110 or 112 lsa
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Le Mans Master
Joined: Oct 2010
Posts: 6,930
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From: melbourne florida
2023 C3 of the Year Finalist - Modified
110 or 112 lsa
talking to my cam grinder about a replacement for my L-82 cam. he thinks it may be safer from the engine vacum aspect to do a 112 lsa to play nice with power brakes and headlights. were right at 10-1 compression were talking 280 ish duration and .500 lift. his thought is with the 1.6 rockers i have with 112 lsa i won't gain much but 110 would allow a bit more horsepower. any thoughts? please none of this roller cam is better stuff. these guys grind high quality cams that I've used several times in over 40 years. otherwise i will stay with what i have. thanks for any intelligent input.
Safety Car
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From: New York
Thread Starter
Le Mans Master
Joined: Oct 2010
Posts: 6,930
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From: melbourne florida
2023 C3 of the Year Finalist - Modified
I may just leave what I have it runs killer with what I've done. If I thought I'd be ok with the power brakes and headlights with the 110 lsa I'd do it but vacum cans are a pain.
Dr. Detroit
Joined: Mar 2012
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From: New Braunfels Texas
What is the spec of the cam? I doubt you would see much difference either way......splitting hairs.
All of my vacuum stuff works with 11 inches of vacuum.......the trick is making sure every line is sealed.
Jebby
All of my vacuum stuff works with 11 inches of vacuum.......the trick is making sure every line is sealed.
Jebby
Team Owner
Joined: Apr 1999
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From: Reno Nevada
2024 C3 of the Year Finalist- Modified
My experience with hotter H-flat tappet cams was that the brakes always worked fine, but the head lights became super lazy. When you turned on the lights only one head light would slowly pop up and the other would come up until I was down the street. I considered a vacuum pump, but just lived with it for years. DCR calculators are not a perfect science. They do get you into the ball park of what duration fits in with any given static compression ratio.
A fun thing to do and it only is the cost of few gaskets and some man hours is to just change the keyway on the timing set and dial in 4 degrees or even just two degrees of advance on your existing cam.
A fun thing to do and it only is the cost of few gaskets and some man hours is to just change the keyway on the timing set and dial in 4 degrees or even just two degrees of advance on your existing cam.
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Le Mans Master
Joined: Aug 2017
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From: Cool Northern Michigan
For what its worth, this is from a dyno test engine at Bruele' West Tech, SBC. Of course every engine & cam will be different, but this will give you a general idea.
Lobe Separation Angles, compare.
Narrow: 101 - 108
Wide: 114 - 120
In the middle: 110 - 112
Test engine vacuum:
LSA 101 = 9.8 inches of Vac
LSA 107 = 12.2" of vac
LSA 113 = 14.4"
I suppose you could fill in the blanks guestimating a LSA of 110.
I only have 11-12" of vac with a 110 LSA. I don't worry about the lazy headlights. Have brakes, have vac advance. What more do you need?
Lobe Separation Angles, compare.
Narrow: 101 - 108
Wide: 114 - 120
In the middle: 110 - 112
Test engine vacuum:
LSA 101 = 9.8 inches of Vac
LSA 107 = 12.2" of vac
LSA 113 = 14.4"
I suppose you could fill in the blanks guestimating a LSA of 110.
I only have 11-12" of vac with a 110 LSA. I don't worry about the lazy headlights. Have brakes, have vac advance. What more do you need?
Thread Starter
Le Mans Master
Joined: Oct 2010
Posts: 6,930
Likes: 842
From: melbourne florida
2023 C3 of the Year Finalist - Modified
Well that's the kind of reassurance I was looking for. I feel a bit better with the 110 Lsa what I have now can really use more cam and that's what my cam guy was saying. Go big or go home, but don't be stupid.i don't drive much at night and if I did it wouldn't be the first time I had to get out and open the headlight door, who hasn't done that? Looks like that ,2800 convertor will work out well.
Thread Starter
Le Mans Master
Joined: Oct 2010
Posts: 6,930
Likes: 842
From: melbourne florida
2023 C3 of the Year Finalist - Modified
My experience with hotter H-flat tappet cams was that the brakes always worked fine, but the head lights became super lazy. When you turned on the lights only one head light would slowly pop up and the other would come up until I was down the street. I considered a vacuum pump, but just lived with it for years. DCR calculators are not a perfect science. They do get you into the ball park of what duration fits in with any given static compression ratio.
A fun thing to do and it only is the cost of few gaskets and some man hours is to just change the keyway on the timing set and dial in 4 degrees or even just two degrees of advance on your existing cam.
A fun thing to do and it only is the cost of few gaskets and some man hours is to just change the keyway on the timing set and dial in 4 degrees or even just two degrees of advance on your existing cam.
Le Mans Master
Joined: Aug 2017
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From: Cool Northern Michigan
I would bet a cheeseburger, fries and a cold one, that your cam already had four degrees advance. So now, you are at eight.
Its very common for cam companies to build in four degrees advance to give the engine that down-low-grunt. That's what 99% of "street / strip" customers want.
They want instant gratification of their new purchase and they want that extra grunt where the engine operates the most: 1000-4,000 RPMs.
So, with eight degrees advance and 1.6 rockers, I would be slightly concerned about piston / Intake valve, kiss of death.
Its very common for cam companies to build in four degrees advance to give the engine that down-low-grunt. That's what 99% of "street / strip" customers want.
They want instant gratification of their new purchase and they want that extra grunt where the engine operates the most: 1000-4,000 RPMs.
So, with eight degrees advance and 1.6 rockers, I would be slightly concerned about piston / Intake valve, kiss of death.
Last edited by HeadsU.P.; Jan 15, 2020 at 09:43 AM.
Le Mans Master
Joined: Aug 2017
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From: Cool Northern Michigan
I could be wrong but I believe that means four degrees of advance GM built-in from stock. (Take the LSA and subtract cntr line, 114 minus 110= 4*)
So, the stock 4* + your added 4* = 8* total.
But hey, its your car. Do what you want. Lots of people have done that. The RPM power band drops off early is all.
Last edited by HeadsU.P.; Jan 15, 2020 at 03:24 PM.
Le Mans Master
Joined: Sep 2001
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From: Unreconstructed, South Carolina
comparo OE iron Vortec L31 LSA = 111*
FWIW as a comparison
OE iron Vortec L31 350ci LSA = 111* (FYI: that OE cam has Plenty of vacuum for brakes).
Specs for Melling replacement cam (M1320) for above is .414/.428, 191*/194*, 261*/263*, ICL 106*, ECL 116*, LSA 111*
Specs for Melling replacement cam (22210) for OEM 3896962
.450/.460 224*/224*, 291*/287*, ICL 114*, ECL 114*, LSA 114*
IO -3* BTC, IC 47* ABC
XO 46* BBC, XC -2* ABC
**Melling cat 010118-1 c2018
OE iron Vortec L31 350ci LSA = 111* (FYI: that OE cam has Plenty of vacuum for brakes).
Specs for Melling replacement cam (M1320) for above is .414/.428, 191*/194*, 261*/263*, ICL 106*, ECL 116*, LSA 111*
Specs for Melling replacement cam (22210) for OEM 3896962
.450/.460 224*/224*, 291*/287*, ICL 114*, ECL 114*, LSA 114*
IO -3* BTC, IC 47* ABC
XO 46* BBC, XC -2* ABC
**Melling cat 010118-1 c2018
Last edited by jackson; Jan 15, 2020 at 01:23 PM.
Thread Starter
Le Mans Master
Joined: Oct 2010
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From: melbourne florida
2023 C3 of the Year Finalist - Modified
Been running that way for 6 years. Also it depends how your figuring by crank degrees or cam degrees
Pulls good till 5500, don't usually rev it past that.
Pulls good till 5500, don't usually rev it past that.
Last edited by 7t9l82; Jan 15, 2020 at 01:42 PM.
Le Mans Master
Joined: Sep 2001
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From: Unreconstructed, South Carolina
FWIW
Manufacturer grinds CenterLInes where it wants and user can advance or retard install where he wants.
Manufacturer grinds Centerlines where it wants and that determines how much separation angle LSA is between the two.
User cannot change LSA (or overlap); It's ground in. If you can change your LSA, you must have one helluva grip to match that big chip.
Manufacturer grinds CenterLInes where it wants and user can advance or retard install where he wants.
Manufacturer grinds Centerlines where it wants and that determines how much separation angle LSA is between the two.
User cannot change LSA (or overlap); It's ground in. If you can change your LSA, you must have one helluva grip to match that big chip.
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,810
From: Cool Northern Michigan
FWIW
Manufacturer grinds CenterLInes where it wants and user can advance or retard install where he wants.
Manufacturer grinds Centerlines where it wants and that determines how much separation angle LSA is between the two.
User cannot change LSA (or overlap); It's ground in. If you can change your LSA, you must have one helluva grip to match that big chip.
Manufacturer grinds CenterLInes where it wants and user can advance or retard install where he wants.
Manufacturer grinds Centerlines where it wants and that determines how much separation angle LSA is between the two.
User cannot change LSA (or overlap); It's ground in. If you can change your LSA, you must have one helluva grip to match that big chip.
I was simply stating that most "street cams" have four degrees advance built in / ground in. This advance in valve timing gives the car that off-idle, gobs of torque that most customers want on the street, but few want on the full time drag strip.
So when you dial-in a cam a additional four degrees by moving the crank sprocket to a different slot, you more than likely now have eight degrees advance.
If you want a screamer that seldom runs below 5,000, then you retard the cam or set it up at zero. The power band is then moved from 5,000 - 8,000 for example.