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305 and 350 engine and OMC Out drives

H

herve88

New member
I have a 1978 305 engine and l

I have a 1978 305 engine and looking at purchasing an out drive was attached to a 350 engine for parts. Are the out drives the same?
 
"if the 305 was the 185HP with

"if the 305 was the 185HP with a 2BBL, the upper will be 1 tooth different in gearing from the 350.

for the lowers there is the whole hydromechanical (78-81) vs. full mechanical shift (82-85) thing to watch for."
 
"So, if I upgrade my original

"So, if I upgrade my original 305 to a 350 but keeping the original drive, what if anything will I have to do with my drive? Btw, mine is a '78."
 
"ok, well, that's not the

"ok, well, that's not the original carb so without knowing how the engine was equipped new, can't tell what gears are in the drive, so you might have to change props (2" higher pitch) to compensate for the extra power, or you might not have to change anything. Just a case of running it and propping it for correct WOT rpm"
 
"Don't want to hi jack Cha

"Don't want to hi jack Chad's post but my issue may be the same as his anyways. Hy Stat, that Holley carb and Edelbrock intake were installed by the previous owner. Here are some numbers I pulled off my engine if it helps any:

engine model: 990255A

outdrive model: 981114"
 
"Hy Stat,

quick update her

"Hy Stat,

quick update here: I should have noted that my engine has 225 stickers on the valve covers and they appear stock original. Its my understanding that this particular model originally came with a 4 barrel Rochester carb(the previous owner just upgraded to a slightly bigger Holley carb)."
 
"then it would've original

"then it would've originally been equipped with the same upper gears as a drive behind a 350. So the uppers should be the same unit.

The lower unit may or may not be any good to you though, depending on year and whether hydromech or full mech shift"
 
"Mine is a '78 so its the

"Mine is a '78 so its the hydromechanical. The drive itself works fine. If I had to, upgrading to a Mercruiser unit might be more headaches than I want due to the large hole this OMC unit would leave."
 
oops I think I was confusing y

oops I think I was confusing you with Chad who was purchasing a 350 ratio drive....
 
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