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Ok My friend has a set of vortec heads off of a 97 350. He's wondering if the 170cc intake runners can be ported to 200cc? The valves are 194s now but, they will be bored out to 202s. He is wondering if the intake runners will increase the CCs if the valves are enlarged to 202s?

Also he has the vortec roller cam out of the truck. We are wondering if the cam would be compatable with a 91 305 TPI (my car )?
THANKS FOR ANY INFO!
-Abe



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1991 Z28 305 TPI.

Mods: Hypertech Airfoil, gutted airboxes, K&Ns,polished 91' rims (they turned pink!), and all rear end bushings & tranny mout are energy suspension poly ones now

MORE TO COME: Any suggestions on what to do next? I really want to try and make the 305 run 13s (i've mostly been doing basic repair to the car, but now most of its done i have money to mod!)e-mail me@ abraham_39@hotmail.com

 

Abe,

I''ve never had a pair of Vortec heads on the bench (nor even one) but my understanding is that the raw castings are very much like a clone of the LT1 heads with slightly raised ports.

If this is true, I have had those cross the bench, and was able to to raise the intake port volume to over 200cc without getting too viscious with the mill and grinder. I installed 202/1.60 valves and opened the valve bowls accordingly. Raising the top of the runners and lowering the floor to almost eliminate the short radii, then taking the left and right turns out as much as possible raised the flow from whatever it was before to 262 SCFM @ 0.1"SPWC. (Robertshaw flow tester). The valve/port free area was increased from 2.714in² to 2.996in². Calculated flow increase was 11% without touching the intake runners, which probably only increased with matching/enlarging. I did lose low-end torque, but the midrange and top end MORE than made up for it.

If the Vortecs are that similar, with already raised ports, they are probably worth the effort in valve/port work, especially if you can get them at a good price.

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Later,
Vader
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"No matter how hard you try you can't stop us now"
Adobe Acrobat Reader 4.0

 

Vader, I'll show him the information you gave us about the heads, also hes getting them at a GREAT price, Free! somone spun a bearing on the truck that he is getting the parts from. At his work they were going to trash the motor so, they let him take ANY parts he wanted..its a 5.7 w/vortec heads.. he got the cam and the heads b4 any of the other mechanics there got to it. He said he doesn't need the cam, and if it would work in my car i could have it for free. So, with the head question out of the way, would the cam be a fair cam to replace my peanut cam? Oh, and i was in there today, and the truck motor is still there on the engine stand, almost completely stripped. he said he was going to get the bare block, but the crank messed up the block bad? (i don't know what the crank messed up, but thats why he isn't gettting the block.) Oh, and my car is a 1991 305 LB9 TPI.
Thanks,
-Abe

[This message has been edited by Abe91Z28 (edited January 05, 2001).]