[68WarDog]

IF the cam card reads ABDC 104 deg, and ATDC 116 deg. Does that make the ICL 110 ( 104+116=220 divided by 2=110.
And if installed “ straight up “ that would put the cam’s icl at 110?

[Stan Weiss]

Can you post up your cam card. ABDC is IVC and ATDC is EVC.

Stan

["QUICK-SILVER"]

This an Ultradyne cam card?
If so, ABDC and ATDC belong to the numbers in front of them.
Last numbers on each line are lobe centers. And that's why your lobe sep math worked out right.

If the cam doesn't have any advance ground in... Dots up is the same as straight up.

Clay

[68WarDog]

Stan here is what I'm talking about

["QUICK-SILVER"]

That cam has 6° advance ground in when installed "dots up".

To install it "straight up", ICL would have to be degreed to 110°.

Clay

[68WarDog]

Originally Posted by "QUICK-SILVER"

This an Ultradyne cam card?
If so, ABDC and ATDC belong to the numbers in front of them.
Last numbers on each line are lobe centers. And that's why your lobe sep math worked out right.

If the cam doesn't have any advance ground in... Dots up is the same as straight up.

Clay

Clay I may be confusing myself. I am thinking putting the cam In dot to dot, places it on a 110 ICL. Where the card states it should be installed / degreed in on a 104 ICL. I'm trying to understand camming terminology

["QUICK-SILVER"]

Pontiac is both "dots up".
A cam with no advance ground in will have the same numbers for ICL and LSA.

Your cam could be installed "straight up" but it would need retarded 6°.

Straight up and dots up can be different or the same depending on the cam. They do get confused or used wrong regularly when talking about cams.

Cam

[68WarDog]

Originally Posted by "QUICK-SILVER"

That cam has 6° advance ground in when installed "dots up".

To install it "straight up", ICL would have to be degreed to 110°.

Clay

Thanks, that's the answer I needed.

[Stan Weiss]

Originally Posted by 68WarDog

Stan here is what I'm talking about

Interesting cam card. I know that UD cams are asymmetrical.

I get the 72 degrees overlap and 287 degrees Intake duration and 295 degrees Exhaust duration, but I also get 105.5 ICL, 113.5 ECL and 109.5 LSA.

Stan

PS: I believe these are your lobes.


Master___Adv_____0.050_____0.200_____Lobe_________ _________
Number_Duration_Duration_Duration____Lift_____104_ ____106_____108_____110_____1.5_____1.6_____1.7
ROLLER_Profiles_Adv_=_.020"
---------
These_are_original_designs_with_slower_ramps_and_s tandard_valve_lash_.026-.030
---------
R81______287______254_______173_____0.3883___0.123 ___0.115___0.107___0.099___0.582___0.620___0.660
R88______295______262_______180_____0.3883___0.140 ___0.132___0.124___0.116___0.582___0.620___0.660

[68WarDog]

Originally Posted by Stan Weiss

Interesting cam card. I know that UD cams are asymmetrical.

I get the 72 degrees overlap and 287 degrees Intake duration and 295 degrees Exhaust duration, but I also get 105.5 ICL, 113.5 ECL and 109.5 LSA.

Stan

PS: I believe these are your lobes.


Master___Adv_____0.050_____0.200_____Lobe_________ _________
Number_Duration_Duration_Duration____Lift_____104_ ____106_____108_____110_____1.5_____1.6_____1.7
ROLLER_Profiles_Adv_=_.020"
---------
These_are_original_designs_with_slower_ramps_and_s tandard_valve_lash_.026-.030
---------
R81______287______254_______173_____0.3883___0.123 ___0.115___0.107___0.099___0.582___0.620___0.660
R88______295______262_______180_____0.3883___0.140 ___0.132___0.124___0.116___0.582___0.620___0.660

If I add duration of 254 + 262 = 516 divided by 2= 258. Multiply LSA by 2, 110 x 2=220. Now take duration of 258 - 220 LSA= 38* of overlap , Not 72.
Stan I think I my have made a mistake about the 72 * of overlap. Pleasecorrect me if I’m wrong.

[Stan Weiss]

Originally Posted by 68WarDog

If I add duration of 254 + 262 = 516 divided by 2= 258. Multiply LSA by 2, 110 x 2=220. Now take duration of 258 - 220 LSA= 38* of overlap , Not 72.
Stan I think I my have made a mistake about the 72 * of overlap. Pleasecorrect me if I’m wrong.

72 Degrees overlap is correct. IVO 38 BTDC, EVC 34 ATDC

38 + 34 = 72.

Stan

[68azbird]

these days we use vvt

[pastry_chef]

Originally Posted by 68azbird

these days we use vvt

Freevalve
https://www.youtube.com/watch?v=S3cFfM3r510