PRH wrote: ↑
Sat Aug 17, 2019 4:05 pm
Here’s another cam anomaly story........
Early 90’s, my friend decides he wants to go NHRA Stocker Racing.
Is tired of the straight up bracket racing.
So, we get another set of head castings, stock manifold and carb, put all that on his old street motor and see what it does.
At that time, it seemed like getting cheater cam lobe data was like pulling teeth.
I was primary using UD at the time, and they didn’t do any of that.
The guy I dealt with there gave me the name of someone at Lunati to talk to.
We had no idea where to even start, so we just left it up to him to set us up.
Put it all together, go to the dyno...... we don’t know what’s good or bad, tune what we have and put it in the car.
It’s a 68 GTO, and at the time it was an E car.
Go to the track...... won’t run the index.
Send the converter back, blah, blah....... no better...... need more power.
Well, the cam had what I thought was quite a lot of duration...... and I felt like if it was 6-8* less it would be better.
I get a copy of some Crane lift rule masters..... pick out a couple lobes, they grind it up.
Back to the dyno with the new cam...... power is up everywhere.
Put motor in car....... 3 tenths quicker!!
But...... keeps putting pushrods through rockers.
That wasn’t an issue with the Lunati.
So, we call Lunati ask if they have anything smaller than the first cam.
They do, so we order it.
My friend puts it in and plots it out.
Lift and .050 numbers on the intake are correct, but the .006 number is like 375*.
Ex lobe if fine...... maybe 300@.006.
Call them up..... phone tech asks us how that’s possible since there only 360* in a circle.
We remind him there’s 720* available, since the cam runs 1/2 speed.
They need to confer about it, then tell us to send it back and they’ll measure it.
Cam goes back, we get a call telling us that there’s nothing wrong with it, the duration @.050 is right on.
We tell them that’s not what we’re concerned with, it’s the 375@.006 we didn’t like.
Never any confirmation about that from them, but they’ll grind us another one.
I ask to have the lsa changed 1* to insure they don’t just resend the same one back to us.
New cam shows up....... same exact problem.
I talk to my guy at UD, he said that more than likely what happened was the wheel wasn’t removing any material off the base circle during the final finishing.
Mike can probably elaborate on that.
Needless to say we sent it back as well, and went on to try a few different offerenings from Comp and Lazer....... back to Lunati...... then back to Comp again.
Yeh...... we tried a few cams in that thing.