Showing results for 
Search instead for 
Did you mean: 
Hagerty Employee

Piston Slap: False economies and engine rebuilds

Redvett writes:

I have a 1968 Corvette with the 327 CI engine that smells like an oil refinery. The car has 101,400 miles and compression is low but the car runs good. How do I tell if the car might just need a top end rebuild or a complete rebuild?


Sajeev answers:

It smells like an oil refinery? Strong oil smells generally mean there are leaks from gaskets, not failing engine internals: Check the valve covers for leaks that could drip oil on the exhaust manifolds, and transmission fluid leaks too. That said, none of this answers your question ...


Read the full article on

Pit Crew

Take it from experience: if the rest of the motor is tired, rebuilding the top end will make your oil consumption/blowby worse.


One of the first hard lessons I learned as a young mechanic, was when you redo the heads on a tired engine, you increase compression, and that in turn often blows out your piston rings.  Either rebuild the whole engine, or buy a new or rebuilt crate engine.  Sometimes it is cheaper to replace than rebuild.


I'd say it's time for a supercharger and/or Nitrous oxide and figure out just how many pieces you can break the crankshaft into.  🙂  Oh, just kidding.  Since it's a more desirable '68 model I'd rebuild it with a little more cam and maybe good aftermarket heads and a bigger radiator.  The new combination will create more heat and Corvettes don't have the best cooling to start with.


Low compression? What about cylinder to cylinder to cylinder balance, leakdown, and oil pressure once it's warm?