Can anyone advise me as to what is involved in uprating an A65-8 to a A 75-8 Spec? The extra 10 horses would be useful for short field performance
Thanks
Continental A65-8 to A75
Moderators: John Dean, Moderator
There are few differences and they are not easy changes. The A65 pistons have a larger piston pin, this means different conrod bushes for that 1/16" bigger pin on the A65 . A75 are supposedly having stellite exhaust valve faces but as the barrels are the same probably so do the A65 after this many years.. The A75 camshaft is slightly different and can only be fitted to later crankcases. Eismann mags were fitted to the A75 although both probably now have Slicks.
There are no other changes other than it revs faster up from 2300 to 2600 and that means a finer prop as the A65 one would limit the A75 to the 65 ponies. an A65 revved to 2600 would give a higher power if fitted with the finer prop and 'overrevved' both compressions are the same at 6.3 to 1. There are difference to the timing A65 -30 and 30 / A75- 29 and 32
Not a lot really but the cam and prop are the real changes. Apart from more noise and fuel use.
regards
Graham.
There are no other changes other than it revs faster up from 2300 to 2600 and that means a finer prop as the A65 one would limit the A75 to the 65 ponies. an A65 revved to 2600 would give a higher power if fitted with the finer prop and 'overrevved' both compressions are the same at 6.3 to 1. There are difference to the timing A65 -30 and 30 / A75- 29 and 32
Not a lot really but the cam and prop are the real changes. Apart from more noise and fuel use.
regards
Graham.
I'm surprised there aren't some changes to the carb, like either the overall throat size of the carb, or the jetting inside it.
Whenever I look at the spec differences for A-65 / A-75 / C-85 / C-90 etc engines it always seems to me that they just made the things different just for the sake of creating a range! I bet they charged more for the bigger ones, despite the fact they must have cost pretty well exactly the same to make.
I'm sure they could have just produced a 75, a 90 and a 100 (for different applications) and saved a lot of head scratching.
Maybe I'm just a cynical old Hector!
Whenever I look at the spec differences for A-65 / A-75 / C-85 / C-90 etc engines it always seems to me that they just made the things different just for the sake of creating a range! I bet they charged more for the bigger ones, despite the fact they must have cost pretty well exactly the same to make.
I'm sure they could have just produced a 75, a 90 and a 100 (for different applications) and saved a lot of head scratching.
Maybe I'm just a cynical old Hector!
Rob Swain
If the good Lord had intended man to fly, He would have given him more money.
If the good Lord had intended man to fly, He would have given him more money.