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Just received a cam from Sallee Chev which is their advertised "350 take-out" base 14088839 cam. The cam has casting marks of "CWC" and "USA" and a stamping on the distributor end of 232178. There are also some two character casting marks. I was thinking the CWC was a Crane Cams thing since I know Crane makes a "839" grind witch GM sells in a kit #12364051.
Question is....Can anybody verify that this is really a 14088839 based on these identifing stampings and casting marks?
I've seen the "CWC" casting mark on other GM cams. I don't know what it refers to but I don't think that it refers to Crane. I suspect it refers to the foundry that produces the cores. The Crane-manufactured cams included in the GM kit which you refer to is a SERVICE-only item; I don't think that any of these parts were/are used in PRODUCTION.
It is very possible that some outside supplier does manufacture the 14088839 camshaft, though-----at least the cores. I'm sure that with production of these camshafts so low now, GM no longer produces specific cores for them. So, generic cores are used. This has no effect, whatsoever, on the finished product. High volume= specific cores to minimize machining; low volume= generic core more economical overall.
I feel very confident that the cam in question is a GM piece. As always, a GM piece does not necessarily mean that it's manufactured by GM. A vast array of parts are GM parts that are not actually manufactured by GM.
These days virtually all components for small blocks that are still manufactured in-house by GM are manufactured at the GM engine plant in Toluca, Mexico. ALL Gen I and Gen II small block major componts that are manufactured in-house by GM are manufactured there. In this case, it's possible that the camshaft cores are produced at some outside supplier to GM in the USA and shipped to Toluca for machining.
The distance from the CENTER of the base circle to the POML is .922/.924 for both lobes. The base circle RADIUS for the inlet lobe is .66346/.66746; exhaust lobe BCR is .65098/.65498, and the max lift, inlet/exhaust is .25654/.26902.
So if you run a caliper around the lobe, the maximum distance from the base circle to POML should be as follows plus or minus about three thou max tolerance stackup:
Thanks Duke and Joe...you guys both amaze me! Duke your spot-on 1.575 and 1.588 on a digital caliper. What's interesting is that the original OE GM cam looks to be about .030 under these measurements. Does that sound right?
Original cam is from late June 65 built motor...see pic of cam casting marks. My measurements are coming up over those your quoted....hmmmm Is the OE 66+ cam different from the 65 300hp?
Are we talking about the same cam? My OE cam has the 2798 casting as pictured above. I understand from previous posts that is part number 3733431. Are the specs you quoting for the 9630 the same as the 2798?... Pardon my confusion, although it sure would be quite provocative to have a growing cam shaft...!
I will recheck my recheck on the 2798....and report back
Okay, that's the early "300HP cam" - OE from '57-'66 in base engines and some optional engines - part number 3733431 (cam and pin assy.) finished camshaft part number 3732798. Both lobes are identical, 196 degrees duration @ .050" lifter rise, 109.5/112.5 POMLs.
Base circle reference radius: .695
Center of base circle to POML reference dimension: .955
Gross lobe lift: .26581
So the bottom of base circle to POML is 1.650 based on the reference dimensions or a little more if you add twice the base circle radius to nominal max lobe lift. So it sounds like there is a good amount of wear.
Since the total lobe eccentricity is less than 180 degree, you should be able to measure the base circle on a dimeter normal to the radius of the POML. Check this to be sure it measures 2(.695) = 1.390. There should be no wear on this radius.
This cam is not the GM #3896929. It's a GM #3733431 which is the predecessor of the 3896929. The casting number of the 3733431 is 3732788, the derivative of which is seen in your picture.
The GM #3896929 was first used for the 1967 model year.
This would yield a nominal 1.557 top to bottom. Since my measurements come range from 1.540 to 1.554 there is anywhere from .017 to .003 wear on the old 2798. Interesting the new 8839 has a considerably bigger base radius than 2789, and a bit LESS effective lift.
I will verify the base circle measurement on both.
Sorry, I listed the as cast dimensions. (My excuse) It's a VERRRY old drawing (redrawn and revised 1959, last change 1967).
The machined base circle radius is .64460/.64660, and base circle radius center to top of lobe is .91041/.91241, so the nominal bottom of base circle to top of lobe is 1.55701.
IMO if you measure .005" less than this nominal, which is .003 less than the minimum with maximum tolerance stackup on any lobe, the cam is the limit for a precision rebuild, and more than .010" wear definately warrants cam replacement.
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