Variations in Timing Chain Tensioner housing nut

[pharriso]

I am in the middle of a cylinder head changeover (as you already know by now ) & at the stage of setting the cam timing & adjusting the chain tension.

The thread on the old tensioner screw was a little beaten up, so I grabbed a spare assembly that I happened to have & assembled it into the front cover. Only problem is it bottoms out before the sealing washer is clamped:

Took the tensioner assembly out again & compared the housing nut of the "new" assembly to the old one:

The threaded section is .110" longer.

So I will use the "old" housing nut with the "new" Tensioner screw...

Anyone know what's going on with the difference in the housing nuts / assemblies? I thought all parts were original...

[rgh0]

Lotus changed the design of the front cover may be around 1966 - 1967 and introduced a reinforcing web on the cover where the adjuster screws in. Maybe they changed the screw in adjuster length at the same time ??? Another unrecorded Lotus change and a great find. I must go back to some of my old covers and adjusters to see what I can find

cheers
Rohan

[2cams70]

The one on the left is a repro. one and has stretched. The repro. ones are thinner at the neck and can't take the torque if you tighten to the workshop manual torque figure.

Do yourself a big favour and do not use any reproduction tensioner nuts regardless of supplier . Always use an original one. The repro. tensioner screws are OK but not the nuts. It's not a component that wears so ok to just re-use.

I speak from experience on this one!

[Emma-Knight]

On my car, a replacement was fitted. It was an M8 allen screw adjuster, so incompatible with the original. The whole settup was kind of „handcrafted by incompetent persons“. I got an original one... but it came like this...
By chance, I had a thread rerolling tool I bought for the outboard driveshaft, that was killed by a stover nut. So the original adjuster screw with the same tpi could be restored.

Cheers
Anna