Chain Tensioner upgrade

[Huds71j]

Hi all

I'm a newbie to actually posting anything so hello one & all

I'm in the process of restoring a 71 Targa

It was a bit of a barn find as the previous owner bought it with no motor or box in 2013 and never did anything to it

I've sourced a 75K mile 2.2 motor and am in the process of rebuilding it however i would like a bit of advice if anyone can?

Is there an easy way to identify if my motor has the old style of cam chain tensions (part numbers from them are 1.901.105.049.2 & 901.105.519.0R ??

Thanks in advance

[tim69s]

They are the early chain tensioners.
The later mechanical ones have a 930 part number and so do the oil fed ones.
Just happen to have all 3 types kicking about my work bench so here is a pic.

Left is an early 901 type with safety collar still on it.
Middle is a mechanical 930 type, note the thinner end section on the arm.
Right is an oil fed 'carrera' tensioner.

If you have the Dempsey engine rebuild book he goes into the differences.
If you don't have the book, highly recommend getting a copy.

Good luck
Tim


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[Huds71j]

That's awesome ... only problem is it looks like i'll have to get my hand in my pocket and upgrade them !!

[bjmullan]

A lot of people (including me) would recommend the 930 style tensioner rather than going for the oil feed one.

[alastairp]

A lot of people (including me) would recommend the 930 style tensioner rather than going for the oil feed one.

With chainsaver collars of course.

[Gary71]

A lot of people (including me) would recommend the 930 style tensioner rather than going for the oil feed one.

With chainsaver collars of course.

Seconded

I like the idea of having that mechanical stop in there

[tim69s]

I've just done a top end rebuild on an engine where the oil fed tensioner had failed. That's the culprit tensioner in the picture.
It had blown the cap of the pressure release ball valve, exactly the failure Wayne talks about in the book.
Cap and spring were found in the bottom of the chain housing. Ball bearing nowhere to be seen. I'm hoping it's somewhere on my garage floor rather than hiding in the bottom of the case!

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[Huds71j]

Thanks for the replies - so if i try to find some 930 ones are they both the same part number and is anything else required ie chain wheel ... ?

[tim69s]

Same part for both sides, 93010505304
and you need the spacers 93010551300

They are listed on type911 and design911 but very expensive.

Other option would be aftermarket fixed tensioners, but my understanding is they need regular adjusting.


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[tim69s]

https://www.ebay.co.uk/itm/Porsche-911- ... 890.l49292

Obviously these are used, but then so are yours.

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[deano]

Oooh, interesting thread.

I have no idea which of the non-oil fed tensioner type I have in my 73T, but I have always had it in the back of my mind to change them to oil fed as seemed to be recommended in the old days. More recently, I had seen a preference to keep non-chain fed and decided then that I didnt need to change.

Those collars look like a must-have, and easy to fit, so thanks to all for recommending them!

If I happened to have the 901 type of tensioners, are there any good reasons to switch to the 930 type (+ collars)?

[tim69s]

Lots of threads out there if you want to Google it. But the general consensus is the later 930 mechanical units were an update by Porsche with a higher spring rate and generally the lowest failure rate.
The narrow pivot arm also means you can use the later idler arms which are also recommend as an upgrade.
You need to replace chain ramps as well, but if rebuilding this would be done anyway.


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[Boydyrs]

I have a brand new pair of stromski tensioner in spares stock if of use?

[Strictly]

I've just done a top end rebuild on an engine where the oil fed tensioner had failed. That's the culprit tensioner in the picture.
It had blown the cap of the pressure release ball valve, exactly the failure Wayne talks about in the book.
Cap and spring were found in the bottom of the chain housing. Ball bearing nowhere to be seen. I'm hoping it's somewhere on my garage floor rather than hiding in the bottom of the case!

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You can safety wire the ball/relief valve, drill either side of tensioner and safety wire over. Obviously in your experience you would not be so keen. I personally like the 3.2 pressure fed tensioner with idler arm upgrades (bush length).

I have even bought the 3.2 tensioners second hand, and had them apart for cleaning etc, then oil them with a hand held oiler (oil them in place by hand (pump the oil into them until it comes out from all the correct places) like when running, rather than on the bench). Ive had no problems, and the idler arm/bush upgrade is a bonus.

N.B longterm, I would upgrade my chain housings as well too aluminium, as the mag one crack at the back on the shaft which the chain idlers operate on. At least so I have read, ive not seen it myself, but I have not had that many engines apart