Will underdrive pulleys make you over heat?

[hazzard1976]

Ive been searching on here for a few days and found alot of useful info on here. My question is,  will underdrive pulleys make you overheat?
I have a set of march??? underdrive pulleys. My crank pulley is very small.
I have a 69 rt 440 charger, 750carb, 509.cam,355.gears.all rebuilt new. new 26''rad,180ts,high volume water pump,7 blade original fan,with shroud. No leaks,no air bubbles did all the leak down test. Im running around 230 all the time. Only thing i can think of is the underdrive pulleys.
Thanks for any help. Yall have a nice board here.

Adam

[RD]

underdrive pulleys will not turn the water pump at a rotational speed similar to OEM specs.  hence, the coolant flow is not moving as quickly through your engine block as if you had an OEM crank pulley on your engine.  Yes, it can make the engine run much warmer.

do you have a serpentine march system or v belt system?  are you running power steering and a/c?  if you are running a v belt system and you have just an alt and a power steering... i would forego the water pump pulley with a belt and put on a electric moroso water pump kit to free up hp.  i dont particularly care for underdrive systems on street cars, the 5 hp is not that big of deal, especially when there is always someone faster than you on the street.

try removing your thermostat to see if there is a difference.  if there is a substantial difference, just put in a 160 stat and call it good.

[hazzard1976]

I have a v belt system, no ac and I do have ps. I have tried without a ts and with a 160,180, and 195. all the same, It actually ran hotter with the 160 in it.Thought about the electric water pump setup but i have the original pulleys and am like you and dont care about the extra horsepower. I just got them basically for looks.
Thanks for the quick response?
So you think it will make a difference if I put the original pulleys back on?
Adam

[RD]

if it doesnt, then you have some type of blockage within your block.  best way to remove any bubble in your block is to jack up the car at a substantial angle and gently shake your car to move the bubbles towards the front... secondly drill a small 1/16" hole in your t-stat.

is your radiator aftermarket or a stock replacement?  do you have a fan clutch or just a spacer?  I take it you have a mechanical temp gauge.  what is your timing set at?