I am going to rebuild a 21 stud engine from 1938. It is going to be used in a 32 Roadster. I would like to build a sharp/fast and reliable engine and have already a few performance parts. I have an original PM7 with original paint and everything, a pair of aluminum head from Canada and a harmon collins ignition. I was considering a Isky 400jr but are in doubt since I dont know if that is the right set up when using the PM7. Any good advise is appriciated also where to buy new engine parts thx
What Cam to choose
- Thread starter Carsten
- Start date
HotRodmicky
Senior Member
The probblem is that the 400jr is too big for a 221ci engine. A 1007B would be better
I cant remember the source exactly but i did some readinh on cams and found a guy who had done a long trip with another flathead powered car. Both were setup the same except one was a 221 and the other a 239. No problems and they both ran great. Pretty sure he was running the l100. I just had Pete grind me up a 1007b for my 245 and a h&c 6372 for my next motor which will be a big striker with possible blower.
Ol' Ron
Well-known member
The 21 stud engines are short on torque and installing any aftermarket cam will reduce low enf torque. The 400 jr is a great racing cam, but not practical for ANY street application. Yes the 1007B would be a good choice and would probably clear the heads. Make sure the piston to head clearance is very close to the .o45/.050" recommenced, this is especially important in small, near stock displacement engines. You have to consider drivability when modifying an engine.
thx
GOSFAST
Well-known member
Pay close attention to Ron here, it's "dead-on" correct (as usual)??
I posted up here recently I inherited a build to finish for a local customer. It is a 59A, 1/4" stroker going into a 1948 Ford, OEM four-door. Not certain about the "empty" weight but the total weight of the ride will also include 4 passengers and all the fluids. The owner explained to me he wanted to "cruise" around some local towns with an average speed of about 40 MPH. He doubts he would ever see the legal speed limit in our area of 55 MPH??
The parts were picked AND sold to the owner direct, not by the shop, but by one of the larger vendors in this business who the owner contacted directly. This vendor claims to hold numerous Flathead speed records and "knew" exactly what this customer needed???
I have so many "wrong" parts handed to me that I warned the customer I wasn't going to be responsible for the outcome here. We are "up-in-the-air" about his direction as of today still.
This vendor sold the customer a brand new "Potvin Super 3/8" cam here, 245* @ .050". Not even close to what he really needs for this ride? It would be most uncomfortable driving this cam around at speeds of 40 MPH with a combined weight of possibly over 4500#+.
Thanks, Gary in N.Y.
P.S. I was given a pair of 8BA heads gaskets here for this 59A?? Also included are wrong valves, springs and retainers! I'm really glad the shop didn't attempt to finish this build with all the supplied parts! With the exception of the head gaskets they probably would never have suspected what was right or wrong and the owner would have suffered!
Ron, Tell us about the H&C 6372, I am trying to put together a blower motor, I want to check out all the possible better cam for the build, Is it a wild grind with streetability downfalls or is it a good all around cam for a blower, I have an L-100 b, and a 1007b,I assume the b in the cam number designates as for a blower with wider lobe separations. I want to put it in a 59 ab in my 46 ford 1/2 ton to tune it in and then put it in a lighter car, which flywheel is best , I understand some of the aftermarket flywheels are a little lighter than the factory ones, I am trying to find someone to line bore the Mains as I am using the mike Davidson main caps with support plate, I don't mind shipping the block somewhere to get the job done right.