Trixie Gets the Anne Boleyn Treatment

Dan1950 said:

Jim Schmidt called me today regarding my JE piston order and I ran the hybrid flat/radiused lifter idea by him.

He didn't see any problems with my idea as long as the oversized intake valve didn't tangle with the exhaust valves given the cam grind.

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The 312a will be fine with +1.5mm valve, which is what i have. (Can't remember what you said you had?)

Dan1950 said:

Jim Schmidt called me today regarding my JE piston order and I ran the hybrid flat/radiused lifter idea by him.

He didn't see any problems with my idea as long as the oversized intake valve didn't tangle with the exhaust valves given the cam grind.

Click to expand...

That's good to know.

BTW, I still wouldn't do it myself. I'd stick with the cam grind as is with the radiused lifters. It won't be that hard to start with radiused lifters unless you have a knee or other leg issue on the right side. You said you bicycle. That does help with the kicking. I'm not blowing smoke up your exhaust. I bicycle regularly, have those JS pistons for long rods, have more cam, and am 71 years of age. Also short and shrinking daily. No problem starting the bike with my right leg. Not sure I could do it with my left leg though. I put a Bultaco foot peg a couple of inches into my left leg just behind my knee on a get off. Did it sometime in the 70's. I still walk kind of funny from that motorcycling episode. So even a gimpy old guy can start a Norton with 10:1 compression pistons and a nice cam.

Be sure to report on how it works out. Maybe you can become a Norton trend setter and influencer.

Schwany said:

That's good to know.

BTW, I still wouldn't do it myself. I'd stick with the cam grind as is with the radiused lifters. It won't be that hard to start with radiused lifters unless you have a knee or other leg issue on the right side. You said you bicycle. That does help with the kicking. I'm not blowing smoke up your exhaust. I bicycle regularly, have those JS pistons for long rods, have more cam, and am 71 years of age. Also short and shrinking daily. No problem starting the bike with my right leg.

Be sure to report on how it works out. Maybe you can become a Norton trend setter and influencer.

Click to expand...

Easier kick starting is only one reason for having the closing of the intake valve retarded. The bigger benefit of reduced cylinder pressure at low RPM is resistance to detonation.

As it is, I am considering just using the tappets as is (flat) to increase duration and overlap as long as valve head interference during overlap isn't a problem.

I plan to mock up one side on the bench to check clearances. I can do that for flat tappets, hybrid flat/radiused tappets as well as fully radiused.

This is not my first rodeo.

Dan1950 said:

Easier kick starting is only one reason for having the closing of the intake valve retarded. The bigger benefit of reduced cylinder pressure at low RPM is resistance to detonation.

As it is, I am considering just using the tappets as is (flat) to increase duration and overlap as long as valve head interference during overlap isn't a problem.

I plan to mock up one side on the bench to check clearances. I can do that for flat tappets, hybrid flat/radiused tappets as well as fully radiused.

This is not my first rodeo.

Click to expand...

Agree with the detonation potential issue.

Dan1950 said:

Easier kick starting is only one reason for having the closing of the intake valve retarded. The bigger benefit of reduced cylinder pressure at low RPM is resistance to detonation.

As it is, I am considering just using the tappets as is (flat) to increase duration and overlap as long as valve head interference during overlap isn't a problem.

I plan to mock up one side on the bench to check clearances. I can do that for flat tappets, hybrid flat/radiused tappets as well as fully radiused.

This is not my first rodeo.

Click to expand...

312a with 4" radius lifters and 9.5:1 was no issue at all to kick start. How much harder can .6 be? ;-)

gortnipper said:

312a with 4" radius lifters and 9.5:1 was no issue at all to kick start. How much harder can .6 be? ;-)

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I'm going to be running the JE pistons at about . 040 Quench height. That should be a bit over 10:1 "static" compression ratio. I may opt for the flat tappets to reduce "dynamic" compression to alleviate detonation tendencies.

Reducing static CR by increasing quench height can often exacerbate detonation tendencies.

Ideal quench height is between . 040" to . 050". One can go as tight as . 035" with an automatic transmission but that doesn't apply here.

The composite head gasket I removed was approximately .033" compressed. My head has negative .0125" head deck at the quench area. The stock flat top pistons are about . 003" negative deck.

Right now the quench height is about .161". The JE pistons have a deck height of + .120 compared to the stock flat top pistons. The should yield an ideal quench height of . 040" or very close to it.

Making some progress on rebuilding the engine.

After removing the head I had it bead blasted and gave it a coat of high temp cast aluminum paint.

Before


After


I took the head to Precision Cycle in Ottawa and Dan installed an aluminum/bronze threaded insert. Great service with a quick turn around.

Dan1950 said:

Making some progress on rebuilding the engine.

After removing the head I had it bead blasted and gave it a coat of high temp cast aluminum paint.

Before

After

I took the head to Precision Cycle in Ottawa and Dan installed an aluminum/bronze threaded insert. Great service with a quick turn around.

Click to expand...

'bead blasted' that's the last thing I'd do to a commando head
How can you ensure you have all the debris out ?

baz said:

'bead blasted' that's the last thing I'd do to a commando head
How can you ensure you have all the debris out ?

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The kitchen sink with lots of Dawn dishwashing liquid and Q-tips is your friend.

Been there done that more times than I can remember. Worst offenders are blind threaded holes. That's were using Q-tips in a pumping motion with lots of soap suds does the trick.

I've had enough time to mull over my options and have developed a plan.

I have enough experience putting engines together with altered geometry to realize the importance of mocking up the rotating assembly and valve train to check clearances, and if necessary, make changes for proper clearances.

After temporarily installing the WEB 312a cam in the cases I will assemble the engine with existing bearings, pistons, etc. to check valve clearance at overlap with the original valves in one side. This will initially be done while utilizing the OEM (flat) tappets. and will be a mock-up assembly using a minimal amount of fasteners and the used OEM head gasket. Depending on the clearance at overlap, I will have several options to consider.

Ideally, there will be enough clearance to allow 1.5mm oversized intake valves with standard sized exhaust valves using unaltered flat tappets. Worst case scenario would be not enough clearance with standard intake/exhaust valves using unaltered flat tappets.

Dan1950 said:

The kitchen sink with lots of Dawn dishwashing liquid and Q-tips is your friend.

Been there done that mort times than I can remember. Worst offenders are blind threaded holes. That's were using Q-tips in a pumping motion with lots of soap suds does the trick.

Click to expand...

Porsche thought they could clean all the debris out from bead blasting too
Until the heat cycles released the debris months later
Hopefully you got every last bit out
Cheers

Using the old parts to check clearances would be a waste of my time during a rebuild. It is going to work fully assembled with the new parts. The 312a cam is not that big.

I know people gotta do what they gotta do, but doing the mock up once sure seems like a better use of time to me. I went to different rodeos though. lol