View single post by Esprit2
 Posted: 01-24-2018 04:54 pm
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Esprit2

 

Joined: 05-01-2005
Location: Minneapolis, Minnesota USA
Posts: 321
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Simon,

There's no standard for how badly damaged a journal can be, and still be useable. IMHO, this one shouldn't be used as is. But take it to a machine shop and see if they can restore it welding metal back onto it, then grinding it to the correct diameter. If you go that way, then take the following specs to the shop. These are un-published specs you won't find anywhere else. I got them from a Lotus engineer.

Cam Bearing Journal, OD
Front, #1 = 49.746 - 49.759 mm (1.9585 - 1.9590 inch)
........ #2 = 49.492 - 49.505 mm (1.9485 - 1.9490 inch)
........ #3 = 49.238 - 49.251 mm (1.9385 - 1.9390 inch)
........ #4 = 48.984 - 48.997 mm (1.9285 - 1.9290 inch)
Rear , #5 = 44.412 - 44.425 mm (1.7485 - 1.7490 inch)

Cam Carrier Bore, ID
Front, #1 = 49.835 - 49.860 mm (1.96201 - 1.96299 inch)
........ #2 = 49.555 - 49.581 mm (1.95098 - 1.95201 inch)
........ #3 = 49.301 - 49.327 mm (1.94098 - 1.94201 inch)
........ #4 = 49.047 - 49.073 mm (1.93098 - 1.93201 inch)
Rear , #5 = 44.475 - 44.500 mm (1.75098 - 1.75197 inch)

Running Clearance
All ......... = 0.0508 - 0.0889 mm (0.00200 - 0.00350 inch)

Cam carrier bores are to be straight, and all working surfaces (machined bottom) are to be parallel to the cam bores (ie, no bent/ warped cam carriers are allowed).

Side Note:
When a cylinder head warps, the whole thing warps like a banana. Simply milling the bottom flat may leave the top side seats for the cam carriers warped. When the cam carrier is bolted to the warped seats on the head, it may be pulled into a matching warp of it's own. That's not acceptable. At the least, getting a leak-free seal between a straight cam carrier and warped head seat will be an exercise in frustration.

Good luck,
Tim Engel