Unusual Cam Pulleys

[michaelj]

Anyone know what car these fit? They have fifty teeth, not 42. Teeth are thinner. Bought them without looking close enough. The seller mentioned they were used in Fiat and Lancia engine development. It looks like they are fixed in place as though they were on a car for awhile. Someone ran a screw thru one of the holes and cut the head off, making them permanent (at least until u get out the extractor). There also seems to be a couple of marks/knicks in the outer diameter to indicate a precise setup. ANy thoughts appreciated. Thanks. Mike

Oh, this is what the seller had on the ad:

Original FIAT camshaft pulleys modified to be used in engines cam timing performance evaluation.

This set of pulleys was used to study the effect of cam timing on Engine Emissions and Performance of FIAT engines (1972-1983).

The pulleys can be used on FIAT/Lancia 2 Liter, Twin-Cam, 4 cylinder Engines and others for tuning purposes (including Racing).

The pulley design follows the vernier-type concept to accurately change cam timing by re-positioning the reference Set Screw. This approach to cam timing change removes the need to re-adjust the Belt Tension.

The Modified FIAT 50-tooth Pulleys have the following characteristics:

1st Pulley: Range +/- 5 deg., Resolution 1 deg. (Cam angle)

2nd Pulley: Range +/- 10 deg., Resolution 1 deg. (Cam angle)

3rd Pulley: Range +/- 18 deg., Resolution 6 deg. (Cam angle) This pulley has 7 positions ONLY (additional holes are not usable)

[carl]

I think it pretty obvious that if the tooth count and tooth configuration is not the same as the usual Fiat cam belt sprockets that they are Not for Fiats....at least not for the 124 and X1/9s. That key way in the center bolt hole is not for a Fiat either. Send them back for a refund.

carl

[FiatMac]

To add to what Carl said, it might be possible that these pulleys were used on a Development engine where special camshafts were manufactured to fit the keyed detail of the the pulleys. However, the crankshaft pulley would also have to be special because it would need to have 25 teeth to give the proper 2 crank rotations per camshaft rotation and a special belt would be needed to allow for the greater length required to fit around the larger pulleys. Also note that the two pulleys stood on end in the first picture have different tooth profiles.

So, even if they were used on a Fiat engine in the past, it was a very special engine, and the parts are not useable on any production Fiat engine.

[michaelj]

Ya I agree. He swears they can be used. The keyway really is just a slot to accommodate different locator pins for different cams. so that's not an issue. Its the teeth.

I may just trash the outer part and cut a solid pulley to fit these hubs. Still researching.

[michaelj]

Just noticed, I forgot to mention the pulley on the left was a regular one. The right is the oddball.

[bradartigue]

Ya I agree. He swears they can be used. The keyway really is just a slot to accommodate different locator pins for different cams. so that's not an issue. Its the teeth.

I may just trash the outer part and cut a solid pulley to fit these hubs. Still researching.

Can be used, sure, it will fire correctly the first time around. By the 25th rotation you'll be 180 degrees out of time and your valves will crash into your pistons. That gives you about 1/2 second at 850 RPM.

I'm not sure that's all true, being a bit tongue-in-cheek, but why even bother? They obviously are not for the 8-valve TC engine, so return them. Get new wheels made for your car.

[131]

16v