Vortec Heads

[jwaller]

does anybody care to share information about what McCoy is doing to his Vortec heads to make them flow what they do?...I don't so much care about the intake as I do the exhaust. I was trying to find some pics of what his port work looks like. does he remove the casting around the valver guid boss.....does he raise the ceiling of the exhaust port where it meets the header?...what is it that makes it so special?....I mean 3k and more is a lot for some heads

 

[jwaller]

didnt think so.

 

[4C FED]

Jerry's kinda tight lipped about stuff.
When I asked about the cam spec's, he replied, ".514 lift, it's a special grind made for us".

And that's cool with me, I just wanted to have the info for my personal records.

As for your question about the height of the exhaust port at the header, I would say yes.
I trimmed my gaskets to match my ATR headers. And now the gasket matches the top of the header and the top of the exhaust port.

The bottom is another story. The exhaust opening on the header is much lower than the exhaust port on the head, by about 1/4".

HTH a little,

_________________

Rick
Sy#458
Galt, CA

<font size=-1>[ This Message was edited by: 4C FED on 2002-01-10 18:54 ]</font>

 

[ALLTRAC]

On 2001-12-26 18:57, jwaller wrote:
what is it that makes it so special?....I mean 3k and more is a lot for some heads

Nothing makes them special(maybe the price).

They are vortec heads, just ported. Nothing there that any good head porter couldn't do.

I think he charges 2K for his. Even at 2K the price is way out of range.


Ryan

 

[jwaller]

I totally agree and thats the reason I do my own...but I was just looking for some help in porting...so that I dont destroy a nice set of heads.

 

[ALLTRAC]

Exhaust:

In the exhaust port the majority of combusted products will be flowing near the roof and not on the floor. Just run a sanding roll over the floor of the port to get rid of the casting flash and thats it for the floor. Concentrate on widening and raising the port. Don't take to much material out or you will be inducted into the miners association.

Aluminum can be welded , Cast iron can't.

Concentrate mainly on the bowl area since this is where most of the flow will be gained. Grind the valve guide boss down so that it tapers away from the valve stem. Clean up the short turn but do not remove any significant amount of material.

The venturi in the exhaust should be ground to about .200" - .250" smaller than the size of the valve depending on head design. The head design we use likes a larger venturi(around .220" smaller than valve).

VENTURI - This is the smallest place in the port. This is located above the valve seat in the intake and the exhaust.

Most of porting is done by measuring. If you don't have a set of snap gauges and a dial caliper I would not suggest doing a full port job.

A flow bench is also a wonderful thing. If you have one that you can use I would suggest doing some R&D on it. When ever you get the flow you want just measure the port and replicate it.


Ryan



_________________
"It's not a war on drugs it's a war on personal freedom"

<font size=-1>[ This Message was edited by: ALLTRAC on 2002-01-10 23:05 ]</font>

 

[jwaller]

this is just what I wanted to know....I do have access to a flow bench and a spare vortec that is cracked...so I plan to practice on it first..once again thanks for the info

 

[Blake]

This is not about vortec heads in particular, more about the L-35s. I found a product called Resbond that was supposed to be good for up to 2300 F. It is the toothpaste consistency stuff that is air cured. Takes a LONG time to cure. I was wanting to use this to help clean up(fill) the egr ports in the exhaust ports. Anyone ever tried the stuff on a set of cast iron heads?
Thanks!
George Blake

 

[jwaller]

I wouldnt use anything in the exhaust ports...you could really destroy the turbo if it comes out. but try it if you want