'63 340 Shp

[Jim C.]

With new forged pistons, 3.70 rear, and a .30 overbore does anyone have an idea ( i know this is dependent on many variables) what would be a generally acceptable rate of oil consumption over 1000 miles perhaps. Assuming there will be some fun runs to 5000 rpms for a good .
Just want to get a general idea . I 'm assuming the forged pistons have wider tolerances and perhaps some oil usage beyond that of a modern auto is the norm. etc. Thanks

[Joe C.]

Re: '63 340 Shp

With new forged pistons, 3.70 rear, and a .30 overbore does anyone have an idea ( i know this is dependent on many variables) what would be a generally acceptable rate of oil consumption over 1000 miles perhaps. Assuming there will be some fun runs to 5000 rpms for a good .
Just want to get a general idea . I 'm assuming the forged pistons have wider tolerances and perhaps some oil usage beyond that of a modern auto is the norm. etc. Thanks

1 Quart per 1000 miles, mean, with extremes at 500 -1500 miles.

[Domenic T.]

Re: '63 340 Shp

I agree with Joe 100%.
I build all my blocks to use 1 qt per 1000 miles and keep all tolerences in the book.
I started out racing in the 60's then a chevy mechanic till my hands wouldn't take the abuse any more. I think the bigest mistake builders make is in the valve seals (intake) the complaints then was that the new car made a puff of smoke at start up and after a high vacume back off such as letting the engine slow the car down then hitting the gas again.
The solution then was to get rid of the chrome rings, machine the valve guides for perfect circle seals from the factory and it worked, but with conciquences.
The smoke pufs were all gone and the car made it's scheduled oil change just at the add mark. When these engines got milage and came in for a valve job the valve guides were worn from lack of oil and further inside the rings were worn more than expected. But by then the engine was years out of warranty.
I use the O-ring type valve guide seal and it lets just enough oil down the valve guide to keep it and the top rings in good shape. The draw back to that is that your intake valve gets dirty and heavy if you don't get on it once in a while.
We used GM top engine cleaner to get the burnt oil off the valves and water injection devices also worked well if you had the time to keep them full. The oil we have now burns at a higher temp and the valves stay cleaner now.
The 1 qt per 1000 is not accepted any more because now the milage for oil change is much higher and the good old guy that lifted your hood when you got fuel is gone.

DOM

[Bob H.]

Re: '63 340 Shp

I have a fresh rebuild in my 63' 340hp. It's actually an RF block/car with the 340hp manifold/afb carb. It's punched out 60 over, forged pistons, duntov solid lifter cam, 461X heads, built to the factory 360hp FI specs and it also burns about this same amount of oil. Glad to hear this is normal.......