srw1960

Ok need a little help..I have 4 ops engines and they all say 67 on the side of the cases yet they do not all have the same piston and liner in them and I am just learning that OPS made an 80 size and used the 67 cases..Ok so can someone please tell me how to tell the differance..dimensions on piston and sleeve perhaps or what other identifier can be used....

Any help is greatly apreciated..

THANKS..Yall have funnnn and take care

f16man

The bore size will tell you as most still use the same crank as the 60 size ,Rossi ,OS and picco did the same for ducted fan and marine engines, with very good results I might add.................

srw1960

Ok so any idea where I can find the dimensions at to determine for sure which is which????

f16man

Well if you want to get technical you can measure the bore and stroke and find the volume of the cylinder but as I said the larger bore will be the 80 and the stroke should be the same as the 67. Does that answer your question or am I not on the same page with ya ??????

srw1960

Sorry..had a brain fart...you are right of course all I need to do is measure bore and of course the larger bore would be the 80..THANKS for putting up with my moment of stupidity

f16man

We all have brain farts,,,, join the club ha ha

srw1960

Ok finally got off my butt and tore heads off to get measurements..have 4 engines 2 say 60 on the side of the case and they have a bore diameter of .940 inches. one case just says ops on the sides but the back plate is marked 666 ( ya I know bad numbers) and the bore measures .956 with a stroke lenght of .900 inches and the other is had no cy;inder or piston in it but the case was stamped 60 on one side...sooooo my question now is how do I turn these dimensions into something usefull do I have 2 67s?and an 80? or 2 60s and a 67???? if anyone could share the formula to calculate the displacement of the cylinder I have diamter and stroke on I would really appreciate it..

Ok found a sight that calculated the dimensions and it says for a .956 bore by .900 stroke it should have a volume of .64 cubic inches and the smaller bore came to .62 cubic inches??????????????? Ok so its safe to assume my stroke dimension may be off a bit but I guarentee my cylinder dimension is dead on ( I do know how to read calipers) should I assume I have 1 67 and 2 60's?? or is it more likely I have 2,67's and 1 80????..Ill try to get a more accurate stroke length tomorrow

f16man

Yup 2 60's and 1 67, OK now that we know that, what are you going to put them in????

srw1960

Ok..I tore em back down and the stroke was differant between them so remeasured and I was way off with my first stroke dimension anyway its official I have 1 67 and 2 60's..
Thats ok wish I had a 80 but the 67 will still do nicely and from the looks of the guts im not sure it has ever been fired up no residue at all and none in the button either and the 2 60's are in great shape as well....I have an atlas van lines hydro in need of rebuilding that the 67 will probably go into and since I have a set of twin 60's Ill probably start looking for a hull to put both of them in...I am wanting one of dreamin hemi's nemesis hulls real bad is there such a thing as a twin nitro powered cat??????..

Anyway THANKS A TON for all youre help if I can return the favor please let me know

Steve

f16man

I haven't seen a succesful twin cat as the sponson will lift in the turns and pull the prop out of the water, that does not mean it coulden't be done I suppose......

srw1960

Well I think ill save them for some type of twin imwatching a good looking mono hull on e bay or will see if I can find a good twin rigger hull somewhere..been downloading a bunch of free plans maybee one of those could be made into a twin rigger I think thatd be tons of fun..anyway again thanks a bunch..
Take care and have funnnnn

Steve