I C valve grinding paste

[Dougie SwanParticipant @dougieswan43463]

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

[Dougie SwanParticipant @dougieswan43463]

[JasonBModerator @jasonb]

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

[bernard towersParticipant @bernardtowers37738]

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.

[old martParticipant @oldmart]

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

[noel shelleyParticipant @noelshelley55608]

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.

[JasonBModerator @jasonb]

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.

[HopperParticipant @hopper]

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.

[Dougie SwanParticipant @dougieswan43463]

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

[Rick HannParticipant @rickhann79631]

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

[Dougie SwanParticipant @dougieswan43463]

Thanks

Where is the sampler pack available from

Dougie

[Ramon WilsonParticipant @ramonwilson3]

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

[JasonBModerator @jasonb]

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

[Rick HannParticipant @rickhann79631]

Posted by Dougie Swan on 21/02/2023 17:59:27:

Thanks

Where is the sampler pack available from

Dougie

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

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