Re-shaping combustion chambers?

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Just out of curiosity. would it be safe to reshape the combustion chambers on the six head to a more kidney type shape with smoother walls instead of a large ridge?

regardless if the power gains are miniscule to me every scrap of power means more power and is thus worth the time to me.

I have expearance to do this however lack the knowledge or how much can be take off a head on ford six

(sorry for posting so much, would it be ok for me to just make a thread dedicated to my questions instead of constantly making new ones?)

Thanks
Alex
 
Lordred,

I'm not sure how much it would effect combustion efficiency either good or bad, but if you take much material out of the combustion chamber, you will have to mill the head back down to maintain the combustion ratio. Depending on what head that you start with, you will be already milling off material to get a decent CR. For example, a D8 or E0 head will have to be milled somewhere around .060 or so anyways just to bring the CR back to the ballark figure of the early 200's If you also deck the block and remove material from the chambers themselves, once you mill enough off to cc at the right volume, you could possibly have to worry about a valve hitting a piston. So, I'd be carefull.

That said, everybody says that a pollishing of the combustion chamber is good to remove hot spots.

I'm sure that the experts will chime in.

Kris
 
Thanks Whitepony.

I have a C5 head on a C5 engine :D

I am also aware of what happens due to the increase in combustion chamber size. However I plan to deck the block a little (mill to be accuret) as little as possable to have a true mating surface. The head will also be milled slightly for the same reason due to age. I remember from when i out the alpine together that reshaping the chambers was a must for power increase (as those chambers on the alpine were also far deeper and with huge walls.)

I dont plan to be running any super high cam and I have the adjustable rocker arms I have every plan to polish the combustion chambers, intake log and exaust ports.

Hopefully if any one has expearance in re-shaping the chambers on a 6 that would like to share it. I would be thirlled.


Alex
 
Alex,

If you haven't already seen it, check out this thread by Dennis Schjeldahl (One of the authers of the Falcon Performance Handbook). There is a good drawing showing where exactly to grind on the head.

What Porting is

Kris
 
Howdy Lordred and all:

YOur '65 head is a small, 52 cc chamber head with 1.69 intakes and 1.38" exhaust vavles. The best things you can do for this head is to specify a three angle valve job, backcut the intakes, smooth the chamber surface, clean up the intake passages as best you can, and port the exhaust to a smooth, flowing shape. In general, the inch on either side of the intake valve will have the greatest effect on flow.

In reshaping the chamber you will want to-
*maintain a high quench to bore ratio. That is best done by decking the block to zero and using a NAPA head gasket.
*not exceed the line of the bore in unshroading the intake.
*Unshroud the intake valves slightly between the cylinder walls and the spark plug. Shrouding is not as big of a problem with 1.69" intake valves as it is with the later 1.75" valves.
*measure each modified chamber in ccs and equalize to the largest.
*save milling as the last step after determining chamber size. Mill to achieve goal CR.

Adios, David
 
I don't think reshaping the chamber is going to help much since the valve won't actually be contained as part of the new shape you are making.
 
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