The final bit of confidence that I needed after replacing the head due to burnt out exhaust valves was a high speed run, just to make sure all was well. I should point out that I have now changed my definition of a 28 Chev doing a high speed run to 45 MPH, as opposed to previously 50 to 55MPH, which may have encouraged the valves to burn out after 38 years of faithful service.
Anyway I set off for Chelsea this morning, a return trip of 50 miles, half on East link Tollway at 45 MPH, the return trip on public roads at 35 to 45 MPH.
No problems, no issues, and fingers crossed all seems well. Did a compression test when I got home, with between 62.5 to 67 PSI across all cylinders, which I am pretty happy with.
The best part about all of this is the Red Chev is running this well with what I have been calling a test head that was originally asked to do no more than help test the compression of the rings and pistons when the engine was cold. I did not want to put a fully reco head on the engine only to find out it had to come off again to rebuild the short engine. When I fitted the "Test Head" I used a new head gasket with a liberal coating of thick silver frost on both sides.
Was I confident that this "Test Head" would work. Well lets just say I did the cold compression test with just the push rods and rocker arms in place. No manifolds connected as I did not want to have to pull them off straight away if the head failed.
What were my concerns why the "Test Head" may fail:
1. I had machined the face of the head back in 1973 at the tender age of 20 during a night school class, so had I done it correctly?
2. The head had not been crack tested.
3. Back in 73 the valve seats were re cut and the original Chev valves were reground. There was, and of course still is a bit more slop in a couple of the valve guides than I would like, but there is no smoke, no burning oil.
4. Last but not least, there was a fair amount of surface pitting on the machined face of the head that had "grown" after being in storage for over 35 years. Not wanting to spend money on having a suspect head machined, I tried something different, possibly radical, possibly stupid. Using the flattest piece of chipboard in my garage, about 300mm wide and 900mm long, I stuck several sheets of fine wet and dry on the chipboard, painted the surface of the head with a black marker, and kept dragging the face of the head across the wet and dry until the black finish was removed from the head face. I did this a few times until the surface pitting of the head was removed.
Now back to the story
Once satisfied the piston rings were OK, decided to push my luck with the "Test Head". Connected both manifolds to the engine, fired her up, and with a 3 stage process torqued the head to 60lbs using new studs that replaced the original head bolts. Threw some water (did not want to waste $40 of coolant) in the radiator, ran the engine to hot, checked the torque of the head, did a compression test, then a road test.
That was about 150 miles ago, all is well, so leave well enough alone is my motto. The "Test Head" is running fine, and I have a fully recod head sitting in the spares cupboard in case its ever needed.
My only concession to protect the old Chev valves is I have changed from using 100ml of Flash Lube per tank of petrol to 1 litre of diesel per tank of petrol. This will give me good upper cylinder lubrication and lower the temperature in the combustion chamber, well that's what I have been told so I will give it a try.
Some ole bush mechanics thrown in there, good to see Ray!!
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