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Using a degree wheel to degree in your L series cams


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Pete,

I am attempting to meet the cam card specs, but as I stated earlier, I am not reaching that goal with the stock sprocket setting-at least not #1 position. The readings are coming up retarded, which is the way I ran the engine the last 5k miles.Not looking for any magic, just to see if i notice a power change getting closer to stated specs on card. Schneider tech guy told me at the initial installation that my numbers were coming in slightly retarded, but running a manual gear box would help offset that and i would be losing some bottom end. So that's the way I ran the engine till this point. Now I want to dial it in closer to specs.Also, as I stated in reading Racer Browns article, it seems that you already get a retarding penalty from running a chain driven cam, so I don't want to leave the valve timing retarded. Though I must say the engine ran very good at lower rpms-lots of torque, so it will be interesting to see if feel any difference.

Advancing the cam from where it was will give you more bottom end at the expense of top end breathing. How much of a difference depends on how much it is advanced. I've suggested to have #1 hole be 4 degrees retarded, which will make the #2 hole "straight up" and #3 hole 4 degrees advanced so you have some +/- adjustability with the stock sprocket.

 

since writing the last post I have searched and found how to change the sprocket setting-thanks Leon. When you stated off by a tooth-do you mean too many links between the cam and crank?

Essentially, yes. Too many links between reference marks on the cam and crank upon installation would cause the cam to be retarded. I think the stock sprocket has 40 teeth? So that would be 360 degrees/40 teeth = 9 degrees/tooth. If that's how much you're off by, then there's a good chance you've skipped a tooth. However, be sure to check TDC with the method in BRAAP's first post before worrying about this.

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Thanks Leon.I am confident that I am dead on as far as TDC. I set that up before installing the head. I doubt I am off a tooth, but I will check that out. Bottom end seems really good on little L24, but if she'll give more-I'll take it! The cam is just a 274f grind, so I believe the grind is goaled more for torque then higher rpm power. At this point, I want to get the intake valve closing point on the mark, since this is the most important.

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It's not "HP magic", what you achieve by changing cam timing is altering the torque curve, essentially shifting it one way or the other. There is no requirement written in stone that you must time it that way. Best performance for the given requirements is found by using the adjustable sprocket and a dyno and it won't necessarily be what the cam card says. You should make sure that the valves don't hit, but if the cam is fairly mild then it shouldn't be a problem. I suppose you could time it "straight up" but make sure that you do so on the #2 hole if using the stock timing sprocket. That way you'll have 4 degrees of advance/retard if you want to play with your torque curve using the stock sprocket.

 

 

I understand in theory what changing cam time could "potentially" do.

 

Don't assume anything, especially when it comes to piston to valve clearance. Again, you need to start somewhere, so you might as well start where the cam manufacturer suggests. Just assuming that advancing it will make more power when you haven't measured the power straight up is a waste of time, and could cause catastrophic damage.

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Pete,

I am attempting to meet the cam card specs, but as I stated earlier, I am not reaching that goal with the stock sprocket setting-at least not #1 position. The readings are coming up retarded, which is the way I ran the engine the last 5k miles.Not looking for any magic, just to see if i notice a power change getting closer to stated specs on card. Schneider tech guy told me at the initial installation that my numbers were coming in slightly retarded, but running a manual gear box would help offset that and i would be losing some bottom end. So that's the way I ran the engine till this point. Now I want to dial it in closer to specs.Also, as I stated in reading Racer Browns article, it seems that you already get a retarding penalty from running a chain driven cam, so I don't want to leave the valve timing retarded. Though I must say the engine ran very good at lower rpms-lots of torque, so it will be interesting to see if feel any difference.

 

As far as valve clearance, I am ASSuming that my meager 480 lift cam should have ample clearance if I am close to specs on the valve timing.

 

As far as head gasket goes, the one I took off measures around 1.2mm and that is what the Nismo measures at once compressed(if I ever get it).

 

since writing the last post I have searched and found how to change the sprocket setting-thanks Leon. When you stated off by a tooth-do you mean too many links between the cam and crank?

 

Any significant material taken off the head? Cam towers shimmed accordingly? 1.2mm is close to stock of 1.25mm, so the gasket shouldn't change the timing. Try the different holes in the stock sprocket to see if you can get closer to the cam card specs. You can also use the method I wrote above which doesn't use a degree wheel, but assumes that the cam has a symetrical lift profile.

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Just so I'm not misunderstood, I am not looking to advance the cam BEYOND specs. The numbers are coming up retarded, so I want to advance the cam to get to spec. If I could have a choice betwwen the cam slightly retarded or slightly advanced- (because i couldn't get the specs EXACT)- I would rather be slightly advanced.

 

Head is early e-88 with .010 shaved with bigger valves. Flat-tops with no reliefs. I will probably measure piston/valve clearance at some point in all this for future reference to go with a bigger cam.

 

Pete, I will try your method later since this is a symetrical cam profile

Edited by madkaw
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I understand in theory what changing cam time could "potentially" do.

 

Don't assume anything, especially when it comes to piston to valve clearance. Again, you need to start somewhere, so you might as well start where the cam manufacturer suggests. Just assuming that advancing it will make more power when you haven't measured the power straight up is a waste of time, and could cause catastrophic damage.

To clarify, not I nor Steve mentioned anything about making more power anywhere. Nobody made those assumptions. Changing cam timing shifts the torque curve, period. It's what happens when you delay or advance valve events and is not a mystery. I completely agree that you should check to make sure valves don't hit pistons. What I said is that retarding or advancing this (mild) cam should not cause any problems. This does not mean, "don't check clearances".

 

I also didn't say to not measure power "straight up". I'll just quote myself:

 

Best performance for the given requirements is found by using the adjustable sprocket and a dyno and it won't necessarily be what the cam card says

Test as many data points as needed. Ultimately, the dyno tells you what to do.

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This is exactly what I've been saying...

 

Do you have a problem here? I don't. If you can't reply in a respectful manner, then don't reply at all. I am only trying to help madkaw. And what you may think is obvious, was not obvious to me when I first learned it. Food for thought.

Edited by z-ya
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Do you have a problem here? I don't. If you can't reply in a respectful manner, then don't reply at all. I am only trying to help madkaw. And what you may think is obvious, was not obvious to me when I first learned it. Food for thought.

 

I don't see any disrespect on my part. I'm trying to help Steve, and explaining my process clearly. It doesn't help when you start implying that I said one thing when I said another. Your sarcasm in a previous reply about "HP magic" was all the disrespect I've seen so far. If you have a problem, then PM me. I don't want to clutter a good thread.

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I don't see any disrespect on my part. I'm trying to help Steve, and explaining my process clearly. It doesn't help when you start implying that I said one thing when I said another. Your sarcasm in a previous reply about "HP magic" was all the disrespect I've seen so far. If you have a problem, then PM me. I don't want to clutter a good thread.

 

There was no disrespect intended. I guess I am tired of hearing about if you do this or that, you will get this, without any actual measurements to prove it. Again, no disrespect. People are quick to say "that's easy", or "it should work", when in fact to do it right is not easy. That was the reason for the "magic". I completely believe in measuring performance, making changes, and measuring again. I've probably dynoed my own, and other's cars more than most on this forum (and posted results too!). My last 13:1 race motor build was on the dyno three times (one engine, twice chassis). I've learned a whole lot building that motor. I'm just trying to share the knowledge.

 

Here is the build thread if you are interested.

 

http://forums.hybridz.org/index.php/topic/96584-road-race-enduro-l28-engine-build/

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Pete,

I understand what your saying. This is the whole reason I didn't just throw the cam in and say-well the power is okay, but I better get a bigger one. This is the whole reason I didn't just throw the nearly new Mikunis 40's on my car yet-even though I'v owned them for years,why-because I haven't finished doing the tune on there with my SU's. I am trying to do this the right way and LEARN more than anything.

There will be dyno trips involved to. I did my first on the way to ZCON 2010 and found the engine made good power, but was out of tune-and the cam was just thrown in, but now i want to properly dial it in as well as other things and DYNO once again with the SU's----THEN and only THEN the Mikunis go on and then DYNO time.

I want to know for sure if I am making progress and learning too, so there will be many trips to the dyno.

I appreciate the shared knowledge of all you guys.

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There was no disrespect intended. I guess I am tired of hearing about if you do this or that, you will get this, without any actual measurements to prove it. Again, no disrespect. People are quick to say "that's easy", or "it should work", when in fact to do it right is not easy. That was the reason for the "magic". I completely believe in measuring performance, making changes, and measuring again. I've probably dynoed my own, and other's cars more than most on this forum (and posted results too!). My last 13:1 race motor build was on the dyno three times (one engine, twice chassis). I've learned a whole lot building that motor. I'm just trying to share the knowledge.

 

Here is the build thread if you are interested.

 

http://forums.hybridz.org/index.php/topic/96584-road-race-enduro-l28-engine-build/

 

Sure I understand that, but I never made such a contention. You claimed I made assumptions that I never made. I never said anything was easy, nor anything about making more power. If you are referring to the valve interference statement, I was saying that he should check but I doubt that it would be a problem. Reread the statements I made, maybe you'll see them in a different way?

 

I am all for dyno testing and scientific method, and can appreciate your efforts in sharing your knowledge with the community. What I do know and did inform Steve of, is that advancing the cam will shift his powerband down. Therefore, it would be wise to set the cam on the #2 hole (which would put it at zero advance) and then have +/- 4 degrees of adjustment (instead of -4/-8 degrees if set on #1 hole) if/when he decides to test. This has been exactly my point the entire time, I just felt like you were protesting assertions that nobody ever made.

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Okay, looking for some guidance here. I am awaiting and hoping Schneider will return my call-but meanwhile here is a pic of my cam card. I have made some assumptions since I haven't confirmed with Schneider yet, but I assume the degreeing numbers on the right are made with zero vlave-lash and at .050. Haven't recieved my Nismo adjustable sprocket yet, so this is using stock sprocket.

 

This is what I cane up with using #1 hole:

 

Intake opens @ 1 degree BTDC

Intake closes @ 43 degrees ABDC

 

Exhaust opens @36 BBDC

Exhaust closes @4 ATDC

 

 

 

Using # 2 hole on sprocket:

 

Intake opens @5 degrees BTDC

Intake closes @ 40 degrees ABDC

 

Exhaust opens @40 BBDC

Exhaust closes @1 BTDC

 

My concern is that trying to get close to the card for Intake closing is just going to take me further away from the other closing and opening points.See next post for attachment

post-1083-062118900 1320417041_thumb.jpg

Edited by madkaw
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Okay, looking for some guidance here. I am awaiting and hoping Schneider will return my call-but meanwhile here is a pic of my cam card. I have made some assumptions since I haven't confirmed with Schneider yet, but I assume the degreeing numbers on the right are made with zero vlave-lash and at .050. Haven't recieved my Nismo adjustable sprocket yet, so this is using stock sprocket.

 

This is what I cane up with using #1 hole:

 

Intake opens @ 1 degree BTDC

Intake closes @ 43 degrees ABDC

 

Exhaust opens @36 BBDC

Exhaust closes @4 ATDC

 

 

 

Using # 2 hole on sprocket:

 

Intake opens @5 degrees BTDC

Intake closes @ 40 degrees ABDC

 

Exhaust opens @40 BBDC

Exhaust closes @1 BTDC

 

My concern is that trying to get close to the card for Intake closing is just going to take me further away from the other closing and opening points.

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Sure I understand that, but I never made such a contention. You claimed I made assumptions that I never made. I never said anything was easy, nor anything about making more power. If you are referring to the valve interference statement, I was saying that he should check but I doubt that it would be a problem. Reread the statements I made, maybe you'll see them in a different way?

 

I am all for dyno testing and scientific method, and can appreciate your efforts in sharing your knowledge with the community. What I do know and did inform Steve of, is that advancing the cam will shift his powerband down. Therefore, it would be wise to set the cam on the #2 hole (which would put it at zero advance) and then have +/- 4 degrees of adjustment (instead of -4/-8 degrees if set on #1 hole) if/when he decides to test. This has been exactly my point the entire time, I just felt like you were protesting assertions that nobody ever made.

 

Let's both stop polluting what was a great thread. Thanks.

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Okay, looking for some guidance here. I am awaiting and hoping Schneider will return my call-but meanwhile here is a pic of my cam card. I have made some assumptions since I haven't confirmed with Schneider yet, but I assume the degreeing numbers on the right are made with zero vlave-lash and at .050. Haven't recieved my Nismo adjustable sprocket yet, so this is using stock sprocket.

 

This is what I cane up with using #1 hole:

 

Intake opens @ 1 degree BTDC

Intake closes @ 43 degrees ABDC

 

Exhaust opens @36 BBDC

Exhaust closes @4 ATDC

 

Using # 2 hole on sprocket:

 

Intake opens @5 degrees BTDC

Intake closes @ 40 degrees ABDC

 

Exhaust opens @40 BBDC

Exhaust closes @1 BTDC

 

My concern is that trying to get close to the card for Intake closing is just going to take me further away from the other closing and opening points.

 

No, I think the all of the measurements on the cam card are when the lash is set according to cam card. This will have an effect on cam timing.

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Pete,

your exactly right on both posts!

 

Just got off the phone with Jerry at Schneider and yes valve lash needs to be set since I am taking measurements off of the retainer. Some new numbers with the sprocket in #2 hole;

 

Intake closes 33.5 ABDC

Intake opens 3 BTDC

 

Exhaust opens 37 BBDC

Exhaust closes 6 BTDC

 

Jerry worked some numbers and felt the intake opening needed to fall inbetween 2-4 degrees opening. I acheived this with the sprocket in # 2 hole. With this setting I am no more than 2 degrees off on any specs.

My arm and back are wore out!

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Pete,

your exactly right on both posts!

 

Just got off the phone with Jerry at Schneider and yes valve lash needs to be set since I am taking measurements off of the retainer. Some new numbers with the sprocket in #2 hole;

 

Intake closes 33.5 ABDC

Intake opens 3 BTDC

 

Exhaust opens 37 BBDC

Exhaust closes 6 BTDC

 

Jerry worked some numbers and felt the intake opening needed to fall in between 2-4 degrees opening. I acheived this with the sprocket in # 2 hole. With this setting I am no more than 2 degrees off on any specs.

My arm and back are wore out!

 

 

Awesome :2thumbs: Great job!

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Okay guys-need some more help. My Nismo cam sprocket arrived and I threw it on there since it was easy at this time. I set it up on #2 since that was what the stock was set-up on. The timing came in slightly retarded from where I was. Dialing in #3 puts me too far advance. Not sure where to go from here. I see the letters on there A-D. If I want to advance beyond #2 do I use the letter that falls between the numbers?

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Okay guys-need some more help. My Nismo cam sprocket arrived and I threw it on there since it was easy at this time. I set it up on #2 since that was what the stock was set-up on. The timing came in slightly retarded from where I was. Dialing in #3 puts me too far advance. Not sure where to go from here. I see the letters on there A-D. If I want to advance beyond #2 do I use the letter that falls between the numbers?

 

You have to use the chart that came with the sprocket. Hole 2 is 3 degrees advanced. See attached.

post-274-087093800 1321402157_thumb.jpg

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