Powered valve lapping tool

[Cobbler]

I was told, many years ago that in the factories they ground the valve & seat, put the valve in & tapped it with a hammer. This would have been back in the mid 60’s & the source wasn’t reliable though.

 

[Morris]

This is the sort of thing I'm working on

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Just got to remember to check for valve seat distortion after dropping it in a bucket of boiling oil

Careful how you grind those in, you could lose 1.6bhp at 8500rpm+ if it's not a good seal.

 

[harveyp6]

I think the first set of valves I ever lapped in were on a Jaguar mk10 which after assembly need shimming , again the first time I ever used a set of feeler gauges ( remember them?) and a micrometer.

When I was an apprentice I bought a 1966 S-type Jag where the cam bucket had broken and chewed up the cam lobe. I took the camshaft out, had the lobe re profiles, decoked the head, then refitted it all. So to checking all the valve clearances, and I bought an expensive set of snap-on cranked feeler gauges designed to set OHC engines. Went to do the job and found the clearances were 4 and 6, and the feelers only went down to six, so I could only use them for half of the clearances, and use ordinary ones for the others.......
Another waste of money.

 

[keithski122]

Try fine..

I probably won't ever be lapping another valve in my life again.

 

[Keithmac]

I use a piece of pipe over the stem and alway hand lap new valves.

You know in minutes if a valve and seat are going to be fine.

Hand lapping with fine paste is as much about seeing the contact patch as taking off material.

There are exceptions through, working with Titanium valves you will destroy them with lapping (removing the coating will make the valve face wesr out in no time at all).

 

[premmington]

I probably won't ever be lapping another valve in my life again.

No me...

I got a vehicle repair workshop - all replacement engine we fit come hole and all cylinder heads come new or reconditioned.

@keithski122 - Apart from a lawnmower and I always buy Honda's so that not likely or an aging motorbike - I doubt I will be ever laping another valve again in my lifetime...

 

[Bornfree]

I will be lapping valves next week. I've got a Perkins 4.248 to rebuild, someone ran it out of oil, it seized cylinder one big end ripped the rod cap off and pushed the rod through the block. Purchased a pattern short engine probably made in China it will be interesting to see how it lasts.

 

[premmington]

I will be lapping valves next week. I've got a Perkins 4.248 to rebuild, someone ran it out of oil, it seized cylinder one big end ripped the rod cap off and pushed the rod through the block. Purchased a pattern short engine probably made in China it will be interesting to see how it lasts.

Last Perkins engine I did from that era was a 4108 - fitted into Bedford CA vans and Transits of the time - done one years later that went into a Narrow Boat.

 

[Bornfree]

Last Perkins engine I did from that era was a 4108 - fitted into Bedford CA vans and Transits of the time - done one years later that went into a Narrow Boat.

I like Perkins engines they are well made with UNF threads that clamp well without needing massive torque figures. And no silly stretch bolt's

 

[harveyp6]

I had a Perkins 4-236, which was reliable, but slow and noisy. I took it out and because I can't stand trying to sell things and people coming round and trying to chip me because it's a bit oily, I stripped it, and made a garden table out of the flywheel crankshaft and front pulley with one side of a cable drum on top. The block I hope to use as a stand for an anvil. (When I can get hold of an anvil).
I also have a 6-247, which revved well, but up hills the speed bled off so quickly even with a good run up. I don't know what I'm going to do with that one yet.

 

[premmington]

I like Perkins engines they are well made with UNF threads that clamp well without needing massive torque figures. And no silly stretch bolt's

Perkins at Peterborough been owned by Caterpiller for over 25yrs now - they don't make small engines now...

 

[Bornfree]

Perkins at Peterborough been owned by Caterpiller for over 25yrs now - they don't make small engines now...

They sell the 400 series engines under the Perkins name but they are made by shibaura. They are great little engines. We run several 2.2 four cylinder models.

 

[premmington]

They sell the 400 series engines under the Perkins name but they are made by shibaura. They are great little engines. We run several 2.2 four cylinder models.

shibaura...?

Had to google that - Japan...?

 

[Bornfree]

shibaura...?

Had to google that - Japan...?

Yes I think perkins own them.

 

[premmington]

Yes I think perkins own them.

Reword that - "Cat' owns them"...

 

[Ruffian]

Last valves I lapped in where in a perkins ad3-152 engine.
Had to cut the valve seats they where that rotten first though.

New valves lapped in after.
Ran mint.

Do miss jobs like thst at times.

 

[brewdexta]

This was in my dad's tools that came my way, no idea if he used it in anger or just bought it on a whim at a car boot.

I may give it a check over and see if it runs.

 

[Melvyn Best]

This was in my dad's tools that came my way, no idea if he used it in anger or just bought it on a whim at a car boot.
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I may give it a check over and see if it runs.

The old Vibro centric , used one many times

 

[whm_fab]

Well I wouldn't want the inlet valves to be red hot - the exhausts? not that important. Ultimately the valves will just grow, the head and seats will move and deform. But to eliminate what you can makes sense to me, otherwise why bother trying to make your race engine better than anyone else's. You carry on having the shivers, I build race engines to win, not fart about at the back. Sometimes these tricks don't work, but I've never had a catastrophic failure, I have mostly made progress though.

Ok so. The seat sealing on the exhaust valve is not important on the compression stroke? Without precise accurate data of temperatures on all the components under operating conditions of your application, and tons of F1 level testing with this, your eliminating nothing, only adding variables. You’re talking about things you can’t measure with any degree whatsoever of accuracy. Anyway, I see where this is going with the attitude so il say no more

 

[whm_fab]

As I understood it, its more to do with the distortion from the bolts, rather than the actual head. Some engines you can see polishing around the areas where the head bolts are, with honing marks still visible around the rest of the bore.

Heard of some race engine shops using heated oil, using plates with galleries in to circulate the oil to create thermal distortion too. I guess with race engines on the limit, every teeny, tiny, bit helps. But for engines where the head bolts drop into a ladder under the block, so no distortion around the bores . . . ?

I suppose it's a little extra you can charge the customer for.

For one of our highly stressed machines, we do machine with a substitute component bolted up to create the same effect as in use - seems to work, certainly reduced the number of failures/increased service life.

It’s also application dependent too based on the design of the block and material, a cast iron inline 4 will see basically no distortion with a head / torque plate, an alloy straight 6 bmw I’ve seen 4/5 thou of ‘egging’ without one. The thickness of the plate ‘should’ be tuned to give the same distortion as tests made with a head