Engine and Transmission Tech

Hi Dan,

Thanks and PM send.

Cheers
Rik

Dan, HR is computed with a .700" roller dia. ? Base circle of cam is ? By 2.57 ramp rate, means .00257" lifter rise, per 1 deg. cam rotation ? Thanks, roverman.

> Dan, HR is computed with a .700" roller dia. ? Base circle of cam is ?

Roller diameter is not required for the initial design. When you cross it
against a specific lobe catalog, the roller diameter is required. The base
circles in the catalogs are usually reflective of SBC or SBF but vary when
applied to Buick base circle. Woody sent three different lobes and the
base circle of each was different.

> By 2.57 ramp rate, means .00257" lifter rise, per 1 deg. cam rotation ?

That's my guess but I've never tried to check the units. No units are given
in the documentation. The scale is listed as:

1.00 Very Low Acceleration, Mild Street, Extended Valvetrain Life
2.00 Stock Production, OEM Camshafts
3.00 Performance OEM and Aftermarket Street Performance
4.00 Drag and Oval Track Racing, Limited Street
5.00 All-Out Racing, Very High Valvetrain Acceleration
6.00 Maximum Drag Racing, Limited Valvetrain Life
7.00 Extreme And Experimental

Dan Jones

Clan. Steve Smith Racing Cams, says .009-.010" lift per 1 cam deg., is fairly common, for a mech. roller cam. Cheers, roverman.

The blank rollers from Woody are with .550" lobes, LSA of 110 which can be changed + or - 2 degrees.

Cheers Rik

Rik, Can you post a picture of that lobe. .550" is HUGE, for such a small base circle. My most radical lobes are .400" max. Cheers, roverman.

Art,

0.550" is at the valve, assuming a 1.6:1 rocker ratio. Uncut lobe lift is 0.550"/1.6=0.34375".

Dan Jones

Art,

Dan is correct, sorry for the confusion.

Rik

So my fault for not paying attention to this post before I bought a cam for my 231 Buick evenfire. Its a Crower, 235*/242*duration, .483"/,486" lift and 107* lsa. Its a mechanical lifter cam and I have a Inglese 2-3c IDA Weber induction system and non- tuned length headers. The heads are late model evenfire and basically stock. Do I even think about installing this cam or should I look for something closer to 112* lsa. I like mechanical lifters and after looking around would probably have to have a custom grind to get mechanical lifter profile or can I run mechanical lifters on a hydraulic profile which all seem to have greater lsa. Hate to tap into a great data base oriented around very high performance for a engine that I want to have a modicum of performance and a wow factor when I raise the hood of the old TR3.
Regards
Greg Hornbostel

Greg,

It's not wise to run a mechanical lifter on a hydraulic profiled cam, lobes are different and you will run into trouble.
Overlap of the Cowler is about 70 degrees so you should be able to run the cam with LSA 107.
Inglese is advising to use a cam with a wide, LSA 112 or higher with minimal overlap with their Weber induction.
This is to avoid reversion through the carb when both intake and inlet valves are open.
When installing my first Weber 8-stack on a RV8, the installed cam had 104 LSA and it had still a good idle at 800 rpm and no problems when cruising around, although probably not the best cam for this induction system...
Alternative would be to ask a cam company to grind a mechanical can with a wider LSA.

Cheers
Rik

Rik, thanks for the reply. To the people involved in this thread this must be a "want-a-be" situation as the car is nothing more than a cobbled together hot rod. I just didn't want to get into a impossible to drive/tune situation and have to pull the engine down shortly after I got it running. I installed the Webers last May and actually got them to what I considered acceptable tune. The performance was much better than the 2v carb and it was returning the same fuel economy. I will probably contact Crower again and opt for a custom grind as I don't want to listen to the occasional "one lifter clack" after a spirited run. Once again, sorry for the intrusion on this thread.

Regards
Greg