What ruined Granny's Nova?

[adreed24]

I have a question that I've been wanting to ask for a while.

My grandmother bought a 1970 Chevy Nova, brand new. She drove it until about 1999, when something went wrong with the engine.

My uncle has the car now, and he put a new GM crate engine in it.

He told me that the car took leaded gas back in the 1970's, and that is what was put in it. Years later, when leaded gas was phased-out, she put unleaded gas in it (without any lead additives put in the tank, with the unleaded gas).

I was wondering what long-term harm would be caused by using unleaded gas in an engine designed for leaded?

 

[JDP]

It likely wore the valves into the head. The lead in the gas was a lubricant and enabled the use of softer material for valve seats. When they took the lead out and replaced it with (??) they went to hardened valve seats much like used in propane conversions.

Not much difference in lower end operations between leaded and unleaded.

JD

 

[mechtech]

If you only get 30 years out of an engine, shame on you.

 

[novadude]

If it was your grandmas car, it is VERY likely NO harm was caused by running unleaded. Problems usually only arise in marine / towing applications where the engine sees heavy load.

I have a '69 327 in my '65 Chevy II without hardened exhaust seats, and I have had no problems at all from running unleaded, and I DO drive the car hard from time to time.

PS. Love them Novas! I have owned a '65 (still have it), '70, and '76.

 

[JHZR2]

My father had a (I think the dates are right) 64 chevy II (blue) and a 73 with the moon hubcaps (rust/orangish).

JMH

 

[TR3-2001SE]

I have a 60 tr3 which has been run on unleaded for years. If the break in is done with leaded gas the lead coating stays intact is what I have been told. We have lots of cars in the 60's that where only run on Amoco unleaded which was the only unleaded at the time. Never had a problem with any valves so I am not sure this would have been her issue. The belief then was unleaded gas kept the inside of your engine extremely clean. No lead deposits on valves or cylinders. Maybe valves didn't last as long then as most engines only went 100,000 at that time before a rebuild.
I did rebuild the TR3 in 1987 at 100,000 but the rings are what went not the valves.

 

[Bamaro]

The problem is 'valve seat regression'. The harder an engine is run, the worse this becomes. On a lightly used engine, VSR is probably minimal. Just to be safe, I always use a lead substitute in my 70 Camaro.