water pump pully size

[cudaman51]

whats the good pully size ratio between the water pump and crank for a near stocksmall block, i am thinking 1-1. my car starts to creep up over 70mph on hot days. its got a decent 3 core radiator hood to radiator seal and fan shroud. i noticed my water pump pully is almost one inch bigger than the crank and that mite be a factor. its a 340 67 barracuda stock size radiator

 

[lemondana]

The AC cars in those years used a smaller water pump pulley-speeds the water pump up, it should help some. You will probably need a shorter belt though.

 

[cudaman51]

thanks thats what i will do

 

[dodge freak]

whats the good pully size ratio between the water pump and crank for a near stocksmall block, i am thinking 1-1. my car starts to creep up over 70mph on hot days. its got a decent 3 core radiator hood to radiator seal and fan shroud. i noticed my water pump pully is almost one inch bigger than the crank and that mite be a factor. its a 340 67 barracuda stock size radiator

When the engine gets hotter the faster you go its got a clogged rad, you need a new rad. Pump speed can be too slow at idle, not at 70 mph

 

[Oldmanmopar]

If you do not have a thermostat in the coolant could be flowing to fast and not have enough time in the rad to cool. Rule of thumb is a washer with a 1 inch hole. If this is not the problem yes he is correct your rad is clogged or its lean on the top.

 

[bohica2xo]

I would like to collect some more information on pulley sizes.

I have a 273 car with factory A/C. It is slightly overdriven with a 6.750 diameter crank pulley, and a 6.130 diameter water pump pulley.

I am very interested to hear the relative drive sizes on other mopar LA engines.

Thanks.

B.