for those of you with the AMR timing cover mod

acadian · Mar 5, 2017

When I last had my cover off, I made sure to deburr/smooth the spigot prior to reassembly, and used a buna o-ring replacement. Again, I think getting the o-ring crush just right is the important part. A synthetic ball might offer a better seal. The spring tension is not very strong, and I'm not sure if the flow rate of the pump depresses the ball entirely clear of the intersecting oil gallery, but even if it doesn't, oil will still flow past the ball... isn't that what makes this the "safe" solution to sumping?

Craig · Mar 5, 2017

I'm wondering if this AMR modification presents any risk of failing and oil starving engine similar to the inline valves we are all very familiar with .... thanks
Craig

kommando · Mar 5, 2017

Has anyone bothered to ask Mike @ AMR what size O-ring he uses?

Its a 1/4 id 1/8 cross section giving a 1/2 od. Until I get one and fit it I cannot check if the 1/4 ball seals on the o ring or the oil pump spigot but the spigot is most likely.

JimNH · Mar 5, 2017

Craig said:
I'm wondering if this AMR modification presents any risk of failing and oil starving engine similar to the inline valves we are all very familiar with .... thanks
Craig

The inline valves close the inlet, this mod, like the MKIII closes the outlet. Since oil can get to the pump and being a positive displacement pump it will develop whatever pressure it needs to force the valve off the seat.

Craig · Mar 5, 2017

Thanks for the explanation , have been wondering 'bout that since this thread started
Craig

worntorn · Mar 6, 2017

For those interested, Rabers has a limited number of new old stock Mk3 timing covers complete with fixins for $229. I picked one up at their old price of $199 last month. Either way it's a deal if you need one. I needed one to go with my eBay Mk3 cases, however some owners fit the Mk3 timing cover to earlier models. It would be wise to do a search for info on this, there may be complications. Reg price is more like $500!

madass140 · Mar 6, 2017

I bought one from Rabers to but it was missing one of the blanking grub screws for the main feed drilling. so check that otherwise kaboom!!
Don

worntorn · Mar 7, 2017

Thanks Don, will check on that.

Glen

kommando · Mar 8, 2017

The O rings for the oil pump spigot came today, the ball definitely seals on the spigot not the O ring. So the plan is now 1/4" EPDM ball and a 1/4" bull nosed cutter for a ball shaped seat on the steel spigot to increase the sealing area.

acadian · Mar 8, 2017

kommando said:
The O rings for the oil pump spigot came today, the ball definitely seals on the spigot not the O ring. So the plan is now 1/4" EPDM ball and a 1/4" bull nosed cutter for a ball shaped seat on the steel spigot to increase the sealing area.

don't use anything metallic to compress the spring/ball when installing the cover, will score your nicely lapped spigot... a plastic zip tie works well

MikeG · Mar 8, 2017

IIRC-the correct O ring is a number 106. I did this mod to my engine over a year ago using a generic hardware store spring and a 1/4" diameter ball like you would find in a BSA or Triumph steering race. Used a small zip tie when installing it and no wet sump or troubles since.

kommando · Mar 8, 2017

Already there, from my earlier post

I tested a Unit Single non return valve spring, it may be a bit long but I was able to compress the ball and spring far enough to get a zip tie through the X hole to keep it all in place before mounting the cover.

for those of you with the AMR timing cover mod

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