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I'm curious,
Can the Intake Valve guide boss be modified on the pinto head, legally that is, to increase the CFM?
Are the runners inside the head considered part of the port? I question this after reading David Vizard's book " How To Modify Ford S.O.H.C. Engines"
Thanx, Jeff
Call Curtis Boggs at RaceFlow Development, he knows the ins and outs of porting 1600 and 2000 heads, not to mention 600 Cubic Inch Pro Stock Monster motors. He has a computerized flow bench and has spent countless hours trying things.
If you read the GCR you will see porting is allowed...extensive even... but you must meet certain deminsions at the gasket face and around the valve seats.
Thanx, Mike.
It's the "WITHIN LIMITS" thing that I was questioning. Seems like a simple enough task to the uninitiated, a die grinder ond good stone, maybe? According to David Vizards book, a slight removal of the boss can result in 4 - 6 cfm.
So the GCR seams to address the port OPENINGS for the most part, or so it seems.
Within the rules, what's in between the gasket opening and the valve seat is yours, to do with what you will. The advice to go to Curtis Boggs, or another top head guy, is well founded. We are having an engine built for a OFFC Class B car for next year, and dyno'd the new engine with the cast iron head that came with the car - a quite good, winning head from the mid 90's. The engine made poor power, compared to what our builder expects today, down about 8 hp. He put on an early aluminum head, gained 4 hp. A new Boggs head is in the mail that will probably pick up the other 4 hp. That's the difference a decade makes.
Brian
I had a feeling someone was talking about me, .. my ears where burning. ;-)Quote:
Originally Posted by jiffyh
Hate to tell you but most of the stuff in David's book does not work on our style
of 2.L engine. The limited cam lift and carb make this an odd animal to work on.
The guide boss really doesn't get much action, .. if you can picture this, ..
the air flows down the floor or deck side of the intake port, .. does NOT make the turn
at the valve to exit but travels across the back of the valve and out the back side of the port.
The roof by the guide boss doesn't see much flow and the valve opening at the short turn side
doesn't feed much to the chamber.
For flow, .. if you looked up an example of the WORST design , ..
it would have a picture of a 2.L intake!
Curtis
Thanx for the feedback, guys. It was a matter of curiosity for the most part. I have a couple of pinto heads in addition to one prepped and ported one. What does a good head prep cost these days? Another curiosity question.