MerCruiser 470 lower unit and a MerCruiser 153 engine

[RonWilder]

Will these two match up? I am having difficulty seating my foot. I am 2 inches away from being lake worthy

 

[achris]

Apart from the gear ratio in the top box, the drive (both halves) are identical.

Are you having trouble getting the drive all the way into the bell-housing, or the lower onto the upper?

 

[Bt Doctur]

you dont list a year but a 8 spline upper will not accept a 13 (12?)spline lower unit

 

[RonWilder]

Lower onto upper. I have about a half inch gap

 

[achris]

Shift shaft splines, water tube or drive shaft splines.

 

[Bt Doctur]

lower unit driveshaft spline to upper gearset spline must match

 

[RonWilder]

MerCruiser 153 2.5L and a 470 foot

When I tighten the foot up the last 1/4 inch the engine will not turn over easy. When I back out the foot bolts about a 1/4 inch the engine runs like a top. Any ideas folks?

 

[Scott Danforth]

you should be keeping all related topics in one thread.

 

[RonWilder]

This isn't related to matching up splines. This is about a bind on the flywheel coupler

 

[Bondo]

This isn't related to matching up splines. This is about a bind on the flywheel coupler

Ayuh,..... Welcome Aboard,..... Ya haven't mentioned 'bout what vintage this ole stuff is,...

But, I'll venture a guess anyways,....

Back with the ole MC-1s, the Chevy based In-line motors, used a shorter input shaft, than All the other motors, 'n drives,.....
'bout an inch difference,.....

I'm guessin' yer stuffin' a drive with the now standard 9" input shaft into a transom assembly that requires the 8" input shaft,....

Or, the gimbel bearin' is massively outa alignment with the motor's drive coupler,.....

 

[RonWilder]

The 153 Chevy is a 64-76 year range and the 470 foot is an 83ish.

 

[achris]

The 153 Chevy is a 64-76 year range and the 470 foot is an 83ish.

And there's the problem. Early in-line engine drives use a shorter yoke than the later ones.