new 4/9/03
Thanks to Sarah for the Digest this week, always good reading.
Thought I would add one other bit from the Illinois Camfest.
I may have been the first to buy the new lower priced SHO V8 cams from Ford. My local GOOD dealer (Mangold Ford Eureka, IL...highly recommended) got for me, in two days, a new cam at the new lower recommended price of $150 (with my discount it was a bit less).
My hope was that the new cam would indicate some change from previous designs, but I wasn't betting any big money on it.
Visual inspection indicated that the cam appears the same as previous units. Same construction.
Things we know:
1. The cams are built up from parts that a slid onto a smooth shaft. Teeth marks on the shaft show how the parts are shoved onto the shaft with a slight interference fit.
2. The shaft is then expanded somewhat to force the teeth on the back side of the lobes/sprocket etc. into the camshaft, thus when you take one apart, you see deeper markings in the softer shaft material.
3. The new cams are made in Japan if you can believe the notice on the box. Not sure where the old ones were made.
4. After the shaft is together, the bearing surfaces are turned down, otherwise, sliding on the various parts would be tough.
5. The main sprocket mount is then driven into the end of the shaft to a depth of about 2.5" or so. Just before the first cam lobe, and UNDER the sprocket that fails, thus when you pin a cam, the pin goes through a totally solid shaft, not just a hollow shaft. I wonder if the older cams had this sprocket mount this deep...can someone with an older cam in hand measure to see?
Kirk is now in possession of the new cam and it is our hope he will find a way to do some measurements to see if any difference can be found.
Speculation is that the process of expanding the cams might be quite tough on the tool for that process. Could be that when the cams were first made, that a service life was extended too far and later cams did not expand enough to keep the sprockets in place, thus the failures, and why some cams don't fail.
Could be that the new cams are expanded a tiny bit more, possibly very accurate measurement of old and new cams will reveal any change there?
I wait to hear from Kirk.
Eventually this cam (suitably welded just in case) will wind up in a customer's car at Kirk's place.
Don Mallinson
Don,
Using Mike Frey's old design cam as reference;
1/ Non-ground shaft OD (re: component mounting surface) 1.043" - 1.045" (26.49mm - 26.54mm)
2/ Non-Drive End bore ID dia. (this is the secondary dia. about .25" in from the end. First dia. Is most likely machined relief for the dead centre used in the grinding the "don't call me a bearing" surface. *<:)
.717" (18.21mm)
3/ NDE bore depth 14.48" (+/- 1/64) (367.665mm)
4/ DE bore dia. (same note as #2) .425" (10.80mm)
5/ DE bore depth 1.30" (+/- 1/64)
6/ Cam lobe height in reference to again the "don't call me a bearing" surface. .57" (14.48mm)
Unable to ascertain what the OD dia. is of the solid shaft due to no reference surfaces being available.
These known dimensions put the end of the solid shaft just shy of entering the first lobe or about .50" past the sprocket mount.
Wrt the shaft being solid under the sprocket, that has been around for a bit. Carter's been onto that from the start and kindly reminded us a few times that indeed it was solid.
John Hamilton
Ida, ON, CA
'97 ES
'91 Mocha/Mocha
'89 S10 Blazer 2WD