Topic: 1970 CB750 Camshaft Holder - Determine which side of the head for each holder

[cfairweather]

I am almost ready to install the camshaft and have a question about the camshaft holders.  Keep in mind that the previous rebuilder mixed up the caps with the holders, so the cam was in a bind.  I can easily match the correct cap with the holder, but I don't see a way to make sure the holders are on the correct sides.  The holders were bored from the factory as a pair, so it seems there should be an ID mark that reveals which side of the head matches each holder.  On both holders there is a "H" painted on one end.  The other end of one has "03E" and the other holder has "0AB" on it.     I have seen these types of markings on  other CB750 engines and have seen no consistency, but the letters must match something, right?

On the head, near the puck holes there are markings:

Looking at the engine from the front: Reading from Right side of engine to the left:  ?    E    I   H

Is there a way to determine which side a holder goes?

[cfairweather]

Here are some pictures:

[cfairweather]

More information and a theory: 

Holder 03E:  Cap numbers are Z3 and Z4
Holder 0AB:  Cap numbers are V7 and V8

I think the "H" on one end of each holder was written with some very permanent black ink.  It has survived, so I think the factory must have done this.  Could it stand for "Hole," so the mechanic  would put that end next to the camshaft chain hole?  I know, this might be ridiculous...   

[bryanj]

They were NOT bored as pairs, any cam holder can go in either position in any 750 as long as the dowels are in place.
Mismatching caps can make the cam tight but i have seen odd caps used in a pinch

[cfairweather]

Thanks for the info.

[Don R]

 One end of the cam has a washer, I look for a witness mark from the washer. I try to keep them paired when possible. It might only matter to me though.

[BenelliSEI]

One end of the cam has a washer, I look for a witness mark from the washer. I try to keep them paired when possible. It might only matter to me though.

+1 to this. I like putting things back where they came from.

[HondaMan]

The 2 cam bearings that were [previously] toward the cam sprocket will show the most wear. The outer ones wear very little unless there was some catastrophic event.

[bryanj]

I really should have said when replacing with different they can go in either position, if rebuilding an engine its always good practice to put things back in same place thay came from.

Big thing with these engines is NO SILICONE SEALER ANYWHERE

[cfairweather]

Good suggestions to help figure out where they were originally installed.  I think Honda may have positioned the holder with the 3 letter/number markings on the far ends, instead of being covered up by the cam.  If my theory is correct, it would be a way to make sure they go back to the original position. 

[bryanj]

Doubt it, cos if you put them in the other position you dont turn them round

[PeWe]

Is head flat?
My shop mechanic always check if head is flat, not banana before working on it.
Both sides, upper without cam holders to avoid binding cam.

Important to tighten head nuts in right order from inner to out. If tighten outer first and inner after, head will probably get a banana shape.

I usually tighten in several steps
Just lightly,  5, 10, 15, 20....
Everytime from inner to outer , the first inner 4 + 2 on each side going outwards.

The small M6 get their final when all are done. Around 9Nm.

20 ft lbs no problem with stock studs.
I use HD studs so a little bit more. MLS head gasket need 22 ft lbs.

Honda manual say very high torque on cam holders.
Why tighten harder than recommended  max torque for a steel 8.8 bolt ?

Alu threads not that deep do not like it.
I tighten 8-9Nm (6-6.5 ft lbs) despite time-sert thread inserts.

I have a good torque wrench for small . 2.5-25Nm 1/4 sockets.

Another for head and clutch, 10-60Nm.

Nm vs ft lbs
https://www.unitconverters.net/energy/ft-lb-to-nm.htm