Atlas valve guides

Hiyah Neil - When I found that a similar new guide was only a push fit into a cold casting I used a suitable locktite adhesive after I had cleaned the hole down into the combustion chamber adequately. It's been fine for many years. There should be no problem with just fitting one phosphor-bronze oversize guide however. It'll save on the valve lapping procedure if nothing else assuming the others aren't leaking. A quick test with white spirit will prove that. Why would you strip a head anyway ? Was it burning oil of just noisy ?. They did have that stupid pressure fed rocker system on the late Atlas's. Put a jet in it - that system is more trouble than it's worth. Get riding asap, Autumn's on the way. Cheers, Howard

yes carlboroe bronze valve guides are the best see RGM MOTORS forget the old cast iron ones that break inside the guild holes and when they do they make a real mess of things that costs a small fortune to put right , believe me its not cheap even though your a skilled engineer yours anna j

Neil - Bearing lock will be adequate. There are lots of threads about pressure fed rocker feed system problems on this Message board and there are solutions mentioned. If you are getting over-oiling symptoms you could revert to the early Atlas method but it will be quite expensive to change the whole system ( scrolled rocker spindles, three start oil pump gears, oil tank unions etc ). Several people have restricted the flow to the rockers rather than do all that. If you enter "Jet fitted in rocker feed" into the Search site window you will find threads and suggestions. I should go for the fitting of a jet into the timing cover or banjo bolt ( a pilot jet from a Monobloc carb). Experiment at will with different sizes. Obviously the jet will have to have a smaller hole than timing cover banjo bolt. The rockers and valve gear can run dry satisfactorily for several miles if you want to prove that the over-oiling is caused by the high pressure feed. People have brazed up the hole in the bolt and then re-drilled from very small to find a suitable solution. Paul Dunstall used to sell a special banjo bolt with 25 stamped on the head to stop over-oiling. Could have been 25 thou hole ?? Good luck , Howard

Hello Over oiling is caused by poor drainage there is drain holes in the cylinder head and these get blocked so if you have stripped your cylinder head is a good idea to clean all the drain holes you find then at the sides of the valve spring seats collars, And your Atlas was not built at Norton workshops by then atlas was built by AMC Plumstead in London the engines were built at wolverhampton shops and old valve guide holes need reaming and smoothing out before fitting new valve guides and you must heat the cylinder head to over 200 degrees fahrenheit the kitchen oven is the best way of heating the cylinder head for 30 mins get it good and hot, and then fit the valve guide cold is a good idea to place the valve guides in the freezer over night you need a good interference fit, and do not forget the clean the oilways at the back of the cylinder barrel as well as the right hand crank case elbow oilway, On the exhaust side the oil runs down the push rod tunnels and lubs the cam followers and cam shaft and some of this is blown out of the cam breather to open air yours anna j

Previously neil_waterton wrote:

Used Loctite 638 and put a piece of studding, large washer on the vaklve seat and 2 nuts to keep it under pressure overnight.. Job well and truly done. Tighter than a duck's a***.

Thanks to all contributors.

hello if its not interference fitted it will come lose in times as over size guides are made to be interference fitted and you reame the guide hole under size then heat the cylinder so the guide fit snug and you will not need loctite 638 or any other stuff and I never now use cast iron guides any more both my bikes have bronze guides in now witch are ten time better, yours anna j

Are bronze valve guides ten times better? Proof required.

Does the valve spring cup and heat insulating washer hold the valve guide down (if it is the shouldered type as per Dommie)?

Oddly - about bronze guides - Norton used bronze for tappet guides (set in the top of the crank case) before the War. But they were not subject to the same heat, and they stuck to cast iron valve guides in the head. No idea why they used both materials. The tappet guides are much more complicated, with hex nut on top and threaded shanks.

Previously Gordon Johnston wrote:

Are bronze valve guides ten times better? Proof required.

yes bronze are better as castiron guides break up in the head and sometimes will destroythe cylinder head, bronzeguide will not break up in the head and are far better just ask Roger at RGM motors he race tunes commandos with bronze guides fitted, and see Steve Maney he fits his own made bronze guides, and many other race parts he makes, including the 1006cc commando big engine kit, yours anna j