Engine Gearbox compatibility

[GarysMK1]

Eveng gents.
Q. My 850 mini seven engine is a little underpowered. Can i replace it with a 1275 motor and still retain my new hybrid 4 syncro box and wand shift or will they not mate up ? Also, can the box take the extra horsepower ?
Regards Gary

[Daz1968]

Any mini gearbox will physically fit a 1275 block, only early 3 synchro cases need modifying for clearance according to gizzard book, as yours is a 4 synchro casting can’t see an issue, as you have had it rebuilt then it will be strong enough for a standard 1275, I would think fitting a 3.44 diff would help with the larger engine for cruising,

[Spider]

Yes. All the 4 Synch boxes will accept a 1275, you'll need to find a 1275 Primary Gear though and yes, no problem with the power.

[Southwest]

Any mini gearbox will physically fit a 1275 block, only early 3 synchro cases need modifying for clearance according to gizzard book, as yours is a 4 synchro casting can’t see an issue, as you have had it rebuilt then it will be strong enough for a standard 1275, I would think fitting a 3.44 diff would help with the larger engine for cruising,

Excuse my ignorance but what is gizzard book?

[Spider]

Any mini gearbox will physically fit a 1275 block, only early 3 synchro cases need modifying for clearance according to gizzard book, as yours is a 4 synchro casting can’t see an issue, as you have had it rebuilt then it will be strong enough for a standard 1275, I would think fitting a 3.44 diff would help with the larger engine for cruising,

Excuse my ignorance but what is gizzard book?

Maybe this one ?

https://www.amazon.com/Tales-Gizzards-G ... 0060009594

[Southwest]

Any mini gearbox will physically fit a 1275 block, only early 3 synchro cases need modifying for clearance according to gizzard book, as yours is a 4 synchro casting can’t see an issue, as you have had it rebuilt then it will be strong enough for a standard 1275, I would think fitting a 3.44 diff would help with the larger engine for cruising,

Excuse my ignorance but what is gizzard book?

Maybe this one ?

https://www.amazon.com/Tales-Gizzards-G ... 0060009594

Mmm..probably more gearbox info that HAYNES!

[Daz1968]

Sorry yes it’s vizard how to modify your mini, spell checker on iPad changed it, it shows early 3 synchro cases needing some grinding to clear the crank throw, but all later boxes should be ok. Book seems expensive though now, he my copy for years

https://www.amazon.co.uk/Modify-Your-Mi ... 0863430414