Very impressive. Perhaps this old dog really needs to learn new tricks. Thanks for sharing/motivating.
Porsche 917 flat 12 engine
- Thread starter Foketry
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Both camshaft housings are installed and the holes for spark plugs and valves are made in correspondence with the valve head holes .
Next step: cages assembly in the heads, valves assembly , tappets , 4 camshafts whit gears , camshafts housing final machining , sandblasting.
Next step: cages assembly in the heads, valves assembly , tappets , 4 camshafts whit gears , camshafts housing final machining , sandblasting.
All 24 cages are assembled with Loctite 620 and I milled the intake and exhaust holes
I preferred to mill rather than drill the holes to avoid deformation of the cages
This, I hope, it will save me a long lapping of the valves of which I have already done an initial lapping before assembling on the heads
I preferred to mill rather than drill the holes to avoid deformation of the cages
This, I hope, it will save me a long lapping of the valves of which I have already done an initial lapping before assembling on the heads
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I wish i could Visite your shop and watch you doing the magic.
Awesome work!!
Awesome work!!
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Logan200
New Member
Fantastic! Keep on 
While you come to the sea in Italy, my shop (ex garage, my cars sleep outdoors) is always open to all visitors
I'm waiting for you....
Logan200
New Member
ajoeiam
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Hmmmmmm - - - - If you would develop some good connection(s) with some reasonable bed and breakfast places I would bet that my wife would love that beach too (I prefer snorkeling on a reef but that water looks great!!!). Your shop would be the draw for me! (grin - - - wacky - - - I know!!)
Valve assembly
After a final lapping I assembled the valves with oil seal, spring, 2 spring retainer, seeger . The second lapping was fast, there was no deformation of the cages when pressing into the holes of the heads.
I put the oil seal because being an engine with double overhead camshaft, where the cam pushes on the tappet it is necessary to lubricate. When the piston sucks fuel through the valve, it could also sucks oil from above.
After a final lapping I assembled the valves with oil seal, spring, 2 spring retainer, seeger . The second lapping was fast, there was no deformation of the cages when pressing into the holes of the heads.
I put the oil seal because being an engine with double overhead camshaft, where the cam pushes on the tappet it is necessary to lubricate. When the piston sucks fuel through the valve, it could also sucks oil from above.
Amazing work!
JonnyC
New Member
Hi a41capt, whats the old trials bike?
1976 Bultaco Sherpa T 350
Cams
I designed 2 different cams, one for intake and the other for exhaust as the duration of the intake and exhaust phases is different , 14 degrees greater the exhaust . I used hardenable steel, the tempering will have after having assembled everything with the correct timing and fixed in position through a hole made simultaneously on the shaft and cam. They will be disassembled , hardened and then reassembled
I designed 2 different cams, one for intake and the other for exhaust as the duration of the intake and exhaust phases is different , 14 degrees greater the exhaust . I used hardenable steel, the tempering will have after having assembled everything with the correct timing and fixed in position through a hole made simultaneously on the shaft and cam. They will be disassembled , hardened and then reassembled
the pre-turned steel round ready for milling
milling with a 6 mm end mill
milling with a 6 mm end mill
The camshaft design
Camshaft will rotate on 6x12x4 2Z ball bearings, 8 each shaft , the gear in the center of the shaft will have a phase adjustment by means of 3 slots and 3 M3 screws.
This will allow me to adjust the opening between the 2 camshafts, about 110/120 degrees, once the cams have been phased one by one
In the original engine there are a series of holes on the gear to find perfect timing
Camshaft will rotate on 6x12x4 2Z ball bearings, 8 each shaft , the gear in the center of the shaft will have a phase adjustment by means of 3 slots and 3 M3 screws.
This will allow me to adjust the opening between the 2 camshafts, about 110/120 degrees, once the cams have been phased one by one
In the original engine there are a series of holes on the gear to find perfect timing
I know I’m quite the new kid on the block, I had a hard enough time setting the valve timing on my “Kitchen Sink” engine, but that valve timing looks absolutely overwhelming!!!
Once again, spectacular work and I so look forward to hearing it run. Thanks for keeping me wondering how the hell I’d EVER reach that level of craftsmanship…
John W
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Got a couple of questions about the cam sections.
1) I can see how the setscrews will allow you to adjust each cam section's position on the shaft to get the correct timing, but will the setscrews be enough to hold that position on the shaft? It would seem to me that the side forces applied to the cam section each time the valve is actuated would want to twist the section on the shaft.
2) Once you've got the sections timed where you want them. are you going to pin them in place?
3) Are you going to harden the cam sections? Or, since this is a model engine that doesn't have to run for thousands of hours - just leave them soft.
Don
1) I can see how the setscrews will allow you to adjust each cam section's position on the shaft to get the correct timing, but will the setscrews be enough to hold that position on the shaft? It would seem to me that the side forces applied to the cam section each time the valve is actuated would want to twist the section on the shaft.
2) Once you've got the sections timed where you want them. are you going to pin them in place?
3) Are you going to harden the cam sections? Or, since this is a model engine that doesn't have to run for thousands of hours - just leave them soft.
Don
the cams will be fixed to the shaft initially with a screw, when the timing is ok, they will be locked in position with a spring pin
The bearings will be held in position by bearing caps and spacers between the end of the cam and bearing .
I will do this assembly in a few weeks, I am waiting for bearings, August in Italy is month of 1- 2 week of holidays.
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the fixing screws are only for timing, the engine cannot work, I will put sprig pins to prevent the cam rotating on the shaft.
In the cam drawing you can see the hole for screw and 2 pin holes
All the cams, once the timing has been carried out, will be take apart and hardened.
This engine, if I can get it to work, will rotate for a few hours in its life, perhaps hardening is not necessary, but I prefer to do it in a workmanlike manner .
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