Help New Transplant Overheats:

[T2vigil]

Finished installing my pumped up 250 in my 64 and it runs real strong. Only one problem now. The new motor overheats. Fan belt is tight and a new water pump was installed with the rebuilt. My question is could the new motor with flat top pistons a marine type cam and porting run that much hotter than the stock 230? Would it normally require a larger radiator?

[tincan1966]

Just throwing ut an idea- have seen this a few times.

with the heater cores mounted so high, it is possible to get an air pocket and not allow the coolant to flow completely. As I am sure many others do,after filling the system with coolant in the radiator, I always remove one of the heater hoses from the core, put the radiator cap on and finish filling the sytem. That way I know it is full. With a new engine being dry, sometimes it's hard to get full,especially with hoses above the radiator inlet.
Just a hint, and hope it's nothing more than something simple for you.

[chris91]

I had a similar problem. My timing was too far advanced. I was also told to drill a small hole in the thermostat to prevent the air problem.

[T2vigil]

Now the race is over its time to make sure I have water in the heater and see if that is the problem. Right now the timming is set at 8 degrees BTC. Is that too far?

[gimmy 64]

a new motor will run hot at first because everything is tight. how hot is it running?

[T2vigil]

After some more checking and making sure the heater did have water I removed the T-Stat and that fixed it. Thanks for all your help.

[T2vigil]

Originally Posted by gimmy 64

a new motor will run hot at first because everything is tight. how hot is it running?

It pegged the temp guage within 5 minuets after starting and would not come down even at hwy speed. Now that I know it is the T-Stat I will have to get a new one.