now that regular gas has gone down to $3.64/usgal from $3.90 it may be time to try a tank of premium.

It may be the BBD is not keeping up and things get lean.

Yeah we always drive it hard.

I hope the motor is just tight.

The car always cooled really well before.

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Yeah....Im the one who destroyed this rare, vintage automobile.....

When I changed from 8 btdc to 15 btdc the temp dropped about 8 degr. celsius.

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Lasse

Signet -66 225
Holley 600 Offy-5270 Dutra Dual,regrind. cam 272 0,420 110, head shaved 0.100 slight.ported
MSD6A
A904
7 1/4 3.23

My bet is that it's now lean. Might try drilling out jets a little or get a bigger carb for that beast. I was getting 22-23 mpg out of a Holley 500 2bbl, so size is not a big issue. Tuneable TBI in the works?

Lou

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Home of Slant6-powered fun machines since 1988

It may well be lean...the car ran very well with this carb on a stock motor. The carb shriek is impressive at full throttle now.
The carb is a stock 318 BBD on an aluminum Super 6 manifold.

My GF just bought an Eagle Talon TSI awd,,,the Valaint is just a little slower to 70 mph. The Talon weighs the same and is 200hp.

The tunable TBI is next but probably not until the summer,,,too cold and too busy now. A 400 cfm throttle body sounds about right.

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Yeah....Im the one who destroyed this rare, vintage automobile.....

Well!,,,the winner is...whoever suggested the motor is still tight. 3 weeks of daily commute (50 miles/day)and the thing runs as cool as before the rebuild. Still just a tickle of ping on full throttle on regular fuel. Smells just a tad lean.
Next I need to reset the valves....reset the idle mix and drive the ever livin hell outta it!

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Yeah....Im the one who destroyed this rare, vintage automobile.....