3.0 QV or 3.2 Cam Pulley Lock Tool

I'm working on a timing belt/tensioner change on my 1984 Euro 308 GTS QV, it's been 6 years already since they were last done. At that time I did the full 30K major, and since I was taking the cams completely out to change seals and valve shims I didn't need to make any sort of locking tool for the cam pulleys at that time.

This time it's just the belts and tensioners, so I'll need to lock the cam pulleys from moving. I've seen the blocks of wood drilled for a bolt, but as I've been getting to learn a 3D printer for a while, I decided I should do some basic CAD work and make up a 3D printed equivalent of the scrap wood cam pulley tool!

TL;DR version - here's the file on Thingiverse: https://www.thingiverse.com/thing:4649593. You can download and print it yourself if you have a 3D printer. I used Taulman Bridge Nylon, but any rigid material should work. The only additional item is a 1/4"x3" bolt, nut, and a few washers. I know it's not metric, but it's the only bolt long enough that I had around the workshop. A single 11mm wrench fits just fine and is all that's needed to operate this tool! I wanted to share this with everyone here - I hope some of you will give this a try and find it useful.

NOTE - I'm pretty sure the cam pulley size and spacing on the 3.2 is the same as on the 3.0 QV engine and this tool should work on the 3.2; I know it's not the same on the 2V engines, so this particular iteration won't work on those.

Image Unavailable, Please Login

I'm just getting back in to drafting and design (old school mechanical engineering degree from 40 years ago), so I used the kiddie CAD program, TinkerCAD (www.tinkercad.com ) - really easy to pick up, and surprisingly capable with basic shapes.

(Side story) For practice, I designed my own Iron Ring (a Canadian Engineering tradition for nearly 100 years) in TinkerCAD, an Iron Ring is supposed to look like this:
Image Unavailable, Please Login
Every Canadian Engineer wears one on their dominant hand's pinky finger - you can read a bit about it on the Wikipedia page for Iron Ring: https://en.wikipedia.org/wiki/Iron_Ring

The design needed this assembly of objects to create the required facets on the ring:
Image Unavailable, Please Login

Merged together, and it comes out like this:
Image Unavailable, Please Login

I did print the ring in a few different materials, but I won't bother showing those, as the resolution of a home 3D printer isn't great for small objects that should have smooth finishes!

Practice CAD out of the way, the Cam Pulley lock tool started like this:
Image Unavailable, Please Login

Merge those objects to create the wedge with the appropriate curved sides, add a hole down the middle, replicate, then add a hex space at the top of one wedge, gives this print design:
Image Unavailable, Please Login

Print two sets so you can do both banks at the same time:
Image Unavailable, Please Login

Image Unavailable, Please Login

I had to add a few extra washers under the bottom nut, because the unthreaded length of the 3" bolt was a bit too long to tighten the lock wedges. It works!
Image Unavailable, Please Login

Placing the cam pulley lock tool in place - no wrench needed on the top side, just a single 11mm wrench needed on the bottom. They don't need to be tightened too hard to hold the cams stationary.

Image Unavailable, Please Login
Image Unavailable, Please Login

Image Unavailable, Please Login

I hope that's of some use to you guys who have a 3D printer at home.

Cheers,
Gordon

 

FWIW on my ‘82 308GTSi I use a hockey puck cut in half, flipped and used like an hour glass with a long bolt through it and a wing nut. Just saying.... works like a charm.....

 

Image Unavailable, Please Login

You can modify the puck to fit all 308/328.

 

Nice work, Gordon!

What would it take to modify your parts so to fit the 2V engine series?

P.S. My U.S. engineering school had an 'Order of the Engineer' service upon graduation, involving a smooth stainless steel pinky finger ring, which I've worn ever since. Many of my Canadian engineer friends have mistakenly assumed that I'm Canadian when they first see it.

 

Hi Wayne, I remember looking at a puck for this 7 years ago, and thinking that it wouldn't fit on a QV - I think the cam spacing is quite a big larger on the 2V engines. On the QV there isn't, or is just barely, room to squeeze a half puck under the top belt span between the pulleys.

Thanks Dave! From my rough notes when measuring, the gap between the closest points of the cam pulleys on the QV is ~10mm. If someone measured the gap between the 2V cam pulleys (closest points, ie tops of the teeth), then I could ungroup the objects, widen the centre block by the added distance between the pulleys, then re-group the objects to make a 2V version.

Cheers,
Gordon

 

Creative people thinks alike I have been using this home made locking tool for fourteen years now.

Image Unavailable, Please Login

 

Unobtainiium has been supplying a 4V camlock set for several years now:

Image Unavailable, Please Login
Image Unavailable, Please Login

Unlike hard plastic cam gears that can slip(been there). They are made from a very firm urethane rubber will compress slightly into the gear teeth thus ensuring the cams are truly locked in place. If you take a close look at the top picture you can see where the cam gear teeth are indented into the camlock.

Also, as you can see, the thru bolt is molded into the top piece which makes it easy to attach the lower piece.

Currently the 4V cam lock is on page 6 of our catalog. See: www.UnobtainiumSupply.com

These are made to order, usually ship 3 to 5 business days after payment is received.

My apologies: We announced this tool on Facebook & some other forums but it appears I failed to post it to FChaat.

 

That looks real ice Verell

 

Thanks for your comments, Verell, and I admit that even though I've gone through your offerings catalogue multiple times I've missed that item listing - otherwise I would have bought it from you!

Cheers,
Gordon

 

OK, then, might someone here have easy access to a 2V head and can thus provide the measurement that Gordon notes?

 

Gordon,
BTW, Your cam locks look pretty good. Obviously great minds think the same.
;-)

From the material you used I deduce you have a FDM 3d printer. I opted for an EPAX X1-DJ LCD printer so I could print mold patterns with very fine detail & precision. The patterns for the 4V CAMLOCKs were one of my first designs. & Yes, my CAD technique was pretty much the same as yours except I rounded the corners & added the logo.

BTW, Your cam locks look quite good. However, you really want to radius the top & bottom corners of your cam locks. Years ago I made a very similar set out of maple & a couple of times the sharp corners would snag a gear tooth & drag the cam out of alignment. If you take a look at one of the pix you posted you can see where the top corner of one of your locks is trying to grab a cam tooth.

 

Verell, yes, it's a Lulzbot TAZ 6 FDM printer, using 2.85mm filament.

I appreciate all the feedback, I've revised the design an re-printed it in polypropylene, which has enough 'give' in this shape to grip the cam pulleys nicely. I changed the sizes a bit, and embedded the text 'UPPER' and 'LOWER' in them to keep track. I had to give up the hex insert for the bolt head, the material isn't rigid enough to hold the bolt head from turning.

Image Unavailable, Please Login

Compared to the nylon version:
Image Unavailable, Please Login

Now in place on the cam pulleys:
Image Unavailable, Please Login

Image Unavailable, Please Login

I would have finished my timing belt and tensioner pulley change a couple of days ago if I'd just grabbed a couple of blocks of scrap wood and my jigsaw instead of messing around with these!

Gordon

 

Sounds good!

[QUOTE="GordonC] I ...embedded the text 'UPPER' and 'LOWER'
Gordon[/QUOTE]

Good idea! Wish I'd thought of that!

Now get going on your belt change

 

...... anyone?

 

Hello Dave,
If it would help, Unobtainium has been supplying these 2V cam locks since 2004.
Image Unavailable, Please Login
See:
https://www.ferrarichat.com/forum/threads/cam-gear-locking-tool-for-quick-belt-changes.40071/page-4#post-136366773

BTW, there's a picture of the prototype for my 4V cam locks in the same thread. Had totally forgotten about it.

 

I made a lock out of hardwood for my 308qv. I did superglue a thin strip of soft rubber/foam on the edges contacting the cam drive gears. It keeps them from moving with minimal pressure, as the rubber bites into the gear edges. Works perfectly and cost less than 2 bucks.