I need to advance my cam 4 more degrees. I'm on the highest degree setting on my 3way sprocket.

Using lunati's method of checking the Intake Opens @ .050.

How does a degree bushing work? My understanding is that you drill the dowl hole bigger and put in the offset bushing. But if you do that, isn't that going to misalign the 3 bolt holes on the cam sprocket?

I also don't understand how the 3 key way sprocket works in the first place. There is a circle/square/triangle symbols. Each keyway has its set symbol. The circle straight up or standard has it's mark right on a tooth. The other two have it offset from the tooth just a hair. How do I align that? There is only one dot on the cam sprocket.

Help!?
-Paul

They are offset bushings that get inserted into the cam gear alingment peg on the top gear (at the cam). Because the bushing is offset you are only rotating the gear, so the bolts will line up. You drill out your upper gear and put one of these bushings into the hole with offset you need, thus advancing your cam to crank. Kits I had were either all odds or all evens with 5 different ones.

Circle is straight up (0 advance), triangle is 2 degrees advance, square is 2 degrees retarded. The dot on the upper gear should align to either of these symbols. The upper gear has the dot at 6 o'clock and the bottom gear has it symbol at 12 o'clock, that is how you start out with dot to dot (0 degrees).

Either of these methods work, they both change the timing between the crank and the cam.

Hope this helps

So, is there just enough play in the bolt holes to the cam to allow that shift?

Yes with the bushing being offset. I was editing my post when you posted again.

Is there any trick to drilling out the alignment hole in the upper gear? And do the new bushings have to be super tight and allow the torque of the bolts to take over, or can the bushing be able to spin inside the hole?

Thanks!

Drill the hole from the back of the gear but don't go all the way through, that way you won't need something to hold the bushing in. Just make sure you make the hole deep enough so the bushing doesn't stick out the back of the gear. The bushing doesn't have to be super tight the bolts will do the work.

Originally posted by dave_silva:
Circle is straight up (0 advance), triangle is 2 degrees advance, square is 2 degrees retarded. The dot on the upper gear should align to either of these symbols. The upper gear has the dot at 6 o'clock and the bottom gear has it symbol at 12 o'clock, that is how you start out with dot to dot (0 degrees). I could be wrong but I though the extra marks were 4º plus or minus.

Paul, Don't forget the marks on the timing set are in addition to any advance ground into the cam.

Well the advance in the cam is 4º. Using Lunati's method... All I am doing is making sure that at 11.5ºBTDC my #1 intake is @ .050 lift.

The best reading I could get was 7.5ºBTDC.


When drilling the back to fit the bushing.... if I don't drill all the way through, I'd have to hack down the alignment/dowel pin some to make it fit behind the gear also.. is that something I should do?

Or am I doing something wrong here? I followed Lunati's instructions to a T....

No just drill part wat till the hole enlarges just a bit on the front. You'll have room for the dowel to offset a bit. You'll have to enlarge the 3 bolt hole a bit too.

Did you check the intake centerline?

No I havn't checked the centerline. Not exactly sure how to do that. I think the comp method does that.

Just thought I'd follow Lunati's instructions since it's their cam. A Harold cam actually. Heard him say a few times that it doesn't matter what is off that makes the cam need to be adjusted, it just needs to have the specs on the card, match the cam in relation to TDC of the piston.

Does the Centerline method work for unsymetrical cams?

Originally posted by Twilightoptics:
No I havn't checked the centerline. Not exactly sure how to do that. I think the comp method does that.

Just thought I'd follow Lunati's instructions since it's their cam. A Harold cam actually. Heard him say a few times that it doesn't matter what is off that makes the cam need to be adjusted, it just needs to have the specs on the card, match the cam in relation to TDC of the piston.

Does the Centerline method work for unsymetrical cams? =
Pretty easy & yes it will work with most any cam.
First thing is recheck to be sure your TDC setting is absolutely correct.
This is very important no matter what method you use.
Best way is with a positive stop.
Don't try to use an indicator to find TDC, it is very easy to be off by a few degrees which will screw up all your measurments.
To find the intake centerline, you find the highest lift point of your lobe with you dial indicator.
Set the indicator at zero at this point.
check it two or three times, it's important.
Back the engine up until the indicator reads about .100 less than this zero point.
Slowly rotate the engine in the direction of rotation (clockwise) until you are exactly .050 before your highest reading.
Write the degree wheel reading down.
Keep turning the engine until you go past the zero on your indicator & stop when you are again at .050 down from this zero.
Write this down.
Add the two numbers together & divide by 2.
This will be your intake centerline.
Again, check it a couple of times.

BTW, reading your posts it sounds like something isn't right. You don't normally need to be moving the cam more than a few degrees.
Did you check the .050 closing point as well as the opening point?

On using the bushing, you will need to drill the hole all the way through the gear unless you have an end mill or flat drill.
It goes in the same place as your original pin hole, what you are doing is enlarging this hole for the offset bushing.
You can use a cam plate to hold it in.
You may need to enlarge the bolt holes in the gear to move it 4 degrees if necessary.

Alrighty. After yesterday afternoon I took a brake from degreeing.. and put the heads on.

This time I found TDC with the piston stop and obtained these readings:

140 + 72 = 212 / 2 = 106 ICL
Got that answer twice.

140.25 + 72.25 = 212.5 / 2 = 106.25 ICL

This is with the timing set on the triangle and my cam card wants a 108 ICL.

This method was 10times easier! No need to move the dial indicator from the piston to the lifter. Just leave it on the retainer. These measurements are assuming I got to zero lash right? But either way it's still going to hit the peak of the lobe at the same place even if I was a few thou off on the lash.

Will a Cam Locking Plate work to secure the bushing? The ones I see, seem to have a hole for the peg. I guess I could grind that hole just enough to get the peg in, which should leave plenty to keep the bushing from going anywhere.

Got a set of Comp Bushings, and upon approval from you guys, will go get a 13/32 drill bit and the locking plate.

THANKS GUYS! I'd be beating myself up if it wasn't for you all!

What cam do you have?
You are actually advanced 2 degrees from where your cam card is telling you to put it & this may not be a bad thing for street use ;)

Yes, the plate will secure the bushing. The cam pin goes through the center of the bushing & the hole in the plate.

Just thought of something while I went and picked up the lock plate.

This is a Harold-Lunati TF80/TF72-112. 239/247@.050 Solid Flat, .510/.530 Lift, 112LSA.

This is an unsymetrical cam. The centerline method can't work, unless we knew for sure that max lift minus .050 is the same degree on both sides of the lobe! (which we don't know for sure)

So I'll try the Lunati way again this time with the piston stop and see what I get that way.

And are the 3 keyway 4º incriments or 2º incriments. Because I'm on the most advanced.. if it's two degrees, I can just bring the sprocket back to the middle keyway.

Originally posted by Twilightoptics:
Just thought of something while I went and picked up the lock plate.

This is a Harold-Lunati TF80/TF72-112. 239/247@.050 Solid Flat, .510/.530 Lift, 112LSA.

This is an unsymetrical cam. The centerline method can't work, unless we knew for sure that max lift minus .050 is the same degree on both sides of the lobe! (which we don't know for sure)

So I'll try the Lunati way again this time with the piston stop and see what I get that way.

And are the 3 keyway 4º incriments or 2º incriments. Because I'm on the most advanced.. if it's two degrees, I can just bring the sprocket back to the middle keyway. =
Sounds to me like you are right where you should be at 6 degrees advanced.
You can check with Harold but on most of his grinds he recommends 6 degrees advance using the intake centerline method.
BTW, the centerline method works just fine as the lobes do not change enough for you to measure that close to the centerline of the lobe.
I believe part of the reason Harold recommends 6 degrees with the centerline method is because of the way he opens & closes the valves.

You may find that using the .050 lift or seat timing figures that the centerline figure will come out different.
I would suggest leaving it alone until you can discuss this with Harold himself, not the Lunati "tech" folks.

If the lobe sep is 112, and the centerline is 108.... that would mean 4 degrees correct?

I'll start a new post to see if I can get harolds attention!

That is correct but you posted that you came up with 106??
Forget the cam card when using the ICL method with Harolds lobes, it was written by Lunati & I believe they use the generic 4 degrees on almost everything unless Harold has straightened that out ;)

Ask Harold :D

The degree readings on that particular keyway have the cam installed on 106Centerline.... if it needs to be 108 I need to move it.

Hopefully Harold will post or I'll give him a wake up call monday mornin!