I C valve grinding paste

Hi

Can anyone suggest the best size of grit for lapping in ic engine valves

I'm thinking of getting some of the finer diamond grades

Any advice

Thanks

Dougie

I usually do mine with 600grit silicon carbide powder mixed with oil to form a paste. 100grams off e-bay will last a lifetime

Carborundum is the paste to use as it does not bed into the valves or seats, I think I would be worried that diamond would do the opposite as its virtually indestructable.

I went into Halfords ten years ago and asked for a tin of valve grinding paste, to my astonishment, they had never heard of it. I went to a small car bits shop and the guy said that there was a choice of two different makes in stock. I would choose the finer grade in the double ended tin. I would avoid diamond  abrasive for valves.

Edited By old mart on 20/02/2023 21:09:39

I would use the double ended tin, it will last for years, Holts and chemico both do it, I'd go for chemico, If you have a branch of MPD near they will have it. Noel.

I expect Dougie want's it for model engine valves and even the fine half of a tin of automotive grinding paste is way to coarse for model use.

Metal polishes such as Brasso and Solvol Autosol aluminium polish are a good fine abrasive for smaller jobs. Brasso is a bit too fine sometimes but the Autosol works well. As does Mothers Aluminium Polish. Never tried it on small model IC valves though.

Thanks for all the replies

I have used the fine end of car valve grinding paste and as Jason says it's a bit rough

I will try to get my hands on some finer carbide

Thanks

Dougie

Timesaver Sampler Pack. 8 different grades. 4 each for ferrous metals and 4 each non-ferrous metals. Non embeding! I have used it for more than 25 years. Rick

Thanks

Where is the sampler pack available from

Dougie

Dougie - I have plenty of Silicon Carbide (Carborundum) powder in 280 (too coarse for piston/liner lapping actually) 320, 600 and 1000 grits.

Send me a PM if you want some.

'TimeSaver' is great but far too expensive when only small quantities are required.

Diamond is a definite no no if the surfaces are not hardened. It will embed itself into the material and no amount of solvent cleaning will release it all. You need a good ultra sonic cleaner to do the job properly.

Silicon Carbide is ideal - does a good job and is easily removed with a solvent such as cellulose thinner. I haven't done any valves but I have done the odd piston and liner.

I am disposing of some of my workshop - Silicon powder is no longer required nor some genuine Kasenite case hardening powder - if anyone else wants some then PM me.

Best Tug

Edited By Ramon Wilson on 21/02/2023 18:38:32

Heritage steam do the sets, but at about £100 a pop that's a lot of valves you could grind in compared to £3-4 for 100grams of 600grit off e-bay

You could buy just a jar of very fine but it is still coarser than 600g

I bought mine years ago from McMaster-Carr. There was a discussion a while back and if I remember correctly, it was hard to find in Europe and expensive. Probably not worth it for one or two jobs. I have built numerous engines over the years and I would not be without it. Still have 50% of it left. A Google search should turn something up if you are still interested. Rick