Timing an E Cam

[Frazier]

I am about to time the cams on my 911, I have E cams, a 70.4 crank, and S P/C's. I noticed that the E cams from 69-71 have a valve overlap of 3.15 and the 72-73 have an overlap of 2.9. Can anyone please explain why the difference, isn't an E cam an E cam regardless of year? What would you advise for my engine. Thanks for the help.

[RoninLB]

on p207 of Wayne's 911 Engine Rebuild Book is the part no. and timing for the different year E-cams.

The part no is the same for the 1969-71 & 1972-73 E-cams

The timing is different.
I did the early timing no, 3.0-3.3mm, because I'm using carbs and want an advanced cam timing......... Ron

[Tim Walsh]

Actually according to the BA book the early E cam is wilder than the later cam and thus the need for a different timing spec.

[RoninLB]

Originally posted by l33t9eek
Actually according to the BA book the early E cam is wilder than the earlier cam and thus the need for a different timing spec.

all I can offer it that before Pelican arrived in my world I ordered new E-cams from Stoddard.
and the Stoddard E-cam numbers match the numbers in Wayne's book.

So maybe the BA info refers to the E-cam timing....... Ron

[911pcars]

"Actually according to the BA book the early E cam is wilder than the earlier cam and thus the need for a different timing spec."

Tim,
I'm confused by this statement. There is only one E cam. What earlier E cam is wilder than the early cam?

With a 70.4 crank, I'd go with the 2.9 mm spec. This setting should help the E cams which tend to run out of breath at higher revs. Low and mid-range torque should be sufficient using the long stroke crank.

Sherwood
http://members.rennlist.org/911pcars

[RoninLB]

Originally posted by 911pcars
I'd go with the 2.9 mm spec. This setting should help the E cams which tend to run out of breath at higher revs. Low and mid-range torque should be sufficient using the long stroke crank.

ditto on Sherwood's comment..
I want it advanced for lower rpm torque curve.......Ron

[Frazier]

Thanks Sherwood. I didn'y think there were different E cams. Sounds like the longer stroke makes the difference. Sorry for the double posting, I posted in this forum by accident as I thought I was in the 911 engine rebuilding when I posted. Thanks for the help...

Neil