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jenevers

Tappets

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Checked the valve clearances on my 4LW. No adjustment required.?

Had to tighten up those on my Mitsubishi Genny which were a bit slack.

2 questions. How much “drag” on the feeler gauge do members adjust to and what’s effect on the engine if the gap is higher or lower than recommended?

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The correct adjustment is when the feeler gauge has a slight drag when pulled out.

 

Too tight can cause rough running, especially when cold and too loose can cause damage to the valves, camshaft, cam followers and rockers. However i think they need to be a fair bit out for a long time to do any damage.

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Modern engines seem to have very light valve springs, so light you can often depress the valve with your thumb so those (the generator) need to be set with a very light drag. If you try to set them as we did older cars then the valve will be held open by the feeler gauge and the gap will be too small. I expect the Gardiner will have much stronger springs so the feeler will jamb before it tries to open the valve.

 

Clearances too tight - This will affect the valve timing but probably not to any noticeable extent on an engine driving via a propeller but when the engine is hot the clearance may totally close up and hold the vale open a little. This would result in a loss of compression and mean effective pressure when running so the engine might lack some power, burn valves, chuff through the air cleaner/exhaust, or misfire, probably at idle.

 

Too loose - noisy in operation and will also affect the valve timing and volumetric efficiency but on a boat it is very unlikely to be noticeable performance wise. If very bad such as when an adjuster totally unscrews itself the engine will misfire.

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Best way is not the amount of drag but go-no go.

The correct feeler should go in the gap, the next size up, say 1 thou, ( 0.02mm ) more should not go in.

Too slack = noise and wear and shortens the scavenge time leading to more emissions of unburnt fuel.

Too tight = risk of valve and seat burning and loss of compression.

Edited by hider

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Guest
1 hour ago, Tony Brooks said:

Modern engines seem to have very light valve springs, so light you can often depress the valve with your thumb so those (the generator) need to be set with a very light drag. If you try to set them as we did older cars then the valve will be held open by the feeler gauge and the gap will be too small. I expect the Gardiner will have much stronger springs so the feeler will jamb before it tries to open the valve.

 

Clearances too tight - This will affect the valve timing but probably not to any noticeable extent on an engine driving via a propeller but when the engine is hot the clearance may totally close up and hold the vale open a little. This would result in a loss of compression and mean effective pressure when running so the engine might lack some power, burn valves, chuff through the air cleaner/exhaust, or misfire, probably at idle.

 

Too loose - noisy in operation and will also affect the valve timing and volumetric efficiency but on a boat it is very unlikely to be noticeable performance wise. If very bad such as when an adjuster totally unscrews itself the engine will misfire.

My Honda bikes were similar.

I have one of those tools that adjusts the tappets by counting the "clicks" but have never tried it properly on the boat yet, though a quick test seemed to suggest it was accurate.

Edited by Guest

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Adjusting tappets on OHV-OHC engines is a piece of cake compared to many old S/V engines like a Pontiac  Silver Streak straight 8 S/V engines and the old Ford V8 S/V engines as used in the Ford Pilots and trucks. As well as the Ford V8 another of the worstest were the old 10 and 8 HP E93A ford engines which had no screw adjustments at all, one had to keep removing the valves and grinding the stems down bit by bit to get the clearance right, well once only really if you got your measurments right. This involved keep tapping out the split guides with a special half onion shaped tool to remove the valves because the valve stems were widened at the tappet contact end. All done by feel and a mirror.  But they were good times. :(.

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1 hour ago, hider said:

Best way is not the amount of drag but go-no go.

And that is how less sophisticated Lister engines describe the process

 

Richard

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30 minutes ago, bizzard said:

Adjusting tappets on OHV-OHC engines is a piece of cake compared to many old S/V engines like a Pontiac  Silver Streak straight 8 S/V engines and the old Ford V8 S/V engines as used in the Ford Pilots and trucks. As well as the Ford V8 another of the worstest were the old 10 and 8 HP E93A ford engines which had no screw adjustments at all, one had to keep removing the valves and grinding the stems down bit by bit to get the clearance right, well once only really if you got your measurments right. This involved keep tapping out the split guides with a special half onion shaped tool to remove the valves because the valve stems were widened at the tappet contact end. All done by feel and a mirror.  But they were good times. :(.

I remember watching one of the car restoration programmes in the USA (possibly Fantomworks) where it seemed to be a really big task to adjust the valve clearances on an American classic car. Can't remember the finer details now.

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1 minute ago, catweasel said:

I remember watching one of the car restoration programmes in the USA (possibly Fantomworks) where it seemed to be a really big task to adjust the valve clearances on an American classic car. Can't remember the finer details now.

They call S/V engines ''Flatheads'' well that little fellow Wayne Torini does. It takes a lot of patience and self control to adjust valves on flatheads. Many remove the engines and turn em on their side to do it.

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25 minutes ago, bizzard said:

They call S/V engines ''Flatheads'' well that little fellow Wayne Torini does. It takes a lot of patience and self control to adjust valves on flatheads. Many remove the engines and turn em on their side to do it.

I have heard them talk about flatheads but never realised they were SV. Obvious now that you have explained it. Cheers! 

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Hmm. My thoughts were ....if I can push the feeler gauge in between the stem and rocker it must be OK, otherwise it wouldn't fit.  However the drag is quite stiff.?

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31 minutes ago, jenevers said:

Hmm. My thoughts were ....if I can push the feeler gauge in between the stem and rocker it must be OK, otherwise it wouldn't fit.  However the drag is quite stiff.?

That's much too tight

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1 hour ago, RLWP said:

That's much too tight

? I’ll slacken them off tomorrow.

But how does Go - No go work?

Edited by jenevers

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1 minute ago, jenevers said:

? I’ll slacken them off tomorrow.

Ignoring all the problems associated with wear on the end of the rocker, you are trying to get the gap to be just as big as the thickness of the gauge. The 'drag' is your indication that the gauge is touching the rocker and the valve at the same time, not pinched, not loose. It's terribly subjective

 

That's why the go/no-go is better as it is relatively idiot proof

 

Richard

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8 hours ago, bizzard said:

Adjusting tappets on OHV-OHC engines is a piece of cake compared to many old S/V engines like a Pontiac  Silver Streak straight 8 S/V engines and the old Ford V8 S/V engines as used in the Ford Pilots and trucks. As well as the Ford V8 another of the worstest were the old 10 and 8 HP E93A ford engines which had no screw adjustments at all, one had to keep removing the valves and grinding the stems down bit by bit to get the clearance right, well once only really if you got your measurments right. This involved keep tapping out the split guides with a special half onion shaped tool to remove the valves because the valve stems were widened at the tappet contact end. All done by feel and a mirror.  But they were good times. :(.

 

God, I remember the Ford E 93a days. It was where I learnt to service a car (my dad's) as a schoolboy. ( and an illicid drive around the block)

 

Frank

  • Greenie 1

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Hi,

In the early '60's I sure the handbook for Pop's Vauxhall Victor suggested 'setting the tappets with the engine running' - an almost impossible job and ruined several feeler gauges.... anyone remember the SPQR tool for setting tappets.. distributed by a specialist firm in Leighton Buzzard.

This posting reminds me - must check them on the 2LW!, and I actually saw a mechanic checking the tappets on a BMC 1.8 yesterday.

 

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1 minute ago, LEO said:

Hi,

In the early '60's I sure the handbook for Pop's Vauxhall Victor suggested 'setting the tappets with the engine running' - an almost impossible job and ruined several feeler gauges.... anyone remember the SPQR tool for setting tappets.. distributed by a specialist firm in Leighton Buzzard.

This posting reminds me - must check them on the 2LW!, and I actually saw a mechanic checking the tappets on a BMC 1.8 yesterday.

 

Is this the one that counts the clicks as you rotate it? If so I have a copy of one.
I think my mates Kwacker 650 bike had tappets set whilst running. 

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3 hours ago, catweasel said:

Is this the one that counts the clicks as you rotate it? If so I have a copy of one.
I think my mates Kwacker 650 bike had tappets set whilst running. 

 Probably similar. I never purchased one, it made adjustment a 'one handed 'operation. The firm specialized in Triumph tuning bits, for GT6's and Spitfires and TR models. I bought a 'camber controlled' transverse leaf spring from the to try to improve cornering in a Spitfire. Personally I have never really had a problem with adjusting tappets with a spanner and screwdriver.

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11 hours ago, LEO said:

Hi,

In the early '60's I sure the handbook for Pop's Vauxhall Victor suggested 'setting the tappets with the engine running' - an almost impossible job and ruined several feeler gauges.... anyone remember the SPQR tool for setting tappets.. distributed by a specialist firm in Leighton Buzzard.

This posting reminds me - must check them on the 2LW!, and I actually saw a mechanic checking the tappets on a BMC 1.8 yesterday.

 

 

I once had a Vauxhall Chevette whose handbook suggested setting the tappets with the engine running.

 

During the process the end of the feeler gauge snapped off and disappeared down a pushrod hole. I drained the (freshly changed) oil and thankfully the missing end of the feeler gauge came out with the oil.

 

Not wishing to wreck the engine or more feeler gauges, I measured the gaps on the tappets that I had managed to set with the engine stopped and reset the others to that. Did it with the engine stopped every time after thst. Never had any issues in the 3 years I kept it. 

 

By the way, it was the worst car for reliabity I ever owned. Needed two re-con gearboxes, a distributor and oil pump In the time I owned it.

 

I swapped it for an Alfa Romeo in 1981 - a much more reliable car. ?

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9 hours ago, LEO said:

 Probably similar. I never purchased one, it made adjustment a 'one handed 'operation. The firm specialized in Triumph tuning bits, for GT6's and Spitfires and TR models. I bought a 'camber controlled' transverse leaf spring from the to try to improve cornering in a Spitfire. Personally I have never really had a problem with adjusting tappets with a spanner and screwdriver.

Same here. I just bought this because it was sill cheap.then never used it. I have a collection of similar door stops :)

1 hour ago, cuthound said:

 

I once had a Vauxhall Chevette whose handbook suggested setting the tappets with the engine running.

 

During the process the end of the feeler gauge snapped off and disappeared down a pushrod hole. I drained the (freshly changed) oil and thankfully the missing end of the feeler gauge came out with the oil.

 

Not wishing to wreck the engine or more feeler gauges, I measured the gaps on the tappets that I had managed to set with the engine stopped and reset the others to that. Did it with the engine stopped every time after thst. Never had any issues in the 3 years I kept it. 

 

By the way, it was the worst car for reliabity I ever owned. Needed two re-con gearboxes, a distributor and oil pump In the time I owned it.

 

I swapped it for an Alfa Romeo in 1981 - a much more reliable car. ?

My mate had a Chevette with similar experiences. He called it a Vauxhall Shove-it.

Odd really because I think they were the same mechanicals as the Viva which in my experience were OK.

ps that was lucky with the feller gauge! It would have been sump off time the way my luck goes!

Edited by Guest

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7 minutes ago, catweasel said:

ps that was lucky with the feller gauge! It would have been sump off time the way my luck goes!

 

I'd have just left it there, lying on the bottom of the sump where it would almost certainly stay for the life of the engine. 

 

Even if it got picked up by the oil flow, it would get caught by the oil pump pick-up pipe strainer. More likely it would end up on the magnet in the sump drain plug. 

 

 

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7 minutes ago, Mike the Boilerman said:

 

I'd have just left it there, lying on the bottom of the sump where it would almost certainly stay for the life of the engine. 

 

Even if it got picked up by the oil flow, it would get caught by the oil pump pick-up pipe strainer. More likely it would end up on the magnet in the sump drain plug. 

 

 

I expect there is a very good chance that it would do no harm, except if I owned it!  As my workmate from Yorkshire used to say "If it weren't for bad luck, I'd have no luck at all!"

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16 hours ago, catweasel said:

Is this the one that counts the clicks as you rotate it? If so I have a copy of one.
I think my mates Kwacker 650 bike had tappets set whilst running. 

Kawasaki often had double overhead camshafts with bucket and shims atop the valve stems, directly operated by the cams.  You needed to check the clearances, remove the camshafts, measure the existing shims and then replace with different shims before before putting back the camshafts -and checking the new clearances.

 

The bike I bought was a poor starter - as some valves were being held open even when cold.  So, it wasn't possible to work out the size of the required shims without a couple of tries.  

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2 hours ago, Tacet said:

Kawasaki often had double overhead camshafts with bucket and shims atop the valve stems, directly operated by the cams.  You needed to check the clearances, remove the camshafts, measure the existing shims and then replace with different shims before before putting back the camshafts -and checking the new clearances.

 

The bike I bought was a poor starter - as some valves were being held open even when cold.  So, it wasn't possible to work out the size of the required shims without a couple of tries.  

I see, must be my memory playing tricks. Perhaps it was the cam chain adjustment whilst running? There was something unusual about the engine IIRC, compared to my Honda's anyway.

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Fellow wanted to tune up the 6LW in his boat........decided to screw each valve cap down one thread ,and refit the pin.........then he refitted the rockers, reset the tappets,put the covers back on ,and pushed the button........broke half the rockers in a couple of seconds.........knew another guy couldnt get adjustment in one cylinder of a Perkins,actually the pushrod wouldnt go in far enough...........using a torch I could see a little stone had fallen into the socket in the lifter......How does a boat motor get gravel inside it?.......well says the owner,that was probably when it sank.

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