| Author | Message | ||
| Verell Boaen (Verell)
Member Username: Verell Post Number: 713 Registered: 5-2001 |
Paul (Pcelenta)- The plastic cam gears can be replaced with metal ones from a newer model. Nic's Forza Ferrari sells ones machined from billett. I'm pretty sure a couple of F*Chat or F*List members have had their own gears custom machined from billett also. Try searching the archives. | ||
| Henry D. Chin (Hanknum)
Junior Member Username: Hanknum Post Number: 125 Registered: 2-2002 |
Verell, I agree with you, it by no means makes sure that everything is timed correctly. It just is an easy way to replace timing belts without disturbing the existing timing (which is what I read into the original post). Marks can be made, but need to be made carefully. If possible, yes check the original marks and follow the service manual. Henry | ||
| Verell Boaen (Verell)
Member Username: Verell Post Number: 711 Registered: 5-2001 |
Henry, That trick can be made to work. I've successfully used it myself on a Dodge stealth 24Valve & it worked like a champ. It seems to be much harder to use it on a 3x8. Altho, RobertGarven has managed to pull it off a couple of times. Reasons it's hard to do on a 3x8 are: It's very hard to get a good set of marks on the belt due to the cam gear with an outer flange on on each bank, and the flanged drive gear. It's also very very easy to end up 1 tooth off & not spot it for the same reasons. Also, What many of us have learned the hard way is that the previous service was sloppily done & the cams were not properly aligned to start with. Transferring the marks will propagate the initial misalignment. Only way to verify alignment is to pull the cam covers & make sure the marks line up. The little metal arrows on the back of the cam cover aren't accurate enough either. Next time I'm going to see if I can't make a 3x8 specific cam gear locking tool. I have some ideas for 1 that would sell for $55-$65. | ||
| Henry D. Chin (Hanknum)
Junior Member Username: Hanknum Post Number: 123 Registered: 2-2002 |
A trick I've done is to get a marker and mark all the pulleys with a corresponding mark on the belt. Next remove old belt and match it up to the new belt. Now transfer the markings on the old belt onto the new belt. Install new belt lining up markings on the belt with the pulleys. | ||
| Verell Boaen (Verell)
Member Username: Verell Post Number: 709 Registered: 5-2001 |
The 308GT4 service manual has the best description. I use both it & the 308QV/328 service manuals. .PDF files are located at: http://ferrari.jenkins.org/books/ See Ric Rainbolt's write-up at: www.expensivecar.com clickon Ferrari, then online service manual, and finally cam belt replacement Also, check the archives for several long threads that I & others have written. There are a lot of little tips about sealing cam covers, avoiding pinching the o-rings, etc. One of these days I'm going to try to roll everything up into one procedure, get Ric, JRV, & others to review it. Meanwhile you'll have to assemble what's available for yourself. | ||
| Paul (Pcelenta)
Member Username: Pcelenta Post Number: 322 Registered: 7-2002 |
verrell, I still have the plastic gears on my 78 and they have always concerned me...what are the alternatives...can you just swap to a later one (which one?) | ||
| Paul Jeffery (Peajay)
New member Username: Peajay Post Number: 33 Registered: 4-2002 |
Yes I think you are correct, it is the pulley flanges that make this unworkable in this case. Where did you get the owners manual by the way? I presume you don't mean the one that comes with the car because that certainly does not have details showing timing marks etc. I have been looking for recommendations on a good manual but nobody seems to be able to help. Paul | ||
| Ken (Allyn)
Member Username: Allyn Post Number: 864 Registered: 10-2001 |
Just an observation: it's been stated the tensioners go before the belts do; you'll have a new belt on questionable tensioners. | ||
| Verell Boaen (Verell)
Member Username: Verell Post Number: 702 Registered: 5-2001 |
Paul, CLOSE BUT NO CIGAR... 0) The major show-stopper for this idea is the 1/4" high outer flange on one cam gear in each bank. The new belt is just too short to sit 'cocked' over it. In fact, It's a tight fit to slip the belt onto the inner flanged cam gear when you have belt in place on the cam gear w/the outer flange, the drive gear, & the tensioner retracted. 1) The next show-stopper is the older style plastic pulleys. They're getting pretty brittle/fragile. You can't cut the belt around a pulley w/o nicking the plastic & risking eventual pulley failure. Also, the flanges on these pulleys is extremely fragile(ask me how I know). 1) Rich is right on: The front bank intake cam wants to turn big time. With the engine on PM1-4, it's holding a pair of valves fully open. The front exhaust cam also wants to turn, but isn't so adamant about it. The rear bank cams stay in place. David, Where did you buy the cam gear locking tool for $40? I'll take 2 at that price! Snap-On gets $154.00 for the cam gear locking tool, and Baum tool asks even more: http://buy.snapon.com/catalog/pro_det.asp?P65=yes&qt=1&tool=all&catItem=true&INV_ONHAND=&FREIGHT=&qty=1&Item_id=57330&PartNo=ML4500&Price=154.95&ListPrice=154.95&FORMNAME=0&Desc=Tool%2C+Engine+Timing+%2F+Sprocket+Locking%2C+Universal&SUB_Cat_ID=1468384&SUB_Cat_NAME=Timing&Cat_ID=1468373&Cat_NAME=Engine+Service&group_id=1552&group_NAME=Timing&store=snapon-store&dir=catalog At $154, I think I'll make my own 3x8 specific tool. | ||
| David Moore (Speedmoore)
New member Username: Speedmoore Post Number: 30 Registered: 4-2003 |
I wouldn't cut the belt either. You can buy a universal overhead cam clamping tool from Snap-On or even via the web like Baum Tool which is universal and under $40. I had to modify mine to fit 355s on my bridgeport. But, you could also modify it by hand. The thing is adjustble and locks the cams in place by putting pressure on the cam sprockets. Simple and easy. However, I also did them for years on all F-cars with no tool at all. Cutting the belt is going to be way harder to do than you think and then it is probably going to be too stretched to slip a new one on anyhow. Just line up the marks like it shows in your owner's manual and you will be fine. | ||
| rich (Dino2400)
Junior Member Username: Dino2400 Post Number: 217 Registered: 10-2001 |
Do the 328s want to move when the belt is off? Most cars (old Fiats, new various) I've done can be put in place and nothing is going to really move while you are changing the belts so i just made note of where things are and go for it, checking to see they are still there before rotating the engine. Never really worried about it much. | ||
| Phil Good (Feelnotbad)
New member Username: Feelnotbad Post Number: 36 Registered: 1-2003 |
Agree with Peter. Would not recommend. | ||
| Peter Topman (Peter_topman)
New member Username: Peter_topman Post Number: 40 Registered: 8-2002 |
I don't think I would try this  | ||
| Steve Magnusson (91tr)
Intermediate Member Username: 91tr Post Number: 1757 Registered: 1-2001 |
Ditto what Craig said (you could lose a limb trying to cut a timing belt in half lengthwise!). Anyway, that "slip-on" method is only possible if all the outward flange(s) on the pullies can be removed (which I think is not the case on most, if not all, Fs) -- just an observation... | ||
| Paul Jeffery (Peajay)
New member Username: Peajay Post Number: 32 Registered: 4-2002 |
Yes I know what you mean, I think a compromise would be just to cut a portion from the belt at the three pulley positions, just enough to get the belt on then once engaged slice through the full belt and push the new one on. | ||
| Craig Dewey (Craigfl)
Member Username: Craigfl Post Number: 585 Registered: 1-2001 |
It sounds interesting but it may end up to be one of those deals where the "laborsaving" project turns into a major effort to figure out how to cut the belt in half. You may lose sight that the goal is just to put a new belt on which really isn't that hard of a job...(even if the cam slips and you need to realign it). | ||
| Paul Jeffery (Peajay)
New member Username: Peajay Post Number: 31 Registered: 4-2002 |
I just heard a clever trick used for changing cam belts, with the original belts in place. Using a sharp blade like a scalpel or X-acto knife cut lengthwise around the old belt at about half width. Cut the most outward half of the belt off and discard it. This leaves a half width original belt in place. I suppose you need to loosen the belt at this stage, because the next step is to slide the new belt into position up against the old half belt, it will only engage half of the width of course. Now at this point cut off the remaining half old belt and then fully slide on the new belt and re-tension. The beauty of this process of course is that the original timing is never lost. I am just about to change the belts on my 328 for the first time and this sounded like a very clever trick. Anyone ever tried this ??? |