Cams

[Ka3acmah]

Fellow pan heads.
Whats all your opinions for what is best cam to run, for a stock 48EL?

[kitabel]

The one you have, unless there's something wrong with it.

[vph-d]

The Andrews J cam works well in Panheads.
VPH-D

[pan620]

Stock work well for me, I have few if you are in need.

[Ka3acmah]

Thanks 620, I have a "J" that I ran in my knuckle, so will try that.

[kitabel]

I have a "J" that I ran in my knuckle
Yes, it fits, more or less, since the tooth count and journal sizes match.
However, the "clock" positions of the lobes are very different than the panhead (and shovelhead) cam. Every open and close point for each valve is not what it's supposed to be, which is what happens when the tappet blocks do not match the cam type for that engine. A knucklehead engine with panhead cam and panhead tappet blocks (or a panhead engine with knucklehead cam and knucklehead tappet blocks) will have the correct (as intended by H-D or the manufacturer) cam events, but the pushrod angles are screwed up. In addition, the knucklehead will have very low lift (.270"?) due to its 1:1 rocker arm ratio. and the panhead will have coil bind (and potential valve-to-piston interference) with the reverse condition; tall lobe X 1.5 rocker = .540" lift. A knucklehead with a J has .283" lift.

W/r/t use of a J cam in a panhead - yes, it works OK in an FL. However, the EL (18% smaller; not a big deal? a 74 is 18% smaller than 90") is a special case, and much less tolerant of long duration for these reasons.
1. low static compression ratio means low intake vacuum
2. very large port volume and diameter (same as FL) reduces velocity
3. very large 2.13:1 rod ratio (the FL is 1.88:1) traps less cylinder volume @ intake closing with the same cam than a smaller rod ratio

If you want to use an Andrews cam, I suggest the #1, which is the mildest cam, but it's not specifically mentioned for the EL. Even with its relatively low (.427") lift it may still require spring adjustment.

H-D knew exactly what they were doing in 1936-39 with the smaller EL manifold and ports, and cheaped out (accountants make very bad engineers) by using the same FL (large) heads in both engines after 1940.

[exeric]

Great information, kitabel. I've never heard OHV cams explained so well.

[Ka3acmah]

As Eric said, well put. After reading your response, I will shelf the Andrews, and go with a stock cam.

[Carl Olsen]

Andrews makes a cam for the 61 panhead that I have used for years with great success.
Carl

[kitabel]

Not listed currently. What grind number?

[TomL]

J&P Cycle lists Andrews "K" Grind for 61" Pan Heads 48-51. From their 2018 "Vintage" Catalog. Says its a stock replacement cam .367" lift.

[kitabel]

That's a typo. Andrews identifies that as a knucklehead cam with .368" lobe height and 278 degrees duration @ .053" lift.
From AP http://www.andrewsproducts.com/motor.../2017-catalog:
"212980 K 35/63 63/35 278 318 .368" Knuckle performance cam for stroked motors; strong pull to 6000 RPM. This is the Knuckle equivalent of a “C” cam"