Help needed !! Ferrari 308 1979 carburetor engine noise

Looking at the diagram that gear meshes with another one the same, the movement would be the clearance between the 2 gears. Is there any movement between the gear output shaft and the timing belt pulley. The pulley looks to be sitting on a woodruff key and these need careful fitting to get the correct tight fit

 

The drive gear is loose or not seated. . Or the bearing is damaged or the bearing may not be seated is my guess
Check to see if the inner drive gear noses are the same length on each sprocket .as in seeing how much thread is showing in the nut in the sprocket . Also do both sprockets stick out the same amount from the cover. Just a starting point. To see if the inner drive gears are fully seated to one another behind the cover.

 

just listened to the video of engine running and I didnt hear anything unusual . Listened again exhaust leak?

 

Motor sounds great !! , thats the extent of my ability to answer !!

Than you

 

Well I dont think that noise would come from the cam drives gears. I really dont know. Talk to your engine builder. That sux

 

Ok good luck

 

The lower drives have helical gears, there's practically zero backlash. The lower drive pulley should not rock back and forth by hand. If they are, it could be due to a variety of things, however the builder should be able to identify exactly what.

As to the sound, always very hard to identify those. Sounds like it's in time with valve events.

 

Nasty. Can’t tell from vid where noise is. I would guess valve train but if you hear it low there are timing cover bearings that hold those gears

 

The tapping sounds like a loose valve clearance or exhaust leak. The bearing hum could be any of the bearings, use a mechanic’s stethoscope to touch on different parts (timing case, water pump, drop gear housing in the other side etc.) It is probably the cam drive bearings as they are a known weakness (which is why they switched to 44mm bearings on later engines.) Worn bearings would cause the backlash and could cause premature wear on the teeth. I assume you checked the nut on the pulley is still tight and the punched lip is still in the slot. They can come loose if not torqued and locked which then causes the woodruff key to wear.

 

Probably a silly thought but have you checked the oil level? Or what type did you use?


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This car has brand new bearings. I haven't heard of failures of the drive gear outer bearing on 2V motors but I have on QVs.

 

2V and early QV have the smaller 40mm bearing which are weaker and known to fail. There are also a lot of counterfeit bearings out there (many SKFs are fake.)

 

Did you replace the inner bearings with the engine in situ?

 

Actually Derek, this is partially true. While they both use the same bearing SIZE, the bearings are different. The QVs have no lubrication and no outer seal while the 2vs have an oil feed for the bearing that exits in the grip ring groove therefore lubricating the 2v bearing. The 2V has a seal as well. The QV has a sealed bearing, no lubrication and no seal for the outer bearing - which might explain the higher failure rate in QVs

 

For what it’s worth, MN Exotics (one of the guys here) loaned me the tools needed to enable removing the nuts, sprockets, the bearings (with a small bearing puller) and seals all from the front/outside. It can be done without removing the lower cover.

 

Yes, not a simple job but straightforward. What I don't understand is why someone needed to change the inner bearings.

 

You have to remove the cover to get to the inner bearings. They seldom fail due to the constant oil lubrication and the low loads but I've heard of a few failing on this forum and elsewhere.

 

You have either a bad inner bearing or the hole where the bearing goes in is out of spec. For an engine this old, it is not too surprising. It's just a very difficult thing to change out, as you already know.