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Webster IC Engine build log.

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raynerd:
Jack - thanks for the info - very informative stuff!


Firstly, I`d like to apologise for this next post! I`m so sad that I made a little video because I was so pleased with the piston seal! This is the longest bore I`ve done and I can safely say that turning it between centres was a great suggestion, it is true all the way through. I`m sorry, you`ll have to wait for photos of the piston as I put it together before taking any. But here is the video....

My finger is over the end of the cylinder bottom and I`m getting such good compression that is blows my finger away or in the reverse direction, sucks the crank back around! I`m very please with this as you can tell. All my other piston/cylinder seels on my other engines have been pretty poor! This is the first to give me a satisfying pop when removed!

NickG:
That looks superb Chris  :thumbup:, presume that is with the o ring in place? What is the friction like? Don't think it will matter as much on an engine like this but I'd still aim to get it quite low if I were you.

raynerd:
No !! No O-ring or it wouldn't be as impressive!!

The groove is cut ready for the o-ring but it is not in place yet. I tried it with out and got this great seal !! It is just cast on cast so turns very very smooth yet excellent seal.

NickG:
Excellent - told you, you don't need an o ring! You'll probably find the friction is quite high with an o ring, mainly the starting friction but the dynamic friction shouldn't be too bad, depending on how much you make it compress. The seal will obviously be even better but it might make it more difficult to start etc. With a hit & miss type engine you'd want to reduce the friction to as low as possible, but with this you should be able to live with the trade off of friction vs best possible seal.

Nick

raynerd:
Yes, I`m going to try without. The groove is in place ready for the o-ring and the orings have arrived. I`m just thinking that after a bit of running the cylinder bore and piston might lap/smooth out (what is the right word?) and make a poorer seal. That being said, I lapped the bore to a good finish and also have highly polished the piston to get such a good fit so hopefully it might not.

Chris

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