Originally Posted by 12second6
Thanks for posting those pics of the heads and intake the casting numbers on my 4.3 vortec heads are 10235772 and they wer cast in 1996 I was gonna have them machined for 2.02 and 1.6 valves i have a spare lower syclone intake so i can start drilling and machining without taking the truck apart.How much power did you feel from doing the head swap to these over how the orig heads felt?
You have the correct heads if they're 772's. If I had to do this over again, I would have used a #2114 edelbrock
bolt on lower intake and something like the following intake elbow rather than all the drilling, welding and machining of the syclone lower. http://www.intakeelbows.com/lt1_twin_52mm.htm
people have reported very nice gains going this route. Some people have produced data that shows the syclone intake unevenly distributes air at really high horsepower and boost levels.
Just by swapping to vortecs, I was able to run a few more safe lbs. of boost and other syty people say they can run alot more timing by swapping to vortec heads. No other real notable differences for me because I had been running heavily ported L35 heads (93-95) before these lightly ported vortecs anyway.
Some people report 50hp increases on the dyno when going from the stock crappy syclone heads to vortecs. Regardless, the vortec heads offer great bang for the buck.
If you do decide to mod a syclone lower, keep in mind that it is very important to mock up the heads and lower intake with the thick intake gaskets you'll be using for the purpose of getting those holes suitably lined up. also, it appears the angle of the intake port surface vs. the port surface of the heads seemed to be about a degree or so off and caused me some sealing problems at the bottom of the ports at first. I haven't heard to much about that so maybe it was only me and another guy from canada that reported it.
I'm not trying to scare you away from using the syclone intake just offering another option before you go drill a perfectly good set of heads that you really worked on and spent $$ on.
I built my truck on a total budget and have had passengers tell me that the acceleration of it separated their body from their soul.
But I don't exactly push the limits by running a max of only 20 psi boost and 19 or so degrees of timing so I don't see the unevenness of the air whenever I pull my plugs to read them. Some of these guys are running from 28 psi to over 30 psi of boost, so I guess you could say I feel like I'm running mine conservatively. I also spray methanol for more preventative measures also.