The Blue Box
Well-known member
Okay so when i (eventually) degree my cam how do you advance and retard it? I know some have the 3 different keyways but i dont know which i have. The only thing i know is that its a double roller timing set.
Econoline":2huugvek said:Chances are it has multiple keyways. With your compression issues you might consider retarding the cam if it is currently advanced 4 degrees. This will shorten the effective stroke and lower cylinder pressures a bit. Do you have the specs for the cam? I.e. advertised intake and exhaust duration and the lobe separation angle? Assuming 270/270-110, if you install it with zero advance the effective stroke drops to 2.441" vs 2.523" when it's advanced 4 degrees. Using the earlier example this would take your dynamic compression ratio from 8.4:1 to 8.16:1, which is not insignificant. If you have the cam specs we can get more precise about the effects.
But i thought .478 was the lift? I am confused. I just recently did a bunch of research on cam numbers but still am not 100 percent understandingpmuller9":3671n6xe said:If the LSA is 110 the intake lobe center will be at 106* ATDC if the cam is 4 degrees advanced.
With a 214* .050" lobe lift duration the .050" lobe lift point will be 214*/2 - 106 or 1 degree BTDC.
If you want to do a quick check to see if the cam is close, remove the rocker arms and put a dial indicator on #1 intake pushrod, turn the engine clockwise intil the pushrod rises .050" and the timing mark on the harmonic balancer should be 1* BTDC. (or close to it)
.478" is the valve lift.The Blue Box":1jfennnj said:But i thought .478 was the lift? I am confused. I just recently did a bunch of research on cam numbers but still am not 100 percent understandingpmuller9":1jfennnj said:If the LSA is 110 the intake lobe center will be at 106* ATDC if the cam is 4 degrees advanced.
With a 214* .050" lobe lift duration the .050" lobe lift point will be 214*/2 - 106 or 1 degree BTDC.
If you want to do a quick check to see if the cam is close, remove the rocker arms and put a dial indicator on #1 intake pushrod, turn the engine clockwise intil the pushrod rises .050" and the timing mark on the harmonic balancer should be 1* BTDC. (or close to it)
I have a copy of the handbook (and read through it) and have read a lot in the tech section of cichad":15fzyp2h said:"...new to cam..."
not me, but it's still esoterica.
8^0
Don't forget to order/read the "Handbook" & while waiting for delivers peruse the free "Tech Archive" @ the big blue box w/crossed screwdriver/wrench above.