Flathead Questions and concerns!!!!

Ol' Ron said:
I like the 425 Potvin, It will make a great deal of power. It's about the best cam for doing so. It requires a great deal of spring pressure and is best made form a steel billet. It uses a standard flat tappet. The cam requires a hi idle to prevent lifter/lobe failure. Unfortunately getting 200hp might not be possable. I suggest you go to a roller cam.
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OL'RON;:o WHILE YOU HAVE YOUR CAM SPECS, OUT WILL YOU PLEASE POST ON TWO HOWARDS I HAVE, ONE IS M-8, I'VE BEEN TOLD ITS A GOOD, MILD STREET CAM ?? THE OTHER IS M-12, WITH 360 LIFT ?? HOPE ITS A GOOD PULLER, FOR A HEAVE CAR:rolleyes:... 39 FORDOR?? YOUR INPUT PLEASE,...,ALSO I HAVE AN UNKNOWN, CAM WITH FLATS ON TOP THE LOBES, ABOUT 1/4" WIDE,IT WILL A GOOD LIFT AS THE HEAL OF THE LOBE IS GROUND TO THE SHAFT, LIKE THE WEBER F-6,THAT WAS PICTURED LAST WEEK ... AGAIN ... THANKS .... OLD....BILL :cool:
 
The Potvin 425 is a great cam. I have drag raced with one, but never tried one for the street. A strong motor for the street is not all about the HP. You want a broad power band and good torque for the best drivability.

I have run a 296 motor with a 400jr on the street with good results, I'm sure there are other choices too.

The 425 potvin will pull to at least 7000 rpm in the dragster, but I wouldn't want to be doing that over and over in a street car. That is a lot of piston speed with a long stroke flatty.
 
flatheadz-forever said:
what are the specs on that cam and does the 1007b have a lopy'er idle than the 400jr
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In 20/55
Ex 60/18
Lift .360
255 dur
Rate of lift .008 per degree sq.
Lobe sepearation 112
In .011 Ex .013
Lopey idle

Whether the idle is more lopey than the 400jr is purely subjective.
 
Yes the 1007B is a good cam, but i Prefer the L-100. Now rather than start an argument I suggest you build two engines exactly alike except for the two cams and pick the one you like best. The L-100 has 246*@.050 intake and 235* lift @.050" exhausr. Grose lift is .375 Clearance .016.


M-12 30/67 int. 23/71 ex .360" Lift. This is calssed as a full race drag cam, should idle lopy

M-8 23/57 intake 11/70 ex .328" lift .014.016 clearance This cam is classed as a 2/3. I've never tun the M12 so can't comment on it. I have run the M-8 and feel this cam has the potential of giving excellent fuel mileage is an econo engine and is slated to be used after I run the tests with the EAB cam.

Choosing a cam for street is a crap shoot and is ony a personal choice. I have a 1007B in KGS engine and the idle is very nice with alittle lobe. Most of my engines have the L-100 and is the cam we;re using in our mileage tests. More on this later.
Good luck
 
flatheadz-forever said:
ok so what are your guys opinions on main caps I was wondering if having all three main caps billet would be over kill.
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Either steel caps or straps....Your choice.
Straps are cheaper...You don't have to align bore...Some of the 100% nitro drag engines only use straps.
 
Pete
I have a potvin 400, never realized how close it was to the 425. How does it run in compairison to the 425?. What's the application? New, I think I might sell it>
 
Ol' Ron said:
Pete
I have a potvin 400, never realized how close it was to the 425. How does it run in compairison to the 425?. What's the application? New, I think I might sell it>
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The 400 is bigger than the 425...NO midrange.
Good race boat or Bonneville cam.
 
My friend Dick from Cape cod runs the 425 in his 345ci Flathead dragster. can't believe it's still in one piece. You should hear this thing!!!
 
NO OFFENSE GUYS; ..but this engine your building and the model A peeckup your going to put it in, if you get it to hook-up to ground (road).... you will "corkscrew" your frame, don't ask how I know this.... and ... OLD....BILL opens another can of worms .... lets be safe out there .... yes; I do care... O.B.
 
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