Valve lapping

[Welderpaul]

The valves in this little Perkins 3 cylinder, especially the exhaust valves, were very pitted so I have changed all the valves and lapped them in.

The condition of the valves was much worse than the seats.

All but one are perfect after lapping an honing except one. I have marked where the pitting remains but it is quite deep, if i continue to lap until its gone the valve will end up too deep.

As it is now when I put the valve in, it seals and holds water.

Does it matter?

 

[johnik]

going by what i learnt over many moons on petrol engines, i would say that seat would burn out if used on a daily basis, probably ok for ocational use, can you get a new seat ?
i always used wd40 or similar to see if a valve was seating as it,s not as "thick" as water, also blow air up the exhaust port to see if it seals with your pinkie holding the valve down.

 

[Ubique]

It's sealing enough to hold water at atmospheric pressure, it'll be different during cylinder compression. with it being a three-potter, I'd say it will make the engine slightly unstable.

 

[Ruffian]

Is that the a3.152 (or ad3) massey engine.

If so a new head is only cheap.
You can get away with cutting the seats but they do pocket into the head and not as nice as normal.

Personally a vapormatic or sparex head, (I think are circa £200 complete) would just be getting slung on.

 

[tom2207]

Id not be putting it in if you expect it to work daily , if its only a toy thats used 20 hours a year , no harm really .
not really an answer . Just something to think about.

 

[mike os]

Guessing you already know... but if that leads its back to where you are now...... get a new seat in it

 

[500e]

Cut the seat see how deep the valve is.
In a tractor ? If it is was never a racer.
Would thin the seat down on lh side it is very wide a go with a burr will help look at seat L & R sides

 

[zzr1200]

Its an exhaust valve seat so it might seal up with running once the carbon has built up a bit..

Its only a weekend toy for shows, I'd chance it if you dont want to fit a valve seat insert or replacement head.

 

[Bornfree]

I would just cut the seat a little more it's not going to need much.

 

[brightspark]

as above but cut it with a proper valve seat cutter then lap the valve in

 

[Alan Reynolds]

I can supply some of my lightweight valves for that!

 

[8ob]

I would bin the exhaust valves and get new, looks like water/rain damage from the exhaust being left open to the elements when stood up .

Bob

 

[brightspark]

I would bin the exhaust valves and get new, looks like water/rain damage from the exhaust being left open to the elements when stood up .

Bob

you can get seat re cut and oversize valve its only the one

 

[8ob]

you can get seat re cut and oversize valve its only the one

Just read Pauls post again and he mentions he has already replaced them


Bob

 

[brightspark]

Just read Pauls post again and he mentions he has already replaced them


Bob

yes with standard valves you can buy oversize one though if the seat is cut back to be honest cut back a standard will still be ok its a diesel not a racing engine . as long as it seals

 

[mr migwire]

My landy dropped a valve seat a few months back, ive just finished an engine rebuild on it and had the head skimmed and a new valve seat fitted,

 

[mr migwire]

bet that was rattly , love the nato stock colour not seen that in a while ,,

sounded like a bag of spanners but all good now, did the engine in mod recon blue as the rest of the vehichle is going back to olive drab so makes sense,

 

[Munkul]

You could try it as it is and see if you have trouble with it, if you're feeling tight. It's a gamble though.
It doesn't even look like valve seat material there, it looks like the head casting itself!

 

[brightspark]

You could try it as it is and see if you have trouble with it, if you're feeling tight. It's a gamble though.
It doesn't even look like valve seat material there, it looks like the head casting itself!

probably is . a lot engine seats are just in to the cast head / not all have inserts

 

[julianthegypsy]

At Massey, we used tungsten valve seat cutters, they were expensive but brilliant. Two turns and they came up like new. Massey used quite a lot of 3.152's!