Camshaft timing check height ?

[70rcode]

Anyone know the 1960 to1970 factory camshaft timing lifter check height ? ...I can easily find the various factory street & race engine package duration specs but Not the lifter check height & i KNow it's Not 0.050" ...Appreciate any help,...Tom.

 

[wyrmrider]

there is none
chrysler uses their blueprints to figure advertised durations and timings
they take where the clerance ranp meets the acceleration ramp , note the point then subtract 4 degrees (for 8 total to get fsm duration) so who can tell what the height is at that point up the flank?
it works out to about .008 but not exactly
is useful for comparig stock and DC cams
what cam and I or someonre may have the .050
or use split over;ap to start with or split + 4
or the overlap triangle methodor if you plot .008 on a big circke the 4 events and overlapthen
compare to publishe you can get close

 

[BSB67]

Anyone know the 1960 to1970 factory camshaft timing lifter check height ? ...I can easily find the various factory street & race engine package duration specs but Not the lifter check height & i KNow it's Not 0.050" ...Appreciate any help,...Tom.

What are you trying to do?

 

[70rcode]

What are you trying to do?

Just for comparison purposes between the classic '60's A864, A990, etc factory Race Hemi drag package cams to the standard A102 & 103 Street Hemi cam timing spec...When considering upgrading a factory street cam, it's interesting using factory dyno developed cam specs as a historical "known performance"

 

[70rcode]

And for valid spec comparisons, want to know if same lifter check height was used by Chrysler for all their factory supplied G2 Hemi mechanical lifter cam specs.

 

[BSB67]

That actually sounds like a fun and cool thing to do. That'll be great basis for learning, comparing and predicting. You must be an engineer.

Unfortunately, I got nothing for you.

My gut tells me that if Chrysler used a specific method or standard, it was likely used by development engineers and not readily available.

Certainly someone has spun these cams in a block with a wheel and indicator, but are they still around and is the data available?

Maybe multiply the advertised duration by 0.85 for the 0.050" duration. Just kidding.

Good luck.

 

[wyrmrider]

as i said chrysler does not use lifter heck heights
all are different
but the method mopar uses takes the height of the ramp out of the equation
so you can compare them
and you can compare ft and hft
I like the way mike jones gives adv duration
lash + .006 takes lash out of the picture
and you can compare his solids and rollers to ny .006 hyd

 

[70rcode]

Engineer ?.I wish BSB ! .interesting & aggrivating..Chrysler certainly did cam (big & fat) & head (big valves & lite aluminum) their Race package Hemis..but they deff left us factory Street Hemi guys hanging out there with asthmatic short cammed, big & heavy rides. Giving up 800+ rpm plus hauling 500+ lbs extra against L78-79 Nova's kinda tough !

 

[BSB67]

Engineer ?.I wish BSB ! .interesting & aggrivating..Chrysler certainly did cam (big & fat) & head (big valves & lite aluminum) their Race package Hemis..but they deff left us factory Street Hemi guys hanging out there with asthmatic short cammed, big & heavy rides. Giving up 800+ rpm plus hauling 500+ lbs extra against L78-79 Nova's kinda tough !

Agreed. It seems to me that the street hemi is only a cam change away from a bunch more power. Where as, the rest of the Mopar line-up (LA, B and RB motors) seems to be well balanced with well matched parts. JMO. But I really don't know much about hemis - Outside of my pay grade.

 

[Fran Blacker]

That actually sounds like a fun and cool thing to do. That'll be great basis for learning, comparing and predicting. You must be an engineer.

Unfortunately, I got nothing for you.

My gut tells me that if Chrysler used a specific method or standard, it was likely used by development engineers and not readily available.

Certainly someone has spun these cams in a block with a wheel and indicator, but are they still around and is the data available?

Maybe multiply the advertised duration by 0.85 for the 0.050" duration. Just kidding.

Good luck.

Years ago in older Mopar Performance books there was a number like .85 to get approximate duration @.050 lift. It was in the cam choice section. Think it was at the of the cam section. That .85 sounds about right. Sorry I gave away my catalogs from late 60's and 70's. Part guy once gave me dealer cost price sheet, markup was 25/30%.

 

[BSB67]

No offense, but the 0.85 was total BS and way off for most of their cams. I've measured some as well as other trusted hobbiests, and some of the MP cams are 10° off from the 0.85 multiplier. Thety were not even consistant on how they measured "advertised" numbers. Direct Connection/Mopar Performance never wanted the average Joe to be able to actually compare their cams to the competition.

 

[Fran Blacker]

Found one mopar parts book. BSor not the .85 is there with the caveat don't use for cam selection.

 

[BSB67]

Yep. Exactly.

 

[wyrmrider]

MP changed vendors over the years but I doubt that the .85 method was even close even at that one point in time
you can use the adv duration for cam selection as ling as you estimate the Hyd at .008 in other words BIGGER than a same adv duration at .006 and much bigger than a Crane or Melling or Sealed Power or Summit at SAE or .004 which show much longer advertised seat durations for the same cam

 

[70rcode]

Was comparing the various factory mechanical G2 cams spec for spec & "felt" .006 SAE lifter check height could consistently be used 'cause the duration to lift aspect ratios seem 'bout right..& looking for supporting thoughts on that..Always felt a 250 deg @ .050 would've made a great unleashing the "Beast" factory compared to the anemic 226 050 factory stick

 

[BSB67]

Was comparing the various factory mechanical G2 cams spec for spec & "felt" .006 SAE lifter check height could consistently be used 'cause the duration to lift aspect ratios seem 'bout right..& looking for supporting thoughts on that..Always felt a 250 deg @ .050 would've made a great unleashing the "Beast" factory compared to the anemic 226 050 factory stick

Don't look at cam specs in a vacuum. Compression ratio matters too, along with the rest of the motor/car details, and your goals.

 

[wyrmrider]

sure if you are measureing the MP cams yourself
or find a cam doc
.0006 will give you the idle and low end
do .200 &300 for the top end
MP cams have big noses and wear well

 

[PRHeads]

As for the .85 thing.....

The 590 cam is 312 “advertised”, so .85 of that is 265.
That cam measures 270@.050

The 620 cam is 324 “advertised”, so .85 of that is 275.
That cam measures 283@.050

The .85 factor just isn’t that close if you ask me.

No reason in the world they couldn’t publish the correct info.

The “advertised” numbers are also taken at some mystery lift point.
The 312 and 324 numbers are not taken at .020.

 

[PRHeads]

As for the factory hemi cam data........ I don’t know that I’d trust anything I found on line to be gospel.
I’d want to have examples of the cams on hand, and test them myself.
Just take readings of all of them at several lift points to get an idea of how they really compare.

 

[BSB67]

MP 272, 0.455" hydraulic. The 0.85 number is 231° at 0.050, actual is 221°