Valve replacement

[Ahmedsinc 414]

Righto, so I've swapped the exhaust valves that I believed to be bent on the M54 head.

Whats the best way to check if they're all seated correctly? Bear in mind I'm a DIY hack and it's my first ever go at tackling valves.

My best idea so far is to invert the head and fill each bowl with kero and see if anything comes through the zorst ports. Would this give a reliable result or is there a better way to work this one out?

Cheers!

[KwS 2378]

i think that was a pretty common way to do it. Close the valves, invert head, fill bowl (usually measured with a syringe) and leave overnight and see if the capacity is the same. Not sure on what liquid to use, have heard water but dont quote me on that. Need something that wont evaporate overnight.

Edited November 21, 2014 by KwS

[allan 295]

Could be a bit hit and miss to answer with out some more info are the valves new, old have they been refaced along with the seats. Have the valves been lapped in with grinding paste. Could check by smearing the vale face with bearing blue then insert it into valve guide and slam it onto the valve seat this should leave you a mark on the valve seat an hence what contact is being made between the seat and valve face.

Edited November 21, 2014 by tim 325

[Ahmedsinc 414]

Haven't lapped them in as yet, no grinding done at all.The set came from a spare head I have, M52TUB28. Engine was overheated but it's the only damage I'm aware of.

Wouldn't be too keen on using water as there is the chance the stems will begin to rust. Figured kero would be good but it would evaporate a little. Am guessing a solvent would be ideal as if there are any gaps it will find it, but will evaporate.

0W / 5W engine oil? ATF? Diff oil maybe?

[thorburn 120]

+1 for what Allan has suggested.

If the seats are in bad shape I've got a simple tool that'll fix it

[Auzeras 28]

You'd want to lap them first? Not sure if I'm talking smack, but as far as I know any valve work should ideally be accompanied by lapping to ensure a good seal. I'm guessing if you haven't lapped them, dropping different valves in will leave you with a less than perfect seal as the old valves will probably have a slightly different wear pattern or profile compared to the new ones.

Correct me if I am wrong though.

[Ahmedsinc 414]

Stopped by Wallace Heron on Monday and grabbed some fine lapping paste and the doofer that sticks to the valve. Been laid low with some kind of a tummy bug, so progress has been nil til it passes through.

+1 for what Allan has suggested.

If the seats are in bad shape I've got a simple tool that'll fix it

Cheers James, will have a go at seating these ones and holler if the seats need more attention

Am tempted to have the head skimmed a tiny bit to raise the comp ratio but will do more research before I rush into anything. I suspect the potential risks will outweigh any benefits but it'll make for an interesting read

[Auzeras 28]

Am tempted to have the head skimmed a tiny bit to raise the comp ratio but will do more research before I rush into anything. I suspect the potential risks will outweigh any benefits but it'll make for an interesting read

You'd have to take quite a bit off to make any significant difference to the ratio, how much were you thinking? Normally you'd get it skimmed to take a few 1000ths off to ensure a perfect fit once it went back on. Some people swear you should always have it skimmed, others are fine with using their experience to judge how flat it is. Personally I'd rather pay $100 or so bucks to get it level after doing all the work rather than risk it and put it back together only for it to leak because it warped a bit.