powerhead

[vxtech]

has anyone here ever rebuilt there own powerhead themself including replacing rod bearings?

 

[bktheking]

Re: powerhead

has anyone here ever rebuilt there own powerhead themself including replacing rod bearings?

Trendsetter just finished rebuilding his entire powerhead days ago.

http://forums.iboats.com/showthread.php?t=361179

Really good thread with pics.

 

[Dhadley]

Re: powerhead

Yep, rebuilt one myself. Well, maybe more than one........

 

[Faztbullet]

Re: powerhead

Yep, Like Dhadley said one or two.....

 

[rolmops]

Re: powerhead

Yea,like Dhadley, maybe ten or fifteen,but certainly not the hundreds or maybe thousands that Dhadley, Rodbolt,Steel Spike,and many other forum members have rebuilt.
You must understand that many of our members are current or retired outboard technicians and owners of outboard repair shops.

 

[vxtech]

Re: powerhead

and how did you check the rod to crank clearance (how tight or loose were needle bearings on crank and in rod)

 

[rolmops]

Re: powerhead

I never did check the clearance.Instead I always use new needle bearings so there never is a question about clearances.If you rebuild a block it is better to replace all bearings.That way you don't have to worry about worn parts that may render your labor useless.

 

[trendsetter240]

Re: powerhead

and how did you check the rod to crank clearance (how tight or loose were needle bearings on crank and in rod)

Use a micrometer to measure the journals on the crankshaft. If it is within tolerance than your clearance should take care of itself. Replace all the bearings at the same time. Don't mix old and new.

The connecting rod caps must fit together exactly as they did when they were first broken. Take your time to ensure that they are lined up perfectly during assembly. Use a pencil to test to see if you can feel any ridges where the rod cap meets the rod.

 

[vxtech]

Re: powerhead

so the clearances are not as critical as a car requiring plastigauge to check brg clearances?

 

[bktheking]

Re: powerhead

so the clearances are not as critical as a car requiring plastigauge to check brg clearances?

I don't think you can use Plastigage on roller bearings, since they are rollers and not a flat bearing how would it work.

 

[1946Zephyr]

Re: powerhead

That would be funny using plastigauge on a roller bearing set up. Bump bump bump bump bump bump bump bump. Just make sure you measure each of the flattened bumps. Just kidding. I've rebuilt several of these things too and I've found that they're quite a bit simpler than a car engine. Just make sure all the jurnals spec out to what they're supposed to be and use new bearings and you should be good. If your pistons don't have any scoring, then they'll likely be okay to re-use. Just make sure your cylinders and pistons spec out good. Hone the cylinders out and install new rings and that's about all it takes. Pretty much all the engines I've rebuilt had good cylinders in them, but occasionally, I've had to replace pistons. If they over heat, then they are likely to be scored.

 

[billy4hp]

Re: powerhead

so the clearances are not as critical as a car requiring plastigauge to check brg clearances?

Not to get off topic but, plastigauge is not an accurate form of measurement....

 

[1946Zephyr]

Re: powerhead

Oh I know it isn't, but they sure sold a lot of that ****

 

[Dhadley]

Re: powerhead

The roller bearings are very very hard. So are the bearing surfaces, unlike "car motor" bearings and surfaces. Years ago we sent outboard needle bearings and rods to a lab to have them checked for wear with a lazer and air micrometers and hardness tests. Bottom line is that they are so hard that if they look good, they are good. Even ones discolored were still good. If a needle or surface looks like "orange peel" or is rusted it's obviously bad.

Every once in a while you'll find a rod that looks OK but is twisted lengthwise or misaligned inside the bearing area even though the outside alignment is good. But you'll feel both as you assemble the powerhead. Not common for sure but can happen.