How to align your engine to jet unit with basic tools

[Midjet]

As described in the subject.........  Please post your ideas on how to align your engine to your jet unit with the use of basic tools (just the basic tools that most would have in the garage) if it is possable to do it this way.

   Cheers Dan

[Karl]

This has been "discussed/argued" numerous times before, a search will reveal all!!!

Anyway;

1) Cut a piece of steel the exact length of the driveshaft with square ends. Place it in the gap where the drive shaft normally sits with the back edge hard against the unit drive flange, then adjust engine angle to line up the front face of the steel plate. Needs to be done for up/down and left/right orientation. The crankshaft and unit shaft should be parallel with a driveline angle of no more than 3° A rough rule of thumb is if these centrelines are out by more than 15mm then the driveline angle is too great. 

2) Can do the same thing using two squares.

[MRM]

If you have a DTI you can secure it to the flywheel near the edge and put a straight length of square section steel across the unit flange pointing straight up. Put the tip of the DTI on the steel, and rotate the 2 flanges together.
Should measure the same straight up as it does all the way left and right.

Would be good if I could figure a way to have the driveshaft in there so they automatically rotate together, but it might not be necessary.

[MRM]

Its a bit hard to find all the different ways that have been discussed so it would be good to have it all in one place.

Karl, with the way you mentioned using the bit of steel, Im guessing you mean a big rectangular piece of plate?
So you have one side the same length as the gap between the flange faces to do the vertical alignment right?
But it would be too short to reach between the flanges when you try to do the left/right alignment, so do you make the other edge the right length so the plate is on an angle same as the driveshaft when you do the l/r bit?

[mohawk]

You can bolt a pointer to the unit flange and just rotate it checking against the flywheel as you go. I used a bit of threaded rod on the big boat, but had too use karls method on the wee one.

[MRM]

You can bolt a pointer to the unit flange and just rotate it checking against the flywheel as you go.

Yeah the bugger with that is that I have a flex plate with holes in it!

Good idea about using the threaded rod tho.

[MRM]

Come on, there has got to be more than just mohawk and karl that do their own alignments. How do you do it?

[Karl]

Yeah the bugger with that is that I have a flex plate with holes in it!

Good idea about using the threaded rod tho.

Bolt your driveblock onto the flex plate and use that to run your pointer against.

[Paul]

For vertical alignment:
Put a spirit level vertically on the jet unit flange and adjust the jockey wheel up/down, until the jet unit flange is vertical (it's possible you need to put the trailer wheels on blocks if the trailer draw-bar won't go low enough).  Test with both sides/ends of the spirit level as spirit levels sometimes aren't correct.  Then tweak the vertical alignment on your engine, so that the flywheel/flexpate is also vertical.

Horizontal alignment:
Put a straight-edge about a 0.3m long across the jet unit flange.  Use a steel rule/vernier to measure distance from straight-edge to flywheel/flexplate, for both sides.  Then tweak the engine position so the measurements match.


All of the above is easier if you clear the stuff out of the middle beforehand - measuring around stuff is difficult.  Having a helper makes it easier.

[Tonz]

 What about a splined unit?

[Paul]

What about a splined unit?

You need one of these, and hope your splines are in good shape!   

[johnmead]

I used the system outlined by Karl in reply #2, but used a piece of nice clean and square plywood  I have waaayyy more than 15mm  and waaayyy more than 3 deg,  and it works fine When I was blaming the driveshaft for vibrations recently, it was bent impellers that were the problem

[CBBR]

tools required, a tape measure and level. i think most ppl have those in their garage.

when setting up Pauls boat we measured the height to center of the spline on the unit and made the center of the flex plate the same. leveled the boat with a level on the delta, worked out what 5 deg was on the level then put the level on top of the engine and lifted the front up until it was at the right angle, then we measured the alignment of the engine by picking a point central on the pulley made them the same distance and did the same at the rear of the engine.

both rookies but i think its worked  

[aston_driver]

Right - I'm confused because the Hamilton jet technical manual shows that the engine flywheel doesn't have to be vertical with a spirit level - the engine can be tilted towards the jet, e.g. a V6 Essex. The flywheel doesn't even have to be parallel to the face of the coupling on the jet.

[CBBR]

Right - I'm confused because the Hamilton jet technical manual shows that the engine flywheel doesn't have to be vertical with a spirit level - the engine can be tilted towards the jet, e.g. a V6 Essex. The flywheel doesn't even have to be parallel to the face of the coupling on the jet.

read it again, we leveled the boat, then lifted the front of the engine so it sits at a 5 deg angle.