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.
Anyone running a weber 38 on a 200? Cam selection?
- Thread starter The Blue Box
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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.
The Blue Box
Well-known member
Econoline":2huugvek said:
It says 1.6 (rocker ratio?) then 270 .214@.05 478 lift. im assuming it means 270 intake and exhaust duration. Pretty sure this isnt a dual pattern cam. On the ci tech page it said that clifford doesnt list their lobe separation angles but i would guess its 110 because mike said that he talked to the clifford guy and listed some clifford cams as 110 on the cam page of ci
also the idle is way to good to be a tight angle overlappy cam
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)
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)
The Blue Box
Well-known member
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:
.478" is the valve lift.The Blue Box":1jfennnj said:
The .050" lobe lift duration is the amount the crankshaft turns from the time the lifter has risen .050" to when the lifter is .050" from being all the way down.
In this case it is 214*
The advertised duration (SAE standard) is the crankshaft rotation fom .006" lifter lift to .006" lift which is 270* in this case.
The Lobe Separation Angle (LSA) is the angle between the Intake lobe center and exhaust lobe center in camshaft degrees not crankshaft.
If the LSA is 110* and the intake lobe center is set at 110* ATDC that puts the exhaust lobe center at 110* BTDC making both lobe centers equal distance from TDC and is considered straight up in position.
If the cam is advanced 4 degrees the intake lobe center is set at 106* ATDC which places the exhaust lobe center at 114* BTDC.
The Blue Box
Well-known member
Okay this makes sense now thank you. One is measured at the valve and the other at the lifter. Sorry i am very new to cam stuff
"...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.
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.
The Blue Box
Well-known member
I have a copy of the handbook (and read through it) and have read a lot in the tech section of cichad":15fzyp2h said: