Belt Drive Gear/Pully Confusion

Guys,

Some confusion here.

Which drive gear/pully belongs on which Year/Model of 3x8s?

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Mark, As you heard via email, the longer "nose" on the left goes through the outside oil seal used in the engines up to '78. I read somewhere on Fchat that the change happened at engine No. 03045. After the change the bearing was pushed outwards to put it closer to the pulley and reduce the "lever" effect and it was a sealed/greased 2RS bearing. The oil seal was moved to inside of the bearing and it sealed against the shaft. I have sold pulleys for both early and late style engines and an '81 engine must have the later short nose pulley unless the timing cover, gears, etc have been changed. Given that the timing covers are machined with the block to match, it would be easier to re-stamp an engine number than change a timing cover
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The pully on the left in my photo came off my '81 GTSi.

There was no washer between it and the bearing which has a black 'rubber(?)' ring covering the ball bearings.

I never tried to left the ring to see what was behind it.

How can I tell if the timing cover has been changed or something else modified? What signs should I look for?

According to Ferrari SpA, the engine # is OEM to my car, VIN 34641, NOV 80 Build Date.

This 'abnormality' like a lacking Pininfarina badge and no holes for such a badge on either side, has me quite perplexed.

 

Mark, if you have a sealed bearing behind the pulley that is good because that is what you should have. Someone may have fitted new pulleys that were wrong. I think the belts can take a fair bit of misalignment so the old long-nose pulleys would work with the newer design but you may notice a wear line in the teeth of the old belts. Run a straight edge down from the cam pulleys to check where the lower pulleys should be.

 

Will do and report back.

 

Derek,

I did run the ''straight-edge' test.

The Cam Gear outer edges are 'on-plain.' One does NOT stick out further than the other.

The Drive Gears (long snout) when measured against one of the Cam Gears, are INWARD from the Cam Gear by MAYBE 2 mm.

NO More than for that for sure, and probably a little less.

A 'short snout' Drive Gear in that place instead, would be MUCH Further INWARD by several millimeters.

So now what?

 

My car Build Date is NOV 1980.

My engine number Confirmed by Ferrari is:

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Mark, If you are measuring with the new HTD pulleys then they should line up but with an extra 3mm width as the belt is 29mm and the cam pulley teeth 32mm wide (on the one cam pulley add 3mm more for the outside "fence.") The lower pulleys have an extra 2mm of tooth width towards the inside. It is very strange that your correct later outside bearing lower drive was paired with long nose pulleys when you took it apart but perhaps they were changed at some point and the gear/shaft modified to suit. I can send you some long nose pulleys or some 9mm long stainless spacers that you can machine to whatever length you want to give the correct offset. Change the bearings and oil seals behind the bearings while the lower pulleys are off.

 

Those steel long-nose pulleys in your photo that were on your 308 should stick out further. Has the engine run with those pulleys?

 

Yep. It ran with them for years.

How many? Don't know.


NO, I put the old Sqr Tooth pulleys and new belts back on and measured with them in place. I'll go to the round tooth system design a bit later in time. Incremental changes.

In 3 years and I plan an engine-out and SS EX Valves put In.

 

Outer bearings, YES?

How hard is that REALLY; OUT with the Old and IN with the New?

 

If there is very little play in the bearings and no oil leak then you could leave them until you take the engine out. It’s not a difficult job but you need a special tool (small insert bearing puller.)

I would check an old timing belt— if there is a wear line or damage to either of the belt sides I would sort out the pulley alignment.