Obnoxus
 

They didn't pick up any horsepower by switching to the roller camshaft. The duration figures are the same. They picked up a smoother idle, better fuel economy and extended oil change intervals. The same reason why all of the automotive manufacturers have switched to roller cams.
Dennis Moore

THANKS FOR RESPONDING DENNIS !!!!!!

Im glad to here that,,, I was perfectly happy with it, but everyone says about this MAGICAL HP in a roller setup,,,,,

You said once before,,,,,but I cant find it,,,, without remapping my ecu can you give me camspecs,,, my builder was asking so he can order a camshaft.

AND,,, is JUST a bigger cam and remapping going to net any gains,,,recomondations? I am suddenly willing to do it,, how about gasket matching heads?

What are you opinions on timing ?
FYI,,, ECU will be done on a dyno.

THANKS AGAIN !!!!

Ask Comp Cams
 

The roller camshaft designed by GM has about 224/224 degrees of duration. The opening and closing ramps are slow, not because GM doesn't know much about camshafts, but because they have to worry about warranty claims on thousands of engines. The faster you open and close the valves, the more often you need valve jobs and more often you need to change the oil. GM doesn't like paying for warranties so they are conservative with the camshafts. Buying an aftermarket camshaft with aproximately the same duration but with quicker opening and closing cam lobes will increase horsepower and torque but generally not require reprograming the ECM. Buy a cam that has a slightly closer lobe separation angle. About 114 degrees would be fine. If you stay with lobe lift below .550 you will not have to change the valvesprings or go to an adjustable rocker arm. An aftermarket roller camshaft will be the best choice, call Comp Cams and ask them. This will be a lot of work for 20 to 25 horsepower though.
Good Luck
Sincerely
Dennis Moore

STOCK IT IS !!!!!!!!!!! Did we ever agree on what the specs were on the stock flat tappet cam !!!!!!????

Again,, thanks for the help

Crane 741
 

Blown 1500

What are the specs on the Crane 741???

MAV

stock specs / per merc publication
 

here's the #s from the Merc service manual -- keep in mind -- some people will tell you that you can't trust "published specs" ( then everybody would have the magic!!

int/ ext @ .050 lift on both intake and exhaust
224/224 .510 flat tappet motor ( merc 502)

MAV

crane #139741

.632" intake
.632" exhaust

[email protected]" intake
[email protected]" exhaust

112 LC ground with a built in +5 advance.
14 degree overlap @.050"

741
 

Thanks for the spec.s

That's a TON of lift!??!??!?!?!? How much head and valve work needs to be done to support that cam AND how much compression is needed to make it work???

Also, with this kind of lift -- how many hours between "tear downs" - for a look for broken inner valve springs?????

MAV

Figure springs every 150.
That's a dollar an hour. Cheap.

Re: stock specs / per merc publication
 

OK,, now Im loosing that warm fuzzy feeling !!!! Anymore input on the stock cam subject?