Narrow Boss 930 Chain Tensioner Part #?

[JKarow08]

Aloha,

I'm looking to buy a set of narrow boss 930 chain tensioners to have rebuilt and use along side Supertec's modified idler arms. The problem I'm having is I'm seeing a discrepancy in the part #s listed for these post-'80 930 tensioners, some threads list it as 930.105.053 yet I've been offered and have seen a lot of pictures for 930.105.501. Does anyone know if both of these part #s are the same or if not, what the difference is? Thanks in advance for the help!

-Josh

[Jonny042]

930.105.053 is two digits short of a part number. Last two digits of any part number are the revision, starting at zero. The latest version of these is 930.105.053.04.

930.105.501 is, I guess, a casting number? Or an old part number they never removed from the molds? No idea.

So you are going to find this:

[JKarow08]

Originally Posted by Jonny042

930.105.053 is two digits short of a part number. Last two digits of any part number are the revision, starting at zero. The latest version of these is 930.105.053.04.

930.105.501 is, I guess, a casting number? Or an old part number they never removed from the molds? No idea.

So you are going to find this:

Yeah, sorry, I included the revision #s on my wanted post but omitted them for simplicity here. If these are the same it's strange they have a Porsche part # on them that isn't correct and the correct # is no place to be found on them. So these in the picture below are the narrow boss 930 tensioners then correct?

[Jonny042]

Yes, it is strange, and yes, those are the tensioners you are looking for, complete with safety collars!

In case it's not common knowledge, once installed you do not put the collars all the way down to the tensioner, there needs to be some clearance so the tensioner can do its job and take up the thermal expansion that occurs when the engine warms. IIRC it's in the range of a couple mm's.

[pmax]

Originally Posted by JKarow08

Aloha,

I'm looking to buy a set of narrow boss 930 chain tensioners to have rebuilt and use along side Supertec's modified idler arms.
...

About those modified idler arms, the choice of material is interesting, the OEM housing being all steel.

Is that extension bushing press fit ?

[JKarow08]

Hopefully Henry will chime in here with a full explanation, my understanding is Henry's arms aren't necessarily "better," not a lot of performance improvement to be had, just a high quality alternative that is more reasonably priced than the originals for those of us that don't have cores. I'll let Henry fill in the details on the exact construction process, but I'm guessing it is easier and just as effective to make the extension out of the bushing material and it is likely stronger being one piece than having an extension with a separate bushing pressed into it. This thread has a little more info on them...

https://forums.pelicanparts.com/911-engine-rebuilding-forum/1160215-tensioner-idler-gap.html