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Old 12-14-2002, 06:43 AM
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Post Big Block piston gas ports, expert help needed

Ok i have decided to put new heads on my 454, the heads on the car are now 1970 "mid-chamber(113cc)" ovalport heads. The heads that ive decided on are AFR 315 cnc. (i have to change to rect. ports as my enderle stack manifold is rect. port) now i can either angle mill the AFR heads to get the chamber volume relatively close tio the 113ccs of the GM heads. or i can up and buy a set of new pistons.

in any event i will have to remove the pistons on the brock (either for flycutting to the new valveangle, or for replacement)when they are out anyway i was considdering going with low tension rings and now for the question: should i have the pistons drilled for gasports,

gasports are the 8 or 10 small holes in the perifery of pro stock pistons to vent combustionchamber pressure into the top ring groove behind the ring to help the low tension ring seal better. Is it a race only deal that just increasas wear to an extent that street driveing just ruins the bores??? or is it the best thing after sliced bread??

compression is 11:1 and horsepower is projected at 650, so cylinder pressure should be considderate.
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Old 12-14-2002, 07:07 AM
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Unless this is a track only vehicle forget the gas ports, street cars don't need them and they don't need low tension rings either. Stick to the basics and forget the race only mods, your goal should be durability since your going to be making enough ponies already.
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Old 12-14-2002, 12:59 PM
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4-jaw is correct all the trick race parts will do on the street is burn oil, and the drilled ports will fill up with carbon .
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Old 12-14-2002, 03:28 PM
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I agree that gas ports are not needed,even on most race engines.Only when you uses extremely this rings with very low tension will you need the added pressure that gas ports offer/Here is another bit of info you might not know.Many racers have run rectangualr port manifolds of oval port heads with great results for many years.I thought this was way out of whack myself,but I have come to find that it is somewhat common,and have found it on some really good running bracket motor,even maing upwards of 650 horsepower.9 out of 10 of these mismatches involved large oval port heads being run with a 454R edelbrock intake on 468's that ran powerglides in somewhat heavy bracket camaros and novas{3200 to 3400#}.It tried it the other way with a Team G oval port on a set of rectangualr heads and I gained 60 foot but loost mph,and the top end loss was greater then the low end gain so I lost overall.If you dont already own the heads,I would look further into this setup.Good luck.
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