Master-O-Turbonics Posted April 24, 2011 Report Share Posted April 24, 2011 I am trying to identify this Racer brown L4 camshaft... did some quick research... 1074-114 means produced in october 1974, serial number 114. of the cam grind, 325-R, the -R means race cam. I have been unable to find out anything on the actual grind of the cam.108 I suppose is the Lobe separation angle... maybe not? Anybody? Quote Link to comment
datzenmike Posted April 24, 2011 Report Share Posted April 24, 2011 See if this guy ever found out... http://www.the510realm.com/viewtopic.php?f=2&t=10416&view=next Quote Link to comment
datsunwizard Posted April 25, 2011 Report Share Posted April 25, 2011 325R is 275 degrees at .025"lift, 250 degrees at .050" lift and .475" lift at zero lash. Monte 2 Quote Link to comment
Master-O-Turbonics Posted May 2, 2011 Author Report Share Posted May 2, 2011 See if this guy ever found out... http://www.the510rea...10416&view=next That cam and this one are one and the same. :-) 325R is 275 degrees at .025"lift, 250 degrees at .050" lift and .475" lift at zero lash. Monte Thank you Monte! Much appreciated! Quote Link to comment
metalmonkey47 Posted May 2, 2011 Report Share Posted May 2, 2011 Sweet score man. How'd you get that? Quote Link to comment
Master-O-Turbonics Posted May 2, 2011 Author Report Share Posted May 2, 2011 Sweet score man. How'd you get that? I haz mannnyyyyyyy secrets...... Thats about the only pic of that head y'all will get before it gets installed with a valve cover. ;-) Quote Link to comment
datsunwizard Posted May 17, 2011 Report Share Posted May 17, 2011 I just thought that I would add something additional to this cam thread. Racer Brown back in the day, recommended that the lash be set at the valves( between the lash pad and rocker tip), not at the cam as you would do with the stock factory method- cam and rocker arm. Of coarse you need a narrow feeler gage to do this. Racer Brown cams had bad rap for being noisy, but I think that it was because lash wasn't adjust to his way, people just adjusted them with the factory method. Using his method is really the best way, it assures that there is clearance where it really matters at the valve - not holding the valve off of the seat. Because of the lift ratio of the rocker arms, which varies between rockers, you really don't know what the clearance is at the valve using the factory method. When I was building lots of L series motors, we would by 60+ rockers and using a dummy head and cam we would match the rockers for lifts in sets, so that the lift at the valve was consistent, for all cylinders. It is surprising how much the lift varied between the rockers. On the Racer Brown street cams he wanted .006" lash on the intake and .008" exhaust lash at the valves. Which if you divide this lash by the rocker arm ratio of 1.5 you have very little clearance at the cam/ rocker arm. Of course you need to adjust the lash with the engine hot. I little added info from a old Datsun guy. Monte 2 Quote Link to comment
Master-O-Turbonics Posted May 23, 2011 Author Report Share Posted May 23, 2011 I just thought that I would add something additional to this cam thread. Racer Brown back in the day, recommended that the lash be set at the valves( between the lash pad and rocker tip), not at the cam as you would do with the stock factory method- cam and rocker arm. Of coarse you need a narrow feeler gage to do this. Racer Brown cams had bad rap for being noisy, but I think that it was because lash wasn't adjust to his way, people just adjusted them with the factory method. Using his method is really the best way, it assures that there is clearance where it really matters at the valve - not holding the valve off of the seat. Because of the lift ratio of the rocker arms, which varies between rockers, you really don't know what the clearance is at the valve using the factory method. When I was building lots of L series motors, we would by 60+ rockers and using a dummy head and cam we would match the rockers for lifts in sets, so that the lift at the valve was consistent, for all cylinders. It is surprising how much the lift varied between the rockers. On the Racer Brown street cams he wanted .006" lash on the intake and .008" exhaust lash at the valves. Which if you divide this lash by the rocker arm ratio of 1.5 you have very little clearance at the cam/ rocker arm. Of course you need to adjust the lash with the engine hot. I little added info from a old Datsun guy. Monte Thank you for the info Monte, I'll just make up some thin lash pad width feelers. We do this with our Dodge and Chevy (600+hp circle track)race motors to measure at the valve rather than on the push rod side. What would be a good number to start at on a cold motor for lash at the valve for these Racer brown cams? .009 and .011 ish? Got to break the motor in and don't want to shut it off before the rings are seated and my break in procedure is completed. This is a new bottom end with a head that has "500 miles on it since it was built". Quote Link to comment
datsunwizard Posted May 23, 2011 Report Share Posted May 23, 2011 I would run the cold lash about .002" more than the hot spec. Is this a new cam/ rockers or a used one? Have you checked the wipe pattern on the cam? Quote Link to comment
Master-O-Turbonics Posted May 31, 2011 Author Report Share Posted May 31, 2011 I would run the cold lash about .002" more than the hot spec. Is this a new cam/ rockers or a used one? Have you checked the wipe pattern on the cam? Entire head was shipped to me, and all I have done is take pics of it. All due diligence will be taken. I have a set of NOS rockers sitting around but I think the ones on the head now will work for what I need (just to get the motor running) Quote Link to comment
datsunwizard Posted June 1, 2011 Report Share Posted June 1, 2011 All due diligence will be taken. Good to hear. Quote Link to comment
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