Potvin cam specs

6

61Klassic

Member
Good afternoon all.
I’m in the UK and in the process of building up a 293” 8BA.
I have a good cam grinder over here and would like to have a 425 Eliminator ground. Does anyone have a complete list of specs available that a cam grinder would need to grind this cam.
I have most of the specs but looks to have an unusual profile at full lift.
Thanks
Kev
 
Kev
Heres the specs when we were getting them from Cam Techniques


POTVIN 425 ELIMINATOR

Lift intake and exhaust .425 lash intake .014 exhaust .016
Duration intake and exhaust 284 advertised 246 at .050 valve lift
Valve timing at .050 Intake open 12 BTDC closes 54 ABDC
Exhaust open 54 BBDC closes 12 ATDC
111 Degree Intake C/L

Nice mild cam for fuel economy LOL

Ronnieroadster
 
Not sure how any of these spec's give you much of an idea what the actual profile is. It provides a few points along the profile, but there is a lot more data required to define the whole profile.
 
JSeery said:
Not sure how any of these spec's give you much of an idea what the actual profile is. It provides a few points along the profile, but there is a lot more data required to define the whole profile.
Click to expand...

That’s what I was thinking, does anyone have the complete profile of the cam available?
Thanks
Kev
 
61Klassic said:
That’s what I was thinking, does anyone have the complete profile of the cam available?
Thanks
Kev
Click to expand...






Kev what your asking is not easily supplied. I had the cam copied so a master was made for the cam grinding machine each profile we coppied cost a few hundred dollars at the time. Also had the Crane R-450 copied. Its not a simple task. Also note the lobe/ramp profile on the 425 is similar to a chizzel. I think i still have the original cam we used so long ago for the master.
Ronnieroadster
 
The easiest/best way to acquire what you're looking for is to have either Kiwi Tony or Pete1 grind you a 425. Keep in mind that the original Potvin versions were usually ground on a 32 billet core, with the journals resized to .010 under. Given the nature of the profile and the thin "base circle" of the cam, the steel core is the best way to go . . . though few people have these cores in their mitts.

Good luck!
D
 
Like Ronnie I too made my master from an original that I still have. I also now have in my collection a “”Brand New” never used Potvin 425 Eliminator. A thing of beauty. The originals were ground on original 1932 Ford “Steel” cams with the press on nose being modified to take a later bolt on gear.
Cheers
TP
 
I know at least 7 people that have "original" 425's. I have seen 4 in person. Only 2 had the same lift. (they were ground by Potvin himself) I guess the others changed with age or how they were stored.
The one I got masters off of was ground in 1953 and was handed over the counter to the guy that bought it by Chuck Potvin himself.
It had .416 cam lift.

The point here being, it is doubtful any difference could be seen on the dyno for a few thousandths lift and the word "original" doesn't really mean much after the company changed hands.

One of the reasons it works so well are the spring control ramps (chisel nose) that aid in it being able to turn 7500.
 
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I have a Potvin cam in my 8-BA and it's marked 415 on the end. No one has been able to give me any specs on it. All I can say is it's a strong running cam in my 286 CI flathead.
 
KiWinUS said:
Like Ronnie I too made my master from an original that I still have. I also now have in my collection a “”Brand New” never used Potvin 425 Eliminator. A thing of beauty. The originals were ground on original 1932 Ford “Steel” cams with the press on nose being modified to take a later bolt on gear.
Cheers
TP
Click to expand...

Tony,

Did you buy that one off the HAMB? I think you beat me to it by a few moments. It is a thing of beauty.
 
I think the 425 is a grear cam for Bonneville or the drags. In order to get the benefit of this grind very hi valve spring pressure is needed. So the application of the use should be considered.
 
61klassic, see your p .m.
there is one available here local ( Oklahoma U.S.A ) ,still in the moon speed equip. box.
 
Ol' Ron said:
I think the 425 is a great cam for Bonneville or the drags. In order to get the benefit of this grind very hi valve spring pressure is needed. So the application of the use should be considered.
Click to expand...

It is also a very good street cam in a big engine. (286 and over)

90 lb on the seat and 250 open works fine for street or race.
Single spring with damper.
This cam is very easy on the valve train especially if the components have been lightened.
 
Tim Ayers said:
Tony,

Did you buy that one off the HAMB? I think you beat me to it by a few moments. It is a thing of beauty.
Click to expand...

Sure did Tim. It did not have its original timing card& is a Moon ground cam.
Tim did you use your original Potvin 3/8 in your new build?
Cheers
Tony
 
Pete said:
It is also a very good street cam in a big engine. (286 and over)

90 lb on the seat and 250 open works fine for street or race.
Single spring with damper.
This cam is very easy on the valve train especially if the components have been lightened.
Click to expand...

Part of me wishes I went with one instead of the 3/8ths.
 
90# on the seat, for a street engine?? Just can't comprehend why anyone would want to waste a good cam here? Just for bragging rights. I have an L-100 in a 294 with 50# on the seats. turns 5k with no problem. Now for the race engine, that's another story!!!
 
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