Glad I found this thread.
I've been working on making a couple of hybrid .40s.
1) The series 21 pistons fit in the lightning bolt .40 cylinders really well so I bought a couple .40 pistons and rings from MECOA but I also got a ring from Bjorn Ball. My question is, Is it better to use the series 21 cylinder head or will the old McCoy Red/Blue heads work?
2) The other older McCoy .40 I have to use is an older non-lightning bolt case. So I will either have to find a LB cylinder, or bore the case slightly to use a series 21 cylinder. Which I gotta tell you is not all that fun as either head bolt pattern has to be modified. I did this to a .35 RedHead and was a PIA. I also did a .29 RedHead but the series 21 cylinder drops right in so I only had to fit the RedHead to the S21 cylinder. Again PIA. I've got a rotary table now so it should be a little easier though.
3) What is the best venturi inlet diameter should I be using for these Hybrids? Does the height of the venturi matter? I have a Super Tigre style needle valve but the venturi is I think from an OS .35S. I still need to turn it down a little to fit the McCoy but if its the wrong to use I wont bother and will just make an entire new one out of Delrin.
I've included some pics;
- two are of the Lightning bolt crankcase. The piston fits perfectly but you have to use the series 21 conrod.
- next are the .35 RedHead I fitted with the series 21 cylinder and the boring setup. Its got an ST style needle and a Bjorn Ball ring. I've got some newer Sherline equipment now though.
- and lastly, some pics of the older McCoy 40 crankcase and parts. I will need to fit the Series 21 cylinder but interested in what cylinder head to use.
- I also included a few pics of another McCoy series 21 project I'm working on.
EDIT: It wont allow me to attach more than a couple pics so I'll have to put them in another post.
Thanks,
Mike