timing belt drift

luket · Post by **luket** » Sun Sep 29, 2013 10:57 pm

Hey All, Got my 79 back together after rebuilding the top end and have been driving it to work for a few days and loving the new power of the DFEV and port matched head.

I inspected my timing belt tonight and found that the back surface is slightly worn from the guide. When i put it back together and got it running with the new timing belt, the belt drifted to the back guide and stayed there. The belt is hanging about 1/16" off of the guide pulley next to the alternator and has been since i got it back together. It is just lightly touching the guide on the intake cam pulley.

I looked close tonight and saw a bit of wear on the back surface of the belt where the guides contact, mostly between the belt teeth.

Does anybody know of an adjustment is possible to make it run closer more in the middle? should i be worried that is tending to the back of the pulleys? i installed the belt per the service manual and the tension is good. Never took off the cam pulley so i assume they are still tight. Any thoughts?

seabeelt · Post by **seabeelt** » Mon Sep 30, 2013 9:22 am

The cam pullys and aux pully should all have guides. They face different directions to make sure the belt stays on the pullys. Some cars stray to one direction or another. Mine tends toward the engine. You can see where it contacts the back lip of the cam pully, but it is not wearing into the belt. If you have belt debris, I would be worried, if not, its probably OK.
r/

SpecialTool · Post by **SpecialTool** » Mon Sep 30, 2013 2:09 pm

There is also a wide belt available that takes up nearly the entire width the pulleys.

luket · Post by **luket** » Mon Sep 30, 2013 4:12 pm

There no debris but the wear has me a bit nervous, maybe I'll keep an eye on it to see if it gets any worse. Was thinking I might try torqueing down the from can casing bolts more and see if it makes any difference.

Leaving the car with a friend for a few month (while I do a southeast Asia motorcycle tour, I'm bragging to anyone who will listen) and I would feel really bad if I was leaving him with a time bomb. He's an engineer and former spider owner so he'll take good care.

Maybe I'll take some pics, compare in a couple weeks and if its not getting any worse I won't worry about it

rebar1111 · Post by **rebar1111** » Mon Sep 30, 2013 8:46 pm

My 79 Spider has no flanges (from the factory). If the belt begins to drift it will continue until it reaches an obstruction.
That is one reason why you should never reinstall an old belt.

Tobi · Post by **Tobi** » Mon Sep 30, 2013 9:19 pm

Rebar, are you sure about that? There should be one on the back of the aux-pulley and it should be stopped by the crank pulley in the front.

RRoller123 · Post by **RRoller123** » Tue Oct 01, 2013 8:38 am

Mine has no flanges on the cam pulleys, but one on the Aux shaft. 80 FI.

fiatmike124 · Post by **fiatmike124** » Tue Oct 01, 2013 11:35 am

luket wrote:Was thinking I might try torqueing down the from can casing bolts more and see if it makes any difference.

Be aware that this will most likely affect you valve lash measurements

RRoller123 · Post by **RRoller123** » Tue Oct 01, 2013 1:21 pm

Could this not also distort the cam boxes?

jkn070458 · Post by **jkn070458** » Fri Oct 11, 2013 2:24 pm

On my '78 the belt hangs off the exhaust gear about 1/32" and perfect on the intake side. Well I tore it all apart again to double check all the pulley's. I left the timing cover off and checked runout on the belt, it looks straight to me. After 3200 miles this summer I've decided that's where the belt wants to hang. No wear on the belt at all.

timing belt drift

timing belt drift

Re: timing belt drift

Re: timing belt drift

Re: timing belt drift

Re: timing belt drift

Re: timing belt drift

Re: timing belt drift

Re: timing belt drift

Re: timing belt drift

Re: timing belt drift