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ET: Engine (Twin) Fogging for Mosquitos; Valve Guide Issues and Solutions


timetraveller

Well Known and Active Website User
VOC Member
When it happened on my bike there was no trace of the guide itself and the lock ring was in three pieces up with the valve springs. I have no idea how it could do that but it did.
 

ClassicBiker

Well Known and Active Website User
VOC Member
Update:
Last week I removed the remaining guides and measured their o.d.s and the i.d.s of their respective holes.
Both inlets measured 0.501 as did their respective holes. A light tap with a drift and raw hide was all it took to remove them. The rear exhaust was 0.564 and the hole was 0.563. Rather than beat it out with a drift and hammer, I used a length of threaded rod and made a puller which eased it out in a controlled manner.
The front exhaust hole was 0.568.
So I'm thinking for the inlets 0.502 for a slight interference fit, 0.564 again for the rear exhaust and seeing what the Spares Co. has for extreme oversize.
I also measure the depth of the recess in the heads that the liner spigot into and how proud the liners stood above the muffs. Looks like I'm going to be spending some time with some emery on the surface plate.
Steven
 

Robert Watson

Well Known and Active Website User
VOC Member
Before you start knocking off the height of the liner above the muff, check the depth of the recess in the head where it fits, or do I recall from a previous post that the gap was excessive?
 

ClassicBiker

Well Known and Active Website User
VOC Member
Before you start knocking off the height of the liner above the muff, check the depth of the recess in the head where it fits, or do I recall from a previous post that the gap was excessive?
Hi Robert,
No quite the opposite. The liners protrude less above the muffs than the depth of the recess in the head. I am going to spend time rubbing the heads down. Using a depth micrometer I measured the depth of the heads near the cylinder stud holes and the compared that to how far above the muff the liner protruded in the same areas. The respective measurements either matched or the recess was deeper by 0.001". Which is what I suspected as when I did a leak down test, I could hear air escaping up the front right cylinder stud of the front cylinder. Reading through "40 Years On", "Another 10 Years", and the latest "Into the Millennium" There needs to be at least a 0.002" gap between head and muff. I don't have that, which is a relief in one regards, as the air I heard leaking is not from a cracked head.
Steven
 

vibrac

Well Known and Active Website User
VOC Member
I always found that protrusion of the casting around the exhaust pipe made the flat Emery solution difficult as it restricted the pattern of movement to the edge of the board
 

ClassicBiker

Well Known and Active Website User
VOC Member
Well I had considered inverting the heads on 2x4x6 blocks placed across the cylinder stud holes and clamping down just off of the face and skimming on the mill. :eek: Then I came back to my senses. Thoughts of breaking a fin by clamping down to much or watching a head sail across the garage because it wasn't clamped tight enough entered my head. Plus the nagging doubt of are the top faces of cylinder head bolt holes really parallel to the bottom face, are they actually a single plane or were they just cleaned up to provide a clamping surface without regard to anything? The fact that after the heads are assembled on the engine and the nuts tightened then the brackets that secure the UFM to the engine sit on the nuts leads me to believe locating up down in that location would be okay. But how to secure safely and leave a clear tool path, that is what bothers me. It would be interesting to see how they were located when originally manufactured or how the new replacement heads are done.
Steven
 

oexing

Well Known and Active Website User
VOC Member
Steven,
I machined the faces around the bolt holes at the top first to get same height . Then I mounted the head upside down onto a plate with pillars with same height again. For clamping I think to remember that I put some bit of plastic or cardboard into the exhaust for setting a clamp onto that. At the intake the clamp can go onto the casting so no fins are used. Maybe you can put the whole affair onto a plate in a lathe to turn the recess and big surface in one operation for exact depth all round.

Vic
 

Bill Thomas

Well Known and Active Website User
VOC Member
Steven, I use the same grinding paste on both the liner and the head, So would work out, Both touching at the same time, We are only talking a thou, Seems to work for me. Cheers Bill.
 

ClassicBiker

Well Known and Active Website User
VOC Member
Bill, I haven't disturb the barrels, yet. I have a large thick ring of steel ground on both sides. I was considering turning a shoulder on one end, such that is would fit into the recess in the head. Then I was going to put some Prussian blue on the head and see if where the liner contacts is flat. Then doing the same for the top of the liner. Thus avoiding disturbing the barrels.
Steven
 

vibrac

Well Known and Active Website User
VOC Member
Those barrels will have to come off unless you have real gear the only way is grinding the one thing to watch is to keep the paste off the short vertical head face in itself difficult . Not my favourite job I must admit
 

ClassicBiker

Well Known and Active Website User
VOC Member
After searching through all the usual books and searching here on the forum I couldn't find any reference to the angle between the valves. Obviously I'll indicate it in, but I was curious to see how close it actually is. I've got my rotary table with a decent angle plate attached set up square on the mill. I've also laid out and drilled four hold bolt holes and made two hollow dowels to locate the head to the angle plate. Photos to follow.
Steven
 

oexing

Well Known and Active Website User
VOC Member
Steven,
what is your plan, tidying up the valve guide bores ? Sorry for you, that will be a quite lengthy setup , when really a reamer with pilots would do it in minutes. Maybe you could find a GOOD reamer , best with uneven spaced blades for avoiding chatter effects. That might be upgraded with a sort of pilot replacing one nut on it. Once again the Hunger company in Munich has all sorts of handy tools that don´t require a machine. -- Like on big ship engines, you cannot possibly use a machine for head and valve jobs. So they came up with manual tools for same jobs - for perfect results in a fraction of time . In my photo is one of these piloted reamers that locates with its taper face in the 45 degree seat ring and you can ream the bore from the spring side down. When you set up the head on a machine you will be challenged to stay concentric from seat ring to lower guide to upper guide. No question I did that only with Hunger tools , no mill near . Same idea for line reaming bushes in girder forks, no other ways to do that in reasonable time . So maybe you´d like to find a GOOD adjustable reamer , best with uneven spaced blades to avoid chatter effects, and add a sort of pilot on it by replacing one nut with an extension. While trying to remember, I think I used the upper guide as datum for locating the taper of the reamer and have another taper sitting in the seat ring. Between them I reamed the guide bore - or so . . .

Vic

P1060461.JPG

some more types of Hunger reamers for engine jobs etc .

P1040021.JPG
 

ClassicBiker

Well Known and Active Website User
VOC Member
"The valves are inclined to each other at 65°, the pushrods at the same angle" P.E.I., M.P.H.329 and in "Forty Years On"
Thank you Chankly, I read that in "Forty Years On" and thought he was referring to pre-war Comets only as there was mention of 90° and 100° in the same paragraph. I messed about briefly with a level on the face of the valve cap and an adjustable draftsman's triangle under the head's face and got 57° and thought "no, you're messed up there." Thanks for clearing that up.

Valve angle on big port heads is 32º / 64º included.
Thanks Litnman, I read that on the data bases here and also in "FYO" and thought it referred to the angle of the valve face for sealing.

Steven,
what is your plan, tidying up the valve guide bores ? Sorry for you, that will be a quite lengthy setup , when really a reamer with pilots would do it in minutes. Maybe you could find a GOOD reamer , best with uneven spaced blades for avoiding chatter effects. That might be upgraded with a sort of pilot replacing one nut on it. Once again the Hunger company in Munich has all sorts of handy tools that don´t require a machine. -- Like on big ship engines, you cannot possibly use a machine for head and valve jobs. So they came up with manual tools for same jobs - for perfect results in a fraction of time . In my photo is one of these piloted reamers that locates with its taper face in the 45 degree seat ring and you can ream the bore from the spring side down. When you set up the head on a machine you will be challenged to stay concentric from seat ring to lower guide to upper guide. No question I did that only with Hunger tools , no mill near . Same idea for line reaming bushes in girder forks, no other ways to do that in reasonable time . So maybe you´d like to find a GOOD adjustable reamer , best with uneven spaced blades to avoid chatter effects, and add a sort of pilot on it by replacing one nut with an extension. While trying to remember, I think I used the upper guide as datum for locating the taper of the reamer and have another taper sitting in the seat ring. Between them I reamed the guide bore - or so . . .

Vic

View attachment 27294

some more types of Hunger reamers for engine jobs etc .

View attachment 27295
Vic, not just cleaning up the valve guide bores but the threaded portion of the head where the valve guide lock ring used to reside. It is complete chewed up. My plan is to clean up the bore where the forked end of the rocker operates all the way down to surface that the shoulder of the lower valve guide rests against. Then make a modified keeper that Timetraveller refers too. Once I've got that sorted then I have to address the guide bore to keep is concentric to the valve seat ring. Living just outside of Detroit there are plenty of tool suppliers to source reamers from. Thanks for the post it has given me some ideas.

Steven
 

A_HRD

Well Known and Active Website User
VOC Member
For the record, in a perfect world, the Series 'A' Valve Angle is 62 degrees.
Peter B
 

Cyborg

Well Known and Active Website User
VOC Member
Before folks start retching over this setup, it was only used to trim off the portion of the guide that was protruding into the port. It was beat up and mushroomed over slightly. Given there was no other damage, I assume some freak tried to beat the guide out without removing the lock ring. Unfortunately the photo does't show the jig that screws into the inspection cap hole and holds the head.
It sounds like you have it figured out, but I'm betting Dan Smith has a jig for holding the heads while truing up the head/barrel mating surface. I only know this by the look he gave me when I mentioned lapping the surfaces. Off topic sort of... but when trying to hold impossible things in the mill or the lathe, don't forget Cerrobend.

HRD Head.jpg
 

bmetcalf

Well Known and Active Website User
VOC Member
Likewise, Clev Trev.

Steve Hamel, also. I last saw it ~10 years ago, but i think it had several degrees of freedom, but could lock down concentric with a plug fixed against the upper guide seating that had been trued. Can't remember how that truing was done.

It sounds like you have it figured out, but I'm betting Dan Smith has a jig for holding the heads while truing up the head/barrel mating surface. I only know this by the look he gave me when I mentioned lapping the surfaces.
 

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