General Questions

[1970CUDAAAR]

Hi!
I have a 1970 CUDA with a 440 Holly sniper. Please let me know what are the best sparks plugs for this car = the motor is a streetable model.

Also I changed the clutch fan for a flexible race fan and l did not notice any improuvement - should I pur back the clutch fan?

 

[Cuda Hunter]

I would say yes, put the clutch fan back on.
Mostly due to that one instant when a flex fan fails.

I'm curious to hear the other reasons/reasoning.

 

[DetMatt1]

Ma Mopar had some of the best engineering of the day. Imo these cooling systems in particular are hard to improve upon for normal street use and most certainly a flex fan is inferior to a clutch fan in good working order.

 

[Chryco Psycho]

Champion or Autolite is the plug I would use RJ12YC

 

[Xcudame]

RJ12YC's are a good all around big block Mopar spark plug!

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[Challenger RTA]

Something tells me the fan shroud is not on?

 

[Steve340]

Does the motor have aluminium heads or cast iron?
They use different spark plugs.

 

[pschlosser]

Something tells me the fan shroud is not on?

I concur, the fan shroud is another important element of the OEM factory cooling system. It works really well to funnel more air through the radiator, and many regret removing it, after.

most certainly a flex fan is inferior to a clutch fan in good working order.

But the clutch fans can wear out, and cool less efficiently.

For those reading this post, you can test the clutch fan by spinning it when the engine is cool. It should spin pretty easily, but not spin freely, and offer some resistance, coming to a stop within a quarter revolution or less. As the engine warms up, and heats the clutch, it engages pulling more air through the system. This design is more efficient and robs less power from the engine, compared to a fixed fan.

 

[Chryco Psycho]

Alum heads typically use RC12YC

 

[DetMatt1]

I concur, the fan shroud is another important element of the OEM factory cooling system. It works really well to funnel more air through the radiator, and many regret removing it, after.


But the clutch fans can wear out, and cool less efficiently.

For those reading this post, you can test the clutch fan by spinning it when the engine is cool. It should spin pretty easily, but not spin freely, and offer some resistance, coming to a stop within a quarter revolution or less. As the engine warms up, and heats the clutch, it engages pulling more air through the system. This design is more efficient and robs less power from the engine, compared to a fixed fan.

That’s why I said a clutch fan in good working order.

 

[Xcudame]

I agree, the Chrysler clutch fan and radiator shroud does a great job of cooling! Think about all those Mopar cop cars idling around the country for hours at a time! Between Plymouth, Dodge and Chrysler, Mopar cop cars made up over 85% of the cop car market in the late 60's through the 70's! And then there's the 318 and 225 slant six taxi cabs!
Seriously, on some cold days in winter I would run cardboard in front of half my radiator to have a decent heater in winter!!

 

[pschlosser]

That’s why I said a clutch fan in good working order.

and that's why I quoted you.

 

[pschlosser]

Mopar cop cars made up over 85% of the cop car market in the late 60's through the 70's!

Until the Smokey and the Bandit movies killed them all!

 

[cuda joe]

cardboard in front of the rad i haven;t seen that in the last 40 years .i did it too

 

[pschlosser]

cardboard in front of the rad i haven;t seen that in the last 40 years .i did it too

Hah, cardboard works really well for run cooling system and thermostat tests (by blocking air flow) on a cool day.