|View single post by Esprit2|
|Posted: 11-12-2016 08:56 pm||
Would one of the kits pictured (Kemp High Performance engines) be a direct replacement? They advertise this as an upgrade from the S3 auto tensioner to manual and needs an M10 thread into the block, well we already have that so this may be a good upgrade for the part above plus as a bonus the tensioner nut is integrated into the hub so no more slop when adjusting and you get a new tensioner roller with every change.That's the Lotus version of the eccentric tensioner. All the Lotus tensioners used the double-row bearing/roller, instead of the J-H assembly that uses two 6005 single-row ball bearings in a roller sleeve. The two major differences are 1) the purpose-made tensioner bearing/ roller, and 2) moving the adjuster hex to the front side, where it's easily accessible. The eccentric hub is a press-fit into the bearing's bore.
Garry Kemp has simply pulled all the Lotus parts together into a kit to replace the spring loaded tensioner... plus a couple you shouldn't need. Your engine already has the stud. I don't recognize the spacer sleeve in the upper left of Kemp's picture, above the eccentric hub. I'm GUESSING, but it looks to me that he's using that as a spacer to replace the boss that is not present on the earlier front seal housing (right in the attached JPEG).
But your J-H 907's front seal housing also has a boss for a tensioner eccentric, very similar to the Lotus seal housing. The question is, are the bosses & bores the same diameters for both the J-H and Lotus designs. I don't have a J-H part here to check, but I have a Lotus eccentric hub in my hands. Just measuring with a dial caliper (what the heck did I do with my micrometer?), the male boss is 0.810 OD x 0.720" tall. Check yours.
My guess is that the Lotus eccentric is a direct replacement for the earlier J-H eccentric, and Kemp's kit gives you more parts than you need for the conversion. Before you buy, see if you can get the hub alone for less money (check SJ, JAE, etc). Then buy a bearing, washer & Nyloc nut near you. The bearing is SKF 414871A (excellent), Flennor FS03299 (now sold by JAE), Ford 1500004 (1977-86 Transit Van), 31mm ID x 63mm OD x 30mm wide. Just beware. There are some inexpensive Chinese copies out there that are bad right out of the box. One in partricular has blue seals... pure crap. I make a point of asking for SKF.
I heed your advise on the belt tracking yet as i will be doing tension testing for the Gates Blue Belt. (I now have Kriket and Burroughs gauge) i need to get the tensioner correct.Yup, it is nice to get the tensioner correct. The belt is tightly located fore-n-aft at the crank sprocket.
The curved back side of the V-belt pulley, and the backward curved washer behind the sprocket form a 'funnel' that guides the belt onto the narrow crank sprocket. There's not much room for the belt to wander off. That set's the belt's position on the engine, and is a constant on all the 9XX 4-cyl engines. Any tracking issues at the upper pulleys is a matter of the entire belt loop 'leaning'. Early cam/ auxiliary sprockets were not centered very well above the crank sprocket, so it's not unusual for the belt to be less than centered, even when everything is 'straight'. What looks like incorrect tracking may not be the belt getting off-track. In the mid-late 70's, Lotus adjusted the width of the hub to improve the pulley's position under an otherwise straight-tracking belt.
Attachment: Sec ED - Engine - Front Main Seal Housing - 1974-80 907 74kb.jpg (Downloaded 50 times)