Technical Timing Chain Too Tight

[ronstox]

I'm installing my new timing chain & sprockets from Axel Gerstl on my '71 500F with an unmodified 499cc engine and they feel too tight.
I've got the chain around the crankshaft sprocket which is in place on the crankshaft. the chain is also around the camshaft sprocket which I'm trying to fit into the camshaft but it won't go over it. It looks like it needs another mm to get it to fit. you can see in the photo the sprocket slightly of center. That's as far as it will go.
I've checked that the sprocket does fit into the camshaft, and I've even applied heat from my heat gun to the chain, but that didn't work.
What an I missing? A link?
The camshaft is from Tom (the hobbler) and comes off of a 126.

 

[124BC1]

Iirc, there's a rubber chain tensioner ring fitted between the 2 rows of teeth on the crankshaft sprocket?
I've seen 2 types of ring used - one is flat across, the other has a top hat section (i.e. raised section in the centre). I've encountered problems similar to your's with aftermarket timing chain kits which can have either type or tensioner ring cross-section, the solution I found was to fit a different rubber tensioner ring.
Maybe see if the timing chain and sprockets will fit normally with the tensioner ring removed from the crank sprocket? This way you'll know if the problem is with timing chain/sprockets or with the rubber ring or possibly the depth of the groove where the ring fits on the crank sprocket (iirc, aftermarket sprocket grooves varied in diameter as well as the profile of the ring supplied).

 

[ronstox]

Hi 124BC1, I don't see any rubber tensioner in the kit I bought from Axel Gerstl. There wasn't one in the old parts I removed. Do you have a photo of what one looks like?

 

[fiat500]

Hi 124BC1, I don't see any rubber tensioner in the kit I bought from Axel Gerstl. There wasn't one in the old parts I removed. Do you have a photo of what one looks like?

It can be fiddly to fit because you need the chain assembled over both sprockets and then both sprockets simultaneously offered to their respective shafts. It's a bit like fitting a bearing where all parts must be parallel as they are installed. You also have to get the link spacing right so the timing marks align...it can be trial and error....obviously being a trial.

 

[ronstox]

OK, I got the whole timing assembly on. With the advice of Tom (the hobbler) I gently applied some persuasion with my rubber mallet and the cam sprocket popped onto the camshaft; everything lined up properly.
BTW, I had watched a few YouTube videos on reassembling the engine and in all of them, the cam sprocket slipped nicely onto the camshaft with no issues. So I was expecting the same. Luckily, we have this forum for when things don't go as expected. Thanks for all the helpful advice.

 

[124BC1]

Hi 124BC1, I don't see any rubber tensioner in the kit I bought from Axel Gerstl. There wasn't one in the old parts I removed. Do you have a photo of what one looks like?

Sorry if I gave you a wrong steer, relying on 40+ year old memories of working on Fiats isn't always reliable. I know the rubber tensioner ring was used on the 127, because I had to the same job 3 times on the same car because of mixing timing chain and rubber tensioner ring from different suppliers. I must have assumed the 500 also had a tensioner ring. Once again, apologies.

 

[fiat500]

Sorry if I gave you a wrong steer, relying on 40+ year old memories of working on Fiats isn't always reliable. I know the rubber tensioner ring was used on the 127, because I had to the same job 3 times on the same car because of mixing timing chain and rubber tensioner ring from different suppliers. I must have assumed the 500 also had a tensioner ring. Once again, apologies.

Apologies are rare around here. Bum steers aren't all that rare. Trying to help people isn't always straightforward when memory or differening experiences play tricks with you. Wrong advice or observations ideally should be corrected or retracted. I doff my cap to you by showing humility that is lacking wth some people.

 

[the hobbler]

Apologies are rare around here. Bum steers aren't all that rare. Trying to help people isn't always straightforward when memory or differening experiences play tricks with you. Wrong advice or observations ideally should be corrected or retracted. I doff my cap to you by showing humility that is lacking wth some people.

Totally agree with you Peter----thank you "124BCI" for being so honest and courteous.

 

[124BC1]

@fiat500 and @the hobbler

Ah shucks, you guys are making me blush now