[DeTomaso] Crane cam 520341

[Daniel C Jones]

> maybe with a vacuum reservoir tank?

If not, there are always electric vacuum pumps.  I think Kirby ran
a much larger solid cam with 105 LSA.  Kirby, did you run power
brakes?

> This cam has lsa of 106
> 236/230 duration at 0.050"

What is your compression ratio?  What sort of exhaust do you have?
With 106 degrees LSA, you need a really efficient exhaust.  The
mufflers in particular need to have very little backpressure.

> I want the lumpy idle.

Optimal LSA for your engine (assuming 4.03" bore by 3.5" stroke,
2.19" intake valve, compression between 9:1 and 11:1) is 107 degrees,
the same as my dyno mule 351C.  For that engine, I picked a custom
Reed hydraulic roller of the following specs:

 228/232 @ 0.050" lift (280/284 @ 0.006), 0.588"/0.588" lift, 107 LSA

If your mufflers aren't up to the task, I'd go with a 108 (or even
a 109) LSA.  Crane will grind you the same cam on your choice of
lobe centers, as will others like Bullet.  Another hydraulic flat
tappet grind I know that has worked well with 4V heads and less
than perfect mufflers was a custom Comp grind with specs:

 226/234 @ 0.050" lift, 0.554"/0.574" lift, 109 LSA

but be aware the Comp XE (and Lunati Voodoo) lobes are agressive and
can be noisy (meaning they are likely wearing the seats more quickly).

> but I think it's a fairly agressive lobe profile.

Yes.  Recommended springs are 126 pounds on the seat and 337 pounds
open.  Make sure to use a proper break in oil or the Comp additive
and then use an oil high in ZDDP if you want the lobes and lifters
to live.

> I'm still deliberating on the intake. I'm thinking dual plane.

We'll be testing both the Performer 4V and Blue Thunder dual planes
on the flow bench and dyno.  I'd like to test the Ford aluminum dual
plane too but so far have not been able to locate one.  Previous
experience has shown they both will need work to balance the good
and bad planes.  I won't be surprised if the RPM Air Gap 2V is better
on the 4V heads for that reason but we'll see what the dyno says.

Dan Jones