Question for the flathead gods

Picked up a nos cam for my flathead its labeled almquist 3/4 only trying to get the specs for valve lash etc. any help would be great. thanks Larry

 

Some of the old timers/grinders need to jump in here. Im just a young guy but have heard many different distinctions of a 3/4 race cam all over the place. I am building a 239 Merc Flatty and actually have a few cams labeled 3/4 as well. Here are a few different thoughts that I have found through conversations and research. 1.) Back in the day, there were 3/4 race cams and full race cams...Some say that 3/4 was a little milder and about 75% what full race grinds would be. 2.) Many thought 3/4 race cams were simply for 3/4 circle track racing. Very lopy at idle, high revving, but streetable 3.) Others thought that 3/4 race cam simply had .750 lift, whereas 1/2 race would exhibit .500 lift, but therefore full race is 1.000 lift? lol you're going to get a lot of different takes on this question. Good Luck, if anything make something up to fit the 3/4 name.

As for valve lash...What year Flattie is it? Later Flatties should be around 0.017-0.019 Exhaust - 0.013 - 0.015 Intake. That should get you close.

 

3/4 race was just a marketing thing. Not as radical as the manufacturer's full race cam, but hotter than stock. There are no real parameters. You need to find Almquist specs to learn anything about the cam itself or have it profiled. If you can't find the lash figures, I'd base it off the profile and use somebody else's lash figures for a similar cam.

 

I've got the specs for an Almquist Track 3/4: IO 21, IC 63. EO 67, EC 19. Lift is .312. Don't have clearance specs, but usually somewhere around .012 intake and .014 exhaust should work.

 

Thanks for the help guys