The Stovebolt Site Forums The Shop Area Engine Shop SBC 350 1970's Over heating

I have a 350 that over heats when I run it over 50 mph. She is fine at lower speeds. The engine also loses oil pressure when it gets hot. I am planning on tightening the main bearing bolts this fall. I have taken the hood off to get better air flow and still the same problem.

When u say "loses oil pressure when it gets hot" do u mean even at high speed? A hot engine is going to have less oil pressure than a cold engine. But at high speed the pressure should be at its highest. How many miles on this motor? Low oil pressure and excessive heat at high speed sounds like a very worn engine to me. Tightning the main bearing caps and/or rod caps are not going to help if u have worn out bearings. They are just torqued to a specific tightness and that's it. I would do a compression test first, on the cylinders just to see what condition the engine is in. Lbs. of pressure that vary between cylinders tells a lot.

Is your timing to far advanced? Radiator hose collapsing and blocking flow of coolant? Your 350 has insert bearings and are not adjustable. You will always have more oil pressure with cold oil than hot.

Boy does this thread look familiar. Have you rebuilt the engine or had it apart? If so, check the torque on the head bolts. Mine was a combination of wrong timing and a bad torque wrench. Figured it out after the third set of head gaskets.

Maybe not enough radiator...or needs cleaning.

I rebuilt the engine about 1500 miles ago. When I start the engine, at idle it is about 7 lbs and if I step on the gas it is about 25 lbs. Once it warns up, the idle is 0 lbs and stepping on the gas is about 10 lbs.
I have tried 3 different oil pumps ( regular, high volume, and high pressure). I have two different oil gages on the engine.

I have an oiler cooler on the system and tried 160 to 190 thermostats.

The compression is 130 to 150 on one side and 120 to 135 on the other side.

I have a new water pump and a rubber hose with metal over it so it should not be colapsing.

The timing jumps between 2 different amounts (I think it was about 4 and 9 ) The dwell I have never been able to set, but I no longer use points but that electronic unit that you put in the cap to replace points.

I have taken the hood off, to keep the engine cool.

sounds like a rebuild problem to me, that's terrible oil pressure for a sbc, and the compression should be almost identical every cylinder on an engine just broken in ... and what do you mean the timing "jumps between 2 different amounts"? should normally be set at 8-10 with vacuum advance plugged

Bill

The following could cause those problems;
Cam bearings too loose.
One or more of the main bearings scored, spun or too loose.
Timing chain/gears sloppy or broke.
Distributor bushings or gear are shot.

Rebuild it.

If the engine is quiet, the most likely suspect would be bad/worn cam bearings. Do you have your oil pressure gauge going into the fitting under the distributor, or by the oil filter?

Still should show better oil pressure, but if you move to the port above the oil filter it may show slightly better pressure.

But it needs to opened up and the bearings all inspected and replaced.