493 is a 126cc head right?i read that these engines actually came at 7.8:1 ratio!!!!! well how much can i shave off the head without detonation??can i go as far as .040 to .060 to bring it up to 8.5:1 or higher??any ideas???? i also heard that the 425 heads will bring me to 10:1 compression ratio which is what im looking for, but i reduce flow. can the 425 heads be ported to 472 standards??and is the 425 single plane any good??after reading that it might have so low compression i was thinking of grabinng some 425 heads and 425 single plane.port match both to a 472 intake manifold gasket and polish the chambers and 3 angle valve job to raise the flow????i need ideas !!!anyone has some ???i was originally thinking of edelbrock intake,850 carb headers 240/240 cam @.050 polishing the chambers hei and 2 1/2 exhaust.my goal is 400 hp and 500ft lbs of torque.but the compression ratio is vey low and need ideas on how to raise it and keep airflow which of the two is better??oh and is ther anything special i need to know when putting 425 heads on 472 like passages bolts anything differenet??well thanxs in advance

your block can also be zero decked but make sure you watch your valve clearence. Id deck the block and heads to get the compression you want. avoind the 425 parts they tend to be restrictive. Or there is always edelbrock aluminum heads and manifold out of the box they will out flow ported factor parts

your block can also be zero decked but make sure you watch your valve clearence. Id deck the block and heads to get the compression you want. avoind the 425 parts they tend to be restrictive. Or there is always edelbrock aluminum heads and manifold out of the box they will out flow ported factor parts
Edelbrock does make a Performer intake manifold but they do not make heads for 472's/500's.

Edelbrock does make a Performer intake manifold but they do not make heads for 472's/500's.

Doh your right I had a brain fart i must have been thinking of my olds

Whatever you do ,do not put 425 heads on a 500

A ported 425 head done by someone who knows what he is doing will not flow much better than a stock 493 head

Best bet is taking about .040-.045 off your 493 head
Installing some 2.11-1.77 pontiac valves (I use the 5.09 long ones)
Get a good set of single springs or better yet a kit that has an installed height around 1.85. 120 on the seat and 360 per inch minimum

If you are able to port the heads yourself just do a basic bowl blend and knock back the pinch point in the heads and call it good.

As far as the 240@ .050 goes it should be ok but id go with a good dual spring.
If you want more advice Lux hauler and others know how to contact me
good luck