Cobra from 4 cyl on a V6?

[txmdc]

So after finding that my upper gears were ground smooth, I ended up getting a whole used outdrive. Got a hell of a deal, but the guy that told me it came from a V6 lied! It was actually from a 4 cyl. I know it bolts up (already installed it), but realized it was from a 4 when I tried to put my old prop on. Besides the prop being a different size, is there any major difference? Should I hang onto my old lower incase I need to swap it later? As long as I don't dog it, do you guys think it'll be ok?

Thanks!

 

[Don S]

Re: Cobra from 4 cyl on a V6?

The whole lower unit is smaller in size than used on any other engines.

 

[a70eliminator]

Re: Cobra from 4 cyl on a V6?

you went from a 1.68:1 (V6) final ratio to a 2.00:1 thats 2 times engine rev per 1 prop rev. you can get a bigger pitch prop and try to achieve WOT spec. but it will be hard on that little spline, the spline is smaller right?

 

[txmdc]

Re: Cobra from 4 cyl on a V6?

The spline is the same size, but the diameter of the lower unit is smaller so the old prop won't fit. The prop wants to sit over the lower unit so the prop can't get fully seated on the spline.

If I'm not hard on it, do you think it'll hold up ok? I could always put the old lower back on the new upper if it's all the same. If the old lower would be better, can it wait a week or so?

 

[Howard Sterndrive]

Re: Cobra from 4 cyl on a V6?

The spline is the same size, but the diameter of the lower unit is smaller so the old prop won't fit.

?
not making sense there

early 4 cylinder Cobras had 13 splines
V6 and V8 had 15 splines

in 1990 or 1991, OMC changed to a 15 spline lower on the 4 cylinder. It was a different ratio than V6 or V8, but was the same housing as the V6/V8 units and used the SAME props.

If I'm not hard on it, do you think it'll hold up ok?

If it's a 13 spline propshaft Cobra, they didn't even "hold up ok" behind the 3.0L
If you want it to last long enough to get the boat sold, it'll probably do the trick.

If it's a 15 spline propshaft unit, it should handle the power ok, but finding the right prop pitch could be a chore