Timing chain, too short...?!

[Matt Zerega]

Happy Friday afternoon, Gents. Question for you'all....

I bought this N.O.S. timing chain set thinking it's correct for my 903cc "100GBC" motor...and as it turns out, it doesn't look like the chain is long enough for the cam and crank sprockets to clear each other. What gives? It does appear that if the sprocket centers were pulled hard enough away from each other, the chain might stretch enough to get the sprockets installed....but I'm not comfortable putting that much force against (from tension) on the crank or cam bearings.

Those little tits on the links seem to keep the chain from fully extending. Weird....

Is there anything about this photo that looks "correct" or "familiar" to you?

 

[Chaostoy]

That chain looks odd to me...I'm no expert, but here's an old photo om my chain on a 903cc 100GBC.

 

[Matt Zerega]

Thanks for the photo. That's what I expected...a tiny bit of slack. That settles it for me - my chain IS too short. I'll find a replacement.

 

[Jeff Stich]

What brand/packaging/part number did this have? (so others know what to avoid)

 

[Matt Zerega]

Very well, Jeff. Good idea. The sprockets and chain came loose in lightweight, "SIL" branded, new old stock cardboard box. The chain is so short that it was difficult to get both sprockets installed in the chain. Here's the top of the box; I cut it out of the box. I figured that with the reference to "Spider" on the box meant I was good to go. Not......

 

[NM850]

Interesting. Ive probably bought 7 or 8 timing chains for 850s. As far as I know they were always advertised to fit 600, 600D and 850s. No idea what this short chain might be for.

 

[johnt]

Try one of these timing chain tensionors to remedy timing chain issues in the future!

 

[Chaostoy]

@johnt, is my chain backwards, or is yours?

 

[fiatfactory]

@johnt, is my chain backwards, or is yours?

I'll take a guess and say that Johnt's chain is setup for CW rotation engine, given that his avatar is a 600, the engine shown has the 127/A112 type oil pump and the eccentric to drive a fuel pump on the cam.


Odd with the chain being short/tight, as all chains shown have 22 links....

SteveC

 

[Jeff Stich]

I'll take a guess and say that Johnt's chain is setup for CW rotation engine, given that his avatar is a 600, the engine shown has the 127/A112 type oil pump and the eccentric to drive a fuel pump on the cam.

The block also has the "A112 A2" engine code stamped on the face, visible in the lower right corner in the photo.

 

[Chaostoy]

How can you even see that? man you guys are good!

 

[Matt Zerega]

View attachment 61604

Try one of these timing chain tensionors to remedy timing chain issues in the future!

Cool idea. Is that the Fiat Cinquecento, Seicento, Uno 900 tensioner...and if so, did you have to modify the distance between the holes on the 7711828 bracket.

 

[johnt]

@johnt, is my chain backwards, or is yours?

Depends on the transmission. 850 or 600. They run in opposite directions. Don't always trust the factory manual pictures since the show a mix between 600 and 850. The engines will run with the chain installed either way, but the chain tension won't be at optimum depending the the chain/weights.

 

[fiatrn]

Did you check the gears and make sure they are the proper tooth count?

 

[Matt Zerega]

Did you check the gears and make sure they are the proper tooth count?

Absolutely. In fact, all photos above show the expected 17/34 tooth counts (cam turns at half the speed of crankshaft) on my parts, and in Chaostoy's and johnt's photos. This slightly short chain is mysterious considering its correct number (44) of links.