Cam degree calculation questions
08-22-2021, 02:46 PM
#31
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Thread Starter
I’ve run into many that aren’t wear they should be.
Even pre internet was common knowledge to degree in cans. I would say most that are iff, are retarded. OE’s loved cams in retarded * positions. Smoother idle and emissions I guess.
Most off the shelf petformance cams are ground 4* advanced for a reason.
Even pre internet was common knowledge to degree in cans. I would say most that are iff, are retarded. OE’s loved cams in retarded * positions. Smoother idle and emissions I guess.
Most off the shelf petformance cams are ground 4* advanced for a reason.
Thanks again for everyone's input.
08-22-2021, 04:15 PM
#32
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iTrader: (1)
OP. taking about advance and retarding cams, you may believe the below quote of myself is interesting. Take a look at the flat tappets:
Go to Bam's site www.mercruiserparts.com , go to engine look up tables, find your engine and it's camshaft part # and then look below. Disclaimer: these are my notes from other sources and being human I am wrong sometimes.
Mag BBC 454/502 Flat Tappet (rect heads)
.004” 296*, 296*
.006” 286*, 286*
.050” 224*, 224*
.200” 130*, 130*
Valve lift with 1.7 .510”, .510”
LSA 115.5
Merc Part#431-9830 / GM#14096209
ICL 114 ATDC
ECL 117 BTDC
GM Part#10185060 (same as above but ground with 5 degrees advance)
ICL 109 ATDC
ECL 122 BTDC
======================================
Merc Mag Roller
Merc# 431-850478 / GM#12551622
.004 300*/ 300*
.006 288*/288*
.050” 225*/225*
.200” 125*/125*
Lift .483”/. 483”
ICL 109*
LSA 115.5*
Mag BBC 454/502 Flat Tappet (rect heads)
.004” 296*, 296*
.006” 286*, 286*
.050” 224*, 224*
.200” 130*, 130*
Valve lift with 1.7 .510”, .510”
LSA 115.5
Merc Part#431-9830 / GM#14096209
ICL 114 ATDC
ECL 117 BTDC
GM Part#10185060 (same as above but ground with 5 degrees advance)
ICL 109 ATDC
ECL 122 BTDC
======================================
Merc Mag Roller
Merc# 431-850478 / GM#12551622
.004 300*/ 300*
.006 288*/288*
.050” 225*/225*
.200” 125*/125*
Lift .483”/. 483”
ICL 109*
LSA 115.5*
08-22-2021, 06:21 PM
#33
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Thread Starter
edit: I was wrong. Close, but different. They did use the same cam as the one before and just advanced it though. Is that what you were pointing out?
Last edited by HawkX66; 08-22-2021 at 06:27 PM.
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SB (08-22-2021)
08-22-2021, 10:44 PM
#34
Platinum Member
Platinum Member
If I recall, you are putting together an L29, correct?
If they are factory GM L29 valvesprings, please do:
1) measure the installed height of the spring (telescoping gauge between the retainer and the spring seat.
2) take a few springs to somebody with a spring checker and find out the spring pressure AT THAT COMPRESSED HEIGHT.
3) smash it another .490" and take note of the pressure AT THAT HEIGHT as well.
L29's came in trucks with straight springs and later conical or beehive springs, neither of which are considered performance springs.
I would want to see 90 lbs on the seat (usually at 1.88" ht) and over 300 lbs at max lift.
If they are factory GM L29 valvesprings, please do:
1) measure the installed height of the spring (telescoping gauge between the retainer and the spring seat.
2) take a few springs to somebody with a spring checker and find out the spring pressure AT THAT COMPRESSED HEIGHT.
3) smash it another .490" and take note of the pressure AT THAT HEIGHT as well.
L29's came in trucks with straight springs and later conical or beehive springs, neither of which are considered performance springs.
I would want to see 90 lbs on the seat (usually at 1.88" ht) and over 300 lbs at max lift.
08-23-2021, 06:24 AM
#35
Registered
Thread Starter
If I recall, you are putting together an L29, correct?
If they are factory GM L29 valvesprings, please do:
1) measure the installed height of the spring (telescoping gauge between the retainer and the spring seat.
2) take a few springs to somebody with a spring checker and find out the spring pressure AT THAT COMPRESSED HEIGHT.
3) smash it another .490" and take note of the pressure AT THAT HEIGHT as well.
L29's came in trucks with straight springs and later conical or beehive springs, neither of which are considered performance springs.
I would want to see 90 lbs on the seat (usually at 1.88" ht) and over 300 lbs at max lift.
If they are factory GM L29 valvesprings, please do:
1) measure the installed height of the spring (telescoping gauge between the retainer and the spring seat.
2) take a few springs to somebody with a spring checker and find out the spring pressure AT THAT COMPRESSED HEIGHT.
3) smash it another .490" and take note of the pressure AT THAT HEIGHT as well.
L29's came in trucks with straight springs and later conical or beehive springs, neither of which are considered performance springs.
I would want to see 90 lbs on the seat (usually at 1.88" ht) and over 300 lbs at max lift.
Here are the numbers:
145# @ 1.88"
360# @ 1.297"
Coil bind 1.130"
When I built the heads, I measured the valves and used shims to get everything in spec. I set them at 1.88". I also removed the rotators and cut them for posilocks at the same time.
If I were building this for a car, I never would have gone with a used cam and springs. After this whole debacle I'll never use a used cam again though...
08-23-2021, 06:46 AM
#36
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What’s wrong with the used cam ?
08-23-2021, 07:22 AM
#37
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Thread Starter
08-23-2021, 07:30 AM
#38
Platinum Member
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If you bought that cam new, it would not have come with a cam card; t's OEM. The cam is within the OEM tolerances. You're so deep in trying to figure out a detail that doesn't really matter for what you're doing, that you're missing the forest for the trees at this point.
You've made this much more complicated than it needs to be. And there is nothing wrong with that cam.
You've made this much more complicated than it needs to be. And there is nothing wrong with that cam.
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SB (08-23-2021), underpsi68 (09-06-2021)
08-23-2021, 07:40 AM
#39
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Thread Starter
If you bought that cam new, it would not have come with a cam card; t's OEM. The cam is within the OEM tolerances. You're so deep in trying to figure out a detail that doesn't really matter for what you're doing, that you're missing the forest for the trees at this point.
You've made this much more complicated than it needs to be. And there is nothing wrong with that cam.
You've made this much more complicated than it needs to be. And there is nothing wrong with that cam.
What's made this difficult is me doing something wrong and trying to learn from it. From this **** up I've learned a ton more that I thought I already knew.
Last edited by HawkX66; 08-23-2021 at 07:43 AM.
08-23-2021, 07:42 AM
#40
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Here’s my 2 reasons for telling you to put it in 109-111 icl.
#1: you have been using a degree wheel kit and are using a multi keyway timing set. So why wouldn’t you install it for better midrange power even if not a set world on fire difference? But there will be a difference.
#2: see #1
What movie was this ? “The resistance runs strong.”
I agree. This whole thing has been painful.
Lololololol Oh well.
#1: you have been using a degree wheel kit and are using a multi keyway timing set. So why wouldn’t you install it for better midrange power even if not a set world on fire difference? But there will be a difference.
#2: see #1
What movie was this ? “The resistance runs strong.”
I agree. This whole thing has been painful.
Lololololol Oh well.
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underpsi68 (09-06-2021)
