Cams, again. I'm bored so....

[SATAN]

I just got my new cams from schneider installed and dialed in. Last time I did this I thought my cams were way off until it was brought to my attention that on the cam card it says "-5* BTDC" I though that meant they start to open at 5* before TDC. Oops, it meant 5* AFTER TDC. Well this time around I got the largest cam that schneider offers. Cam card says "intake opens -3* BTDC" This time around I know that means 3* after TDC. So I have both cams set to open at 3*ATDC. NOW, they are supposed to close at 45* ABDC according to cam card. Driver side cam closes at 41*ABDC. Ok thats not TOO bad . But the passenger side cam closes at 36* ABDC. Now thats 9* from what it is supposed to be. :? I cant think of anything I could have done wrong this time around.

0* on degree wheel equals TDC. 180* on wheel equals BDC. cams open at 3* mark atdc. cam closes at 144* mark ABDC. 45* after BDC would be 135* right???? Thats 9* missing right? Or am I smoking crack or somthing. I jumped to conclusions that it was Schneiders fault last time and ended up being wrong. But I dont see what I could be doing wrong this time cause I am aware of how the cam card works now. 222* of durration is what I am supposed to have but I only have 213* WTF am I doing wrong?! ops:

Things I am 100% sure I am doing. NOT measuring off of the top of the lifter (measuring off of the lifter BODY ONLY)

Have the timing gears correct. 40 teeth between each dot on cam gears.(even so that wouldnt effect the durration if I am measuring when it opens to when it closes.)

Degree wheel is NOT moving seperate from crank.

Dial indicator is NOT sticking.

[SATAN]

I see you guys reading it! dont be shy. At least tell me if my math makes sence.

[Firehawk]

The other cam was a bit off too, right? I would guess that the cam used as a core had some wear maybe? Regrind off? Not sure, but this is one reason I am having my own cams built. They will be more expensive than schneider, but they will be dead on.

[Russ84na]

Sounds as if you are off a tooth. Check for the correct number between crank and gears. Also check to see that you adjustable gears are set on the stock setting.

As a thought, does Schneider's numbers take into account the difference of 3* between the right and left cam gears?
Would this have any effect on the setting numbers?

[craZed]

If you are consistently getting different durations between the two, then I cant see it being a problem on your end.
Have you tried measuring each and every lobe, or just a sample from each cam?
You've got enough time invested in that beast, send them back if they aren't balanced.
With the horsepower level you are shooting for, I would think that even the slightest imbalance in cylinder pressures could substantially shorten the engine life.

[SATAN]

Russ84na wrote: Sounds as if you are off a tooth. Check for the correct number between crank and gears. Also check to see that you adjustable gears are set on the stock setting.

As a thought, does Schneider's numbers take into account the difference of 3* between the right and left cam gears?
Would this have any effect on the setting numbers?

I was thinking that maybe cam gears were off or off from the crank or somthing along those lines but then I thought about it and I am measuring from when the cam opens (050" lift) to when the cam closes (.050") It wouldnt matter how off the timing was. The numbers would read the same. The car might run like crap but the numbers would still add up to what they do.

By the way. I cant for the life of me find the instructions for the cam gears. But I wouldnt think it would matter as long as I have the cams opening when they are supposed to on the cam card.

Crazed- I have not measured each and every lobe. I allways start with the intake lobes on the #1 and#2 cylinders. If those are off on a sohc engine then there is nothing you can do about it. I agree though, piece of mind would be good to have. I would send them back but I would have to send another set of cores with them to get it right. I dont have any. Again though, Last time I thought I was 100% sure I was right until somone pointed out a flaw. I just dont want to make that mistake this time, ya know?

[casner]

it would seem to me that it if the cams are set to open at 3* AFDC, and they are mechanically linked, and nothing slipped while you were rotating the engine, that the only result could be that the grind is off. I would get a dial indicator that opens a full inch and test it the easy way before sending the cams back. shouldn't get different results but would bring a piece of mind to approaching schneider. and a phone call shouldn't hurt, they are cam experts :wink: and shouldn't mind helping someone who purchased their product.

[casner]

Russ84na wrote: Sounds as if you are off a tooth. Check for the correct number between crank and gears. Also check to see that you adjustable gears are set on the stock setting.

As a thought, does Schneider's numbers take into account the difference of 3* between the right and left cam gears?
Would this have any effect on the setting numbers?

the only problem with being a tooth off is that they both open at 3*ATDC, if one gear was off then that gear would be 9* off at both measurements. both cam gears are adjusted roughly the same, (as far as being retarted or advanced). but please correct me if I am wrong as I am still learning. and there are 40 between the gears by the way.

and to the other thought, each gear was set to the degreeing wheel so the only difference the 3* variable between the gears should be seen on the face of each gear itself..... right?

[Russ84na]

I am thinking that you may not have the gears set right.

the only problem with being a tooth off is that they both open at 3*ATDC, if one gear was off then that gear would be 9* off at both measurements. both cam gears are adjusted roughly the same, (as far as being retarted or advanced). but please correct me if I am wrong as I am still learning. and there are 40 between the gears by the way.

When you set the adj cam gears you move the cam not the gears. Therefore you could have 40 teeth between the original marks and the cams could be as much as 10 degrees different.

By the way. I cant for the life of me find the instructions for the cam gears. But I wouldnt think it would matter as long as I have the cams opening when they are supposed to on the cam card.

I'll pm you another set of instructions. You are right about the opening and closing is in relation to the cam, but your dial indicator is on the crank. Check to be sure the gears adjustment bolts are tight. If the cam gear were to slip then the result wouldn't be correct.

and to the other thought, each gear was set to the degreeing wheel so the only difference the 3* variable between the gears should be seen on the face of each gear itself..... right?

On the stock gears the 3 degree difference is built into the keyway on the gear so cam is turned 3 degrees. If you lay one gear on top of the other with the timing dots on top of each other and look down through the keyway you will see that they are offset. So the gears will look aligned but the cams are offset 3*. The same is true with the adjustable gears. They appear the same on the face, but there is a 3* offset if they are set on the factory setting.

[benz-tech]

2 possible problems based on my experience with other cars:
i'm sure it is but the belt has to be tensioned otherwise cam snap could play with the duration figures esp on the right cam.
the other possiblility i'm thinking of could just be that i don't know how vg's are timed. the old Ferrari's i used to work on, had 2 tdc marks on the flywheel, one for each bank. could it be that the specs that Schnieder gives for the left bank be based on the extra 60* of rotation needed for for that bank to be at TDC? obviously not a duration issue but they would always screw with my head when setting up 4 cams back in the day.

[craZed]

SATAN wrote: Last time I thought I was 100% sure I was right until someone pointed out a flaw. I just don't want to make that mistake this time, ya know?

I hear ya, but what I'm saying is even if you did make a mistake it wouldn't matter because you used the exact same process to measure each cam, and the biggest issue is the durations don't match.
As long as the gear isn't slipping and you are measuring off of the lifter face( part that rides the cam) i would bet the cams don't match.
They should match each other, as far as the lobe profiles, right?

I wish i had some extra cams, I'd send them your way.

[SATAN]

benz-tech wrote: 2 possible problems based on my experience with other cars:
i'm sure it is but the belt has to be tensioned otherwise cam snap could play with the duration figures esp on the right cam.
the other possiblility i'm thinking of could just be that i don't know how vg's are timed. the old Ferrari's i used to work on, had 2 tdc marks on the flywheel, one for each bank. could it be that the specs that Schnieder gives for the left bank be based on the extra 60* of rotation needed for for that bank to be at TDC? obviously not a duration issue but they would always screw with my head when setting up 4 cams back in the day.

Yeah, the belt was tensioned while I was degreeing them. Its an extra 120* rotation for TDC on the number 2 cylinder not 60 as it would be on a v12. No v12 ferrari's here sad to say :cry: . Either way I see what you are saying though however, I made sure I found TDC for the #1 cylinder, then degreed the pasenger head and then found it again for the #2 cylinder and degreed the driver head.

[SATAN]

[quote]craZed wrote:

Last time I thought I was 100% sure I was right until someone pointed out a flaw. I just don't want to make that mistake this time, ya know?I hear ya, but what I'm saying is even if you did make a mistake it wouldn't matter because you used the exact same process to measure each cam, and the biggest issue is the durations don't match.
As long as the gear isn't slipping and you are measuring off of the lifter face( part that rides the cam) i would bet the cams don't match.
They should match each other, as far as the lobe profiles, right?

I wish i had some extra cams, I'd send them your way.

yeah, thats what I was thinking. Even if I some how had everything completely backwards and off timed and just fubar'd I could still measure when the cam opens and when it closes. Those measurments would be the same no matter what.

[DrewZee87T]

This may well be a complete bullshit answer, so buyer beware---

Don't the hydraulic lifters have to be "pumped up" in order to properly function?

So the question is have you warmed up the engine and ensured that the proper oil pressure was in the lifters and then tried your measurement again?

Flames away....

FYI - thanks for the manifold

[Chris86NA2T]

DrewZee87T wrote: This may well be a complete bullshit answer, so buyer beware---

Don't the hydraulic lifters have to be "pumped up" in order to properly function?

So the question is have you warmed up the engine and ensured that the proper oil pressure was in the lifters and then tried your measurement again?

Flames away....

FYI - thanks for the manifold

in an earlier post he explained that he took the measurment off of the body of the lifter to rule this out. its a good point though, that would certainly cause variations if the lifter compressed.