Need Cam Timing Specs., 911L Cam in 2.7L

[Stophos]

Stock 2.7L with Webers and 911L cams going together today. Need Cam timing specs.
Thanks - Chris

[Grady Clay]

Chris,

What pistons?
Piston-to-valve clearance may be an issue.

For 1968 911L and 911 (both USA and RoW)
Engines 901/06, 901/07, 901/14, 901/17
Left camshaft, RoW: 901.105.109.05.
Left camshaft, USA: 901.105.139.05.
Right camshaft, all: 901.105.110.05

Cam timing spec is: 3.0 – 3.3 mm limits, 3.15 mm desired.

Best,
Grady

[Stophos]

Grady, He is using stock 2.7 us version pistons. Problem?

-Chris

[camgrinder]

911-L cams wont work with a 2.7L cis piston. An Sc or my Dc10 will clear, but still need to be checked.

[Stophos]

Wow, Searched and Searched rather than posting and came away with bad info on this one. I guess choices are to cut pockets in the original pistons sacrificing compression or change cams. We were looking for more low end than S cams could provide. We would like to get this 2.7 installed now so what cam would you suggest at this point that will work best with Webers and stock P&C's. Will the stock cam work ok for the time being?
Also we have another 2.7 which will would consider building using the 911L cams. What p&C's are best for this?
Thanks - Chris

[camgrinder]

The L cams is the same profile as the 911 E. There is some misinformation out there about the L profile, but I have checked and reground many and they are all the same as an E. If you change the pistons to a carb style dome, the DC30 profile fits the L cores and works great.
With the stock pistons you are stuck with a wide lobe center cam. The wider the centers and the less duration you have, the less lift at overlap. (more valve to piston clearance). I have an idea on a custom set that might work pretty good.. let me do some calculations and I will post back later today.

[Grady Clay]

Originally Posted by Stophos

Also we have another 2.7 which will would consider building using the 911L cams. What p&C's are best for this?
Thanks - Chris

A nice new set of 2.7RS 90 mm Mahle Nikasil have the correct valve cutouts for an 'S' cam and are reasonable cost. An ‘E’ cam would clear nicely.

A ‘last forever’ engine if done correctly.

Best,
Grady

[Stophos]

Grady, I am sure you are right. I am thinking that is exactly what the second 2.7 motor will become. Not sure about the one sitting with the L cams in it at the moment. Waiting on John's thoughts on that and I guess we will make a decision to tear it back apart, go back to CIS cams and setup or something else.

Thank you for your timely and informative answers thus far.

- Chris

[camgrinder]

Ok Chris, this is what I came up with..
stock E is 238/226 @ 1mm with .405"/393" lift on a 102 lobe center.
New cam, 232/224 @ 1mm with .430"/.395" lift on a 108 lobe center.
This should fit a cis 911105141 - 911105142 core as a regrind.
I think we have a good chance at clearing the pistons with this grind, and making decent power too.

[Grady Clay]

John,

Nicely done.

Best,
Grady

[AUSTmike]

does anyone have the cam timing setting for a stock 2.7 ltre with flat cis pistons.My engine would have stock cams and pistons.The motor does have the 5 bladed fan so it should be a US engine. And the car was manufactured in 1977...cheers