changing cam caps - how should it be done?

[malmojoe]

I have a couple of early Z1 heads I would like to use which don't have the cam caps.
I know that they are drilled in place, but also remember someone on here saying that it was possible to use 'foreign' caps, if done properly. How should I go about it?

[zed1015]

To be perfectly honest you really need an engineering background to do this correctly and the minimum you should need is an internal bore gauge, some new cam shells,plastigauge, surface plate and at least a handfull of caps.
It is not really a simple case of bolting on a cap that does not nip up on the camshaft as the cap can still be out in several planes.

You can of course just bolt on some caps that don't nip the cams and you will get away with it for a while with the risk of increased shell wear, top end noise and fluctuating valve clearances.
You will need to test fit each cap with the cam bolted in on new shells but with all valves removed so the cam can be rotated freely.
If you used the correct numbered cap for it's location you will have an increased chance of success.
A least use some plastigauge if doing this to ensure the clearances are not too tight.
The spec's for this are in the factory manual.

[jimmock]

I know we have been down this road before......

I personally WOULD NOT fit a second hand alien cap into a head (or block).

When my Mondeo broke the belt a few months ago, it snapped the cam into three and broke no.1 cam cap.
I got a cam cap from a buddy, but I chose to buy a second hand head with cam and caps.

[zed1015]

I have done loads with no problems as i know what i am doing.
Got two heads in now for the same treatment.
My own Z1R has rogue caps on 1 and 4.
15 years and still counting, it's sweet as a nut and that's used most days not a low mile weekend warrior.
The trick is not to have them tight and knowing what to do to correct it.
Anyone saying it can't be done doesn't really know what they are on about.
Please send your "scrap" capless heads or headless caps to me for disposal FOC.

[750steve]

Interesting read guys. I've also seen it mentioned that the caps numbers 1,2,3,4 etc don't necessarily be fitted in numerical order, i have only read this once before so i can't say if it's true.

On a Z650 / GPz / Zephyr etc there are no shells for the cams, they run on an oil film pumped up to them, is it as necessary to get it right in that case.

Ps im only asking, im keeping my cam caps in the order they were on the head when i got it!

[zed1015]

There is nothing to stop say a number 3 cap etc being used in position 1.
There is just more likelyhood that a number 1 cap will be a better initial fit in the number 1 position due to the manufacturing process.
Using caps from another engine that was in the same production run will increase the chance of a match without much adjustment.
All the cams wether shelled or not run on a film of oil and require no less accuracy when fitting caps.
Can't comment on your head as i don't know if the previous owner knew what they were doing or just slapped on any old caps that were knocking about.

[750steve]

Can't comment on your head as i don't know if the previous owner knew what they were doing or just slapped on any old caps that were knocking about.

I don't think he did............but now im paranoid!

[kev edwards]

Done it on my old thou and it's still out there running with it's new owner, there is plenty of arguments about this, as long as the cams run smoothly once in it will be ok, we tend to forget that these were made on very good machinery with each boring tool used for a limited amount of motors before being changed for a new tool thus giving a very good chance of being able to swap caps without running into problems, still with parts now becoming harder to find we have to stop being blinkered and think outside of the box to keep these great motors running.

[malmojoe]

I'm just wondering about the tolerances and I'm going to be devils advocate here for the sake of discussion.
Sure the caps were matched during the manufacturing process but that would be the logical way to do it - doesn't necessarily mean they can never be interchanged - where does that idea come from?, after all they are just housing the shells and its those which contact the camshaft and take up any miss-alignment. Considering that the both caps would be drilled from one side, there can't be much variation between heads, even a 10th of a degree off on the drilling and the cam wouldn't check out.
And if the engineering is so precise, the cams would also have to be matched and irreplaceable.

flame away.


ok Kev just did this already.

[zed1015]

As i said.
Anyone saying it can't be done doesn't know what they are on about.
I've done it loads of times so there is no arguement. Simple.
As for tolerances, use plastigauge and refer to the factory manual as it's all in there.
The shells do not take up misalignment.
I could write an in depth article on how to proceed but it would take up pages and i haven't the time or inclination.
In cases like this all i can say is that if you need to ask how to do it then you shouldn't attempt it anyway.

[kev edwards]

The cams run on a film of oil, if the caps are out the cam will rub on the shell, so if the cam binds when you are bench setting wth no valves in the head one or both the caps is not right, it can take a while but it can be done, as zed1015 if you have to ask then don't do and get help.

[jimmock]

As i said.
Anyone saying it can't be done doesn't know what they are on about.
I've done it loads of times so there is no arguement. Simple.
As for tolerances, use plastigauge and refer to the factory manual as it's all in there.
The shells do not take up misalignment.
I could write an in depth article on how to proceed but it would take up pages and i haven't the time or inclination.
In cases like this all i can say is that if you need to ask how to do it then you shouldn't attempt it anyway.

The film of oil is called a DYNAMIC WEDGE.

Go into ANY main dealer and try to find a part number for a cap for a head or block.

There is no such option.

The caps are supplied with the head or block.

I NEVER said it couldn't be done, I said I WOULDN'T consider it!!!

There are MANY things that "shouldn't" be done that are done.
It is down to the individual in question.

I have scrapped my Mondeo head (worth a LOT less than a Zed head) for the same reason.
If my head was the last one on the planet, of course I would have "chanced it" with the cap I had the option of, I instead chose the second hand complete head for £60.

[zed1015]

As i said.
Anyone saying it can't be done doesn't know what they are on about.
I've done it loads of times so there is no arguement. Simple.
As for tolerances, use plastigauge and refer to the factory manual as it's all in there.
The shells do not take up misalignment.
I could write an in depth article on how to proceed but it would take up pages and i haven't the time or inclination.
In cases like this all i can say is that if you need to ask how to do it then you shouldn't attempt it anyway.

The film of oil is called a DYNAMIC WEDGE.

Go into ANY main dealer and try to find a part number for a cap for a head or block.

There is no such option.

The caps are supplied with the head or block.

I NEVER said it couldn't be done, I said I WOULDN'T consider it!!!

There are MANY things that "shouldn't" be done that are done.
It is down to the individual in question.

I have scrapped my Mondeo head (worth a LOT less than a Zed head) for the same reason.
If my head was the last one on the planet, of course I would have "chanced it" with the cap I had the option of, I instead chose the second hand complete head for £60.

Correct on all counts but my comment was not a response to your post but to all the nay sayers who chime in EVERY time this subject comes up stating it can't be done ( I should also point out that the world is not flat and there is no such thing as witches )
I just decided to get my response in first to stop the thread in its tracks before it dragged on needlessly.
Obviously that approach didn't work
Most people know the caps are machined in situ with the head and are not available seperately for that reason and when i am forced to use a foreign cap (which is becoming more frequent) it takes quite a bit of time and skill to match one up and not just a case of whacking on one that isn't tight, it will take several different caps to find one that is close enough to correct.
The fitting of odd caps is not a recent issue though, the Orient express drag bike i am currently involved with has odd caps too and their use shows no detrimental affect even in a high performance engine that has possibly been that way for 30 years .

[jimmock]

As i said.
Anyone saying it can't be done doesn't know what they are on about.
I've done it loads of times so there is no arguement. Simple.
As for tolerances, use plastigauge and refer to the factory manual as it's all in there.
The shells do not take up misalignment.
I could write an in depth article on how to proceed but it would take up pages and i haven't the time or inclination.
In cases like this all i can say is that if you need to ask how to do it then you shouldn't attempt it anyway.

The film of oil is called a DYNAMIC WEDGE.

Go into ANY main dealer and try to find a part number for a cap for a head or block.

There is no such option.

The caps are supplied with the head or block.

I NEVER said it couldn't be done, I said I WOULDN'T consider it!!!

There are MANY things that "shouldn't" be done that are done.
It is down to the individual in question.

I have scrapped my Mondeo head (worth a LOT less than a Zed head) for the same reason.
If my head was the last one on the planet, of course I would have "chanced it" with the cap I had the option of, I instead chose the second hand complete head for £60.

Correct on all counts but my comment was not a response to your post but to all the nay sayers who chime in EVERY time this subject comes up stating it can't be done ( I should also point out that the world is not flat and there is no such thing as witches )
I just decided to get my response in first to stop the thread in its tracks before it dragged on needlessly.
Obviously that approach didn't work
Most people know the caps are machined in situ with the head and are not available seperately for that reason and when i am forced to use a foreign cap (which is becoming more frequent) it takes quite a bit of time and skill to match one up and not just a case of whacking on one that isn't tight, it will take several different caps to find one that is close enough to correct.
The fitting of odd caps is not a recent issue though, the Orient express drag bike i am currently involved with has odd caps too and their use shows no detrimental affect even in a high performance engine that has possibly been that way for 30 years .

Zed1015,

I never took it personally.

I do NOT doubt your ability and obvious vast knowledge.

It is and always will be a controvesial subject.
Don't get me wrong If I had a zed head with a shattered cap, I would try an odd cap before I scrapped the head. It would be the ONLY way to go.

I chose the head option for the Mondeo as I had that option at the time.

I dare say if a head was not available I "probably" would have used the cap I had.

Keep up the good work.

[garyd]

Don't forget guys...these engines got a reputation for being bullet proof..for good reason...

I learnt how to strip and rebuild these just by doing it.

I even ran an old shaftie that needed to be rebuild with both the cams one out on the cam chain....it felt a but 'fluffy', so I had a look...saw what I'd done ...rectified it and it ran for several years till I lost track of it.

You really do have to be a complete and utter "@" to really screw up one of these....


but that's not to say you shouldn't do it right.