Milled heads and 347 CI swap

eatsgmcar · 08-09-2002, 03:09 PM

I ahve milled my edelbrock alu. head to have a reasonable
10:1 compression ratio with a 302 CI block. Is it possible
to keep those heads if i stroke the engine to 347 CI?
What will be the new compression ratio? (i am not too
familiar with those calculations) Also what could be the
typical gain with ported aluminium head, E303, and edelbrock
RPM intake?

Oh yes i have an other question in mind...

Why is everybody choosing to install superchargers instead of
stroking the 302? Superchargers are very popular compare to
the 347 CI swap. If I had to choose i would take the 347 crank anytime.

any advice is welcome,

Regards,

Sebastien Cote

302 LX Eric · 08-09-2002, 03:42 PM

Your final compression ratio with depend on many factors such as what type of pistons you go with. Obviously a dished piston will have less compression, whereas a flat-top piston would have more. What you need to do is obtain the cc's of the combustion chamber of your heads (53, 54, 55, etc.) and then combine this with the piston your getting to get a good idea of where your finall compression will shake out. Rember that it also depends on where the piston is in the hole at TDC - i.e. how much below deck.

And, as far as the whole supercharging thing...well, I'm putting a ProCharger on my 331. So, I get the best of both worlds!

Good luck with your build-up.

E

LX5liter · 08-10-2002, 11:08 AM

Quote:

[i]
Oh yes i have an other question in mind...

Why is everybody choosing to install superchargers instead of
stroking the 302? Superchargers are very popular compare to
the 347 CI swap. If I had to choose i would take the 347 crank anytime.

any advice is welcome,

Regards,

Sebastien Cote [/B]

Price, and a supercharger effectively increases the the cubic inches the engine "pumps". That is to say that in naturally aspirated form an engine runs on atmospheric pressure (14.69 psi at sea level) and by increasing that pressure you are increasing the efficiency of the engine, so it is actually pumping the same amount of air as a larger displacement engine. 8 psi of boost equates to an approximate cubic inch "displacement" of 500 cubic inches, depending on altitude.
Now add that to a stroked engine and

08-09-2002, 03:09 PM	#1
eatsgmcar Registered Member Join Date: Jul 2002 Location: Pont Rouge, Quebec, Canada Posts: 45	Milled heads and 347 CI swap I ahve milled my edelbrock alu. head to have a reasonable 10:1 compression ratio with a 302 CI block. Is it possible to keep those heads if i stroke the engine to 347 CI? What will be the new compression ratio? (i am not too familiar with those calculations) Also what could be the typical gain with ported aluminium head, E303, and edelbrock RPM intake? Oh yes i have an other question in mind... Why is everybody choosing to install superchargers instead of stroking the 302? Superchargers are very popular compare to the 347 CI swap. If I had to choose i would take the 347 crank anytime. any advice is welcome, Regards, Sebastien Cote Last edited by eatsgmcar; 08-09-2002 at 03:19 PM..

08-09-2002, 03:42 PM	#2
302 LX Eric or '331 LX Eric' Join Date: Jan 1999 Location: Columbus, Ohio Posts: 2,142	Your final compression ratio with depend on many factors such as what type of pistons you go with. Obviously a dished piston will have less compression, whereas a flat-top piston would have more. What you need to do is obtain the cc's of the combustion chamber of your heads (53, 54, 55, etc.) and then combine this with the piston your getting to get a good idea of where your finall compression will shake out. Rember that it also depends on where the piston is in the hole at TDC - i.e. how much below deck. And, as far as the whole supercharging thing...well, I'm putting a ProCharger on my 331. So, I get the best of both worlds! Good luck with your build-up. E __________________ 1991 5.0 LX Coupe - 40,750 miles 331 cu. in. / Tremec 3550 / BFG Drag Radials 12.22 @ 114.31 mph - w/1.89 60'