Shims,bent valve etc HELP

[zman]

So here goes
Whent to check valve clearenss and found only no1 was right two shims where much to big and the rest to tight.
no1 got compresion but not on 2,3,4
I suspect there may be a bent valve in 3,4 as they are big.But an over tight clearaness could hold valve open which would also loes compresion.
ARE YOU STILL FOLOWING ME
THE QWESTION IS
if i re,shim to the correct sizes and i still have no compresion this will indercate bent valve.will removeing had and cams mean i will have to re,shim again

[Big Fluff]

Yes, either way you will have to re-shim the head.

The best way to check for bent valves is like this:
First, get hold of a cylinder leak-down tester. I have mad such a tool to allow this by using an old spark plug, knocking all the crap off it and welding an air line fitting on top. You then screw the fitting into the plug hole.

Next ensure you have clearance on all valves.
Note... If you can't get sufficient clearance with even the thinnest shim, do not be tempted to leave the shim out altogether and turn the engine over as the cam lobes will burr over the cam followers and you'll then struggle to insert shims!Fit the leak-down tester into the required plug hole and compress the cylinder with air at TDC say 5 bar and lock off.
If the pressure holds, all is good. If it doesn't then air will be escaping from either:-
The exhaust (indicating a bent exhaust valve)
The air box/carb inlet (indicating a bent inlet valve)
The crankcase breather/air box (indicating worn bores etc)
Hope this helps, Will

[baz]

hi pal, why do you think a valve is bent, valves don't just bend on there own, have you over reved the eng or heard a noise recently ?. my bet is its a shimming issue but even that will now req the head off to do a proper job, when carbon biulds up on the valve seat it goes rock hard with the valve hammering away at it and won't budge without lapping the valves in again.

[CAT3]

I would say you've got bent valves.
Replacing shims to get the correct gaps for those valves which require adjusting & then doing another compression test is potentially only going to inflict more damage on the engine !
Spinning the engine to do a compression test is not a good idea when you suspect bent valves. Take the spark plugs out & turn the engine over very slowly BY HAND using a spanner on the bigger of the two nuts on the points end of the crankshaft & if you feel ANY resistance STOP.
Take the cam cover off & check the valve timing marks. Also check to see if one or more of the valve gaps has gone big. A bent valve will be partially open & the gap should be much bigger than it would normally be.

Once you've replaced the bent valves fit the smallest shims & measure the gaps, then make any neccessary adjustments.

[zman]

Thanks for help sao far
I think i may have bent valve as i had a someone re,do head about 1000miles ago so would hope it was correct at that point.
I have bean doing a rebuild which involved removing the head and now all gaps a wrong[mined u i didnt check before removal].
i turned engine over by hand and seamed a little stiff but seteled down.
I have read that if you have realy big gaps you could have bent valve

[chrisu]

does sound like you may have bent a valve

doesn't take a lot.........

head off I would suggest.