stupid cam question

[sweatybetty]

ok, maybe this is biting me in the face and i just dont see the answer. how can i fit a higher lift cam in the towers if the cam lobes are higher than the the journals? this cam measures out at .433 lift at the valve. i want to go closer to .500  the lobes right now are almost even with the journals.

[240260280z]

The cam lift is the difference between the long axis and short axis of the lobe profile.  Negligible metal is removed from the nose (top) of the lobe when re-ground.

Below are some drawings I made many years ago. They should make it a bit clearer.

The geometry requires the lash pad to make up for the amount ground.

 

 

[240260280z]

 

 

 

[grannyknot]

And the cam journals are staggered in such a way that they go through the cam bearings at the same time so as to leave room once they are through to slightly move the cam to avoid hitting and scratching the cam bearing. Removing and installing a cam is the most potentially dangerous time there as it is SO easy to scratch the bearing surfaces, very hard cam metal, very soft bearing metal.

Beers only to be enjoyed after the job. 

[Diseazd]

1 hour ago, Blue said:

The cam lift is the difference between the long axis and short axis of the lobe profile.  Negligible metal is removed from the nose (top) of the lobe when re-ground.

Below are some drawings I made many years ago. They should make it a bit clearer.

The geometry requires the lash pad to make up for the amount ground.

 

 

Good job Blue......nice illustrations!

[sweatybetty]

1 hour ago, Diseazd said:

Good job Blue......nice illustrations!

yes, that makes perfect sense now. thanks

[sweatybetty]

ok, so looking at the cam i have, does it look to be factory to you guys? if so, is it cheaper to have it re-ground or a new cam?

[Diseazd]

Looks stock to me......Isky charges $175.00 to regrind. Depending on the lift, you'll need springs and lash pads. You mentioned .500 lift......should not be a contact problem if you overbbore your L24 by .030 inches or more....also, you'll need a shorter valve seal. What engine are you running?

[sweatybetty]

E31  L24

[siteunseen]

I ground a notch on the tops of the bores on the block instead of over boring. Im on a budget.   Exhaust and intake valves are the larger 2.8 size and I'd read from Carl Beck that they will slightly hit making a tapping noise that drove him crazy. FYI

I also have an E31 with the bigger valves.

[sweatybetty]

i dropped the head off today at the machine shop. guy was surprised at how good of shape it is in. $75 to have it all checked out, then go from there

[sweatybetty]

On 9/18/2016 at 4:55 AM, Blue said:

 

 

 

Blue, looking at your pics i see a thicker lash pad after the cam is ground. is this to keep the rocker tip centered on the lash pad?