Potvin 3/8 cam specs?

Cool Kat with Hot Car

Cool Kat with Hot Car

Senior Member
Just dug out an old hot rod flathead I have had sitting around. It was built in the early 1980's. It looks to be pretty stout with a 4 1/8 Merc. crank, real beefy front and center main caps, lots of work on intake ports, etc. It has a cam marked Potvin 3/8. Can anyone provide the specs. for this cam?

Thanks
 
Cool Kat with Hot Car said:
Just dug out an old hot rod flathead I have had sitting around. It was built in the early 1980's. It looks to be pretty stout with a 4 1/8 Merc. crank, real beefy front and center main caps, lots of work on intake ports, etc. It has a cam marked Potvin 3/8. Can anyone provide the specs. for this cam?

Thanks
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In 28-72
Ex 71-29
Lift .375
280 dur.
Rate of lift .008
In cl .012
Ex cl .014
Lobe sep. 112
 
Pete,
Thanks for the quick reply! I know you are a cam whiz, is this a good cam for a street driven full fendered 32 3 Window, 3:54 gears, 6.50X16 tires?
 
old Tom said:
Did not Potvin make a Eliminator grind?
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They made the '425 Eliminator' - one of the best cams out there for a 284 cubic inch engine and larger.

They also made a '400 Climax' - kind of half way between a 3/8 and the 425. I've never had my paws on a 'Climax' - wish I had one!

B&S
 
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I've go a Potvin cam marked that's marked 415. Any details on that. It's got a pretty wild lope and sounds good on my 286 flathead.
 
Here is something I cut out of a Moon catalog back when Bill Jenks was grinding Potvin cams at Moon Eq. Co.
 

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hi all i have a potvin moon cam im trying to find specs on. is this a different grind to a potvin? hope i make sense.
 
camswax said:
hi all i have a potvin moon cam I'm trying to find specs on. is this a different grind to a potvin? hope i make sense.
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Moon ended up with I believe all the Potvin masters and Bill Jenks ground Moon-Potvin cams for years. They should be just as good as the originals (at least that is what I'm told - I've only ran originals and Pete's stuff).

What grind do you have? What numbers are on the front?

B&S
 
One of the issues with that type cam card above here is the lack of the ".050" numbers, these are fairly important to determine how the cam will act in each individual build.

The "advertised" duration (280*) above tells more about the idle quality/sound than the actual performance.

I have 4 builds going on now, 3 8BA's and a "59" and the "59" actually has the "Potvin 3/8" (a copy of it at least), it was a customer supplied piece, he picked it out and handed it to us. It is NOT a good all-around choice for this build, a fairly heavy ride that will see only around-town cruising!

Thanks, Gary in N.Y.

P.S. Here's a photo of the cam card, it has way too much ".050" duration in my opinion on this unit.
 

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GOSFAST said:
It is NOT a good all-around choice for this build, a fairly heavy ride that will see only around-town cruising!

Thanks, Gary in N.Y.
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Hey Gary - how many cubic inches is the engine, what trans, what rear and what car? This is a really good cam for a lot of situations (especially around a 276 cube engine) - am wondering what the situation is that you're dealing with?
 
As I have said, people differ in what they can tolerate and some might like the Potvin 3/8 but is a poor choice for low speed street driving when compared to other available choices.
 
JWL said:
As I have said, people differ in what they can tolerate and some might like the Potvin 3/8 but is a poor choice for low speed street driving when compared to other available choices.
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Bored&Stroked said:
Hey Gary - how many cubic inches is the engine, what trans, what rear and what car? This is a really good cam for a lot of situations (especially around a 276 cube engine) - am wondering what the situation is that you're dealing with?
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Hi Dale, it's for the exact reasoning that John posted above here that I say the cam is wrong for this unit. It is a stroker but I have no idea of the other "important" specs (trans, gears, tire hgt, etc.) about the ride itself as of today. Waiting to meet the owner.

Let me explain where I am on this build now. I "inherited" the job from another shop who isn't able to finish it. Haven't even met the owner of the ride yet. I am told by the shop's owner that it is a '48 Ford (four-door) that will be used for driving "around town" more than anything else. My understanding is the owner chose ALL the components WITH the help of the vendor who sold him almost all the parts.

With what I have he will be well over 100# spring seat pressure alone on the springs. There's many incompatible pieces here. I have a set of valves (correct OEM length's) with the keeper grooves "down" .400" instead of the normal .250" and a set of 185-G Isky's. Some "not-so-good" choices here, will explain some more when I get to meet the owner and get his side of the story.

I was very surprised by many of these components I received, especially knowing that the vendor had a hand in helping put the pkge together. If anyone tried to order this here I would have taken the time to explain why there were better alternatives.

(Add) One other item I received in the parts pkge and refuse to even consider using here is a set of Aluminum valve spring retainers, this would NEVER happen here! If any customer wants "special" spring retainers I keep L/W "tool-steel's" on the shelf for the Flatheads along with conventional OEM "steel" and Comp Cams "Chromemoly's".

Thanks, Gary in N.Y.

P.S. With John's post above I couldn't agree more and it's why I stated in my first post about the cam being not the best choice here. I have found over time that the Isky "88" cam to be one of the best all-around ones for enjoying the ride and having the "sound" AND making nice power in a very comfortable power range. Generally speaking in a "light" ride with a larger unit you can get by with more ".050" duration, in a "heavy" ride you need to pay closer attention to the cam choice, more so in a "daily" driver, an "around-town" ride so to speak.
 
Thanks for the update . . . sounds like a heavy car and a cruiser as well. I don't see many "real hot-rodded" 48 sedans so being a bit conservative might be a smart idea.

Given that we don't know the rear end ratio - a safe bet is a 3.78 and probably a stock trans. I don't know the cubic inches, but another cam I'd consider is the Isky 1007B - has a high rate of lift and runs really well - even in a smaller motor. The duration (from memory) is about 235 @.050 and I think it lifts .355. The opening ramp speed really helps with mid-range torque. Just another choice to checkout. If you want to try one, get in touch with Pete1 on the HAMB - he's a good friend and has been grinding cams for about 60 years - does excellent work.

I agree with you on the spring pressure issue - I don't run 100 lbs on the seat unless it is a roller cam or a special race situation with very high rpms and the cam has a billet core. You get too damn much cam deflection and wear at those spring pressures. I'd probably run something closer to 65 lbs for his application.

B&S
 
Not wanting to get into a "camshaft" debate here, I'll offer my latest engine as realy nice street engine. It's a 280 STOCK flathead. The only aftermaket part in it are the 3 5/16 +.020" pistons. It had EAB heads milled for .045" head to piston clearance and ah EAB cam. Merc intake with 2GC and a GM dist, set up By Richard. Rear is 3.73, Trans is 3 spd w 36% od. Truck weights 3320, You just can't believe how this thing drives through the Green mountains of Vermont. The torque is unbelievable
 
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