Wyvern – errors on drawings

[John PurdyParticipant @johnpurdy78347]

I've just completed E.T Westbury's Wyvern engine and I found the following errors/ problems on the drawings. I checked back to the originals in the '63 ME series and they are there also.

1. The drawing for the mixer shows the recces in the upper body for the throttle as 7/16" deep but for the outlet hole in the throttle and the body to line up it should be 1/2" deep.

2. The front mounting bolts on the main bedplate interfere with lower flange of the water jacket if spaced at 2 1/4" as shown. By machining off the bosses and spacing the holes out to 2 1/2" ( the same as the rear) the problem is alleviated

3. The lubricators are all shown at 3/4" dia. For the two on the main bearings this gives zero clearance on the crank webs. Reduce the dia. of these two to provide clearance.( I made mine .680 dia. but if doing it again I would make them all about 1/2 to 2/3 the size as I think they look out of scale for the engine.)

4. The timing diagram is backwards. Either the crankshaft rotation arrow should be reversed to give CCW rotation or the valve events should be flipped 180 degrees.

5. The cam shaft cannot be assembled with the rear camshaft bearing made as drawn. The drawing shows the distance from the centre line of the camshaft to the flange on the bearing as 1/4", but the camshaft gear is 5/8" in dia. (ie. 5/16" from the gear centre line to the outside) as well one of the bearing mounting bolts is in the way. I moved the right hand mounting bolt down to the bottom spaced out as the left hand one. To make clearance for the gear I mounted the bearing in the mill vice with spindle centred on the bore and plunge cut with a 11/16" end mill to scallop out the mounting flange to give clearance for the gear. (see the picture in the albums section under Wyvern)

6. The left hand 1/2" dia of the crankshaft is shown at 3/4" long. If made at this length the centre lines of the camshaft gears do not line up, in fact they barely engage. The 3/4" length should be lengthened by ,095" to line up the centre lines of the gears. (As well the outer 1 1/2" length could be made longer to accommodate a lock nut on the flywheel retaining nut as without it the nut keeps undoing as the engine is running!)

7. The inner 7/8" dia. hub on the left flywheel had to be chamfered back at 45 deg. for a face width of about 1/8" as I found it hit the camshaft gear.

[John PurdyParticipant @johnpurdy78347]

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