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Author Topic:   vortec heads
dirtbandit
Member
posted July 31, 2003 04:08 PM
You will have to have the guides cut down for clearance with that much lift. Need to have the studs driiled and have guide plates and screw in studs installed. Maybe have to open up the pushrod holes some. Put on a good set of springs. Possibly open up the valves for 2.02,1.6 instead of the smaller valves, but these heads flow pretty well in stock form, and there effecient design can be ruined if the wrong porting work is done.


sdhnc29
Member
posted July 31, 2003 09:30 PM
I'd go with everything that dirtbuster said , especially the 2.020"/1.600" valves . Buy going to these valves and doing a simple 3/4" pocket blend , you will pick up air flow that will support 100 more HP than stock form . You might not get 100 more HP , but the potential air flow is there .

One more note on cam shaft . I would not go much over .550" lift . These heads , even with the larger valves , fall on their face as far as air flow is concerned over .550" lift . The intake port just becomes way too turbulent .

Steve

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Hendren Racing Engines
Rutherfordton , NC
(828)286-0780


istock59
Member
posted July 31, 2003 09:42 PM
Steve, the 'simple 3/4" pocket blend' you talk of, is this something that the average racer can do himself? Can you explain it a little further?

Thanks.

sdhnc29
Member
posted July 31, 2003 11:37 PM
The average guy can do it just as easy as me or any other engine builder , provided that the head was opened up for the larger valve correctly . Try and find a machine shop that has a valve seat machine that uses pre formed cutter's . I'm not speaking about bowl hogs , but seat cutters that will open the seat area up correctly . Anyone with a Serdi or a Newen machine can do this for you if they have the correct seat cutter's . Once the seat area has been opened up , it's a simple matter of hand blending under the area that the seat cutters opened up . Make sure that you do not grind straight down off the seat !!! In other words , you want to leave the area under the seat looking like a ventury ?? . Also make sure that you only blend the short side radius , and do not lay it back . If your rules don't restrict you , you can also do some careful work around the guide boss area in the pockets ........such as narrowing up the guide boss . This will also gain some extra flow for you .

Basically the whole trick is how the heads are opened up with the seat machine . If you find a shop that has one of these machines , send me a PM or an email and I'll give you the cutter numbers that we use . You can buy these cutter's yourself and take them to your machine shop so they can use them on your heads , unless they already have them .

Steve

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Hendren Racing Engines
Rutherfordton , NC
(828)286-0780


dirtbandit
Member
posted August 01, 2003 10:04 AM
It's difficult to say for sure , it depends on where you are at and what your local machine shops charge . I can tell you what I charge , which might be on the high side for some area's , and on the low side in others .
Valve Job (including opening heads for larger valves ) : $200.00
Cut valve guides : $35.00
Machine for $crew-in-studs : $100.00
Flat mill heads : $25.00 ea
3/4" bowl blend : $200.00

This is assuming that your valve guides are within tolerance and don't need replacing , and you are using stock diameter valve springs that don't require cutting the spring seat's .
Steve

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Hendren Racing Engines
Rutherfordton , NC
(828)286-0780


dirtracer14
Member
posted August 01, 2003 10:22 PM
Hey steve these cutters you talk about can they be used in a mill? The guy that does my heads has a older seat grinder that is the hand held type? We have a nice set of the vortecs that i have ben wanting to try but was told that i would be better off with the darts...but for a backup motor i think they will work fine. I also heard that you only can run a flattop with them? What about a mild roller cam?


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