Technical Good cam choice for mild flathead

Does anyone have the specs on the Potvin 3/8's? Lift? Duration, etc?
Thanks
Jim

 

Heck than looks like a wartime John Deere "AR". Pretty rare dude.

 

Heck than looks like a wartime John Deere "AR". Pretty rare dude.

It is a john deer, been trying to figure out how to get it out of it hiding spot but the trees are all grown up around it and its stuck fast.

 

0.37 lift
280 duration

 

I'll pull the timing card about and post them. Will be tomorrow.

 

Thanks Micky.
Seems just the same as the 425, but with less lift.
Thanks again. Seems like A GOOD CAM

 

The 425 is a whole different world than the 3/8
I like the 425

 

im reading this with some interest-I have a o/g jenks 3/8 and a 425-in boxes still-have been wondering about the streetablity of the 425

 

This is my new favorite. It's Cory Taulbert's roadster with a Winfield SU1A.

http://www.youtube.com/watch?v=vTXMcYn6ZgE

 

If you look on the lobes , you will see the 3/8 is round on the
Top , where the 425 has the shape of a (house) roof
The lifter need more spring preasure to follow the shape
On the 425 and i guess lobe and lifter wear will be greater
But its a GREAT cam , you just should check valvetrain wear
More often.
Dont use adjustibale lifters with the 425, too heavy

I have 8000 miles on my 404a radius lifter cam and cant
See or measure any wear and the 404a has a wild lobe design
,too
Btw ,its the best cam i ever used in a flathead .
Wide power range
Just lacks the sound compared to a 425

 

I've heard the SU1A specs are all over the place with the grinders. Apparently it was used as a reference and then adjusted to the setup.


Posted using the Full Custom H.A.M.B. App!

 

im reading this with some interest-I have a o/g jenks 3/8 and a 425-in boxes still-have been wondering about the streetablity of the 425.
Stroked36:
I run the Potvin 425 in a 288" flathead.
It has a rough idle @ 800 rpm, but will idle in gear. Of idle is instantaneous.
I have the timing set at 12 initial, 28 max, all in by 2200 rpm. Dist is helmet type with Pertronix module. Two carbs. Engine pulls hard, sounds great.

 

Lots of choices thats for sure, I didnt realize there were that many manufacturers of cams for these engines.

 

I put one of those 1007B grinds in my 284 stroker on Petes advice and man did that thing pull hard in bottom and midrange that's a perfect cam for street driven flatty. I have a video somewhere of it running sounded great too

 

Break out that video, I want to hear this thing!!

 

I don't know much but I understand that Mr. Winfield used the SU1A as a kind of generic designation that could apply to more than one grind. I believe that H&H built the engine in the video and it seems to have a pretty aggressive idle. I talked to one of the more reputable cam grinders about an SU1A and they advised me that they can only grind a mild version (sorry I didn't get the specs). So they knew there were more.

Then I searched Fordbarn and found a fellow who grinds a lot of banger cams but also does flathead V8's. He grinds the hotter version of the SU1A as well as a milder Winfield grind called an SU1R. But he doesn't grind the milder SU1A. He told me that the specs of his SU1R are between the two versions of the SU1A.

 

I remember that video. The engine sounded great with that cam but I haven't been able to find the video lately. Here's another video of a 1007B and it's another HAMBer's car

http://www.youtube.com/watch?v=JITKQyXKgTk

 

That does sound pretty nice...

 

then again the 400 jr sounds awsome, but im not sure if I want all this....
<iframe width="420" height="315" src="//www.youtube.com/embed/xLqH7eoZiT0" frameborder="0" allowfullscreen></iframe>

 

thanks for the replies/info fellas

 

http://www.jalopyjournal.com/forum/showthread.php?t=726934
Here is the short video.

 

Yep, ill be happy with that.

 

I like the Isky Max 1, Good street manners, in an 8BA dual 97's.

4TTRUK

 

Those videos are badass! Scroll down a hair on the above video for that pre-war nitro. burning car. That thing never gets old....


Posted using the Full Custom H.A.M.B. App!

 

Yeah, that thing sounds friggin' awesome.

 

I'm building up a 255 Merc flatty with tri power 8:1 Edelbrock heads and it's going in a 51 Merc
how much does the weight of the car need to be taken into account when choosing the cam. I was just going to stick an Isky 3/4 race cam in and hope for the best.
I want the rumpity rump but don't need low down torque. It's mainly highway driven at 60mph
Thanks
Neil

 

Here is a basically stock 255 Merc with dual carbs and header, first with the stock 8CM Merc cam, then a max 1.



Red lines are power, green torque, lighter is ISKY, Power scale is left, torque is right

Tweaking engine for 3 deuces and 8-1, Max 1

 

no matter what cam you pick you already made the most important decision by choosing to stick with a flathead imho id go with the 400jr or a potvin grind by pete1

 

How do I post a video? I have a video of my flathead with a 400jr.

 

Does the fact it's going in a 51 Mercury full bodied car make a difference due to the weight of the car compared to a light hopped up jalopy