Cirrus V8 rotary valve engine build 2x scale up

[bazmak]

After i finished the 3 cyl rotary engine i wanted something bigger and more taxing.I downloaded the drws ,many thanks to Chuck Fellows
Again i wanted to make changes
1 I scaled up the drgs /dims x 2 and nudged a few things to suit
2 I plan to fit ball brgs to the 2 outer posns And a split brass bearing to the middle
Everything else will be sorted when i get there,this build is just starting so any comments/input will be welcome.Any thoughts on replacing the timing gears
with a small commercial timing belt
INSTEAD OF JUST ADDING PHOTOS AT THE END OF THIS THREAD I THOUGHT I WOULD TRY SOMETHING DIFFERENT
AND EDIT EACH POST BY DELETING THE OLD PHOTOBUCKET BLANKS AND ADDING NEW PHOTOS

 

[Herbiev]

I'm going to enjoy this build. Is that a wood router bit in the mill Baz.?

 

[bazmak]

Yes Herbie,i have mentioned it on many posts.I have a couple of cheap sets
of carbide router bits and they work well on aluminium and brass
OGee,int and ext rad,g chamfering and dovetail. Mine are only 6mm shank,the bigger ones would be better.Try it they really remove the metal.I have 2 boxed sets the only cost me $10 each

 

[Herbiev]

Thanks Baz. I got a heap of 1/2" shaft router bits so will try them out.

 

[barnesrickw]

they are loud though

 

[bazmak]

High speed,light cuts and then run back.Climb milling gives a super finish
Use them all the time for detailing the corners of stands/plinths etc

 

[bazmak]

Progress with the sump and crankcase.Bought 5kg of alum and threw
1/2 of it as chips in the bin
BLANK PHOTOS REMOVED AND ADDED AT END OF THREAD

 

[bazmak]

3 days ago i decided to make the crankshaft.I realized that it would be easier to make from solid rather than fabricate.So with a lump of mild steel 40mm dia x 240mm lg heres how.I had to spend some time making a turning fixture but it was well worth it.I rough turned one eccentric ,spun 90o and repeated 3 times
removed some more x 4 and again reducing cuts and stress until i was almost there.The ability to remove from the lathe and reset with accurate repeatabiliy
worked really well.I took my time and my fears were not realized.Everything came out to size and concentric within 2 thou
BLANK PHOTOS DELETED AND NEW ONES REINSERTED AT THE END OF THE THREADS

 

[bazmak]

Forgot to mention that i used the collar to drill thru at the headstock end
and drill and tap 4 no M4 holes in the web.I then used a
n M4 capscrew to bolt the fixture to the crank.It can then be positioned at 90o
for each eccentric.The tailstock collar was set in position at the tailstock end
and clamped in position until the whole job was complete

 

[Herbiev]

Really enjoying this post Baz. Don't waste those aluminium chips. Put them in a cake tin and leave them outside. With 40 degree temps for this weekend you'll get another solid blank

 

[dsage]

Hey Baz:
Help me out with the scale of this engine. Maybe the base dimensions of the block or something. Bore and stroke too if you don't mind. As usual it's tough to tell from the photos alone.

Sage

 

[bazmak]

Hi, sump is 6" lg 31/2 w and 1/12 deep.Crankcase is 6x3.3x 2"
Bore will be 3/4" dia and stroke 1".Plans are on the download section
Most things are just doubled.End brgs will be 12mm or 10mm
Centre brass brh is 12mm.* cylinders have been cut to size 32x48x63mm
I think the original size would be too small now for my eyesite regards barry

 

[bazmak]

Just spent a few hours in the shed.40oc outside and 50oc inside
Chips didnt melt herbie but started to go soft like me in the head
Next job was to finish shaping the top of the crankcase and bore
out 8 holes for the cylinders.Made good use of the indipendant jaw vice and
homemade boring tool.Everything went well. PHOTOBUCKET DELETED

 

[mu38&Bg#]

I have to ask, what type of rotary valve arrangement will you use in this engine?

 

[bazmak]

as per drgs,a shaft goes thru the top on Cl with 2 gears from crankshaft
The drgs are in the download section.I have sortedm out the problems in my head but concentrating on the details as i come to them.Too much input all at once causes headaches.The plans are in the download section

 

[toolznthings]

Lot of nice work you have done ! Following along as you go.

Brian

 

[cfellows]

Very nice build. Craftsmanship looks top shelf. The only comment I have is that you'll need a pretty large air compressor to keep it running for any length of time... . If you have any questions on exhaust springs, port sizes, etc., I'm happy to share what I know.

Chuck

 

[bazmak]

Thanks chuck,please keep an eye on me.I am doing the easier mech. parts first
When i get to the tricker bits,pipework ,timming etc i will need advice but hopefullyi will be more into it.I dont have a compressor yet so have not run any models under air,but hopefully will eventually. Regards barry

 

[bazmak]

Next was the conn rods.Drg says alum but i dont like ally as a bearing media
Trying to bush out was too fiddly so i decided to make from solid brass
blank photos deleted and a couple of new ones added with more at the end of the thread

 

[cfellows]

Nice work. Finish on the con rods looks really good.

Chuck