What caused this cam Gear damage?

[Gregs672000]

Per my understanding, what makes this even more difficult is that, every engine/cam grind is different, and what works good for one set up is not necessarily what's right for the next. I know mine was way off, but only the dyno and educated/systematic trial and error will determine what's the best cam timing for my engine. I may do that later this spring/summer. It will be on the same dyno I used for setting up the megajolt timing map and some jetting (at the time we didn't realize how messed up the cam was). So, the HP changes I expect to see will be directly related to improved cam timing.
In regards to your situation, I think however that on a stock engine that factory settings are a very good bet... Has worked well for me so far!

[svwilbur]

update: I have the adjustable cam gear ordered along with tensioner cover gasket, shim kit, tensioner lock, all from JT68 and from another vendor the tensioner gaskets and another non-related part, so hopefully that should cover what I need for this repair.

more updates next week on the install.

[Gregs672000]

Excited for you, good choice I think. I would love to see pics of your cam gear when it's out.

[svwilbur]

I will post some for you. I'm guessing it is some sort of home made adjustable as well. It seemed to have hand written degree marks on it..

[svwilbur]

I received my tensioner gaskets yesterday. I am hoping for my cam gear and other small parts today or thursday.


JT68 - you could start preparing me for my first steps anytime as I may have some questions about the steps.

like what position should I have the distributor, crankshaft pully, cam lobes and tensioner in prior to attempting to remove the existiing cam?

do you remove tensioner first before aligning those things?

if there is slack in the chain should it be on the drivers side, passengers side or split between both once things are alighned? the tensioner would normally put it all on passengers side. but when I first took off the valve cover for some reason it was very slack on drivers side (until I started turning the crank pully and the slack all disappeared? ) why was that?

what should I put down between the chain to keep the chain up and on the jackshaft gears below and small parts from dropping down into the motor? rags, paint sticks etc. will resting chain on the evil-l make the chain fell off the jackshaft gear?

those are some concerns I have or have been warned about.

JT some detailed instructions will be appreciated as I start to wonder about the correct way to mount your adjustable cam gear so I do t botch it up.

Thanks

[JT68]

Will do. I can step you through it all. At this point, don't remove anything other than spark plugs and valve cover. Lmk when the parts arrive and I'll be right back in touch//jt

[svwilbur]

"Lmk when the parts arrive and I'll be right back in touch//jtl"

JT, I got the cam gear today as expected. it was well packaged, no apparent shipping damage.

the spark plugs are out still and valve cover is off still from last week when I found the warn cam gear.

here are the parts pictures, ignore the temp sender (that is another project).

20160601_153428.jpg

20160601_155103.jpg

20160601_160515.jpg

20160601_154942.jpg

20160601_160601.jpg

[svwilbur]

the pictures seem to make the gear look rougher than it really is. I had not wiped it down. it had some packing debree and smuges on it that make it look like it has imperfections. it does not.

[AidanDawn2000]

Looks like a nice pice ( isn't coming home to fresh roadster parts just the best!) If you you have the valve cover off for a long time you might want to get some extra oil on the cam lobs.

[svwilbur]

I have some initial directions from JT.

I will probably start lining stuff up on the engine tomorrow morning.

I'm taking my time on this. I will post pictures as I go.

[svwilbur]

I am progressing through the install of the new cam gear following JT68's instructions. thanks a bunch JT!

I will post a step by step later upon completion so I and my son will know what I did and I can look back at it later and so others could get an idea on what is involved in changing it out to an adjustable hardened cam gear like what JT68 has had made up. see one of the above posts to see images of that new adjustable cam gear/sprocket.

I had some requests to show the old cam gear when I got it out. it is out now so here is a picture of the front below;

20160604_192703.jpg

and the rear that goes up against the cam flange.

20160604_192725.jpg

looking at it off, I can see the old unused holes that show wear marks from lock washers are larger holes than the ones that were in use when I took it off. it appears that they just bored new holes the size of the bolts and mounted it. had they used the larger holes I guess it could have provided a slight amount of adjustability, but those were not in use when I took it off as it used the smaller holes.

when the large timing mark on the crankshaft pulley is lined up with the pointer for TDC and the cam lobes are up at 10 and 2 (or there abouts) for cylinder #1 and the rotor points to #1 plug wire the cam alignment hole on the back of the cam flange was lined up with the arrow on the front capstand and the two cam sprocket bolts were at 9 and 3.

so it appears that it is equivalent to a stock cam sprocket. mounted the stock way and just had worn some in the teeth.

wear is more apparent here:

20160604_192739.jpg

20160604_192754.jpg

so there you have it. I'm not sure why they had additional holes other than they may have wanted them the size of the bolts or maybe this aftermarked gear was designed for use on two different vehicles that had different sized mounting holes in the cam flange?

odd that it shows some wear on the larger holes that were not in use. maybe who ever mounted it had used it on another vehicle. or used it on here with the large holes and later decided to redrill or use the smaller holes.

who knows, I dont really care now.

also I noticed that the evil-L in earlier pictures seems to be off center toward the passenger side. I am guessing it was bent a bit to help keep it from hitting the chain and wearing. the only apparent issue with it is that it made it harder to get access to the passenger side cam sprocket bolt as it blocks access some.

[JT68]

Thanks Stacey, best of luck with your project!

I think you are right regarding the L - they just bent it farther away from the chain since that right horizontal section is where it always contacts.

Personally, I prefer to remove it since as pointed out, it is no-big-deal to drop the chain in the front cover and just to tie a string to it or use a magnet to pull it back up. (Others do prefer to keep the L, so to each their own)

I suspect the re-drill on the sprocket was intended as a one-time, non-adjustable timing correction. It renders the timing mark and cam timing pointer on the #1 cam cap useless since they are no longer correct. In the trash it goes....

jt

[svwilbur]

Yup, Jim is once again correct!

"I suspect the re-drill on the sprocket was intended as a one-time, non-adjustable timing correction. It renders the timing mark and cam timing pointer on the #1 cam cap useless since they are no longer correct. In the trash it goes...."


I took a closer look at the old gear and where it was lined up when the crank pulley was on TDC and the distributor pointed to #1 and the cam lobes were up at 10 and 2ish. They apparently drilled some new holes to added in some advance for cam or sprocket. Looks like maybe 4 to 5 cam degrees difference as it appears by eyeing it that it is about 1/3 a tooth off. The red line is at 90 degrees to the red upright line. The blue upright line is at different angles to the big blue line. It is smaller than 90 degrees on one side and larger than 90 on the other.

Here is a picture showing that the old holes lined up with the teeth and the new holes are clockwise in rotation. They simply drilled holes and repositioned the gear and lined up the now "off center" new tooth to add in some angle. At least that is what it appears to me.

It does not really matter now as I have the new adjustable hardened gear from JT that is much easier to deal with. This old worn out gear is history.

[fj20spl311]

We knew that.

No other reason to redrill the holes.
The question is how many degrees are need to line up your cam with the JT gear?

[svwilbur]

We knew that.

No other reason to redrill the holes.
The question is how many degrees are need to line up your cam with the JT gear?

The answer to that would be "installation dependent".
Depends on how stretched your chain is, how warn your other gears are and the like.

For my installation I have not had lots of time to work on it yet. The gear is on but I need to do the final alignment. JT is helping me, I am the only slow one, JT has been very responsive to my questions.

The whole job would probably take someone that had done it before about and hour or two including re-shimming the tensioner. But since I have never done any of this cam, sprocket, tensioner stuff, I am going at a snails pace making sure I understand each step and don't screw up too badly. If you are not careful you could possibly get your cam misaligned or have it slip while the sprocket and chain and or tensioner is not on and slam a valve into a piston or something. Or if you misalign it and then start the engine it could bend valves and stuff as well I suppose.

So I am taking my time. Plus I have other projects in the works, house re-roofing and some part time work. So this is all dragging on because I am in no rush.

When I do get finished I will probably not have an absolute number of degrees since I do not have a good way to measure it. It will just be positioned differently than stock as a result of my stretched chain. The alignment holes may be slightly off center from each other a hundredth of an inch or so one way or the other. So presumably the Cam (cam flange pilot hole) "may" have to be advanced in relation to the sprocket pilot hole about 2 to 4 cam degrees. We will have to see how it turns out as the new sprocket is not worn like the old one so it took up some of the slack. I have the tensioner with more shims so the chain is not so loose with the engine not running. Hopefully it will help keep the chain from hitting the Evil-L as well.

So all those things may effect the required position of the new sprocket. The goal is to have the cam flange pilot hole at top where the arrow on the cam stand points to it dead center while the crank pulley is on the Largest timing mark DTC for cylinder #1, while the distributor rotor is pointing at #1 and the cam lobes for #1 are up at 10 and 2 and there is absolutely no slack in the drivers side of the chain as it should all be taken up be the tensioner and by me applying pressure between sprocket and crank pulley. All those 6 things have to be just right while holding the crank pulley in place and putting some back pressure on the cam sprocket so the chain has no slack and looking at the position of the cam flange pilot hole which needs to be adjusted to be right at the top center pointed to by the front cam stand arrow. (THAT IS NOT A "HOW TO", THAT IS JUST A GENERAL OVERVIEW OF WHAT IS INVOLVED).

Basically I am just trying to get the cam back to the stock alignment in relation to the Crank and rotor. As the chain stretches and cam sprocket wear they would normally be causing the cam to get retarded a little.

After that you can chose to play with it a little on a dyno or having someone use a cam angle sensor and TDC piston sensor and /or crank pulley sensor type of equipment to verify that they are all really lined up, I guess. I'm just going for close, like in hand grenades and horseshoes and hope for the best.