[Ron Fowler]

This 400S/B is all new in a street rod with a/c it has a 160 thermostat.The engine performs great in every aspect.except for when I have to creep in traffic or stop for a light.It will cool back down when I cruise above 35MPH.I have a new 5 vane Radiator,6 blade 17" Engine Fan and a pusher electric fan on the front side of the Condenser.
I am considering the installation of a upper radiator shroud such as in Speedway's Catlog.It would be very difficult to get a complete shroud installed on this application.Has anyone have experience with this problem?I could use some suggestions.
Thanks a lot

[FASTFORD]

i had that problem in my 34 ford. i hope you have a high flow water pump & thermastat.shroud is a big help.your problem is very common.it is lack of air flow at low rpm/speed.the fans you have are not moving enough air thru the radiator.also,once the air is thru radiator,can it get out of the engine compartment?may need louvers or open it up some way.the mechanical fan should be 1 to pull lots of air at low rpm.the electric fan should be rated over 2500 cfm.hope this helps you,g`luck.

[Jim Weeks]

When I was in trade school years ago I remember the small block 400 had a unique head gasket that had a series of small holes in it it, that the other small block chevys did not have. This was unique to the 400. The gasket in the kit did not have these holes and we had to drill them out ourselves. Did you by chance compair the old gasket with the new one to see if these small holes were drilled in. There is a chance you have the wrong head gasket in there. Think back when you installed this.

Also, my hot rod started doing the same thing that yours is doing and it turned out the head gasket was leaking by an exhaust valve and blowing bubbles into the radiator. On a cold engine fill the radiator as far up as it will go with water. Start the engine, shine a flashlight into the radiator and check for bubbles. This can occur even if you have good compression in all cylinders.

Hope this gives you a couple of ideas. Let us know what you find out.

[Ron Fowler]

Thanks for the tips.I remember when I assembled the Engine and did have the right head gaskets and the steam holes in the head and block did line up.Also there are no bubbles in the radiator.Temp here in Florida right now is very warm with lots of humidity.Car does ok except in June,July ,August and Sept.
Thanks for your tips.
Ron