Topic: Proper method to measure engine height.

Proper method to measure engine height.

Images added: Measure inside of engine J Bracket to a parallel plane to the lower pad.

Straight line the J Bracket points.

Align the lower pad with a 90 degree line from the pad to the J Bracket.

The engine above is at an engine height of roughly 24" in vertical elevation. The image below shows the bar being held along the plane of the lower pad, and at the lowest point.

…………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………... Last edited by Bass Cat Boats on 1:29 AM - May 01, 2010, edited 3 times in total.

This topic has 17 replies, 6 voices, and was last updated 9 years, 3 months ago by Bass Cat Boats.

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January 29, 2010 at 1:37 am #468050

dblplasabre
Participant

I have Detwiler hydraulic jackplate.

If I raise my jackplate until the nose cone is even with the centerline of the hull.

Mark the jackplate at that point then lower down until I reach a desired height, that should give me prop to pad measurement, correct?

Or am I just not understanding this?

January 29, 2010 at 1:52 am #468051

NELACAT
Participant

I’ve got glasses on and still cant read the small print. Will someone type it larger? Thanks!

Glynn

January 29, 2010 at 4:26 am #468052

Bass Cat Boats
Keymaster

Engine heights are like lower unit lengths. The Long shaft standard gearcase is a 20″ case. Most transoms are in the 23″ range for these engines and the actual engine height is in relationship to the lower hull.

Thus the engine is properly measured in this fashion, as shown above.

The center line measurements are more commonly used as things progressed to the high performance thoughts from fast boat fans. Though this is still the proper way to measure engine heights. Which is why you will always buy a 20″, 30″ or a 25″ gearcase length.

BCB

January 29, 2010 at 4:37 am #468053

NELACAT
Participant

Thanks BCB!

Glynn

January 29, 2010 at 4:57 am #468054

dblplasabre
Participant

Bass Cat Boats wrote: Engine heights are like lower unit lengths. The Long shaft standard gearcase is a 20″ case. Most transoms are in the 23″ range for these engines and the actual engine height is in relationship to the lower hull.

Thus the engine is properly measured in this fashion, as shown above.

The center line measurements are more commonly used as things progressed to the high performance thoughts from fast boat fans. Though this is still the proper way to measure engine heights. Which is why you will always buy a 20″, 30″ or a 25″ gearcase length.

BCB

I think I might be getting closer to understanding.

If I have a an Etec with 20″ shaft and my measurement from centerline of pad to the underside of the engine clamp is 17″, I should be about 3″ below pad.

Is that right???

January 29, 2010 at 5:05 am #468055

Bass Cat Boats
Keymaster

You should measure it to verify as engines are not all exactly the same and vary between brands.

BCB

January 29, 2010 at 6:29 am #468056

SPHidalgo
Participant

Is there a certain time of year when it is better to set up your boat or dial it in?

January 29, 2010 at 7:43 am #468057

Bass Cat Boats
Keymaster

Warmer weather is worst possible conditions, and then you are more or less guaranteed to run well year round.

January 29, 2010 at 9:32 pm #468059

Bass Cat Boats
Keymaster

Not actually, as most transoms are in the 23″ range on bass rigs, and the engines are in the 20″ version. So in theory there you would be 3″ higher if you mounted it flush. The shaft length is an arbitrary number and they vary some between brands, though that is the shaft length below the crank in most cases. Or often resembles the drive shaft length.

BCB

January 29, 2010 at 9:46 pm #468060

dblplasabre
Participant

I forgot to add in the measurement of the gearcase in the example above. I beleive the picture below shows where people measure shaft length as BCB mentioned.
Hoepfully I used the right terminology.

January 30, 2010 at 1:44 am #468061

Flyswatter
Participant

Ron, Don’t you need to include the bottom pad of the transom in the measurement?

dblplasabre wrote:I forgot to add in the measurement of the gearcase in the example above. I beleive the picture below shows where people measure shaft length as BCB mentioned.
Hoepfully I used the right terminology.

January 30, 2010 at 1:46 am #468062

Flyswatter
Participant

Todd, I getting there with you. LOL. Hey did you get my files?

smbass wrote:ill have to thing about ths 1, confusing

January 30, 2010 at 2:44 am #468063

dblplasabre
Participant

Flyswatter wrote:

Ron, Don’t you need to include the bottom pad of the transom in the measurement?

I did, I made up a number of 17″ but as BCB said most transom measurements are close to 23″

The corrected equation should look like this— 23″ for the transom and then subtract (the shaft length of 20″ +  the measurement from the bottom of the shaft to the center of the nose cone 6.5″)

So lets use the numbers above   23″- (20″+6.5″) = 3.5″ below pad

January 30, 2010 at 2:55 am #468058

Flyswatter
Participant

So engine height minus prop shaft length gives you the below pad measurement?

How do you confirm prop shaft length? Do I call my dealer for confirmation? I learned to do below pad measurement a different way. This looks easier.

January 30, 2010 at 3:04 am #468064

JohnM17
Participant

dblplasabre wrote:

Flyswatter wrote:

Ron, Don’t you need to include the bottom pad of the transom in the measurement?

I did, I made up a number of 17″ but as BCB said most transom measurements are close to 23″

The corrected equation should look like this— 23″ for the transom and then subtract (the shaft length of 20″ +  the measurement from the bottom of the shaft to the center of the nose cone 6.5″)

So lets use the numbers above   23″- (20″+6.5″) = 3.5″ below pad

That looks like some type of algebro problem er sumthin LOL.
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