Adjusting my engine height. But have 6 bolts already.....

Markyboyo · 02 December 2013, 05:10

Been planning on adjusting the transom height of my E-TEC for the past couple of years but haven't got around to it due to various things life throws at you.

I know the engine needs to come up 1-2 holes from where it is now as the Cav/Vent plate is definitely below the water when running at optimum trim at ~4000 rpm.
I'm hoping this will give me a couple of extra RPM and an extra knot or two.

Thing is I have 6 bolts in the transom, it was installed this way by the original dealer @ the equivalent of approx half a hole up from the bottom.

It has been suggested to remove the lower of the top two sets of bolts but I am worried that the remaining top bolts are too near the top of the transom.

The washers on the top bolts are actually formed to the curve near the top of the transom on the inside where it thins down about an inch from the top....What do you all reckon?? I have attached some piccys....

69cmw · 02 December 2013, 11:29

Never seen an engine rigged that way before.
Are the top bolts sitting at an angle? In the picture it looks like they are.

Markyboyo · 02 December 2013, 12:29

I know it isn't the regular way of doing things

All the bolts are definitely 90° to the back of the transom. As the motor is mounted at the height of being one hole up whilst using the top holes the bolt heads on the inside are pretty much at the edge of the full thickness lower part of the transom. You can see the washers are bent over the edge.

I'm just worried that if I were to just remove the extra set of bolts to raise the engine a hole them being so close to the top of the transom may lead to problems.

I think they probably just drilled the top holes a little high and then decided to put two more bolts in the bottom as a "quick fix".

bosun · 02 December 2013, 17:01

Looks odd to me I only ever use four bolts.
Looks like they drilled the top set from outside without checking inside first and then dressed the washers to hide the cock up and make it look deliberate (which it does !)
How big is your engine ?
I would be inclined to take all four top bolts out and sikaflex (for now) the holes up in the top pair,then slack off the bottom set that are slotted, jack the engine up under the skeg until the holes align with your remaining top set and bolt everything back up , and hope you are somewhere near where you want to be height wise.
I modified a humber destroyer transom to clear hydraulic steering with a jack plate recently and that top set of bolts will only just be catching on the edge of the ply inside the transom.

69cmw · 02 December 2013, 18:27

If they are drilled 90 degrees to the back of the transom, does the top of the transom slope down towards the front?
As I can't see any way why it would be done like that.

captnjack · 02 December 2013, 18:35

I would probably just jack up the engine one hole. That will leave the middle holes unusable. Leave it empty for your trial run. If one hole up is the right height, then fill the middle holes with dowels and epoxy.

The only remedy for the top holes being close to the edge would be a stainless reinforcing plate, perhaps something like a jack plate without any height. For a 115hp I'm not sure how close that is to the max transom weight. Perhaps discuss with the builder?

pow2gran · 02 December 2013, 19:19

I have a Jack Plate if you are interested. It is virtually new. I had it on the back of my rib to try and improve the splashing from my Tohatsu but it did not make any difference. I think that it is the design of the Tohatsu.

I purchased directly from Vance and paid the import costs. Asking 200 if your interested.

Nick

Markyboyo · 03 December 2013, 02:16

I had considered a jackplate but as Bosun said it would require modification of the transom along with the addition of hydraulic steering. Other than the modifications needed I am already at the transom weight limit on a 5.5m destroyer and a jackplate would further increase the loading the engine places on the transom.

I think the best option is definitely a test run or two with the middle bolts removed and the engine raised a hole or more.

When I am at correct height I'm tempted to remove all 4 of the top bolts and fill the holes with hardwood dowel and epoxy. Then re-drilling as it should have been in the first place with the addition of a stainless reinforcing plate as I know the top bolts will only be about 3/4" from the old holes I filled.

I think a reinforcing plate would be difficult maybe with the bolts/washers on the "curve" as they are now?

bosun · 05 December 2013, 09:21

Good idea re filling the holes and starting again.
The reason that I had to modify the transom when using a jack plate was because of the set back of the jack plate meaning that the steering cable or hydraulic steering fouls the cutaway into the transom when you tilt the engine up.
With a four inch set back ,if using a cable then the cable is actually on the outside of the transom which would make routing it interesting.
I nearly gave up but having imported the jack plate thought I might as well use it especially as I intend to try it with a bit more horsepower in future.
Cutting the transom requires a bit of bravery/skill/care/good tools !
but once I had re glassed and flow coated it ,it actually looks factory finished
and the curved section is now square.
And as humber seem to have at least four different transom cutaway designs anyway no one is likely to notice.

Dirk Diggler · 05 December 2013, 11:21

Quote:

Originally Posted by 69cmw

Never seen an engine rigged that way before.

6 bolts is quite common, normally on big motors though! The mistake is in the spacing. They should be top hole and 3rd hole, allowing the motor to be raised by one hole if needed.

Markyboyo · 06 December 2013, 02:10

Aaaahh. That makes perfect sense Dirk and I can see the reasoning on something 200hp+.
If going up one hole gives me what I want then I will probably just fill 2 of the holes and re-drill so I still have 6 bolts but on holes 2 and 4. If I need to go up 2 holes I will fill all 4 and go with 4 bolts and a stainless plate to spread the load a little where I have done the filling.

I found exactly the same as you Bosun, I would have had to either drill a hole or cut a slot in one of the splash plates to allow the steering cable to pass astern of the transom.