C4-Wolf

I'm getting a 102 intake center right now which just seems to early. What can I do to knock it back to about 108?
Thanks

C4-Wolf

Is there some place I can buy offset cam sprocket keys?

BBA

I would make sure the timing chain is in the correct position.

6º is a lot for a cam to be off by. Something is not right...and you should not have to resort to this kind of effort to get it right. Most offset pins allow 2º and 4º changes, either way from straight up...6º is a little much.

bjankuski

You can buy bushings to mave the cam anywhere from 1 degree to 9 degrees, you can also buy timing chains that have keyways at -4, 0, +4 degrees. These parts will allow you to get the 108 intake centerline. It is very unusual for the cam to be off by 6 degrees, are you sure you checked it correctly. With the ZZ-X cam you have to use the .020 down (from peak) method to check for intake centerline not .050 up (from bottom) method. Find your max lift, rotate the engine until you have .020 down from peak and record the degree number. Do this for both sides of the cam lift and then find the center of those numbers, that will be your intake centerline.

EricVonHa

When using the 20 down method, be sure to rotate the motor a full 360 degrees to take out any reversal slack of the timing chain and also to make sure that the lifter travels as intended...

C4-Wolf

I've been using the 50 down method so I think my measurements are fairly accurate. I read a post in the review section on the ZZX, and the person who posted said his was ground to a 99 degree centerline, so maybe these cams are quite a bit off?
My timing chain appears to be in good condition, it only has about 12k miles on it.
Even at TDC you can see how advanced the intake lifter is. It is about 1/16" higher than the exhaust lifter.
Maybe I am not degreeing correctly? I have the D.S. head off, so I found TDC with the dial indicator. Lined up the two dots on the sprockets. Started cranking clockwise untill max lift is seen on the lifter. Set dial to 0. Backed up about 30 degrees then cranked clockwise (there was no slack at this point) again to .05 before max lift. Comes at 88 degrees. Went past max lift to .050 down the closing side. Happens to be at 115 degrees. 115+88=203 203/2=101.5.
I will recheck my TDC and then try .020 down today, but I don't think this will make up 6 degrees.
Any suggestions?

JAKE

I know I'm gonna get some disagreements with this, but here goes anyway.

Don't use a dial indicator to find TDC!

Why? Because of the dwell time the piston is at TDC.

The piston will actually remain at TDC for a few degrees without moving while the crank does, and a dial indicator can't detect this.

Use the positive stop method. It's fool-proof and will establish exactly where the center/middle point of TDC is.

Also, don't use the lobe centerline method if your cam has assymetrical ramps. If the opening and closing sides of the intake lobe aren't the same, and most aren't these days, use the .050 tapped lift method.

The best way is to take your reading directly off the lobe and not use the pushrod or long magnetic base extensions. Parallex error creeps in if the pushrod.extension is not perfectly straight.

99 ain't right. Something is definitely wrong. What is the LSA of the cam? I'm betting it somewhere in the 110/114 range, which means, if the lobes are symmetrical, it should go in around 106 to 110 using the LCL method.

Before you try moving the cam, you must accurately determine where it is. Finding absolute TDC is critical because this has the greatest effect on accuracy. You've GOT to hit it dead on. The Lobe centerline method is sort of an average, so being off a degree or two doesn't have as dramatic an effect.

You can make a positive stop to find TDC out of a scrap piece of metal; drill three holds in it (two to match up with head bolt holes in the block and the third to screw in a bolt and nut to use as a piston stop) really easy to make too. Just make sure the scrap metal is rigid enough not to deflect easily.

If you don't have the cam card, call the company and get the numbers. Then put them up and I'll try to help further.

Jake




[Modified by JAKE, 12:27 PM 4/3/2002]

CFI-EFI

Jake,
You have saved me a bunch of agonizing typing. My blood pressure jumped about 20 points when I read:
Thank you.


[Modified by CFI-EFI, 12:45 PM 4/3/2002]

C4-Wolf

Thanks, I'll look into really getting a good TDC. I have a piston stop, I just don't have the head on right now as I was planning on doing a clay test. I guess I'll bolt it on tonight and give it a shot. Hopefully that's the problem. Thing is, if thats it that would mean I was 12 degrees off TDC on the crank to get 6 degrees off on the cam right? Maybe my math is not right.
I'll be back with my findings in a few hours.
Thanks again

JAKE

Actually, I always find TDC with the head OFF. I have a TDC stop that bolts across the #1 hole with a short 3/8" bolt that extends into the cylinder. As the piston is hand cranked to a point that it touches the bolt, I take a degree reading from my degree wheel. Then going in the opposite direction I again bring the piston up to a point that it again touches the piston and take another reading..

The readings should be exactly the same. The actual number doesn't matter, and will vary depending on how far the bolt extends into the cylinder. Just as long as both readings are the same on each side of ZERO.

If you want a step by step, let me know.

Jake

LPDesRoche

I have also heard and experienced TPIS cams being ground way off. I had bad problems with a ZZ-9 one time, can't remember how far it was off. I know of a fwe others who have had the same problem with their cams.

An adjustable timing set should get you where you need to be. Cloyes makes a nice double roller that has the keyways for a few changes.

JAKE

Excellent point.

I put up a post on another thread recently about the same thing with the ZZ9 cam. Now I'm told that Crane does their stuff, but if so, it doesn't seem like Cranes usual high quality control is at work here.

I had mine checked on a computerized cam checker at Dennis Wells' Racing and found that I'd been shorted 3.8 degrees of intake duration @ .050 and 1/2 degree on the exhaust.

I've got the complete printout on the cam if anyone's interested in seeing it.

Jake

C4-Wolf

Thanks for the help Jake. I'l just throw the head on with a few bolts and that should hold the piston stop alright. Though it would be nice to have one that I could use with the head off.
I bought got my cam used so it is probably predates crane making them though I don't know when that started. So I'm not surprised it's off as I have heard people complain about TPIS cams being off before.
Right now I just hope I screwed up getting TDC, that could end this whole mess.

JAKE

Are you using the type that screws into the spark plug hole?

Jake

C4-Wolf

Yes I am using a sparkplug type of stop.

I just got done rechecking TDC and it was off a little. About 1-1.5 degrees. So now my intake lobe center is at 103.5 and my exhaust lobe center is at 115.5

What Now????

JAKE

Something's still not right.

If the cam is ground with 110 LSA, then 103.5 means the cam is 6.5 degrees advanced - 103.5 + 6.5 = 110. This should change the exhaust to 116.5 - 110 + 6.5 = 116.5.

If you're using the Lobe CenterLine Method, it could be that the lobes' ramps are asymmetrical. If that's the case, TPIS recommends using .020 instead of .050.

With asymmetrical lobes I shoot for the .050 closing point spec and let the remainder of the events fall where they may. In many cases you will never be able to get all four events to hit right on the exact degree the card shows, and since the intake closing point is the most important of the four events, I hit the intake closing point dead on.

Can you post the cam specs off the cam card?

Jake

JAKE

Here's what I'd do:

Remove the driver's side head.

Bring the #1 piston up to TDC ON THE COMPRESSION STROKE as close to being exact as I can make it.

Install the degree wheel and pointer and adjust the pointer to point at ZERO

Install the flexplate/flywheel bolts a few turns, but leave them sticking out to allow the use of a long screwdriver of bar to wedge between two of them, this is how we'll be turning the engine from now on (If you have one of the special attachments that screw on the the degree wheel, it will work a lot better)

Using a pry bar and the flexplate bolts, turn the engine so the #1 piston drops enough so the positive stop indicator can be bolted on across the #1 hole

Install the positive stop indicator across the #1 cylinder bore

Now, working from the back of the engine using the bar/screwdriver, turn the engine in one direction until the piston contacts the positive stop - TAKE A DEGREE WHEEL READING

Now, turn the engine in the opposite , again from the back, until the piston drops all the way down then rises to again contact the positive stop. TAKE YOUR SECOND DEGREE WHEEL READING.

If you were lucky when estimating TDC, the two degree wheel readings will match; if not you need to adjust the pointer. If one reading is 18 and the other is 20, move the pointer to point to 19. If one's 40 and the other 30, move the pointer to 35. What we want is for the pointer to point at the exact same number on each side of ZERO.

Now do this all over again a couple of times to make sure your can repeatedly get the same reading as the piston touches the positive stop.

Trying to turn the engine from the front without having the special adapter will almost always result in error. You'll either bump the pointer out of position or the degree wheel will move without the crank moving.

At this point you will have exactly found TDC for #1. Neither the degree wheel or pointer can be moved from this point on or you'll have to do this all over again.

Now, from the back of the engine, turn the engine enough to allow removal of the positive stop.

Now you install your dial indicator. I use the type that fits directly into the lifter bore, eliminating the need for a magnetic base, extension or pushrods. It's much more accurate.

You now find the two points that are .050 on each side of max lift (or .020 for asymmetrical lobes, per TPIS' recommendation). If you are shooting for the intake closeing point @ .050 then you're working on the other end of the lobe.

If after all this you still get 103.5, you'll need to install a degree bushing in the retard position. Depending on where you want to phase it, you choose the bushing that will get the cam there. A 110 cam usually goes in at 106, meaning you'll need to install a 3 degree bushing for a final 106.5 or a 2 degree bushing for 105.5. What does the cam card recommend?

You'll need a bushing kit (Mr. Gasket, etc.) which comes in even or odd numbers - 0,2,4,6,8 and the other kit is 0,1,3,5,7. You'll also need a 13/32" drill bit to drill out the cam gear dowel hole. You'll need a locking plate too in order to prevent the bushing from coming loose and to secure the three bolts in place.

To install the busing in the retard position you'll need to turn the cam counter-clockwise; the hole in the bushing will be toward the 12 o'clock position.

Let me know how you make out.

Jake


[Modified by JAKE, 8:08 PM 4/4/2002]


[Modified by JAKE, 8:12 PM 4/4/2002]

C4-Wolf

Thanks for all the advice Jake.
I spent the entire day yesterday, and half of today doublechecking everything. The only thing I found so far is that when I double checked my TDC the first time I actually threw something off. I think I bent the pointer. That's why I got a 103.5 reading on the intake centerline. After many hours of doublechecking it's coming up again at 101 degrees.
I thought about getting an adjustable timing set, but since this cam is so radical and may not have worked well anyway, I think I'm going to just buy a different one. I have thought about cam bushings too, but at this point I'm kind of giving up. I may break out this cam later if I am running a larger cid motor.
The cam I think I'm going with is the comp cams 306 which is what the tech guys at comp cams said to use. I will degree this cam in so I will let you know how it goes. Maybe I am just doing something wrong, though for the life of me I can't figure out what. Thanks again for the advice. I have learned more about camshafts in the last four days than in the last four years.
Jeff

danno85

you can also get offset crankshaft keys that will alter the cam timing 4 degrees. They're available in Mr. Gasket brand (at least they used to be, I
haven't checked recently).

JAKE

Hey, Jeff.

If your sig shows the cam you're installing, the ZZX, yea, that's a plenty healthy cam, especially for a 350 CID engine.

If I remember correctly, that cam has 236 degrees @ .050 and if that's correct, I suspect you're gonna have vacuum brake problems with it, not to mention a pretty lumpy idle. A PROM reprogramming is going to be needed too, if you haven't had it done already. Idle speed in the PROM will need to be raised to about 850/900, and the other tables modified.

If you want to try one more thing to verify the phasing of the cam you're working with, try hitting the .050 tappet lift number.

Instead of using the lobe centerline method do this.

Find TDC as I outlined in my earlier post, and work only from the back of the engine to turn it - that way you won't inadverently disturb the degree wheel or pointer.

After getting accurate TDC, rotate the engine until the #1 intake lobe lifter is on the base circle.

(I forgot to mention this - no offense intended - but are you sure you're degreeing the intake lobe and not the exhaust? You know it's the second hole from the front, not the first one - I only mention it because a buddy of mine had the same problem and I found he had his dial indicator set on the exhaust lobe).

Anyway, after getting the #1 intake lifter on the base circle zero the dial indicator then rotate the engine clockwise (as viewed with you standing in front of the engine) until your dial indicator shows the lifter/lobe has risen .050. Take a reading. That should match the cam card .050 intake opening number within 1 degree. Remember we're looking for lifter rise, not valve lift.

Continue on turning the engine while watching the dial indicator. Lifter/lobe should go to full lift then begin to fall. At a point .050 before the lifter/lobe returns to the base circle, take another reading, this should correspond to the intake closing point on the cam card. Of the two, this one is the most important to nail.

I'm using .050 here because most cam cards I've seen have the timing measured and listed for that lift, but if your card has a different number, like .020, then use the number that's on the card. My cam card shows the following timing:
At .050
Intake Open 2 BTDC Intake Close 46 ABDC
Exhaust Open 49 BBDC Exhaust Close 1 ATDC
These numbers are correct for can installed straight up at 114 intake centerline. If the cam is installed at a different centerline, like 110, the numbers would be different. Check your card to see at what lift the #s are correct.

Valve lift is the result of the rocker ratio multiplied by the lobe lift, so .050 valve lift and .050 lobe lift aren't the same.

If you do decide to use a different cam, take a close look at CompCams 3100/3300 series lobes. Man, they are the cutting edge in technology. I just installed one in my engine last weekend and it's really sweet.

Those lobes are the most technologically advanced lobes yet designed for an engine that will be used on the street. They even have IFR/CRC ramp profiles: Inverted Flank Roller (Crane speak) Constant Radius of Curvature (CompCams speak).

I've sung the praises of these type ramps for many years after installing one in a 477 BB for a quarter miler friend a long time. I can't begin to describe how that cam changed the rev characteristics of his engine; engine revved so quickly and accelerated the car so well it was truely amazing. I was shocked! In fact, I've never made a cam change - and I've made more than I can count -that has had such a positive and dramatic effect on power and engine performance.

So I was really happy to see that CompCams now offers it in a hydraulic roller street version. I took out my ZZ9 and installed one with 3192/3315 lobes and had it ground on 114 lobe centers to broaden the torque curve and smooth out the idle. With 1.52/1.6 Pro Magnums it gives .576/.544 lift with 224/230 @ .050

Your duration needs may be different from mine, but just for the sake of comparison, look in any of your camshaft catalogs and see how many cams you can find that will give you .576 valve lift with a 1.52 rocker AND keep .050 duration at 224. I'll bet you won't find a single one until you cross over into the full race cam stuff.

These are not off the shelf grinds, but probably don't cost any more than off the shelf ones and only take a few days to make.

So, back to your situation: If you cam is ground on 110 (this is critical to know) and it's REALLY in at 101, then yours is 9 degrees advanced. Since 4 degrees advanced is usually the starting point to install a cam, 110 minus 4 is 106. So 106 minus 101 equals 5, so you'd need to use a 5 degree bushing installed in the retard position to put the cam at 106. This is where I'd install it, ground on 110 phased in at 106.

I agree with an earlier poster, it's not usual to see a cam off that much, not with today's quality control.

There are really only three ways to move a cam. Install a bushing in the cam gear, use an offset key (Woodruff key?) in the crank or use a timing chain set that had multiple keyways in the crank gear. I don't believe you can get 5 degrees with a Woodruff key or a multiple keyway crank gear; four is the most they offer I believe. So you're gonna have to buy a $10 set of bushings, a 13/32" drill bit and a locking plate.

101 will work, but it'll make the cam seem to have a lot less duration that it actually does. Bottom end will be sharper but you'll lose it up top.

Ain't screwin on these suckas fun!?

Keep me posted.

Jake