V4 75 Hp

[mercury400m]

hey guys i got a kinda broad question for ya but what would some simple mods or any to get more outta a 1963 [(v4al-15e) electric start and electric shift long shaft] im thinking of building a hal kelly 12 ft. MAD CAP for it.

i know its got a 23:1 gear ratio in it at least i was told so thats why these motors were decent for racing outta the box.

any one got a 2 bladed prop for this??? i know there were some around mabee RON?????

[194265]

hey guys i got a kinda broad question for ya but what would some simple mods or any to get more outta a 1963 [(v4al-15e) electric start and electric shift long shaft] im thinking of building a hal kelly 12 ft. MAD CAP for it.

i know its got a 23:1 gear ratio in it at least i was told so thats why these motors were decent for racing outta the box.

any one got a 2 bladed prop for this??? i know there were some around mabee RON?????

The 1958 to 1968 v-4's where duds, with the exception of the XP and Gt 115s that where built in 1967 and 68. The 50 to 85 HP models had a poor designed intake manifold and only a two barrel carb. The gear case stonewalled between 33 and 35 miles an hour no matter how much power was applied. Thats why a new gear case was designed for the 100 HP model in 1966. If you would like more power from a V-4 OMC or BRP look for one built after 1968

Good luck

[Droll-l6]

the gear case stonewalled between 33 and 35 miles an hour no matter how much power was applied. Thats why a new gear case was designed for the 100 HP model in 1966. If you would like more power from a V-4 OMC or BRP look for one built after 1968
Good luck

So I were lucky with my 1964 90hp then , it's running 40 miles an hour on an non performance boat, can't get it over 40.00 miles thou .
( 40 miles at 5000 rpm, 10" X 12" propeller )

Just stay away from those electric lower units......got a completely rebuilt one, still no good , ( even new spring/hub/right oil good coil... )

Engines that might work
1964/65 90hp ( new carb/reed design )
1966> 100 hp

Stay away from
60/75/80/85 hp they all got the downdraft carbs...


Arne Kjetil

[Skoontz]

was a dud gear case, you need to go with the manual shift, grind all the teeth off the reverse gear as well as the nubs on the reverse side of the shift dog.
The downdraft carb is a bit challenging, so, if ya do like my dad did and install a modified manifold and side draft carbs, that will help. the rest is boat and set up.

We had one with the letters W.E.M. on the side cover, and two copper tubes bent out the back of the hood from the water pump. WEM stood for we eat Mercurys...And, mounted on a 14' Yellow Jacket with a 17" pitch Michigan Wheel that dad bought from Carl Stirn, yep it was a 17, Lou Eppel had a photo of this boat on his wall and/or desk for years riding on just the cav plate with the boat aired out about 2" above the Fox River.

All in all, ya gotta use a different gear case...But you can get alot more from that motor if you want to play with it....

[194265]

So I were lucky with my 1964 90hp then , it's running 40 miles an hour on an non performance boat, can't get it over 40.00 miles thou .
( 40 miles at 5000 rpm, 10" X 12" propeller )

Just stay away from those electric lower units......got a completely rebuilt one, still no good , ( even new spring/hub/right oil good coil... )

Engines that might work
1964/65 90hp ( new carb/reed design )
1966> 100 hp

Stay away from
60/75/80/85 hp they all got the downdraft carbs...


Arne Kjetil

I don't see any prop slip in your 40 mph calculations, most props (good ones) run in the 10 to 15% slip area. I will give you 10%, which is 4 mph, 4 from 40 is 36 mph. When I worked in Engineering at OMC in 1968 through 1973 that is range that it would operate in. Granted there are some very good props that are more efficient, but none are made for your 90.

[Droll-l6]

I don't see any prop slip in your 40 mph calculations, most props (good ones) run in the 10 to 15% slip area. I will give you 10%, which is 4 mph, 4 from 40 is 36 mph. When I worked in Engineering at OMC in 1968 through 1973 that is range that it would operate in. Granted there are some very good props that are more efficient, but none are made for your 90.

Those 40 miles are NOT GPS, so they might be off, but are you sure about those slip numbers ??, I got a lot higher slip numbers ......


Arne Kjetil

[mercury400m]

hmm ill see how she works when i get her mounted on the boat i just got for her today. i totally rebuilt the lower unit with a mechanic thats been at this for years and he done million of them so it will atleast work as far as i know. i know that these things are terrible and to stay away from them but the motor was given to me and has a good power head and if i can find a standard shift lower im all for getting one. the other issue would be finding a decent prop for this beast all the props ive seen are like........ no more than 12 pitch. soo say if im running at mabee 5500 rpm due to the low pitch prop with a 11 pitch prop so heres the speed calculation

11 x 5500 / 2 / 1056 = 28.6 mph so.........


Originally Posted by Droll-l6
So I were lucky with my 1964 90hp then , it's running 40 miles an hour on an non performance boat, can't get it over 40.00 miles thou .
( 40 miles at 5000 rpm, 10" X 12" propeller )

well 12 x 5000 / 2 /1056 = 28.4 mph

you may not believe in any way this formula but ill tell ya ive used it hundreds of times and its always dead on.

also for intake modifications for the verticle double barrel carbs what motor?, hp? would be an easy bolt on well some what close to easy

[Bill Gohr]

Who made the manifolds to put the carbs on the by pass covers for the 75 hp's? I used to have the brochure for them. Looked cool don't know if it worked. Someone out here needs to find out where all the props went from Chicago Marine. Cliff the old owner used to race this stuff, when I was at the auction there were dozens of old OJ's and Michigan bronze 2 blades for these pre 66' engines. Up to like 16 pitch. I didn't buy them because I didn't think anyone was running these things.

[Droll-l6]

well 12 x 5000 / 2 /1056 = 28.4 mph

you may not believe in any way this formula but ill tell ya ive used it hundreds of times and its always dead on.

Still not convinced , on all online cals my numbers makes sense...

5000 rpm * 0.870 ( gear ratio = 0.870 or 20:23 ) = 4350 rpm * 60 min = 261000 rph * 12 inch = 3132000 inches * 0.000016 ( 1.0" = 0.000016 miles ) = 50.112 miles in an hour.

Theoretical speed 50 miles
Measured speed 40 miles
Slip... you do the math .


Arne Kjetil

[Ed Hatch]

Your V4 weighs an awful lot for a 13 ft boat (C-D version of the Mad-Cap is 13' ). Finding high pitch OMC props will be difficult. There is no point in spending $$$$ opening up the intake side of any 2 cycle engine without opening up the exhaust side. A better route to go would be to find a Merc KG9 tower & gearcase, put a 44 cube powerhead on it(a bolt-on). That combo would probably be 75 lbs less than your V4 for starters. The Merc can turn higher RPMs out of the box, no intake work necessary and you can still find relatively cheap high pitch props for the KG9, they show up on Ebay fairly often. The props will be brass 2 blades and you should be able to get them re-pitched without too much trouble. IMHO