All Small Six Cam degree off?

[clochard68]

Hi,

I need help with degreeing my new Isky cam. LSA of the cam should be 108.
I put the cam straight in with the double roller timing chain, and the cam was 8 degrees off at LSA 100. Now I put the timing chain in the -8° retarded slot and the cam is now at 108.5 LSA.
I just wanted to make sure that I used the right technique/steps to degree the cam....

I attached pictures of my setup and my degree wheel.
1. I established true top dead center for piston #1 with a dial gauge. After that I arranged the degree wheel and pointer that TDC was set.
2. I have a solid lifter and dial gauge on intake lobe of cylinder #1
3. I rotate the crankshaft clockwise, until the gauge reads 0.050" before maximum lift and write down what the degree wheel shows: 64° after TDC, where my index finger on the picture is
4. I rotate the crankshaft further clockwise until 0.050" after maximum lift and also write the number down: 153° after TDC, where my thumb on the picture is
5. I summarize both numbers and divide them by two: (64+153):2 = 108.5
This is my current LSA for the cam


Is this the corret way (or one of the correct ways)?
I am not sure because it is hard for me to believe that Isky ground the cam 8 degrees off?

 

[pmuller9]

The cam is not supposed to be set at the LSA spec.
It is supposed to be set at the specified Intake Center Line which is different.

The cam card that came with the cam wants you to use the .050” duration method.
All the .050” duration points are on that sheet including the ICL.

Can you post a picture of the cam card/ page that came with the camshaft.

 

[drag-200stang]

Could be the sprockets, could be the cam or it could be both. That is why we say you must always degree the small six, this is common. Mr. Muller will get you right.

 

[clochard68]

@pmuller9 I didn't get a cam card with this cam, I did get one with my Isky 262 that I sold already.

I will ask Isky again to send me the cam card.

 

[pmuller9]

Which Isky cam is it?

 

[clochard68]

Isky Mile-A-Mor 321M

Mile-A-Mor Cam [321M] - $344.00 : ISKY Racing Cams, Do It Right

ISKY Racing Cams Mile-A-Mor Cam [321M] - Mile-A-Mor Cam Hyd. Valve Lift Int/Ext. 0.415 Valve Lash Hot Int/Ext. 0.000 ADV Duration Int/Ext. 248 0.050 Duration Int/Ext. 194 Lobe Center 109

iskycams.com

BUT as I confirmed with Isky, not on LSA 109 but actually on LSA 108!

 

[CNC-Dude]

The cams LSA is not changed by advancing or retarding the camshaft. It is fixed, and can only be changed by regrinding it. pmuller is speaking of the intake or exhaust opening events that can be changed by advancing or retarding the camshaft by using offset bushings or offset keys or any other methods that can be employed to move the alignment of the timing set without moving the crank or cam.

 

[clochard68]

The cams LSA is not changed by advancing or retarding the camshaft. It is fixed, and can only be changed by regrinding it. pmuller is speaking of the intake or exhaust opening events that can be changed by advancing or retarding the camshaft by using offset bushings or offset keys or any other methods that can be employed to move the alignment of the timing set without moving the crank or cam.

Yes I am aware that the LSA can not be altered.

I was in contact with Paul and he suggested to degree the cam straight up, so no retard or advance.
Therefore I thought, if I don't retard or advance the cam, the intake centerline should be exactly the LSA specified for that camshaft.



The camshaft has 108 marked on it, and according to Isky that should be the LSA for straight up (but on their homepage it says LSA 109, they were surprised about that, but it still says LSA 109 on their hompage...). The 0 should indicate that the camshaft has no advance or retard ground into it.

 

[pmuller9]

I forgot that the decision was to install the cam straight up.
In that case it should be ok where it is.
You need to check the exhaust center line also to verify the LSA.

 

[drag-200stang]

If you do not have the open and close events on the intake and exhaust, and check them, how would you ever know what you really have? Maybee that is the idea! I would check total lift at lobe also and would be nice to check at valve when all done later.

 

[clochard68]

I checked total lift, the lift is correct according to the specifications on the homepage.

Isky said the tech department will be reachable in 90 minutes, so I have to wait some more till I get my cam card...

 

[pmuller9]

To check the cam .050” intake duration and timing do the following.
Zero the dial indicator when the lifter is all the way down.
As you turn the crank clockwise the lifter will rise. 050” at 11degrees ATDC. As you continue clockwise the max lobe lift should be .259”.
Continue clockwise till the lifter is .050” from the bottom which should be at 25 degrees ABDC

The exhaust lobe will open .050” at 25 degrees BBDC and close at 11 degrees BTDC

This is the specs with the cam straight up.
The cam card will show all 4 points shifted 4 degrees for a 4 degree advance.

 

[clochard68]

@pmuller9 I checked now a few times:

Exhaust opens and closes exactly as you stated.

But the intake opens at 14 ABDC (too late) but closes at 25 ABDC as it should.

So I guess the intake ramp starts a little later, but intake center line is more or less correct

 

[pmuller9]

Nice work!
That’s about as close as you’re gonna get.

 

[pmuller9]

Just as a note concerning the Isky cam being 8 degrees off.
The Isky cam is specified on the cam card to be installed with the intake lobe center at 104 degrees so it was only 4 degrees off and the other 4 degrees can be in the timing chain set.

 

[frozenrabbit]

Maybe a dumb question, but........ there are so many threads about degreeing cams, why are the not manufactured to be correct at stock cam/crank gear alignment?

 

[drag-200stang]

Maybe a dumb question, but........ there are so many threads about degreeing cams, why are the not manufactured to be correct at stock cam/crank gear alignment?

They think that they are making them right.

 

[comet6]

There are 3 versions of timing set, some cams have advance ground in, and there are stack up of tolerances. Crank key to journal, crank gear, cam gear, chain, slack all have the potential to stack up or cancel out several degrees even if everything was "right".

 

[78_200_C4]

Maybe a dumb question, but........ there are so many threads about degreeing cams, why are the not manufactured to be correct at stock cam/crank gear alignment?

Another question could be how much is say 4degrees either way going to effect the power band up or down on a log head six.
I read that the grinding of the most popular on shelf aftermarket cams are farmed out.
The stock Enginetech 256 large log cam and the 260 Comp Cam that I bought had the same casting numbers.
The 260 Comp Cam that I sent back had .006 base circle run out.
The RockAuto Enginetech 256 cam had zero base circle run out.
I can wind my 78 200 to 5,000+ rpm with the stock cam, original valve springs and a non adjustable timing chain set.
I did install the Comp Cam lifters and timing set. I got a refund on the Comp cam.

 

[alwill923]

On my 240 with a Schneider roller cam and metal timing gears I had to go a whole tooth off to get it right. Why I do not know. maybe they put the dot in the wrong place. I would think it is in the gears before the cam but who knows.