1978 25hp Johnson ventilating

[zdmaster2k]

Hi guys, What I'm finding, especially in a few waves is that, when up on the plane, the revs rise and the prop stops biting. From reading other posts I reckon that's ventilation The model number is 25BA78C. It's on the back of a Dell Quay Dory 13 which I'm pretty sure has a long shaft transom; our other motor, on an identical hull, is long shaft(BE30BALCO [20"])and we have no trouble with it. Does this mean the 25 has a short shaft and that's why it keeps sucking air? It's already lower on the transom than the 30, do we just need to get a long shaft motor? Thanks

 

[OBJ]

Re: 1978 25hp Johnson ventilating

Carpe....your 30hp model number indicates a long shaft....the 25 does not. If you need to make it into a long shaft, a kit is available I believe.....yes....PN 389111. $245.50 American.<br /><br />To double check, place the engines side by side....it will be obvious which is the short shaft.

 

[zdmaster2k]

Re: 1978 25hp Johnson ventilating

Hi OBJ, thanks for the reply. I did that the other day, very obvious the 25 is a short shaft, it also doesn't have a cupped prop. The transom's been cut away, presumably so the prop is actually in the water! Looking on the forum there are many recommendations as to where the anti-ventilation plate should sit in relation to the transom. At the moment, the 25 ventilates very easily so should I mount it lower or just get a long shaft motor (cos it's a bit crappy anyway!)