11 replies to this topic

[Mini-Hazel-Nut]

Having bought my 7 port head complete with valves etc I assumed it ready to fit from that point of view. It turned out that the machinist`s idea of de-burring and mine weren`t quite the same and to do the job properly I had to take all the valves out in order that I could do the the job of de-burring and then flush it all out to remove all the swarf and other bits of ooh-nasty. I haven`t got a valve spring compressor and didn`t feel like buying one for just this one job so I adapted an idea I used back in motorcycle days. Simple you need a fixed fulcrum which in this case is a piece of studding nutted onto a workmate and a piece of scrap metal as a lever. As you can see there is a hole of irregular shape in the lever for access to the cotters and you simply apply pressure to said lever to release the cotters and remove them with refitting just being a reversal of that. It`s simple, effective and at the total cost of bugger-all really quite cheap. Pop a piece of scrap wood under the valves in the combustion chamber and that keeps them from dropping whilst you work on them. The pics----  Head and lever.jpg   50.86K   54 downloads  Cotter close.jpg   29.68K   37 downloads

[Badboytunes]

Brilliant ide. However, are they not called collets and not cotter's?

[cal844]

Looks good, if a bit fiddly trying to keep pressure on the valve

[Guess-Works.com]

Getting the collets out can be done with a socket and hammer, just getting them back in you need a tool.

 

What I would like to know is why you're de-burring a head, this should have all been done by the manufacturer BEFORE you got the head...

[Cooperman]

That is how we change valve springs without removing the head on rally cars during events. Just use a piece of bent metal rod down the plug hole to hold the valve closed then remove the collets, change the spring and put the collets back. A very quick & easy job. With a thin piece of steel rod, a piece of wire coat hanger for example, and the piston brought to lock the wire in place the valve cannot drop. It's a 10 minute job.

[dklawson]

I have done the same as Cooperman except I replaced the coat hanger with a bit of cotton rope.  However, when I did this it was not to fit new springs but new valve guide seals in a futile attempt to postpone rebuilding the head.

 

Sorry that you are having to spend a lot of effort on this new head.  I agree with Guessworks that the manufacturer should have deburred everything prior to delivery.

[Dusky]

What is de-burring?

[Stu1961]

What is de-burring?

Removing sharp raised edges from freshly machined components.

Edited by Stu1961, 10 October 2014 - 05:11 PM.

[Mini-Hazel-Nut]

Hello all and thank you. I think you may be right and I should have said "collets" and not "cotters" which have a similar application. The machinist did do a job of de-burring but as I said - not to my idea of it. After 20 years in military aircraft manufacture one gets a bit finicky about these things.

[Tamworthbay]

Title edited for you.

[Mini-Hazel-Nut]

Thank you, that clinches it - I should have said "collets" lol. In answer to the above point about maintaining pressure on the spring; with that length of lever even keeping my double springs down was easy. However having said that I will admit that having 3 hands would have helped considerably.........

[ibrooks]

I've an almost identical piece of ally angle that I've used this way for years (OK mine isn't so clean and shiny). I do it on the floor though with the head sat on a wooden board and the end of the angle wedged under the horizontal along the front of my workbench. The angle is long enough that it doesn't need much pressure on the far end to compress a valve spring so after a tap with a hammer to free the collets from the spring cap you can easily hold it down with your knee and use both hands to get the collets out.

 

You can buy tools for Pintos and CVH's to do them with the head in place. Generally wind the piston down a little then shove rope into the chamber before lifting the piston again to wedge the valve closed.

 

Iain