Hastech Engineering Tensioner Woes - Help

[P911S]

Do custom idler arms exist that are larger to avoid this issue? see below.

[targa72e]

Yes they are available. The one on the left came out of a engine I recently purchased. The one on the right is stock the left is larger. Unfortunately I do not know who makes these.




john

[P911S]

Thanks John! Looks like mine is 19 teeth, so 20+ teeth would probably be good. I'll keep hunting.

[john walker's workshop]

Maybe a couple of new chains?

[P911S]

I measured this chain and it wasn't any longer than the new chain.

[mikedsilva]

Originally Posted by P911S

I measured this chain and it wasn't any longer than the new chain.

That surprises me.
Look how close the chain is to the upper guide in your photo... pretty sure a new chain wouldn't get that close as per below?

[69 911s]

Apparently, things got narrower after machining.

[Dpmulvan]

A smaller sprocket isn’t going to help, you’ll have to push it even farther up to tighten.

[Dpmulvan]

Originally Posted by Dpmulvan

A smaller sprocket isn’t going to help, you’ll have to push it even farther up to tighten.

Never mind I just got up

[stownsen914]

Is this an engine you’re assembling? How’s your deck height?

[47silver]

take a link out of the chain?

[JoeMag]

What was "machined"?

[Henry Schmidt]

The chains don't actually stretch. The rollers can get play in them creating the situation you see. We built a tool to test this wear.
The larger sprocket comes from an early sixties Mercedes 220, 250, 280? Too old to remember which.
If you had the case halves machined, chain length is only part of your problem.
If you want to shorten the chains, you need a half link. A whole link makes the chain too short.
We haven't done this in 30 years, a little half-assed so forgive me if the answers are a little fuzzy.

[targa72e]

I looked at some old notes. You might try the following companies as I believe they have larger and smaller idler wheels if needed. Once is burnham performance and the other is Rothsport.

john

[brighton911]

I would avoid half links at any cost. The inherent weakness of the bent side plates is something you do not want to experience.

[Turbo_pro]

Originally Posted by brighton911

I would avoid half links at any cost. The inherent weakness of the bent side plates is something you do not want to experience.

What evidence do you have that a half-link is "inherent weak" and would jeopardize longevity in this application?
Chain loads in the application are relatively light. How do I know, one of my older vintage race engines has single row chains.

[P911S]

Rothsport didn't have the idler wheel. Mittelmotor did. We'll see if that helps. Anyone know why the shelf came to exist under the right sprocket? Earlier models don't have that aluminum shelf in the timing chain box.

[47silver]

looks like it would flip oil up to the chain?

[Dpmulvan]

Save yourself time and money just remove the chain box and machine a relief in it.

[MoreGAS]

I can double the advise that removing a link is "a mile" and then your chain will be much too short. You may try JB racing in FL as they may have a larger diameter sprocket to fix your problem . Another item to check: if you narrowed your engine that much by cutting the deck surface, and the heads(the only way this happens) you may want to revisit your cam centering up in the chain box opening with as much as this engine seems to have been narrowed. We, in his situation cut the chain box an equal amount to keep that centered so it doesn't leak like a siv when together. This will ensure a good
seal , however will make your sprocket problem even worse.

Kevin
GAS Motorsport