Author Topic: Two Cylinder Engine  (Read 24692 times)

Offline Roger B

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Re: Two Cylinder Engine
« Reply #195 on: August 30, 2019, 08:04:04 PM »
The valves and head went in the ultrasonic bath together with the injection test pump components. I managed to reassemble the valves and springs without donating any parts to the swarf gnomes. There seems to be quite good compression without piston rings  :) I then started to make some spark plug connectors from some 0.3mm phosphor bronze sheet. The core diameter was difficult to measure, but I got a reasonable chance with two 0.5 mm drills. 2.5mm was the result so I drilled 2.3 mm and then opened out with a Swiss file. The wire connection was drilled 2mm and the connection was opened out with tin snips along with a 4mm deep cut down the middle. Another step done  :)
Best regards

Roger

Offline Admiral_dk

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Re: Two Cylinder Engine
« Reply #196 on: August 30, 2019, 09:15:57 PM »
Looks like you are moving nicely forward - how much is still to come / has to be made ?

Offline Roger B

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Re: Two Cylinder Engine
« Reply #197 on: September 01, 2019, 07:18:12 AM »
Thank you Per, it just needs piston rings and the seals for the water pump.

The next step was to make a base plate, not as elegant as Old Bill's or Vixen's, but will work. The engine, 6V coil and fuel tank (borrowed from the single) were mounted and connected. I checked that the sparks came at approximately the right moment and decided to give it a try as even without rings the compression was quite good.

I initially got a few short bursts of firing and then nothing  :headscratch: Finally I noticed that the fuel was not being sucked up the fuel pipe to the carb and kept flowing back to the tank. I opened the tank cover to check that there really was enough fuel and got a pop. I hadn't removed the block from the tank breather and had built up a vacuum in the tank  :facepalm: I tried again and got a few pops plus some oil from the exhaust. Finally the rollers fell out of the sprag clutch  :(

Back into the workshop to assess what had gone on. The plugs were very oily, only one showed any real carbon traces. The combustion chambers were full of oil too. I guess that all the choking trying to get fuel into the carb also sucked oil passed the pistons which there was no combustion to burn off. I removed the distributor cap to see what had gone on there. There was a slight (0.5mm?) lack of clearance and the rotor had been rubbing on the outer electrodes spreading brass shavings around. I then removed the cylinder block to check the pistons and the bottom end. All looks ok with no signs of pick up, just a lot of oil.

I will have to make a new housing for the sprag clutch as the original was fitted with Loctite 648.
« Last Edit: September 01, 2019, 08:13:04 PM by Roger B »
Best regards

Roger

Offline fumopuc

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Re: Two Cylinder Engine
« Reply #198 on: September 15, 2019, 06:52:12 AM »
Hi Roger, good to the see the R&D department busy again.
Waiting for the next attempt to get it running.
First pops seems to show that the basics are fine so far.


 
« Last Edit: September 22, 2019, 05:05:33 AM by fumopuc »
Kind Regards
Achim

Offline Roger B

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Re: Two Cylinder Engine
« Reply #199 on: September 21, 2019, 08:25:35 AM »
Thank you Achim  :)

I made a new sprag clutch housing and skimmed 0.5mm off the end of the rotor arm to give some clearance. I also found that turning the engine backwards when checking the sparks is not a good idea. As the rotor is not near a plug contact when the contact breaker opens there is a vicious spark down the side of the rotor arm to the cam  :zap:
Next up is some piston rings. Although there is currently only one groove per piston I have space to add a second ring if required and so to allow for breakages I need to make at least 8. The rings are planned to be 0.9mm square. First up I made the setting ring for the skimming jig. This is bored to 0.05mm over the bore size so 2.20mm which was checked using the plug gauge I made for the bores together with a feeler gauge. I then roughed out the piece of cast iron to make the rings and let it relax for a while.
Best regards

Roger

Offline Roger B

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Re: Two Cylinder Engine
« Reply #200 on: September 22, 2019, 08:16:03 AM »
The blank was then bored out to 18mm and the inner surface was polished to reduce the risk of the rings breaking on installation. The outer diameter was finished to 20.15mm and the rings were parted off. The first one was checked in the piston groove and the same feed was used to cut the rest. The faces were polished on some 400 abrasive cloth to remove the flash from parting and the internal corners were smoothed with an abrasive rod. The rings were then split using piano wire rated wire cutters.
Next up is the heat treatment jig and heat treatment. The centre of the jig was turned to 19mm which seemed to give a suitable gap.
Best regards

Roger

Offline Roger B

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Re: Two Cylinder Engine
« Reply #201 on: September 22, 2019, 02:55:29 PM »
Five rings were clamped in the fixture and heated to dull red. After cooling down naturally they were removed and the second five were heat treated. They had grown a little but would still fit in the setting ring as it is 0.05mm oversize.
I then needed to make the skimming fixture. This can be done in one operation in the 3 jaw SC chuck but if I have to use it again it has to be carefully centred in the 4 jaw independent chuck. The body has two steps, one 0.05mm over size and one 0.05mm undersize. The rings a loaded into the setting ring which is centred over the larger diameter. They are then clamped in place and the setting ring is removed. This allows them to be skimmed to the bore diameter.
Best regards

Roger

Offline Roger B

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Re: Two Cylinder Engine
« Reply #202 on: September 22, 2019, 05:25:07 PM »
My initial attempt with 5 rings was a little optimistic, two of them broke away  :( I was able to finish the remaining three from that batch without problems and then did the others as a three and a two.
The gaps on two rings were set in the bores to around 0.05mm and were fitted onto the pistons without problems. Now I need to put it back together and give it a try  :)
Best regards

Roger

Offline Admiral_dk

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Re: Two Cylinder Engine
« Reply #203 on: September 22, 2019, 09:22:29 PM »
Looks like you had some productive in the shop and a satisfactory result - even if a few went into the bin  :ThumbsUp:    :popcorn:

Offline Art K

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Re: Two Cylinder Engine
« Reply #204 on: September 22, 2019, 11:23:00 PM »
Roger
Getting the rings installed without breaking them is always a good thing. :ThumbsUp:
Art
"The beautiful thing about learning is that no one can take it away from you" B.B. King

Offline Roger B

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Re: Two Cylinder Engine
« Reply #205 on: September 23, 2019, 05:44:34 PM »
Thank you both  :)

I put it back together, took it outside and it's a runner  :whoohoo: It fired up on the first choking and after a couple of tweaks of the needle I got this:





Best regards

Roger

Offline crueby

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Re: Two Cylinder Engine
« Reply #206 on: September 23, 2019, 06:27:56 PM »
Terrific!!

Offline fumopuc

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Re: Two Cylinder Engine
« Reply #207 on: September 23, 2019, 07:12:24 PM »
Roger, it is running like hell. Congratulations.
Kind Regards
Achim

Offline Jo

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Re: Two Cylinder Engine
« Reply #208 on: September 23, 2019, 08:22:48 PM »
Nice runner  :)

I was a bit worried about it bouncing around on the top of the narrow wall in case it fell off  :paranoia:

Jo
Enjoyment is more important than achievement.

Offline bent

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Re: Two Cylinder Engine
« Reply #209 on: September 23, 2019, 10:03:53 PM »
Woo hoo!  Nice runner, Roger!