Conkers Swedish Cafe racer Project.

grandpaul · Apr 1, 2012

A small bit of cam bushing tang or some other debris got into the rod big end oil gallery and cut that groove in the bearing shell. Speedtwin has it right.

You need to get a good micrometer and check both rod journals on the crank, there's a chance they'll be slightly different sizes. I'd have the crank re-ground to the biggest undersize possible that matches both sides, and use a new matched set of oiler-drilled bearing shells.

If/when a reputable machinist grinds a crank, they'll stamp the undersize on the adjacent crank cheek face.

Hobot · Apr 1, 2012

oopiespoo, there is no way a cam tab of piece of barrel or piston or anything can get into the rod shell space that didn't enter from the oil pump side. My guess is some tired to clean sump trap by wire and solvent instead of opening crank so dislodged a hunk of mostly metal grit sludge with no way out but rub its butt off like a potato in a vegie slicer. I've seen Combat what happens to the thrust washer tab breaking off, it gets peckered about inside crank case till beat chewed busted up till small enough pieces to enter the sump pump gears or clog its intake or the long internal drain passage from front of cases.

Last yr when I fit new rod shells and assembled to test fit, found they were bindy, so gradually removed the shell high areas by drawing a razor blade across them till turned slick with a bit of oil of course.

conkers · Apr 1, 2012

After much better inspection, the groove is not machined but as you all are saying, caused by contamination.

The crank journals are ok, slight marking but not so bad to need a regrind.

The only washer on the cam was the tapered washer, the manual said there should be a plain washer/shim there too, but I did not have one!

I agree that it is likely dirt that has gone in, or was there from the original build...

Re: Rod bolts. Are the ones supplied by RGM not up to spec?
I can't imagine RGM would be selling substandard parts?!!

Mike

Hobot · Apr 1, 2012

Get and put the missing space washer on the RH thrust side but don't bother with the LH as tach drive sucks cam to RH running.
I'd run RGM fasteners or Anover w/o worry, just check rod seats clear of bolt head and flat square all around. Forget torque, clean and lube threads then measure stretch and stop at .0065" give/take .0005".

conkers · Apr 1, 2012

I'll get a photo of the RH cam bearing, as it had a thrust face on it, I just assumed the tapered washer ran against it.

Thanks for the peace of mind on RGM fasteners and the stretch tip. Haven't done rod bolts by stretch since I built a Rolls Royce engine (by the book)!

Cheers,

Mike

conkers · Apr 2, 2012

This is the thrust face of the RH cam bearing.
Does it look normal?

And the tapered washer on the cam itself

If I am missing another spacer/washer/shim, what does it look like?

How is the end float on the cam controlled/set/measured?

Thanks...

Mike

L.A.B. · Apr 2, 2012

http://www.oldbritts.com/cam_bush.html

bill · Apr 2, 2012

with your flanged cam bush you DO NOT use the tab washer #062601 BUT you have a larger issue from what I can see in your picture. It looks like a NON scrolled cam bush and a smooth cam. you MUST have one of them scrolled or you face camshaft seizure.

conkers · Apr 2, 2012

Thanks guys...

The cam is scrolled, you can only just see it in the picture.

So there is no additional washer or shims missing?
Looks like I have the 06-3020 bearing and 06-1086 tapered thrust washer fitted.
Has the workshop manual confused me where it says to remove the extra washer? Probably referring to the 06-2601 tabbed thrust washer fitted the engines with non-scrolled cams??

Mike

bill · Apr 2, 2012

You are correct in the 063020 bushing DOES NOT use the 062601 washer. The flange on the 063020 replaces that washer. The 062600 NON flanged cam bush requires the washer and ALL combinations require 061086 washer.

conkers said:
Thanks guys...

The cam is scrolled, you can only just see it in the picture.

So there is no additional washer or shims missing?
Looks like I have the 06-3020 bearing and 06-1086 tapered thrust washer fitted.
Has the workshop manual confused me where it says to remove the extra washer? Probably referring to the 06-2601 tabbed thrust washer fitted the engines with non-scrolled cams??

Mike

conkers · Apr 3, 2012

Thanks for the very clear explanation Bill.

I am now confident that nothing was missing.

Mike

conkers · Apr 5, 2012

I was poking around the head today and found these markings:

The "C" stamped on the top of the head and hidden by silver spray paint... does that by any chance stand for Combat?

I have another head here that belongs to my "pile of junk parts" and that has the oil feed unions on the top, is stamped with a "V" and has 3/8 studs and bolt holes.... could that be an Atlas?

pete.v · Apr 5, 2012

Alright, that appears to be a Combat, but what the heck is this all about. Compression release?

conkers · Apr 6, 2012

Compression release?
What are you talking about.....???????????

Hobot · Apr 6, 2012

Ms Peel which don't get that noticed yet.

pete.v · Apr 6, 2012

conkers said:
Compression release?
What are you talking about.....???????????

What are the 2 holes forward of the #1 bolt hole between the exhaust valve covers, bottom center of picture.

L.A.B. · Apr 6, 2012

pvisseriii said:
conkers said:

Compression release?
What are you talking about.....???????????

Click to expand...

What are the 2 holes forward of the #1 bolt hole between the exhaust valve covers, bottom center of picture.

Holes for head fasteners #9 & #10 (studs & nuts)

pete.v · Apr 6, 2012

L.A.B. said:
pvisseriii said:

conkers said:

Compression release?
What are you talking about.....???????????

Click to expand...

What are the 2 holes forward of the #1 bolt hole between the exhaust valve covers, bottom center of picture.

Click to expand...

Holes for head fasteners #9 & #10 (studs & nuts)

I do not know why that looked so odd to me. Sorry for that.

conkers · Apr 6, 2012

Phew.... I was worried that I had another unexplained oddity in my stables!

Just head nuts/studs.... had me thinking though.

Not always clear in photos exactly what one is looking at!

;-)

Mike

conkers · Apr 10, 2012

Next Question Gurus!

About the split the crank, noticed that only the "bottom" pair of bolts have a tab washer and the "top" pair of bolts seem a little short for the nuts.

Is this normal?

Conkers Swedish Cafe racer Project.

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