Replacing my '89 4.3L Merc.

[robwelleosu]

Need some assistance/guidance on what options I have for re-powering my boat.

Currently I have a '89 Merc 4.3L thunderbolt w/ alpha drive. I'm good on the 4.3L options confident those or plug and play. Need some help with moving up to a V-8. Since i'm buying a complete engine i thought it might be worth the upgrade. Would like to look at 5.0L-5.4L merc's. This is going in a '89 Celebrity 187SE. boat actually measures out just short of twenty feet but she's a tubby girl. ran about 36-38 on the old v-6.

Curious about the Y-Pipe and the outdrive. will the V-8 risers connect to the old Y-pipe? and can i just slide the new motor up to the existing outdrive components?

 

[Bondo]

Re: Replacing my '89 4.3L Merc.

Need some assistance/guidance on what options I have for re-powering my boat.

Currently I have a '89 Merc 4.3L thunderbolt w/ alpha drive. I'm good on the 4.3L options confident those or plug and play. Need some help with moving up to a V-8. Since i'm buying a complete engine i thought it might be worth the upgrade. Would like to look at 5.0L-5.4L merc's. This is going in a '89 Celebrity 187SE. boat actually measures out just short of twenty feet but she's a tubby girl. ran about 36-38 on the old v-6.

Curious about the Y-Pipe and the outdrive. will the V-8 risers connect to the old Y-pipe? and can i just slide the new motor up to the existing outdrive components?

Ayuh,... Welcome Aboard,... Go right to a 5.7l/ 350 motor,...

The transom assembly oughta marry right up, no problem,...

Front motor mounts need movin', 'n a bigger motorbox maybe,....
You'll also need a drive with the proper 1.50:1 gear ratio,...

 

[HT32BSX115]

Re: Replacing my '89 4.3L Merc.

Need some assistance/guidance on what options I have for re-powering my boat.

Currently I have a '89 Merc 4.3L thunderbolt w/ alpha drive. I'm good on the 4.3L options confident those or plug and play. Need some help with moving up to a V-8. Since i'm buying a complete engine i thought it might be worth the upgrade. Would like to look at 5.0L-5.4L merc's. This is going in a '89 Celebrity 187SE. boat actually measures out just short of twenty feet but she's a tubby girl. ran about 36-38 on the old v-6.

Curious about the Y-Pipe and the outdrive. will the V-8 risers connect to the old Y-pipe? and can i just slide the new motor up to the existing outdrive components?

Howdy,


Most of the components will "bolt right up" as will the flywheel housing, etc. The riser and y-pipe is compatible with many years of 4.3, 5.0, & 5.7L engines and installations.

Your side engine mounts will likely need to be moved.

Your current drive should be a 1.81:1 ratio. It'll be all wrong for a 5.7L engine.
Ratio Chart, Sterndrive Alpha One Chart, Gear Chart

If you want to take full advantage of the additional HP, you'll need to get a 1.47:1 ratio drive

Regards,


Rick

 

[robwelleosu]

Re: Replacing my '89 4.3L Merc.

Great answers guys thank you. Now for the next question on the outdrive gear changing. is that difficult to do at home?

 

[Bondo]

Re: Replacing my '89 4.3L Merc.

Great answers guys thank you. Now for the next question on the outdrive gear changing. is that difficult to do at home?

Ayuh,.... It's Very specialized, 'n the parts will cost ya More than a replacement drive upper from iboats,....

 

[HT32BSX115]

Re: Replacing my '89 4.3L Merc.

Great answers guys thank you. Now for the next question on the outdrive gear changing. is that difficult to do at home?

Yeah. probably not possible for most people. A better bet might be to just part out your engine AND drive (sell them) and replace the drive with a new SEI drive of the correct ratio.

This way you get some money for the stuff you have and you get a new drive with a 3 year warranty that will serve you for years to come.

The other way might be to "roll the dice" and buy a used drive of the right ratio.

 

[achris]

Re: Replacing my '89 4.3L Merc.

Fitting new a new gear-set to the drive-shaft housing is a time-consuming and expensive option.

You need to strip the drive-shaft housing completely and remove all the old seals. Press the old driven gear off the drive-shaft and press the new one on. Disassemble the drive gear and bearing pack, press the bearings off the old drive gear and onto the new drive gear. Then set the bearing pre-load using a rolling torque setting. Next put the new driven gear in the hosuing and do the gear height adjustment by adding or removing shims. Once that is done you need to adjust the shims under the bearing in the top cover to set the preload on the upper drive-shaft bearings. Once that is set up you need to fit the drive gear and shim it for the correct depth. Then remove that, and fit all the new seals. Then assemble the drive.... Allow around 4 hours if you've done quite a few of them..... You'll also need the 2 gear height shim tools, a special wrench to remove and replace the drive gear and bearing pack. Add to that the torque indicator and associated tooling for setting the bearing pre-loads.

Nope, much easier to sell your drive-shaft housing and buy a new SEI drive-shaft housing here....

Chris...........

 

[Volphin]

Re: Replacing my '89 4.3L Merc.

Not to mention the motor mounts need to be relocated.

 

[achris]

Re: Replacing my '89 4.3L Merc.

Not to mention the motor mounts need to be relocated.

Yep, that has already been mentioned, by Bond-o....
(Post #2)

 

[Volphin]

Re: Replacing my '89 4.3L Merc.

Yep, that has already been mentioned, by Bond-o....
(Post #2)

DOH! I'm beginning to see why I did so poorly in reading class when I was a kid! LOL Carry on, with apologies, my friend.