Cam Gear Locking Tool for quick belt changes

I just posted some of this to another thread, but it belongs here with the other cam lock info:


TIP:
CAM LOCK TOOL IS ALSO A CAM TIMING CHECK TOOL:
In addition to locking the cams, the current versions of the Unobtainium Supply 2V Cam locking tool can be used the same way as the Ferrari 2V cam timing verification tool.

The 2V cam lock has a pair of marks on the uper 1/2 of the tool are designed to match up with the factory timing mark on the flat spot on the back of the cam gear mounting flange.

The cam marks may not be perfectly aligned with the tool, but both cam marks should be very close to the tool's marks, and should off in the same direction by the same amount. If the cam marks are off by different amounts, then one of the cams is miss-timed.

I've tried doing this check just using a strip of belt, but fond that it could look tight, but would have flexed just enough so that the timing could still be off.

ANOTHER TIP:
CAM GEAR TIMING TOOL:
Take about a 6" strip of cam belt & glue it to 6" strip of 1/8" x 1" steel or Al using contact or trim cement.

This gives you a tool to use to verify that the cam gears are exactly timed relative to each other. Just lay it across the top of the 2 cam gears. The teeth in the cam gears must exactly fit into tool's teeth, or one of the cam gears is out of position.

If you don't use the cam locks, This tool can makes a big difference when trying to get the belt on. Also, if one of the gears has shifted on you, it can be used to re-time the gears against each other.

You could also make a longer version of this tool to check the cam drive gear's timing against the cam gear it's directly connected to.

 

The QV uses the same cam gears as the 2V 308s, have the cam spacing somewhere.

This looks very similar to my prototype QV tool pictured earlier in this thread. My QV tool is curved to match the cam gear profile, & I glued strips of rubber to the surface to ensure it distributed the clamping force across as many teeth as possible. I had 2 concerns: Spreading the force ensured that it wouldn't crack plastic cam gears, & I wanted my tool to be usable to hold the cams while breaking the cam gear bolts loose.

It doesn't look like your tool is curved to match the the cam gears. If it isn't, then all the holding force is going to be on 1 or 2 teeth. Probably OK for belt changes, but I wouldn't recommend using it for breaking the cam gear bolt loose, especially with the plastic cam gears.

Also, if it's going to be used with the plastic cam gears, be careful & don't tighten it enough to crack them.

 

I've had some questions about how to use the 2V cam lock to check timing w/o pulling the cam covers as I mentioned in my earlier post #78 of this thread. Hopefully the attached pictures will help.

The 1st & 2nd pictures show a 2V cam lock and the timing marks. I use a small carbide end mill to cut the the marks into the tool, next highlight them with black and finally clearcoat on top them to ensure they're permanent. The marks are very precisely spaced.

In case you're wondering, The large OD recess in the front of the cam lock is to clear the hex flange on the newer 2V cams. This particular tool has the timing marks on both sides as I marked the clearance hole side by mistake(DUH).

First, verify that your cam has the timing marks on the cam gear mounting flange. The earlier carb'd cars don't have them, but the 2V injected cars do. They're pretty faint, can easily be mistaken for a small nick on the flange's edge (See 3rd picture).Highlighting with yellow china marker helps make them visable (See 4th picture).

It takes a good light & a sharp eye, to look down into the narrow gap between the back of the cam gear & the cam lock. However, as the last picture shows, you can see how well the marks on the cam align with the ones on the tool.

The mark1 eyeball is sufficient, but A digital camera with good MACRO capabilities can be handy as it can see into the gap and magnify the results. This particular tool has the marks on both sides as I forgot that they go on the side opposite the flange(DUH)...
Image Unavailable, Please Login
Image Unavailable, Please Login
Image Unavailable, Please Login
Image Unavailable, Please Login
Image Unavailable, Please Login

 

AMA128,
Wood or a high density polyurethane, delrin, or nylon plastic will work fine if you're just changing the belt. I'd recommend maple, it's hard, tough, & doesn't tend to split. Altho you could probably get by with oak.

Wouldn't use a softwood as you can crush teethmarks into it, then you're stuck with whatever alignment it's taken a set to.


But, If you want 2x for <100, then you're going to have to make your own. Plan on it taking a couple of hours or so to do a clean job that conforms to the outlines of the cam gears.

I've got the 328/QV tool on my list, but it's behind a couple of other products. I want a design that will hold the cam gears in place while adjusting the pulley's timing, so don't a design that just clamps on the pulleys.

 

Stevenofkansa,
Yes, the pix were taken during a belt change. Was just trying to illustrate how it worked.

You can use the tool w/o pulling the belt cover by just using the long section.

However, you definitely want to do the checks when doing the belt change as well.

 

There is no factory tool for changing the belts in place. The WSM does not show one, and I have a list of tools from Ferrari that doesn't include one.

The factory dealerships & most independent shops always pull the cam covers, then they have a lot of options for holding the cams in place. They pull the covers because they usually don't know the car's service history & don't trust the cam timing.

Each shop that I've talked to has come up with something different to hold the cams. It ranges from nothing to something they've machined up to just using a pair of vicegrips, 1/cam with the handles duct taped together.

While as robertgarvin says, you can change the 2V belts w/o a tool, and I've done it several times, it's a lot easier and faster with the tool. The tool comes in really handy if you need to re-time the cam gears to the cams.

Birdman & I came up with the tool while fighting with one of his cams that kept wanting to move on us. It was about 15F in the garage & we were getting tired of fighting with the cams & belts. We literally grabbed a couple of pieces of scrap wood & roughed a tool out. It didn't fit very well on the cams, and didn't grab more than a small piece of the surface, but it kept us from continuing to freeze our fingers & toes off.

People heard of it & started PMing me asking for them, so I decided to make a well thought-out & precision drilled tool that also could provide an alignment check.

I use a drill press with a 2-axis digital readout to position the drills for the cam centers to within +/- 0.01". The hole for the cam is made with a forstner bit that I ground on my lathe to be a tight fit on the cam's cast surface + an allowance for drill positioning.



The alignment check cannot be done w/o this tool.

 

Scott,
BEEN THERE

My 1st cam lock design was that way. I prototyped it with wooden blocks contoured to fit the cam gears & strips of used belt glued to them. Tried them once & tossed the idea.

Here's why:

PROBLEM WITH SIMPLE Q&D BELT SWAP:
If all you're doing is a belt change you just want the tool to preserve the current system timing. So you want to install the tool while the old belts are on.

FACT:
When the cams are locked in place, you can't install the new belt w/o rotating the engine a few degrees to adjust belt slack so the new belt will slide into place. Sometimes you have to rotate the engine just to get the old belt off. This is especially noticable on the 4V engines with their shorter belts & closer cam gear spacing.

Consider a toothed tool that forces the gears into rotational alignment with the tool. This alignment is not necessarily the alignment the gears will have when the flywheel is on TDC. If it isn't, then you'll have to rotate the engine off of TDC in order to install the tool with the old belt on. Worst case would be rotating the cams half a tooth spacing to fit the tool!!!!

Once the tool is installed, you have the cams locked in place & timed against each other. BUT, the flywheel is now off of TDC by as much half a cam gear tooth spacing translated into flywheel rotation.

You'll then have to carefully mark the flywheel so you can return it to that exact position. It isn't easy to put a precisely located fine alignment mark on the flywheel at an arbitrary position.

You rotate the engine off the marked position to install the new belt (often just to remove the old belt). You then want to rotate the crank back to the marked position to verify that the new belt isn't off a tooth on the timing drive.

A toothed tool that can be adjusted to simply conform to the current spacing would overcome this problem, and I've worked out several buildable concepts.

TOOTH AREN'T NEEDED:
The tool doesnt need teeth provided you can install the tool & tighten it against the cam gears with the old belt in place. The old belt will provide the necessary timing. Not only that, you can preserve the position of the cams when they're timed against the drive system with the engine on TDC.

The rough QV tool I made while servicing JWise's car just pressed on the gears enough to hold them in place. We were just doing a belt replacement. We trusted the current timing because we'd previously timed the system and knew it was spot on.

TOOTHED TOOL UNDESIRABLE FOR CHANGING CAM GEAR-CAM TIMING:
You've worked hard to degree in your cams with a dial indicator & have got them just where you want them.

Then you discover that you need to re-pin the cam gears to time the the new cam positions against the cam drive gear.

You do NOT want to go moving those carefully timed cams, you want to lock them in place & adjust the cam gear positions against them as necessary to properly time the system.

The above scenarios are what led me to focus on designs that lock the cams instead of the cam gears.

 

Starting a few weeks ago, the 2V cam locks now have a couple of design changes suggested by several customers:

1. The side of the cam tool with alignment marks is now sprayed with a clear coat, rathar than just putting a strip of clear over the marks.

2. The clamping bolts are now M6x1 rather than 1/4-20., so you can use a 10mm wrench
to tighten them.

I've been looking for a suitable M6x1 threaded inserts for quite some time, but hadn't found any I really liked. I have finally found a source in England of steel inserts that are essentially metric versions of the inserts I've been using for several years!

Also, I have begun using my new LittleMachineShop SX3L mill with a 2-axis digital readout to position the drills for the cam centers to within +/- 0.005 mm. The holes for the cam are still being made with the forstner bit that I ground on my lathe to be a snug fit on the cam's, with a clearance for the hex boss on the later 2V cams.