How much is too much

[Dick Steinkamp]

Originally Posted by Tom Wesenberg

NO cam can be reground and match original specs. Either the lift or duration has to change.

Not so. The base circle (heal) is reduced in order to have enough "new" material on the other end to grind the stock profile. Here's a good thread on that...

http://www.jalopyjournal.com/forum/t...am-work.36558/

You do have to make up the difference in the slightly shorter total cam lobe. Usually done with adjustable lifters/rockers. With a stock model a valve train you would need new valves so that you have long enough stems to obtain the proper clearance.

I agree with Mitch to leave it alone since it runs fine now.
BTW, I have a Studebaker V8 and the spec calls for .024" valve clearance. I thought this would make the engine sound like a rear bumper dragging tin cans at a wedding ceremony, but it's quiet.

I have owned many Studebaker V8s and agree they are quiet engines when the valves are adjusted correctly. It is a function of the "ramp" on the cam from the lobe to the heal letting the valve down gently to it's seat. Contrast with a high performance Chevy V8 solid lifter cam that has so much duration that it has to literally "dump" the valve on to the seat. They make a pretty neat hot rod clatter .

[forever4]

Originally Posted by Dick Steinkamp

Not so. The base circle (heal) is reduced in order to have enough "new" material on the other end to grind the stock profile. Here's a good thread on that...

http://www.jalopyjournal.com/forum/t...am-work.36558/

You do have to make up the difference in the slightly shorter total cam lobe. Usually done with adjustable lifters/rockers. With a stock model a valve train you would need new valves so that you have long enough stems to obtain the proper clearance.

I think Tom and George are the only guys on this thread who understands the facts and is correct.

You cannot regrind the cam and get the original lift and duration back back. People make the mistake of thinking it is a simple lift geometry problem. It is not, and it has nothing to do with making the push rods longer.

The cam profile plot of lift versus angle duration represents the time and opening of the valve, which affects the amount of air fuel mixture entering the cylinder. This is directly related to the power capable of being produced. If you integrate the area under the curve, it is profoundly different (less) for a reground cam.

Depending on the regrind, you can bias the torque and power a little, but overall you are at a loss compared to stock.

Many people here seem incapable of grasping this, or unwilling to believe it.

and so it goes...

[Dick Steinkamp]

Originally Posted by forever4

...You cannot regrind the cam and get the original lift and duration back...

...Depending on the regrind, you can bias the torque and power a little, but overall you are at a loss compared to stock...

I respect and admire all you have done for the hobby and have often used the information you have spent a lot of time putting together. Thanks. I'm sure you have forgotten more about Model A's than I'll ever know.

However, I try to deal with facts whenever possible. I supplied links to quality cam grinders who claim they can regrind a stock cam to the same stock profile...and that they can even grind a higher lift and longer duration than stock on a stock cam. I also provided illustrations of how this is done by reducing the base circle.

Is there anything you can link to that would substantiate your opinion that it can't be done?

[forever4]

Originally Posted by Dick Steinkamp

I supplied links to quality cam grinders who claim they can regrind a stock cam to the same stock profile...and that they can even grind a higher lift and longer duration than stock on a stock cam. I also provided illustrations of how this is done by reducing the base circle.

This conversation has been on fordbarn and ahooga 25 times over the years, and the facts are still unchanged.

Your illustrations from Marco / Bob Johnson are correct. Your understanding of them is not.

"OR", versus "AND" and the limits of the physics are key points. This is real life, not a theoretical abstraction.

Also what really matters is the integration of the area under the curve representing valve height and duration off seat, which is the real life breathing and the charge.

Based on the many discussions preceding on the boards, I don't expect to convince you of anything. That is your job. Or not.

As a practical matter, why do you suppose that new repro stock cams outperform all the 'stock/touring' regrinds available for the last 50 years, and that everyone wants to use and recommend a Stipe 330 or clone, when a regrind is a third the cost?

[Dick Steinkamp]

Originally Posted by Dick Steinkamp

Is there anything you can link to that would substantiate your opinion that it can't be done?

I didn't think so.