Grey motor upgrade

[Wrongway Roger]

Hi guys,
One of our club members is upgrading his grey motor and needs a mild cam and a set of piston rings.

Looking for recommendations on a cam supplier and possible grind and a supplier of rings.

I'm not sure if the block has been bored but it is likely that he will do this or what carby set up he is going to use.
I know there is a lot of knowledge within the forum so I'm reaching out for your support.

Cheers,
Roger

[Harv]

For the cam, strongly recommend Clive Cams:

https://www.clivecams.com.au/

Cheers,
Harv

[ardiesse]

There are a few sources of rings: Nornda Automotive (aka JP Pistons) sells rings in single-cylinder sets, so you need to buy six, at around $30/cylinder. Precision International is a major distributor of engine parts. They have most sizes of grey motor rings, and they do sell direct to the public. Failing that, Auto Surplus in Melbourne's worth a try; and there's Nason as well. If you get really stuck, go directly to the manufacturers: Grant (USA), and King (USA). Grey motors take the same ring set as a 3" bore Briggs and Stratton single cylinder.

It's actually easier to get grey motor rings in the larger bore sizes: 3" is hard, 3-1/8" is easy, for example.

And one more thing: listen very carefully to the engine idling before pulling it apart. If there's any sign of gudgeon pin knock, I strongly recommend new piston pins and bushes. Nornda can supply new grey motor piston pins ($25 each); piston pin bushes are still available, and you need to find an engine shop to replace the bushes and ream to size.

Rob

[basic.green]

clive cams is the man

[Wrongway Roger]

Thanks Harv and Rick for the quick response and I did see Clive Cams during a Google search.

Rob, I appreciate your input and will pass this information along. I did have look at Auto Surplus in Melbourne but Nornda Automotive look even better being here in Adelaide.

While have your attention, can you id a cam for me. It's grey motor cam that I was given by Thommo. He can not remember if standard or modified.

Cam 3.JPG (178.86 KiB) Viewed 502 times

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Cam 1.JPG (88.47 KiB) Viewed 502 times

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Cam 2.JPG (90.25 KiB) Viewed 502 times

Cheers,
Roger

[ardiesse]

Roger,

I'll say standard (possibly, because the base circle of the lobes is still higher than the shaft itself); but it may also be a very mild grind (because of the stampings at the rear).

Tell you what - if you've got a digital caliper, measure across the cam from base circle to lobe peak, and I'll compare with a standard cam . . . no, it's not quite that easy . . .

Give me two measurements: one from lobe peak to base circle (the maximum reading you get as you rotate the cam inside the jaws of the caliper), and another at right angles to the lobe peak (the minimum reading you get as you rotate the cam inside the jaws), and I'll compare against a standard cam.

Rob

[Wrongway Roger]

Hi Rob,
From lobe peak to base circle - max measurement- 1.367"
and
right angles to the lobe peak - min measurement - 1.128"

Cheers,
Roger

[ardiesse]

Roger,

1.417"/1.186" exhaust
1.411"/1.186" inlet

Your max is about 40-50 thou less than a standard grind, and your min is 60 thou less than a standard grind. I'm thinking that you have the mildest possible regrind: about 0.015" more lift at cam. Maybe a 15/55?

Rob

[Wrongway Roger]

Thanks, Rob for your help.
You are a wealth of knowledge willing to share and educate us morals.

Possible be able to use as a replacement cam if someone is rebuilding a grey motor and wants little bit more power, without changing to much.

Cheers,
Roger

[ardiesse]

Roger,

(puts hand up).

I wonder whether HHHE is code for 55 51 (i.e. 15/55).

Rob

[Wrongway Roger]

You could be correct, in that it is code for who ever ground the camshaft.