5 replies to this topic

[Hunter2]

What was/is the dish size in Cooper S 19320 pistons?

 

I have a set from a 20 over Austin America block that was built up years ago to go racing...they didn't - in fact probably never got the engine running.  Working out compression ratio on the rebuild.

 

My rebuild includes new A+ crank, new A+ rods, new rings obviously, rebuilt 12G940 head (new guides/springs) to be milled, new 1.3 roller tip rockers, new SW5 cam/lifters, new oil pump, new duplex timing gears/chains....  Block has been milled the minimum to clean up the deck (pistons were down 0.013").  Hoping to see a compression ratio of close on 10:1.

 

Have installed new  oil gallery & freeze plugs and new cam bearings tonight.  Installing cam, crank, rods/pistons tomorrow night to confirm clearances...rod journal clearances were fine, new A+ crank main journals were 1 thou over so polished, mains align honed.  Ready to confirm build specs prior to anything other than minimum head face milling. 

 

Engine will run out through 11 lb. lightened flywheel, standard disc, Orange spring to rebuilt 4 syncro 'Puddin Stirrer' box with 3.44:1 FD (vs. 3.65:1 FD) and pot joint outputs.

 

 

[jaydee]

I'll give you a better option, Measure piston dish with a burette and paraffin, better if you do this with pistons fitted and caps torqued.

[Hunter2]

Thanks.  Have the burette and will use on combustion chambers...was hopeful the cc for a 19320 piston dish were more readily available.

[carbon]

Hunter,

 

With the S pistons 13 thou down the bore you will likely have over 10:1 CR with a standard 940 head, so would go easy on the skimming unless the chambers have been opened up a lot.

 

What octane fuel are you planning to use?

[Cooperman]

I am fairly sure that they are 8.4 cc, but do measure as a check.

[Hunter2]

Yes, cc check of dishes & combustion chambers is necessary also head gasket compressed volume by type as the indicated compression is 10:1 or slightly above (added in crown to ring volume too). Remembering that this Austin America block was built up years ago to be a race engine...but never ran.

 

The engine (with rebuilt tranny, new clutch & flywheel) etc. is going into the 1973 OZ Mini Window Van, a club car not a daily driver.  It will get the best fuel available in North America when out and about.  I also used better fuel when driving the Van around Australia with the factory 1098 power unit.

 

Will know more tonight with crank/rods/piston install & check measurements including piston dish and combustion chamber.  Head has hardened exhaust seats installed, new guides, valves, springs...if the exhaust valves are slightly proud then cc could be less than stock.  Examination of head showed no indication of prior machine work.

 

Will update post.