Cam degreeing help me understand!

-
Yeah, looks like it’s 4 degrees bigger than the cam card calls for. This is exactly why this stuff needs to be checked.

I don’t think 4 degrees will hurt you, but you may want to install the cam so the ICL matches the opening point on the cam card. In other words, set the cam at...wait a minute I have to do some math.
 
Ok, if you install it on a 106 ICL like Kenny has on the card with your numbers your @ .050 opening point will be 5 BTDC. That’s 2 advanced on the 3 degrees he has listed.

At that timing you’d be putting 2 of the 4 extra degrees on the opening side and 2 on the closing side.

If you think that extra 2 degrees is going to affect bottom end power, you can install it on a 104 ICL and that would put all 4 degrees of the extra duration on the opening side and keep the closing point at 35 degrees ABDC.

IMO, IVC and by effect EVO (which affects blowdown) and more critical that the other two timing events.

Me, personally...I’d put it in on a 104 ICL and keep the IVC at 35 degrees ABDC and just open the intake valve 4 degrees sooner. EVO a will also be 4 degrees earlier and that will help bottom end. Late IVC and late EVO move the power curve up in the RPM range.
 
Thanks YR. I really appreciate your input. It's going into a heavy B-Body street only so I am more concerned with street friendly bottom end power. I reinstalled the 3 way adjustable crank sprocket at 4 degrees advanced but haven't taken new measurements yet (working 12's this weekend). If I am understanding this correctly I should be at 106 ICL. I will need another way to get me to 104 ICL. Perhaps an offset keyway. I'll confirm with measurements on Monday before I cross that bridge. Cheers.
 
When Crane cams was still around, they claimed that if you wanted the butt-meter to feel the difference advancing or retarding a cam, the minimum it should be moved is 4*.
 
Finally got around to taking measurements with cam installed 4 degrees advanced. Learned a few things too. Initially I was using one of my roller lifters when I installed the cam straight up. Some of my measurements were inconsistent so I got a spare HFT lifter from a fellow FABO member and gutted it. I used this to take my measurements with the cam installed advanced 4 and man were my numbers jacked up. I spoke with Ken at Oregon and he said big no no and I should be measuring directly on the lifter and it needs to be a roller. Can't do that with my set-up so I went back to my original method in post 144. As you can see I am now where the cam was supposed to be ground. I would still like to advance it a couple more degrees.

IMG_20210302_173210_hdr_kindlephoto-1546882141.jpg
 
Man I can sure use some help. I have spent 3 days trying to figure out why I can't get to a 104 degree int lobe center line. Something is not making sense. In post 155 I last had the crank advanced 4 degrees (with timing gear) and I measured 106 deg.
I purchased a mr gasket 4 degree advance keyway, installed it at the cam sprocket with my timing set dot to dot and now I measure 101 degrees. When I carefully remove the cam sprocket and install the factory keyway I am measuring 111 degrees.
Yes I have re-verified TDC and I am measuring off of the lifter edge. Yes the timing set is dot to dot at TDC. No slack in chain and I am taking my measurements in direction of crank rotation to remove any chance of slack. I am measuring .050 either side of max lobe lift.
IMG_20210315_142720_hdr.jpg
IMG_20210315_142518_hdr.jpg
IMG_20210315_142546_hdr.jpg


IMG_20210315_142518_hdr.jpg
 
Your roller lifter is turning sideways in the lifter bore, when it is suposed to be held straight by the Spider Bracket that holds the lifters straight and keeps the lifter wheels turning in the right direction.

That will mess up your readings.

Screenshot_20210315-133829_Chrome.jpg
 
George Jets said:
Your roller lifter is turning sideways in the lifter bore, when it is suposed to be held straight by the Spider Bracket that holds the lifters straight and keeps the lifter wheels turning in the right direction.

That will mess up your readings.

View attachment 1715708069
Click to expand...


To add to this you need to STOP using the edge of the lifter. You’ve got so much crap down there that it’s a bad way to do it.

Find an old pushrod and cut it off an inch above the deck. Put the end of the dial indicator into the hole in the pushrod. If you don’t have one, let me know and I’ll cut you one up and send it to you.

Then you can get the dial indicator in line with the lifter and the pushrod. And you can get the DI up where you can see it.
 
I was using a pushrod to measure but figured that may have been throwing my measurements off. See post 144. It seems like a stable set-up. I also tried a gutted out HFT lifter but Oregon Ken told me to use my roller lifter. I have a checking pushrod that I will take apart and try with the lifter positioned correctly. Thanks guys.
 
New set-up. No change in numbers. Installed dot to dot (no advance) intake C/L is 111. Replace cam offset keyway and get 101 degrees.
The roller lifter is oriented properly same as before. I could try retarding the crank sprocket -4 degrees and should give me
103 with cam advanced as is but this still does not make sense!!! The offset came key should have me at 107 and not 101.
IMG_20210315_154505_hdr.jpg
 
I haven’t read through all of this, but this last page is a reminder of why I always get the 9-way adjustable timing sets if they’re available for what I’m working on.
No matter how screwed up the cam or keyways are, you can always get within about a degree of the target......without having to drill anything or buy other parts.

For proper degreeing, the correct type of follower for the cam(flat/roller) must be used.
 
I am a weekend warrior not an engine builder. I am also on a budget. Actually waay over. It appears that my cam was not ground to the advertised spec. So you are saying that the set-up I am using is the cause of the 4 degree offset keyway actually being 10 degrees and that by spending another $250 for a one time use cam measurement tool and 8 way timing set will fix all of this? Please understand that I am not trying to be a dick about this I am just getting frustrated. This is a simple process. The set-up I am using has been used thousands of times with success. There has to be something wrong that I am missing here.
 
Not sure why you want to advance your cam another 4° when the custom ground cams usually have the 4° advance ground into them at the start compared to a stock cam.

Try timing it straight up, Cam at 12:00 o'clock and the Crank Gear at 12:00 at TDC. Then your distributor is ready to drop in to fire at #1 at this position.

Then see where your numbers come out. 112 Lobe Centers ???

20200830_175453.jpg


No easy task figuring it out first time out of the gate. Then if you add more advance than it was originally ground for it complicates it even more.

.
 
JoePole1 said:
I am a weekend warrior not an engine builder. I am also on a budget. Actually waay over. It appears that my cam was not ground to the advertised spec. So you are saying that the set-up I am using is the cause of the 4 degree offset keyway actually being 10 degrees and that by spending another $250 for a one time use cam measurement tool and 8 way timing set will fix all of this? Please understand that I am not trying to be a dick about this I am just getting frustrated. This is a simple process. The set-up I am using has been used thousands of times with success. There has to be something wrong that I am missing here.
Click to expand...


What I think is the offset key is probably wrong. I think that’s what PRH may have been suggesting as well.

It’s possible the cam is off by 5 degrees. It’s also possible the cam isn’t off and the cam/crank keyways are off. Or both.

Again, this is why you degree every cam, every time. And the 250 dollar tool won’t do **** except lighten your wallet. I’ve been degreeing cams since 1980 and never used one. Ever.

^^^^^The above^^^^ isn’t directed at you. It’s for anyone reading this who is thinking about the dot to dot deal. Friends don’t let friends do dot to dot.
 
George Jets said:
Not sure why you want to advance your cam another 4° when the custom ground cams usually have the 4° advance ground into them at the start compared to a stock cam.

Try timing it straight up, Cam at 12:00 o'clock and the Crank Gear at 12:00 at TDC. Then your distributor is ready to drop in to fire at #1 at this position.

Then see where your numbers come out. 112 Lobe Centers ???

View attachment 1715708256

No easy task figuring it out first time out of the gate. Then if you add more advance than it was originally ground for it complicates it even more.

.
Click to expand...


That’s what he’s saying. Dot to dot is 111 ICL and the card says 106 ICL. He’s trying to get the cam where the grinder wants it.
 
Can I ask a stupid question??? When there is an advance ground in to a cam, that will be the measurement at the lobe. Correct? Anotherwords....my cam card states 106 intake and 114 exhaust. That should be my actual measurements. No? I guess I am not understanding the "ground in". Is my cam 110 with 4 degrees advance ground in giving me 106? What about the exhaust lobe?
Does advance get ground in there as well? Also, when a cam is advanced or retarded via crank gear or offset cam key, the exhaust should move the same amount of advance as intake. Correct?
 
If you look at post 155 I was able to get the cam set up very close to the cam card by advancing the crank gear +4 degrees. The
cam timing was off slightly but is probably within margin of error. Tomorrow I will try that set-up again and report back.
Then I will either need to live with it that way or purchase an 8 way timing set.
The offset keyway being ground wrong makes sense but man it's hard to imagine an extra 6 degrees from that little hunk of ****.
Maybe I can try it at the crank.
 
JoePole1 said:
Can I ask a stupid question??? When there is an advance ground in to a cam, that will be the measurement at the lobe. Correct? Anotherwords....my cam card states 106 intake and 114 exhaust. That should be my actual measurements. No? I guess I am not understanding the "ground in". Is my cam 110 with 4 degrees advance ground in giving me 106? What about the exhaust lobe?
Does advance get ground in there as well? Also, when a cam is advanced or retarded via crank gear or offset cam key, the exhaust should move the same amount of advance as intake. Correct?
Click to expand...


Here is the truth about ground in “advance”. Any advance ground into the cam is for the sole purpose of hoping beyond all hope that if you line it up dot to dot it will be installed at the correct ICL. Sooooooo, if you cam is on a 110 LSA and Ken wants it in at a 106 ICL and IF he ground 4 degrees advance in it, then you can theoretically line up the dots and it would be at a 106 ICL.

And just as often as not, lining up the dots doesn't produce what the cam card calls for. Which is why degreeing the cam is the ONLY away to know where it’s installed.

You are doing everything right. Something is just giving you grief.
 
JoePole1 said:
If you look at post 155 I was able to get the cam set up very close to the cam card by advancing the crank gear +4 degrees. The
cam timing was off slightly but is probably within margin of error. Tomorrow I will try that set-up again and report back.
Then I will either need to live with it that way or purchase an 8 way timing set.
The offset keyway being ground wrong makes sense but man it's hard to imagine an extra 6 degrees from that little hunk of ****.
Maybe I can try it at the crank.
Click to expand...


If you are within 2 degrees either way for what you are doing you’ll be golden.
 
Thanks YR!! I really appreciate you taking the time to help me out. I appreciate all of you guys who share your experience, knowledge and life lessons. You all are the reason why a gold membership is money well spent for me. Joe.
 
You must log in or register to reply here.
-

Back
Top