Topic: 750 cam cradles, and cap interchange.

[754]

Got two questions here,
If a cam cradle has same marking, as a random sourced from other engines, will the two be perfect fit ? I am thinking probably.
Second, how many marking combos are there, I think we should start a list.
If a letter and a number combo, that is 260 possible combos right there.
 Any thoughts ? Or markings to add to a list?

[disco]

Hi Frank,

Can't help with the first question.

Regards the 2nd question, the CB750 (392) engine that I am working on atm only has two alphabet characters stamped on the cam towers.

Ignore the numbers. I stamped those on so I knew how to put the cam towers back in same position. Attached are pictures.

[kmb69]

Got two questions here,
If a cam cradle has same marking, as a random sourced from other engines, will the two be perfect fit ? I am thinking probably.
Second, how many marking combos are there, I think we should start a list.
If a letter and a number combo, that is 260 possible combos right there.
 Any thoughts ? Or markings to add to a list?

I may be wrong, but I don't think the cam tower markings are related to size like cranks, rods and crankcases.
Pretty sure they were just stamped uniquely at manufacturing to identify which parts were machined as a set.

[754]

I think it is possible to mix and match, but should be plastigaged. .
Also checked side to side, i think an expanding hole guage may show that if you had good feel.
 If the cap were out enough side to side, you may get almost zero clearance on one side, and double on opposite side.. I suppose. Plastiguage at 2 oclock and 10 oclock would show this..

I picked up a pair of nice lower cradles at a swap meet (along with head), but no caps. The vendor, a bike wrecker said they probably have them , but I wonder if same marking caps will be off the actual set or not..probably has a boxful..
 Letter letter combo, can give about 676 possible combos.
 
 It may be possible that the letters have actual meaning, in terms of X or Y coordinates, in relation to the dowels...... Be curious to see what the process at the factory was..

[kmb69]

I'm guessing, cause I never done it, you could check the roundness of mismatched caps with a dial bore gage and find some decent matches.
Over the last few months, I have been reverse engineering some of the "unobtainable" NOS parts. Actually quite surprised to see the variations.
Always thought Honda was super precise in their manufacturing processes, but as I should have known, they had to have manufacturing tolerances.
Most notable variations come in hole position deviations. Typically less than .5mm or .02". Other dimensions like bearing surfaces are quite close.
The trick in machining most castings is holding the casting in the first operation to get the "alignment holes" placed correctly for subsequent ops.
You're a machinist - you know. I'm probably singing to the choir!

[drumstyx]

Do the caps usually wear much anyway? My understanding was that the real wear was on the cradles themselves, so the only way you'd have to swap around is if someone carelessly lost the matching caps...

[kmb69]

Do the caps usually wear much anyway? My understanding was that the real wear was on the cradles themselves, so the only way you'd have to swap around is if someone carelessly lost the matching caps...

That's generally true. Frank bought a nice set of cradles without caps and is trying to figure out how to best match some "cousin" caps.
It's a real shame that many "parters" don't know or care about keeping matched parts together.
New cam towers have become very rare and when found are unbelievably expensive.

[BPellerine]

I put one cap in the wrong place once and the cam would not turn by hand,one way to learn!bill