Tensioner options

mb911 · mb911's Garage

I am currently building a 2.4 with 2.2 s pistons, solex cams etc for my 914-6 gt clone. I will soon be at the point of choosing tensioners and the non carrera with collars really seem attractive to me. I have had carrera tensioners on many engines before but looking for some feedback as 1k for those tensioners seem crazy.

Trackrash · Trackrash's Garage

Well, here is more than anyone wants to know about Carrera tensioners.
http://forums.pelicanparts.com/911-engine-rebuilding-forum/914119-carrera-tensioner-questions.html
and
http://forums.pelicanparts.com/911-engine-rebuilding-forum/947980-tensioner-failure-opinions.html
If the motor I just built had not come with Carrera tensioners, I would not have put them on.
Here is the bottom line. If you want to put together a motor and not have to, in theroy, ever do any maintenance on your tensioners go with Carrera.
If on the other hand you know that every 40 to 50K miles you may have to rebuild your hydraulic tensoners use them. The turbo ones are the way to go.
You may also want to upgrade to the wide bush idler arms.

manbridge 74 · 03-15-2017, 07:16 PM

I'm trying turbo tensioners next time. But no collars -- I've seen the Allen bolt break from, I'm assuming, vibration. I like the Jerry Woods stop piece modification.

Trackrash · Trackrash's Garage

Quote:

Originally Posted by manbridge 74

I'm trying turbo tensioners next time. But no collars -- I've seen the Allen bolt break from, I'm assuming, vibration. I like the Jerry Woods stop piece modification.

I'm not sure if you can use the JW method on the turbo units?

I have had good luck with the collars. Saved me once or twice. You have to pay attention though, and if those chains start to rattle it needs to be fixed pronto.

KTL · 03-17-2017, 08:14 AM

Ok i'll be the one to throw out the iffy option and ask why not the solid tensioners?

Trackrash · Trackrash's Garage

Quote:

Originally Posted by KTL

Ok i'll be the one to throw out the iffy option and ask why not the solid tensioners?

I had not considered them. Do you use them? How are they adjusted? How often do you need to re-adjust? Any other issues?

Maybe the experts will chime in on the pros and cons.

manbridge 74 · 03-17-2017, 05:12 PM

Hmm, maybe l'll try some regular tensioners as I have a set or two.

Never been around the solid type. Guessing they'd need attention after every race weekend.

KTL · 03-20-2017, 05:40 AM

I used them for a very short while on my super loud exhausted racecar engine before I hosed it and have yet to rebuild humpty dumpty. So I can't attest to their long term performance and how they effect chain or sprocket wear, and noise increase. A friend used them for a while and he didn't have anything super bad to say about them.

Here's some instructions from a few of the sellers. Stomski surprisingly doesn't have instructions but i'm sure he'd give some feedback on the use of them. He's a super nice and forthcoming guy

https://www.stomskiracing.com/products/911-mechanical-chain-tensioners

mb911 · mb911's Garage

I would assume they would work great for most 911 engines as most cars don't get driven all that much. In my area I could see it getting adjusted when it gets put away for the winter which could last anywhere from 4 to 6 months so driving season at most is 6 months for me and maybe would put on 3k a year.

Mark Henry · 03-20-2017, 06:53 AM

I'd say no on a street car, they place extra stress and wear on your chain/sprockets, and should be adjusted say every 2nd oil change. The chains/sprocket wear must be monitored and replaced as they wear. Also the engine must be fully warmed up, full hot expansion, before driving.

OK for race car where the engine comes apart often, but IMHO not good for use in a street car. Maybe you could use them in a garage queen that only sees a couple hundred miles a year.

I'd use the mechanicals with collars or the hydraulic with the JW mod.

Steam Driver · Steam Driver's Garage

There is another option for solid tensioners if you decide to go that route. This from "back in the day."

You can make solid tensioners out of a set of old tensioners. Disassemble the unit, drill and tap the bleeder screw boss for a suitable bolt (I dont remember the size) and reassemble the unit. Compress the plunger and lock it with the set-screw.

Then install it in the car and loosen the screw. This lets the plunger put its spring tension on the chain as it normally would. Then tighten the set screw.

This puts more tension on the chain than it would/should have with the engine hot, but this is how a lot of people did it then. A setup like that lasted quite a few miles in my 914-6 (which was my every day driver for much of the time) but I did replace the IMS gear and sprockets when rebuilding later, and by that time the Carrera units were available.

One could combine that arrangement with the clearance suggested in the Stomski kit (to lessen the tension with a hot engine) and have essentially the same thing as the Stomski units for practically no investment. Not as pretty, but who is going to see it.

With the way I did it the chains were quite noisy when the engine was really cold, but it went away fairly rapidly.