>
> What if I have the 248 I was replacing with this 270 bored .0625" over
> standard bringing it to 270 standard bore. I can put the 270 crank in it
and
> use standard bore 270 pistons. Viola! Instant 270!
>
> Will this work, or are there problems with a 270 crank in the 248 block?
>
The 248 can be bored to .0625, unless it's already at .060 and has too much
taper or wear.
The 270 crank and rods will work OK in the 248 block, but be sure that the
block deck heights are the same. Only if they are, and the 270 pistons have
the same dimensions from pin center to crown, can you use a stock 270
piston. If not, you will have to have the block decked, or have custom
pistons made. The only accurate way to do this is to assemble the short
block with the components you hope to use, and measure the deck.
Not to say that this all can't be done, but how much do you want to spend?
There's nothing inherently wrong with sleeving a block, some say it even
makes for a stronger engine - but it's not cheap. $100 a cylinder is the
going rate hereabouts.
GMC's lend themselves to a fair degree of mix and match, but usually it's
done the other way around - 270 or 302 block with 228 or 248 crank for a
more oversquare bore/stroke ratio. This is really only effective with a big
cam and more airflow, though, where higher RPM is the goal - not the smart
setup for a turbocharged engine.
With the going prices for 270 and 302 cores still pretty reasonable, I would
personally not bother trying to use the 248.
Jack / Winter Park FL
oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
|