cam cap work machine shop needed?

[cbcanada]

i have a cam cap i am replacing. same model bike same cap. however the clearance tolerence is appearantly slightly different from bike to bike by VERY small amounts.

is there a machine shop that could match it identical?

if i use the new cap and the tolerence is slightly off (which it seems by feel) then the cam is going to rub. what would happen? would the cam wear out so that its not hitting valve correctly?

the cam is steel and the cam cap is aluminum, so the wear should only be on the cap?

 

[zeniceguy]

if its the same cap from the same year/model there should be no issue. as long as there was no issue with either bike

 

[cbcanada]

if its the same cap from the same year/model there should be no issue. as long as there was no issue with either bike

thats what i figured but was told otherwise. that infact there is small differences. hence i am on here asking

 

[zeniceguy]

there may be some slight wear differances but only that. you may wand to inspec the cap for any grooves but if its clean you should have no issue.

if the tolerance s to large you will have slightly lower oil pressure
if it is to tight it will sound horible

 

[JohnnyP636]

if its the same cap from the same year/model there should be no issue. as long as there was no issue with either bike

That is false cam journals are machined after the alignment pins have been machine and installed. Cam caps and cylinder heads are matching sets, and you can't buy one withou the other because of that. If you want new cam caps you need to buy a whole new cylinder head.

You can't machine them because that would make the journal bores bigger, and there is only one size of cam journal.

You might get lucky and have a different set line up close to perfect, but if they are even slightly off they will bind on the cams and cause journal wear.

Bottom line it might work but it's not proper, you should always use a matching set

 

[zeniceguy]

As far as aluminum heads and steel cams go I have changed of 50+ in cars. (dont see the diff?)
you should be fine as the engines have been made to specific specs and tolerances.

 

[cbcanada]

That is false cam journals are machined after the alignment pins have been machine and installed. Cam caps and cylinder heads are matching sets, and you can't buy one withou the other because of that. If you want new cam caps you need to buy a whole new cylinder head.

this is kind if whAt inwas told .

 

[cbcanada]

what will be the outcome of the journal wear?

 

[Brian P]

If the centerline of the cam was machined a smidge lower on the set of cam caps that you put on, it will be too tight on the camshaft and it won't let the camshaft rotate at all, it'll simply clamp it in place.

If it's the other way then there will be excessive oil clearance. Not ideal but also not the end of the world. It will reduce oil pressure throughout the engine, which will probably shorten its life. By how much ... who knows.

If it's offset left or right then it will act like being too tight.

The worst case is if it's tight but not by enough to clamp the camshaft. Then the engine will start and run, then seize at the camshaft, and possibly break the timing chain in the process, thus causing lots and lots of damage.

Service manuals always state that the camshaft caps are a matched set to the cylinder head. I have heard that a lot of newer engines have machining processes that are accurate enough that the camshaft caps can be interchanged despite what the factory service manual says.

Car engines don't spin as fast and are designed to work with sloppier tolerances.

 

[JohnnyP636]

what will be the outcome of the journal wear?

Journal wear eventually leads to journal failure, as in clack clack clack boom....How fast or how bad the failure will depend on how close the tolerance is between the mismatched head/caps, and RPM at the time of complete failure...And how long you let it run after the damage is caused....Its like crack bearings, if you stop the engine as soon as you hear the bearing spin and start clacking, you will only damage the journal on the crank and bearings...Or you can keep running it till the rod splits open and flys through the engine cases, and or demolishes the valves and cylinder head...

You can measure the roundness of the bores to see how close it is.....If your super lucky it might be passable...I wouldn't do it with an engine I cared about though...If its not close enough it can cost a lot more then buying a used cylinder head with matching caps...