Dave1980

I purchased Comps 4796 kit to degree my camshaft. This kit is really made to use with the heads on the car. I have my engine on a stand right now and will try to do it with the heads off if possible.

I noticed the dial indicator stand threads into the valve cover bolt holes only.

It seems really awkward to get the dial indicator perpendicular to the lifter surface from where this stand bolts up. ( I am assuming that this kit was designed for the valve cover bolts not to be in a central location)

1. So those that have used this kit how did you do it?

I would think it would be easier to bolt into one of the head bolt areas (with the heads off) with some sort of adapter.

2. I also want to know if you have to use a solid lifter to degree correctly. I noticed in the comp cams included video, (from 1989 LOL) they used a solid lifter. Why? I wouldn't think the pressure is there to push the plunger.

quickSS

Might borrow or buy a magnetic base or fabricate some sort of plate to bolt into the head bolts and then bolt your dial indicator stand onto.

I don't know about using a hydraulic lifter. Possibly it won't deflect but if it does then stick a small bolt or glue a dime or penny on top of the lifter which will give a solid surface for the dial indicator probe. A solid roller lifter makes it easy but if you don't have that I'm sure you'll be able to cobble up something to put in top of your hydraulic lifter.

Karl Ellwein

rskrause

It doesn't have to be exactly perpendicular. You are just looking for the same reading on either side of max lift to establish the lobe center line. Get a magnetic base to use with your dial indicator.

Rich

Dave1980

Ok got the magnetic base but running into keeping the degree wheel attached while the hub is off. ( I am using washers and crank bolt.) I am thinking that I am going to need something else to keep the wheel attached accurately and secure.


Also I do not have a piston stop for the bare shortblock, but for when the heads are on. It seems that some use the dial indicator to find TDC. Has anybody found TDC this way?

bowtieman_racin

You can use a dial indicator to find tdc. Just make sure that you bring the piston up in both directions of rotation. This will make sure you get the same reading both ways. If not you take the two readings and tdc will be exactly between the two. It shouldnt be off more tha .001 or so either way though.

As for the degree wheel I use an older sbc hub and balancer and bolt the wheel on with the three bolts that hold the balancer on. Doing this will make sure the wheel never moves from where you set tdc on the crank. you'll never get a true reading just using the crank bolt to hold it on

Dave1980

Ok people tell me if I am getting this right.

I used a piston stop with the heads off. I rotated clockwise till the piston contacted the piston stop. At this point I adjusted the degree wheel independent of the crank and aligned it to 0 with the pointer.

After this I rotated the engine counter clockwise till it stopped again on the piston stop. I took the reading on the wheel and split the difference from 0 to the now newly arrived #. I then re adjusted the wheel to true TDC at this point.

I then setup my dial indicator with the mag base and found max lift on the #1 intake lobe. I then 0'd my dial indicator. I rotated the crank counterclockwise down from max lift past .050 and then back clockwise to .050 and then took a reading on the wheel.

I continued to rotate clockwise past max lift and then back down to .050 then took a reading.

I added the 2 readings up at this point and then divided by 2. I came up with a # that was 3.25 degrees higher then the card spec on the cam card. I did this process over X3 and was within one degree.

So the question should I adjust this accordingly? Doesnt comp have 3 degrees advanced ground into the cam? If that is the case is it 3 past what is on the cam card?

Lastly I have a keyed crank set since I am going EWP that could adjust this if necessary.

I am looking for opinions and advice and possibly other ways to measure this, to make sure I am dead on.

EDIT: this is what I read on comps page about the final #, compared to what your cam is ground on and how it is affected.


Keep in mind that to advance the cam, you must lower the intake centerline. For example, if our cam
has a lobe separation of 110 degrees. Moving the centerline to 106 degrees advances the cam 4
degrees. If we change the centerline to 112 degrees, this would be 2 degrees retarded.

So since my final calc reading is 3.25 degrees higher than my cards centerline, does that mean that my cam does not have enough advancement??

bowtieman_racin

Well I'm for sure no expert but have done it a handfull of times.
Are you saying your coming up with the readings within 1 degree of the 3.25 that you were off? Or are you saying your getting within 1 degree of what it should be? I dont believe the 3 degrees that may be ground in the cam would affect you matching your readings to the cam card they should be dead on. My 847 cam had 4 degrees ground in and still the specs came out to match the cam card.

If your within 1 degree of the cam card then you may just run it like that and it will be fine. But if your looking for every last horsepower then you'll want to know that your readings are precise before you decide on what keyway or cam bushing to get. I've been really lucky with lt1's so far and they have all been dead on or within one degree. But I've never tried degreeing one with the sloppy stock chain I always use double roller or lt4 style.

I worry about degreeing an lt1 due to some people saying that a keyway or bushing throws the computer out for the opti timing. if anyone has real truth to wether degreeing messes anything up as far as the opti or computer please chime in. Also which is better for an lt1 keyway or bushing

Another way to degree the cam which is find tdc then max. follow your cam card and see what duration you have at .50 readings and if they match your wheel reading at the .50 lift numbers intake and exhaust then the cam is right on also. If they are both off the exact number of degrees then that will tell you how much it needs advanced or retard.

good luck

Dave1980

Basicly I did it 3 times and got 3.25 degrees above my intake centerline on my card. BTW I am using a Progear.

Dave1980

I am going to redo all of this. I read on crane cams website that Intake centerline method sux, because you can be dealing with non symmetrical lobes. So I will be going back and taking degree wheel readings at .050 and comparing those to the card.

So here is the rundown on the new way to verify.

1. make sure the lifter is on the base circle. (of course 0 out the indicator here)

2. rotate engine and take wheel reading at .050

3. continue to rotate engine , and take note of max lobe lift.

4. take degree wheel reading at .050 on the descending part of lobe.

5. verify that the dial indicator has gone back to 0.

At this point I should have 3 figures to compare to the card.
Intake open at XXX before TDC@.050
Intake close at XXX before ABDC @.050
And a max lobe lift reading for reference. (even though theoretical)

Do I have this down or what???? Sorry for the all the ????'s but I have never done this before.

bowtieman_racin

Sounds like you got it. Just have to be sure you know you're exactly on the tdc location. Also make sure your taking readings going in both directions to be sure they are pretty much or exactly the same.

Jazsun

Do you always have to degree a cam? On shoebox's site where it talks about installing a cam he has you line up the markings on the cam and crank sprocket..Why is degreeing necessary?

I'm not saying you shouldnt do it or anything, I'm just curious cuz some people don't do it....

Dave1980

It ensures accuracy of the cam and that none of your parts tolerances throw off your cams proper adjustment.
I am doing it because I am being a freak about making sure this is done right


Yeah I am rotating clockwise till piston stops on my fabbed piston stop. I am then re setting the wheel to 0 on the pointer. Then I rotate counterclockwise till it hits the stop and take the reading and then split it by 2. This puts me at TDC and I re-adjust the wheel to read 0 or TDC.

bowtieman_racin

sounds good, once you have that tdc dead nuts just make sure the pointer and the degree wheel never move from where you have them set. Then go through the whole .50" intake and exhaust along with max lift comparing to your cam card 10 times if you have to just to make sure you get repeating numbers. Also wouldnt hurt to check these numbers in both directions too just to be sure nothing is moving on you.

Its kind of a tiresome job sometimes but in the end you'll know that your cam is dead nuts on and have a little more security in your engines performance.

I still hope someone chimes in on what is the best way to change an lt1 whether it be a keyway or offset cam bushing, and the effects on computer and opti.

shoebox

Lining up the marks phases the cam to the crank. It does not degree it. Some degree theirs, some don't. It boils down to how particular or trusting of the cam you are.

Javier97Z28

I found the past two cam installations I have done to be off. Whether it be the timing set, or the cams I don't know.

So that being said I correct them a max of 2* with an offset crank key. If they're off anymore than that I would look into other options.