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Author Topic:   vortex head upgrade
posted August 03, 2003 08:51 PM
I'm currently running dbl. hump,large valve heads (64cc) on a 355 sbc, and want to change to the vortec head now that our rules allow them. (no porting or polishing). I have read that you should keep the smaller valves. Any comments on the valve size?
I will have to get some machine work done because of stock type intake and a .555 lift cam.

posted August 03, 2003 09:23 PM
from what i've heard going to 202 160 valves is the way to go. also be sure to buy the cast intake meant for the vortec heads...not a regular style intake that has been modified.


posted August 04, 2003 12:50 AM
how much is the cast intake and from where??

for vortecs??

posted August 04, 2003 07:16 AM
66jj, click on the Scogins-Dicke banner they're a sponser of the forum. I think the iron manifold is about $170...loojack

"loojackracing, a not for profit organization"

posted August 04, 2003 12:24 PM
also look on ebay...they are between 100-150$


posted August 04, 2003 12:30 PM
I agree if you use a standard intake on vortec heads you are not really getting the full benefit. Plus the ports dont line up right and you can actually have problems getting the ports sealed up.

rico 08
posted August 04, 2003 07:26 PM
Brezinski can machine the vortec's for the older style intake for around $120,some say you need to use a thicker intake gasket to seal it up,most say it can't be done but i've seen it done.

posted August 10, 2003 10:47 AM
I've been running Votecs with the cast iron two barrel intake for two seasons now. Haven't had a bit of problem with sealing. I've been using the same gaskets and have even removed the intake twice with no real problem in the gaskets tearing up. Parts of the gasket had layers that separated, but a little silicone has worked fine. The number of the gasket is Felpro #1255, I think. It's a 1/8" thick gasket to help raise the intake on the head ports. It also has both the old and new style bolt pattern. The top of the ports is where you have to be carefull. There is barely any sealing surface left in that area because the top of the ports in the vortec head is taller than the old style head. The head and intake surfaces overlap by maybe several thousandths. But there is still no sealing problems. Use silicone on all sufaces.

I also carefully redrilled the heads to match the old style bolt pattern. Jig up the head very carefully on a drill press using the new gasket as a pattern.

Now, after all this trouble, I'm can't say for sure if we gained any power. The only reason we went to this setup was the track said we had to start using 350 heads and these were best we could find for the money. The 305 heads we were using had smaller ports and valves, but higher compression. With Vortecs, we have better flow, but with lower compression and the port mismatch we have now, I wonder if it's all the same in the end.

I also changed the springs to T-11 spring material for higher lift cams. They're stock diameter and have worked quite well. It's the stock, vortec style, (self centering) rockers that have caused us problems. We broke three in one race. They were a season old. I think replacing them every season is the way to go.

This is long enough!

Good luck!


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