328 Timing Belt Change

No problem hijacking the thread with me, actually that's an interesting observation. It would make changing the t-belt a bit easier. Determining a safe position for all the pistons with the head on is not a problem. Remove all the spark plugs, put 4 equal length stiff plastic straws through the spark plugs holes, turn the crank until the top of the straws at equal height. I once had to do this during a rebuilt of another dual ohead cam 16v interference engine.

So back to the 328 t-belt, since I still have the "original" t-belts on, using this modified procedure i.e determined safe distance for all rear pistons,
mark the crank AND mark both cams to reflect this new position, change the belt using the rest of "original" procedure, repeat for the front bank.

The advantage would be a bit more "freedom" to muck with the crank/cams during the t-belt install process. Hum, let's think about this a bit more to see if any hole.

- Nguyen

 

Finally, covers of both belts are off. On the first combo images, note the two timing mark pointers on the back of the rear (there's a similar set for the front) bank tbelt cover. The bottom two images show they point to the line marks on the two cams when piston 1 at TDC. These are external to the cam covers, so they can be used as a last (since the back covers are a bit loose) ditch markers.

On the second combo image, I use a dial indicator (note blue extension straw) to determine TDC. Note factory fly wheel mark is a bit off, cam marks through oil filler cap is practically spot on. The previous tech did a good job marking the harmonic balancer, at TDC the white mark is exactly (looking straight at it) in the middle of the two "bars" underneath the "123". The white marks on the cam pulleys are just a tad iffy. A set of marks using a straight edge across the centers of all pulleys would eliminate all doubt.

Looking at all the knock pins (circled yellow and blue arrows) on the cam pulleys, does anyone happen to know if these pins are in OEM positions? Thanks again.

- Nguyen
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There isn't a standard position for pinning the cams. I 've read all of the 3x8 WSMs, & also have read the handouts given to dealer techs in the factory seminars.

IMHO, it's because of cumulative mfg tolerences in such things as the keyways in the timing drive shafts & drive gears, orienting the cam gear teeth relative to the pins, & grinding the cam lobes relative to the cam thru-holes, and also the crankshaft keyway for the gear that drives the drive gears.

Consider if all of those components were held to 0.001, then you could easily have a cumulative tolerence of 0.010" or so which is several of degrees of cam rotation, or 2x that of engine rotation!

 

Yes, but it adds a lot of risk if you're using cam locks which is pretty much the standard approach these days.

I understand your concern. I've used that technique, but once I had cam locks I muchly prefer them as tweaking cam gear positions is a PITA & generally takes a lot longer. Altho, the simple strip of belt on a piece of steel tool I described earlier really helps do it that way.

As it is, you can rotate the front bank cams 360 degrees.


BTW, just the parking brake by itself, even with the trans in 5th gear isn't enough to keep the crank from turning with just a half-inch ratchet on the damper bolt.

Even pinning the rotors against the calipers with a screwdriver in a rotor slot at best will stop it from rotating in one direction. There's enough slack in the drivetrain to let the engine rotate something like 45 degrees in the opposite direction, possibly 90 degrees. Can't remember exactly, but was amazed when I did it to see how much play there actually was.

I'm concerned & make every effort to avoid it, but I'm not panicky about a valve tapping a piston while rotating a cam by a hand. I always go slowly & am prepared to stop at the least unexpected resistance.

While I sure don't recommend doing so, I actually have tapped pistons with valves on 3x8s & other OHC cars while installing or hand rotating the cams, and also I have tapped valves while rotating the engine by hand a couple of times (much more scary, I probably turned white, as you're using much more force to turn the crank over, even with the plugs out).

I have also talked to Ferrari techs who (off the record) admitted they've tapped valves also. I remember it being mentioned in a couple of posts somewhere in the old fchat. In all cases, leak-down & compression tests were done & checked out fine afterwards(whew).

With the exception of the notoriously fragile sodium filled 2V valves, valves are pretty sturdy. It takes a surprising amount of force to bend one. Think of the forces involved when an accidental tap occurrs. The piston cut-out is parallel to the valve face, so much of the force is spread over the valve face, in-line with the valve's shaft, not concentrated on the edge of the valve head.

The bending moment on the valve shaft is due to the unbalance in the forces on the face acting on a valve radius length lever. Try putting a scrap valve in a vice with the the shaft spuported about 3/4" back from the head & see how much force it takes to bend the head a few thou. Certainly doable by hand, but it takes more than a gentle effort.

In the case of 4V engines, you'll be tapping a pair of small radius valves, so would take even more force than on a 2V engine.

EXCEPTION:
The 2V sodium filled valves are so fragile that I absolutely wouldn't want to tap one under any circumstances, no way, nohow. The heads have been known to fall off just with a bit of high reving, or just by laying one down sideways on a hard surface!

 

I have been following this great thread, but no one has come up with a way to lock-up the cams without taking the cam covers. Right?

 

Rather than start a new thread I thought I'd tack this on here.
I'm also doing the cam belts and a lot more on my '89 GTB.

All the auxiliaries are off from the side of the engine so the cam belt covers will pop off easy.

I've now turned my attention to the top of the engine, where I need to remove the front camshaft cover to replace a leaking cam shaft seal.

The little nut holding the air filter box on is a so and so to reach. My question is, once I've got it loose and the filter box off, how should I make enough space to get the camshaft cover off without disconnecting all the little pipes to the fuel ditributor?

Any help much appreciated.
Thanks
Simon
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I've edited the image to help a bit.
The nut and bolt ringed in red is a sod to reach.
I've tried long screw driver from the side and ring spanners from above can't seem to get any purchase on it.


The pipes (ringed in green )from the fuel distributor run very close to the camshaft cover. I don't really want to disconnect all these if I don't have to. Is there enough space to get the camshaft cover out some other way?

Cheers
Simon
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For the 1980 308GTB I undid the Bosch Fuel injection unit and propped it up about 2-3 inches which allowed me to slip the cam cover out. I also removed the top motor mount and cut the tie wraps on the fuel lines to allow them to move a little easier (replaced with new ones after).

 

You actually can get the rear cover off with the distributor in place, but it's a PITA. It makes it extremely hard to do a good job of puting the small dabs of RTV at the corners of the o-rings.

The black CIS lines are reasonably flexable, unbolt the fuel distributor & rase it up far enough to put a piece of 1x3 under it. One end of the board will ride on the front edge of the boot, & the other end should rest on the engine. Now you'll have reasonable access to get the cover out, clean things up, & reinstall it.

 

Agreed- and it will look something like this. The more stuff you get out of the way, the better. Actually, to remove the entire system would only take about 30 extra minutes (remove lines at injectors), but seeing as you are only removing the rear cam cover, there really is no need to remove it completely.
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Thanks for the help guys.
The car's going back together nicely now. Just one little slip up.
When I took the cambelt cover off the front bank (bank directly under the rear window) there was a little collar/spacer on one of the studs. I made sure I took lots of pictures to help putting things back together, but I can't now remember where this collar came from.

I thought it was the one ringed on my photo (difficult to see I know). But if I put it over this stud the bracket for the air conditioning compressor won't fit on properly. Can anyone help? Which stud did I remove this collar/spacer from?

Many thanks
Simon
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Dumb mistake I know, but can anyone help?
Cheers

 

Sleeves like that are usually used to ensure that something is centered on a stud or screw. The matching piece usually has the opening machined to fit snugly around the sleeve, and the sleeve is usually pressed into place around the fastener or the fastner's hole.

I don't remember ever seeing a sleeve like that on any of the 2v or 4v belt covers I've worked on. Just looked thru the FPCs & didn't see anything either.

Any chance you had the WP nose off, the WP studs have alignment sleeves that are about that size.

 

Hi Verell
No, didn't have the water pump off.
I've got everything back on and its all snug I've just got the proverbial "bit left over", bit embarassing really.

The picture I posted of the cam belt cover shows what I thought was the sleeve in situ and I remember it coming from one of the studs there. But like I said, when I pop it on, the compressor bracket doesn't fit. The only thing I can think of is, it came from inside of the cambelt cover, from the same stud.
Is such a sleeve required to position the cover in anyway?
Cheers
Simon

 

is it one of the sleeves from inside the rubber mounts for the a/c compressor or a rubber insert on the alternator tension adjust bar?

 

#6 or #18?
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Woaaahhhh. The man's a genius. I think you've got it. No 18 is the candidate.
You guys in Tech make this site worth it all by yourselves. Thanks for the help guys. I'll have a look over the weekend, but I think when I removed the compressor bracket, the sleeve must have remained on the stud.

Cheers
Simon

 

Where is that exploded view drawing from?

-F

 

1988 parts manual. It's not the york compressor that was installed in the USA/SA cars

take a peek at http://bingo.cdyn.com/ferrari/

 

I took the compressor bracket back off this weekend and sure enough the little collar 18 on Phil's diagram was missing. Thanks again Phil.