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Old 03-13-2016, 12:57 PM   #11
MikeB
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Join Date: Jul 2000
Location: North Texas
Posts: 3,562
Re: Restoring Rusty

Quote:
Originally Posted by Gregski View Post

Basically the holes of the Vortec head and the holes in the Mr. Gasket gasket do not match up, in other words they are not the same exact size. I wonder how much of that bottom 3/16ths of meat could you grind down before hitting a water jacket...
Don't touch the exhaust ports! There is absolutely no benefit in doing so.

Vortec exhaust ports are raised relative to the header bolt holes compared to conventional heads. The trick is to find headers and gaskets that are "tall" enough. A huge percentage of exhaust flow is at the top of the port so it's imperative not to block the opening. As long as the gasket and header openings are the same size or a little larger than the head ports, you'll be fine. As I recall, 1.5" x 1.5" gaskets will work fine.

I used these stock 1997 replacement FelPros on my Vortec heads.


And then raised the ports on my cast iron manifolds.



An old racing trick where rules limit header primary tube size is to raise the headers on the head. Although this covers up the bottom of the head port, that loss is FAR outweighed by the gains at the top of the port where the denser and higher velocity gasses now have more room to move upwards and outward.
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Mike
1969 C10 LWB -- owned for 35 years. 350/TH350, 3.08 posi, 1st Gen Vintage Air, AAW wiring harness, 5-lug conversion, 1985 spindles and brakes.
1982 C10 SWB -- sold
1981 C10 Silverado LWB -- sold, but wish I still had it!
1969 C10 (not the current one) that I bought in the early 1980s. Paid $1200; sold for $1500 a few years later. Just a hint at the appreciation that was coming.
Retired as a factory automation products salesman.
Worked part-time over the years for an engine builder and a classic car repair shop.
Member here for 24 years! This is the very first car/truck Internet forum I joined. I still used a dial-up modem back then!
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