Shock absorber knocking

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Gui.dorey
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Re: Shock absorber knocking

Postby Gui.dorey » Sun May 26, 2019 4:51 pm

Hi Cam,
Suggest you try to get in touch with Simon Holyfield. He did a lot of work and study on oil pressure, the relief valve and the oil lines to the rockers and pressure guage. simes is very helpful and I‘m sure he will be able to give great advice. He also put a lot of information on what he did and found on his blog. I use it as a reference many times. Really worth it going through it if you haven‘t already.
Cheers Gui

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Bob.Murphy
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Re: Shock absorber knocking

Postby Bob.Murphy » Mon May 27, 2019 12:20 pm

What oil viscosity are you using ??

My Square Four used to show a high pressure when cold on 'Straight 50' (Castrol GP), but dropped to 52 psi when on the road and hot. Tick-over in London could drop to around 5 psi ( :shock: ) and I couldn't get near the oil tank. Fortunately I was only there a couple of times.

Mine had a composite MkII motor (gear oil pump with relief valve) and MkI cranks (relief valve in front crank) so not really comparable to you Mk I motor. All I am saying is that I would see what the gauge is showing at normal speeds on an open road when thoroughly warm before worrying about it.

Others may disagree.

Bob.
My avatar shows the late Len Rich in 1970 with the bike I now have - a 1958 Ariel VH

camstevens
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Re: Shock absorber knocking

Postby camstevens » Mon May 27, 2019 12:48 pm

Hi Bob
40SAE..................It's the oiling up I'm really trying knock on the head....starts and runs nice and cleanly, oils to the point where the engine goes rough due to oily plugs, so not a good scenario

Cam

Gui.dorey
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Re: Shock absorber knocking

Postby Gui.dorey » Mon May 27, 2019 5:45 pm

But... where is the oil coming from? There shouldn‘t be any oil getting into the combustion chamber. Even if there‘s a lot of it in the rocker boxes. I never had that problem the few times mine ran, and I also had the thicker oil line running to the rockers.

Are you sure it‘s really oiling up and not running too rich?

nevhunter
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Re: Shock absorber knocking

Postby nevhunter » Tue May 28, 2019 2:26 am

There's a fairly big constant suction in the sq4 inlet ports at low throttle openings, not pulses like a single. If your inlet guides are not a really close fit you will get oil down them especially if there's an excess there. Nev

camstevens
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Re: Shock absorber knocking

Postby camstevens » Tue May 28, 2019 8:19 am

Thanks Nev, understood.
Has anyone retro-fitted guide seals? I'm sure the guy I used to do the machining could find a product.

Cam

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Bob.Murphy
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Re: Shock absorber knocking

Postby Bob.Murphy » Tue May 28, 2019 11:24 am

The Mk I valve guides have short, rounded tops which makes sealing difficult.

The Mk II had taller guides with cylindrical sides and an 'oil scraper' conical top face. Also there was a steel top hat sleeve that fitted inside the inner valve spring and slid nicely over the cylindrical guide - keeping oil mist and liquid away from the valve stem.

Changing to Mk II guides might be an answer (if they fit - I didn't do this and don't know the respective dimensions). Alternatively, getting new guides turned-up with a top that allows the rubber 'valve guide seals' that one gets in car engines to be fitted would be a better option.

The last car top-end I did was a Toyota RAV4 (2.2 litre twin-cam common-rail diesel). The rubber seals with lip springs just clipped over the end of the (16 :roll: ) valve guides. Hand-lapping those tiny valves was a bit of a chore :lol: .

I am not averse to modernising old machinery providing it doesn't detract from the overall look and character.

Bob.
My avatar shows the late Len Rich in 1970 with the bike I now have - a 1958 Ariel VH

pkrichardson
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Re: Shock absorber knocking

Postby pkrichardson » Tue May 28, 2019 8:05 pm

found this bike under a house it had been unused for around 35 years and the oil pipe to the rockers and oil gauge was small to the gauge and big to the
rockers the stud atthe other end of the pipe only has a 1/16 hole so limits the oil flow

pete
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roland robinson
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Re: Shock absorber knocking

Postby roland robinson » Tue May 28, 2019 9:26 pm

To all those people suggesting fitting oil seals to Square Four valve guides, do not waste your time. If you study the valve relationship to the guide when the valve is open you will see that the reduced diameter of the valve where the collets fit goes a small distance down the guide. It needs a redesign of the valve/collet arrangement to overcome this problem.

Roland.

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Re: Shock absorber knocking

Postby nevhunter » Wed May 29, 2019 2:11 am

You might have to rely on a very good fit and finish of the valve in the guide and taper off the top surface of the guide and drive them in on the ridge around the middle if they have one. You can get away with a minimum clearance on inlets where there's an oil supply. Nev


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