Porting a Chy 340/360 head.

[Malvin]

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jfholm hit the nail right on the head in his post.

The person that I did these heads for already had
a single plane intake I wanted him to get a Edelbrock Performer RPM Air Gap dual plane but he did not want it. I felt it would have been the better of the two intakes. He did tell me that
it had lots of face skin pulling tq on take off LOL

Thanks for the link to read about Pipe Max
I am going to buy it I hope it is a user freindly program.

Malvin

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[coulterracn]

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[coulterracn]

Gorden,
When you say your bowl measures 2" and 2.1", is that square inches, as in area?

I'm talking about measuring from inside to inside straight accross with inside calipers. What is that inside diameter dimension?

Ray

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new nail head2.02 installed.

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can only post one pic at a time........
stock X head.

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my ported head after first porting session and 2.02 cut with 75/65/45/30 cut into it.

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and with a shinny new nail head 2.02 valve installed.

[coulterracn]

Gorden,

I'm going to stick my neck out and give you my opinion of where you are with this intake port.

Blend the 70* angle into the bowl, work the back side of the valve guide. Work both port walls with a 60 or 80 grit cartridge roll or shop roll on a split mandrel. Remove the material around the roof of the port past the valve guide boss.

Start on your exhaust port and keep the 1-3/4" headers because you will be using a 1.60" exhaust valve. If you were using a 1.5" exhaust valve I'd step down on the header tube size to a 1-5/8".

Ray

[200cfm]

Gordon, I was reviewing Pipemax today. I noticed in the File section there is a example of a 360 Mopar engine and how it was set up. Try and review that example. As I reviewed it I notice the CSA of the throat is the smallest CSA of the port. Valve is only 1.880 but note the power levels possible. Perhaps I need a Hemi.

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THING I HAVE LEARN SO FAR!

This head is the "exception" to the general rules of porting.............
Such as,..... "over 350 fps is a no no or way to fast"..........but thats were the air wants to go, on my head and on the ssr to boot( quote, port your head the way the air want to go not were you thing it should go)

I posted up or started a new thread, on speed talk about these heads, and one of the guys that responded back said that on "mirrored ports"(like mine and the small block chev....and other too I'm sure) you should focus on the "hot side"(opposite wall of the prp, he said)as thats were the air want to go................
Well my "HOT WALL" is on the prp wall, high on the wall, and then travels down to the ssr......thats were most of my air want to go as of yet.
Still want to try a couple of thing, one step at a time, but then, I think i need to start porting were the air want to go..........

I also read a thread over there that was taking about a old Pontiac head that had the same High speed ssr problem(over 400)
He was instructed, that he could open up the port to equals the flow but would only make a good flow number that would only slow the car down at the track :p

According to Larry M in that thread you can have speed as high as 437 and still not have seperation as long as the radious is right and every other part is right from there all the way thru the valve angles. He said it better then that of course!

[jfholm]

Gordon,
A good way to tell if you SSR is ok is to check the flow at and after the convergence lift. The convergence lift is where the window area created by the valve lift equals the area of the head of the valve. In you case with a 2.02 valve your convergence lift is .505".

If your air flow goes backwards at and after .505" lift, especially at 28" H2O then the SSR probably needs work. This is what mine did. I had to lower and flatten my SSR and push it back out of the pocket some. My flow went from 206 cfm after .513" lift to 263 cfm. Most just from the SSR work.

Even if your lift is .477" I would check it and strive for this. Just remember when you get more air flow your velocity will goe up also.

John