78 small gearcase vs 79 large gearcase

[xikxak]

1978 140 hp v4. manual shift,20 in shaft small gearcase. 1979 manual shift 25 in shaft large gearcase.Will my drive shaft 20 exchange with the shaft on the 25" large gearcase to use on my motor?everything else seems to be the same. ps what is the diff between small & large gearcase. is bigger better? thanks

 

[Dhadley]

Re: 78 small gearcase vs 79 large gearcase

What are you refering to as large and small? Both use the same V4 style (shape and size) case.<br /><br />The basic difference is the drive shaft and shift shaft length.

 

[xikxak]

Re: 78 small gearcase vs 79 large gearcase

diameter of gearcase and propshaft. 79 is larger. I also checked props in boat parts catalog and they show props for both small gearcase and large. my prop is too small for the 79. It has 15 splines. Drive is same diameter but different length. Thanks marine mechanic said 79 came off 115 hp.

 

[xikxak]

Re: 78 small gearcase vs 79 large gearcase

correction:driveshaft is same diameter but different length. thanks

 

[xikxak]

Re: 78 small gearcase vs 79 large gearcase

Just measured. Diameter of prop houseing.small=3 3/4" large=4 1/4" Thanks

 

[Dhadley]

Re: 78 small gearcase vs 79 large gearcase

All 1978 and 1979 V4's use the same prop. Now there are some newer V4's that have the V6 style case but that started in the mid 80's with the V4 loopers.<br /><br />A 1977 115 uses a different length case than a 1978 115 or 140 and wont bolt up but they still use the same prop.

 

[Dhadley]

Re: 78 small gearcase vs 79 large gearcase

Measure the space between the bolt holes on either side. The 1977 85 and 115 are closer together than the 1977 140 and any 1978 V4.

 

[xikxak]

Re: 78 small gearcase vs 79 large gearcase

This is 78 vs 79. they are sitting side by side.every measurment is excatly the same ie;length,width,bolt holes etc. the only difference beside shaft length is the large gearcase is 1/2 inch longer.I guess due to the extra 1/2 of gearcase. Help. thanks

 

[xikxak]

Re: 78 small gearcase vs 79 large gearcase

On several propeller sites I see reference to V4 with V6 gearcase,140 hp 1985, 140hp 25" 1989 and newer. 15 spline. Is this possible what I have. What is the downside? (there always is for me) Thanks again

 

[xikxak]

Re: 78 small gearcase vs 79 large gearcase

Apparently the lower I got is a V6 lower. Since its a "cameoffa" V4 Im not sure of the year.its a xlong,How can I tell what kind of long shaft to get so it will fit my 78 V4 140?Everything <br />else matches up.Bolt holes etc.thanks<br /><br />ps: I had to coin that word"comeoffa"as no one ever knows the exact year of a used part just that it cameofa____________?????