How can you determine how much advance is ground into a cam?
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How can you determine how much advance is ground into a cam?
How can you determine how much advance is ground into a cam? Can you tell from the cam card or is it stamped on the end of the cam??? I know you can get them with 0 +2 +4 advance ground in, I just want to know how you tell how much was ground in.
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Re: How can you determine how much advance is ground into a cam?
Here is exactly what is on my card
Part# 54-000-11
Engine Chevy LS1
Grind# LS1 3728R/3730R HR12
SPC Instr 1:
SPC Instr 2:
Serial NO Z 5633
Intake Exhaust
Valve Adjustment HYD HYD
Gross Valve Lift .601 .608
Duration at
.006 Tappet Lift 285 289
Valve Timing Open Close
AT .050 Int: 10 BTOC 46 ABDC
Exh: 56 BBDC 4 ATDC
These Specs are for CAM Installed
at 108 Intake Center Line
Intake Exhaust
Duration at .050 236 240
Lobe Lift .3510 .3580
Lobe Separation 112.0
Part# 54-000-11
Engine Chevy LS1
Grind# LS1 3728R/3730R HR12
SPC Instr 1:
SPC Instr 2:
Serial NO Z 5633
Intake Exhaust
Valve Adjustment HYD HYD
Gross Valve Lift .601 .608
Duration at
.006 Tappet Lift 285 289
Valve Timing Open Close
AT .050 Int: 10 BTOC 46 ABDC
Exh: 56 BBDC 4 ATDC
These Specs are for CAM Installed
at 108 Intake Center Line
Intake Exhaust
Duration at .050 236 240
Lobe Lift .3510 .3580
Lobe Separation 112.0
#4
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Re: How can you determine how much advance is ground into a cam?
QUOTE: "Lobe Separation 112.0
at 108 Intake Center Line"
_______________________________________________
Your cam has 4 degrees of ground-in advance.
Put it in dot-to-dot
236/240 .601"/.608" 112 LSA +4
Why do you want that much cam?
at 108 Intake Center Line"
_______________________________________________
Your cam has 4 degrees of ground-in advance.
Put it in dot-to-dot
236/240 .601"/.608" 112 LSA +4
Why do you want that much cam?
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Re: How can you determine how much advance is ground into a cam?
Here is the deal... Where I got it from said they looked at the cam and Comp forgot to grind the advance into it. They told me to just add +4 via my adjustable timing chain. So I did. So now I effectively have +8* advance. How much am I giving up on rwhp and ET/MPH. The cam is already installed and running. Would I be at any advantage to retard it 2* and effectively have +2*. I have a 4400 stall and shift at 6800. Will it effect the idle at all?
#7
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Re: How can you determine how much advance is ground into a cam?
8 degrees is too much.
In my opinion, you need to put that cam in dot to dot (if that cam card is correct)
In my opinion, you need to put that cam in dot to dot (if that cam card is correct)
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#8
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Re: How can you determine how much advance is ground into a cam?
Well, he never said he had a 383 ...
BTW, with 8 degrees total advance on the cam, you will loose HP at high revs and loose static compression overall. In fact, with that much duration, and that much advance, you will loose lots of compression. The only thing you may gain with that much advance is a little faster throttle response right off idle. But, you will sure give up A LOT on at high revs.
Ron,
BTW, with 8 degrees total advance on the cam, you will loose HP at high revs and loose static compression overall. In fact, with that much duration, and that much advance, you will loose lots of compression. The only thing you may gain with that much advance is a little faster throttle response right off idle. But, you will sure give up A LOT on at high revs.
Ron,
#11
TECH Fanatic
Re: How can you determine how much advance is ground into a cam?
If you believe the cam card, he will have 4 degrees advance if installed dot to dot.
If the cam card is wrong, and it really has no advance ground in, then the 4 degrees you installed it at would be ok.
Bottom line ... I would put it on a Cam Doctor. Thunder has one. You are really throwing the dice if you don't know for sure what that cam is really ground at.
Again, 8 degrees of advance (if thats now the case) is way too much.
Good Luck,
If the cam card is wrong, and it really has no advance ground in, then the 4 degrees you installed it at would be ok.
Bottom line ... I would put it on a Cam Doctor. Thunder has one. You are really throwing the dice if you don't know for sure what that cam is really ground at.
Again, 8 degrees of advance (if thats now the case) is way too much.
Good Luck,
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Re: How can you determine how much advance is ground into a cam?
It acts exactly as you said. Revs really fast in the lower rpm 's and feels flat as hell up top. Would it benefit me to go +2 instead of +4 since the majority of my time at the track is in the higher rpm range? Since the cam is +4 ground in, I can retard it 2*. I don't want to have to change it again. BTW thanks for the input. I really appreciate it.
#13
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Re: How can you determine how much advance is ground into a cam?
"Would it benefit me to go +2 instead of +4 since the majority of my time at the track is in the higher rpm range"?
__________________________________________________ ____
That will give you a total of 6 degrees advance .. still too much.
__________________________________________________ ____
Well, from what you have said, the cam card is correct (lets hope).
It then has 4 degrees of ground-in advance. Put it in dot to dot which will get you 4 degrees total advance, or go 2 degrees retarded on the cam gear (which will really put it in at 2 degrees total advance)... That's your call
Since that cam is so big to begin with (long legged. if you will), I think I would keep it dot to dot and let it run with 4 degrees advance.
2 degees total advance (made with 2 degrees retarded on the cam gear) will give a little more top end, but may make it feel sloppy down low due to the big duration / overlap the cam has to begin with.
__________________________________________________ ____
That will give you a total of 6 degrees advance .. still too much.
__________________________________________________ ____
Well, from what you have said, the cam card is correct (lets hope).
It then has 4 degrees of ground-in advance. Put it in dot to dot which will get you 4 degrees total advance, or go 2 degrees retarded on the cam gear (which will really put it in at 2 degrees total advance)... That's your call
Since that cam is so big to begin with (long legged. if you will), I think I would keep it dot to dot and let it run with 4 degrees advance.
2 degees total advance (made with 2 degrees retarded on the cam gear) will give a little more top end, but may make it feel sloppy down low due to the big duration / overlap the cam has to begin with.
#14
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Re: How can you determine how much advance is ground into a cam?
Bottom line:
More advance = fast throttle response / lower high rev power (lowers the power band)
Less advance = Just the opposite
Again, I would go dot-to dot (4 degrees total advance), or 2 degrees retarded on the cam gear which will get you 2 degrees total advance (and bring to power curve up higher)
More advance = fast throttle response / lower high rev power (lowers the power band)
Less advance = Just the opposite
Again, I would go dot-to dot (4 degrees total advance), or 2 degrees retarded on the cam gear which will get you 2 degrees total advance (and bring to power curve up higher)
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Re: How can you determine how much advance is ground into a cam?
Bottom line:
More advance = fast throttle response / lower high rev power (lowers the power band)
Less advance = Just the opposite
Again, I would go dot-to dot (4 degrees total advance), or 2 degrees retarded on the cam gear which will get you 2 degrees total advance (and bring to power curve up higher)
More advance = fast throttle response / lower high rev power (lowers the power band)
Less advance = Just the opposite
Again, I would go dot-to dot (4 degrees total advance), or 2 degrees retarded on the cam gear which will get you 2 degrees total advance (and bring to power curve up higher)
#16
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Re: How can you determine how much advance is ground into a cam?
That dot to dot will make a big difference if you are now running with 8 degrees advance ... Jeese that's alot. No wonder it had no top end.
C Ya,
Ron
C Ya,
Ron
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Re: How can you determine how much advance is ground into a cam?
Add all that advance along with Comp 987 springs (valve float) with that cam. I got the new LS6 heads with Comp 977 Springs, YT rockers and Comp R lifters. I am expecting a lot quicker times. No wonder I could only trap out at 116mph. I am hitting the track Saturday, I will let you know how I do. Thanks again for all your help...
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Before you do anything I would get the engine dynoed to find out where peak torque and hp occur. You would want to lock the converter to find real numbers.
Once you have peak hp and torque you will know exactly how much to advance or retard the cam. For every degree of advance/retard you change the peak hp/torque approximately 50 rpm. You want peak torque around 4900 in your case with a 4400 stall and peak hp around 6400 with a 6800 shift point. You may have to change your shift points as peak torque and hp may not fall right where you need them with existing converter. In other words if you go with the 4400 stall then set the cam to peak torque at 4900 then change your shift points to 200-400 above peak hp at that point.
Once you have peak hp and torque you will know exactly how much to advance or retard the cam. For every degree of advance/retard you change the peak hp/torque approximately 50 rpm. You want peak torque around 4900 in your case with a 4400 stall and peak hp around 6400 with a 6800 shift point. You may have to change your shift points as peak torque and hp may not fall right where you need them with existing converter. In other words if you go with the 4400 stall then set the cam to peak torque at 4900 then change your shift points to 200-400 above peak hp at that point.