Question about how to degree my cam

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Zwap

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I'm familiar how to do it but what does the - (minus) sign means on when intake opens at 0.050?
The cam card says -1.5, should I degree it 1.5 degree BTDC or is it 1.5 ATDC as there's a minus sign?
The most cam I've been in touch with use to be degree 7-8 degree (without a minus sign) BTDC, never seen this -1.5 degree before

CamSpecCard.JPG
 
I've never thought or asked about why they do that. I always just went with the number as a positive..lol.
 
install at 108 degrees like it says...Which is 4 degrees advanced.........It is just telling you where the events take place
 
No man, that, it's not!

(LMAO!)
 
Do what Bbrroomm said above, the 108 is the number you'll be working with. If you want to know about the-1.5, do the math. Total degrees of duration is added up as 180 + the event opening degrees BTDC + the event closing ABDC = total degrees at .050 So you have 34.5 plus 180 plus a (negative) 1.5 = 213 degrees at .050. The negative in this example is because the card states BTDC, BUT in this case it's not occurring at BTDC it's actually occurring ATDC, so to keep the math in check , a double negative is required.
 
Are you sure you don't want to answer yes if not being sure causes you to answer no? :D
 
Max1196 said:
Do what Bbrroomm said above, the 108 is the number you'll be working with. If you want to know about the-1.5, do the math. Total degrees of duration is added up as 180 + the event opening degrees BTDC + the event closing ABDC = total degrees at .050 So you have 34.5 plus 180 plus a (negative) 1.5 = 213 degrees at .050. The negative in this example is because the card states BTDC, BUT in this case it's not occurring at BTDC it's actually occurring ATDC, so to keep the math in check , a double negative is required.
Click to expand...

Sweet. Thanks for that!
 
Max1196 said:
Do what Bbrroomm said above, the 108 is the number you'll be working with. If you want to know about the-1.5, do the math. Total degrees of duration is added up as 180 + the event opening degrees BTDC + the event closing ABDC = total degrees at .050 So you have 34.5 plus 180 plus a (negative) 1.5 = 213 degrees at .050. The negative in this example is because the card states BTDC, BUT in this case it's not occurring at BTDC it's actually occurring ATDC, so to keep the math in check , a double negative is required.
Click to expand...

OK, thanks!
I think I got it:
IN open+IN close+180=223
223/2=106.5-IN open=108 because IN open is a negative number (ATDC) I add it instead (double minus become plus).

If I got it right then I should looking for 1.5 degree ATDC at 0.050 to get the cam correct?
 
Why not just degree it off the top of the lobe, at max lift?

You are doing it the hard way.

I personally don't give a crap where the lifter is at .050 but it should be where the cam card says it is. What I care about is where does max lift occur.
 
Zwap said:
I'm familiar how to do it but what does the - (minus) sign means on when intake opens at 0.050?
The cam card says -1.5, should I degree it 1.5 degree BTDC or is it 1.5 ATDC as there's a minus sign?
The most cam I've been in touch with use to be degree 7-8 degree (without a minus sign) BTDC, never seen this -1.5 degree before

View attachment 1715003699
Click to expand...
hi. set dial indicator at zero one heel of lobe. #1 intake. rotate crank until you show max lift of lobe. which is .302. back crank up till you get .200 lift. now rotate forward until you get .275 lift read degree wheel. rotate on over max lift until you get .275 again, read degree wheel. add both numbers together and divide by 2, this will give you lobe centerline. lets say you get 74 and 142, equals 216 divide by 2 equals 108 centerline. cam is in correct. this way is easier to do and more accurate.
 
perfacar said:
hi. set dial indicator at zero one heel of lobe. #1 intake. rotate crank until you show max lift of lobe. which is .302. back crank up till you get .200 lift. now rotate forward until you get .275 lift read degree wheel. rotate on over max lift until you get .275 again, read degree wheel. add both numbers together and divide by 2, this will give you lobe centerline. lets say you get 74 and 142, equals 216 divide by 2 equals 108 centerline. cam is in correct. this way is easier to do and more accurate.
Click to expand...



The best way to do it right here^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
if a builder wants to check opening and closing points, I say go for it. Crane Cams also says go for it
 
Marcohotrod said:
if a builder wants to check opening and closing points, I say go for it. Crane Cams also says go for it
Click to expand...


Sure, I check it...but lifter bore locations etc can change it. I put it where it's supposed to be at max lift and that's where I leave it. I won't move the ICL to get the .050 number.
 
Thanks all!
Did it both the hard .050 way and the ".275 easy" way, ended up at 108 degree both ways, the cam was correct degreed installed dot to dot.
 
Thank You Zwap! you checked her 3 ways and dot to dot is right on! Mopar crank keyways or on! I don't know about china keyways
 
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