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 Posted: 03-22-2015 11:15 pm
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Esprit2

 

Joined: 05-01-2005
Location: Minneapolis, Minnesota USA
Posts: 289
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Barthol wrote:
(Snip)... I have a semi automatic tightener but I cannot find out how to mount it. It looks like I am missing threaded hole in the engine. Is there anyone who have some photos / schematics showing how it is mounted. ?See the attachment. It doesn't show the block mounting hole details, but it does illustrate the general arrangement.

Yes, you do need two threaded bolt holes in the block. And since all J-H 907s are 'early' 907s, and none used the spring-loaded, semi-automatic tensioner, it's possible your engine won't have the second bolt hole.

In Lotus applications, there's usually something between the semi-automatic tensioner and the cylinder block. It may be an A/C compressor mounting bracket, or a belt snubber with short spacers on later engines, but something. On an engine with no accessory brackets, there will at least need to be a pair of longer sleeve-spacers to move the tensioner out to the plane of the timing belt. Examples of those parts are illustrated on the attachment, along with Lotus part numbers (probably no longer available from the factory).

I suggest you contact Lotusbits and ask for whatever parts you need to complete the installation of your tensioner to a J-H 907 with no accessory brackets or snubbers.
http://www.lotusbits.com/

*~*~*
There were several versions of the semi-automatic tensioner as it evolved over time. The early one had a spring loaded metal piston moving in the aluminum housing's bore. It would gall over time, and seize.

Later tensioners have a Nylatron plastic piston that solves the galling problem, and it will fit the early tensioner. However, if the bore is already galled, the damage is done and the plastic piston isn't any help. It needs a smooth, close-fitting bore.

In early versions, the body's central hinge was just a steel pin in bored aluminum holes. If the holes wore, the moving part of the tensioner could cock at an angle, and the belt would tend to run off center on the pulleys. The official fix was to replace the tensioner.

The later tensioner added Nylon bushings (shown in the attachment) to over-size hinge bores. If the bushings wear, just replace them and put the tensioner back in service.

Make certain there is no slop in the hinge that will allow the roller arm to cock off to either side.

Regards,
Tim Engel

Item .. Description .............................. Part Number
040 ... Snubber .................................. B907E1140F
041 ... Spacer, With Snubber ............... A907E1139F
042 ... Spacer, to block without Snubber A907E1138F
043 ... Stud. M10 ................................ B907E0504K
046 ... Bolt, M10 x 70 .......................... A075W2058Z

Attachment: Timing Belt, Pulleys & Automatic Tensioner & Snubber - 1980-87 Esprit.jpg (Downloaded 153 times)

Last edited on 04-25-2015 04:54 pm by Esprit2