Guest HALLOWEEN Z Posted February 8, 2010 Share Posted February 8, 2010 I've got a 4 bolt main with low miles but por performance chevrolet heads on now. It's goin in a firebird and I'm thinking of getting a set of vortec's for it. I've got a 350 with vortecs and edelbroc intake and fastest it ran was 12.35 with none race tires. The firebird is just goin to be a daily driver but I'd like to get the best combo for power. I still need to measure the distance from the top of the piston to the deck of block, they are flat top pistons. Theres not a better head that can compete for price/performance is there? I can get new vortecs from summit for 300 a piece. Quote Link to comment Share on other sites More sharing options...
Guest HALLOWEEN Z Posted February 8, 2010 Share Posted February 8, 2010 oh and the cam in my z is a comp 268h if i remember right. Must be atleast a decent combo. Quote Link to comment Share on other sites More sharing options...
Pyro Posted February 8, 2010 Share Posted February 8, 2010 vortecs flow poorly on the exhaust port so they tend to do better with more exhaust duration than intake. However, a little bowl smoothing under the exhaust valve and full length headers should take care of that and allow an equal duration cam (like a 268H). Also, vortecs are limited to the amount of lift. 0.450" is about it for the stock setup. However, a little machine work can fix that. furthermore, vortecs have fast burn chambers. so they don't require as much total timing as older style heads. This means you can run a little more compression with the same size cam as compared to older heads. Finally, the cam, compression, intake, gear, and stall (if you use an auto trans) all need to match. so, the best cam/intake combo will vary greatly. Yes, the heads are a good deal. However, they require vortec rocker arms, vortec valve covers, vortec intake manifold , and some machine work to allow for more lift. If you don't already have these things then the price to use these heads go up a lot. If you already have an intake, rockers, and valve covers then take a close look at the dart iron eagles and the RHS alum. heads (750/pair). http://www.summitracing.com Quote Link to comment Share on other sites More sharing options...
grumpyvette Posted February 22, 2010 Share Posted February 22, 2010 (edited) your rear gear ratio, and static compression, displacement,header design and the shift points (rpm)will need to be taken into consideration when selecting a cam, and the clearances and spring load rates will need to be known. generally the smaller port vortec heads won,t flow efficiently even when mildly ported, and when clearanced for higher lifts and equipped with better springs at lifts over about 0.540 and durations over about 240@.050 lift, so even when theres been a good deal of work done to the stock small port castings they are restrictive. vortecs are designed to operate most efficiently in the 2500rpm-5500rpm power band,and by about 6500rpm on a 350 or by about 6200rpm on a 383 the powers dropping rapidly so a dual plane intakes the best match like a edelbrock RPM AIR GAP, or WEIAND AIR STRIKE, BOTH WORK, BUT PERSONALLY I PREFER THE AIR STRIKE http://www.summitracing.com/parts/WND-8502C/Application/?prefilter=0 http://forum.grumpysperformance.com/viewtopic.php?f=52&t=401&p=6078&hilit=cross+sectional+area#p6078 http://forum.grumpysperformance.com/viewtopic.php?f=52&t=333&p=1870&hilit=+cross+sectional+area#p1870 http://forum.grumpysperformance.com/viewtopic.php?f=69&t=1040&p=1943&hilit=206cc#p1943 Edited February 22, 2010 by grumpyvette Quote Link to comment Share on other sites More sharing options...
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