Due to the apparent dearth of information on Flathead cam specs, I thought this might be of use to someone out there. I had a set of stock 45" cams reground by Leineweber last summer for a WL stroker I was building for a customer, and I wanted the timing specs for my records so I checked them with a degree wheel. I am listing the timing events at several different locations because it seems that I have seen the specs listed at different points from different sources over the years, and they do you little good if you cannot compare apples to apples. I have never seen specs on a stock 45 cam, however, and unfortunately I did not check these before sending them for the regrind.
Just a note, seat timing is the least useful because it is dependant on how gently the cam starts to lift and then how gently it closes the valve, but if its all you have to compare it would be better than nothing. I included the .010" lift point simply because I seem to remember seeing it used with some other old cam specs. The .020" lift is the checking point that Jim Leineweber uses for his line of cams. The .050" is standard for the automotive industry, and the .053 check point is what most of the Harley industry uses, at least in modern times.
Jim calls this regrind a .360 lift and +10 degree duration.
Intake Opens:
seat - 47.5 BTDC
.010" lift - 30 BTDC
.020" lift - 22.5 BTDC
.050" lift - 7.5 BTDC
.053" lift - 6 BTDC
Intake Closes:
seat - 85 ABDC
.010" lift 56.5 ABDC
.020" lift 40 ABDC
.050" lift 23 ABDC
.053" lift 21.5 ABDC
Exhaust Opens:
seat - 77 BBDC
.010" - 59 BBDC
.020" - 51 BBDC
.050" - 36 BBDC
.053" - 35 BBDC
Exhaust Closes:
seat - 62 ATDC
.010" - 31.5 ATDC
.020" - 13 ATDC
.050" - 5 BTDC
.053" - 6.5 BTDC
This would give an .053 duration of 207.5 on the intake, and 208.5 on the exhaust. Notice that if you calculate the duration at .010" lift you get 266.5 duration for the intake and 270.5 on the exhaust, making it obvious why you need to compare apples to apples. For more info on cam specs and formulas here is a link to an old post I did on the subject.
If anyone has any other 45 cam specs that you would like to share, send them to me (or leave them in a comment) and I will try to get them all posted together in one place.
Saturday, December 4, 2010
Subscribe to:
Post Comments (Atom)
2 comments:
thanks for sharing the info lee. i never put a degree wheel on mine to check timing with the stock cams but .312" lift and i remember taking note how it seemed as if they almost opened at TDC and closed at BDC. How much does Leineweber charge to regrind a set of 45 cams?
I think he was at about $300 the last time I sent a set in. Slow turn around, but excellent work!
Post a Comment