rebuilding V6 150 hp black max

[baja32]

I have a few of these black maxs. I am planning a rebuild of one. 5 of the 6 cylinders have 120-130 psi, one cylinder has 0 psi (hence the rebuild). My plan is to have the dead cylinder bored out and have the other 5 cylinders honed. Would having the other 5 cylinders honed and replace the rings increase the compression or would the honing make the bore large and therefore cause a decrease in compression???

 

[sschefer]

Re: rebuilding V6 150 hp black max

That's a good question because it's not often that folks think about that. If you increase the cylinder diameter by .001 then ring end gap increases by roughly .003. Ideally you'd be at .018 end gap on a stock motor and .025 is max. The wider the end gap the less power they cylinder will make so the answer is yes that it will affect total power.

It's probably not going to matter if you're just expecting a fishing motor when all is said and done. If you're expecting it to be like day one, don't, you need to bore .015 or more and replace pistons to get it like brand new again.

 

[baja32]

Re: rebuilding V6 150 hp black max

What if on the 5 cylinders that have good compression I just replace the rings and skip honing them??

 

[jerryjerry05]

Re: rebuilding V6 150 hp black max

With just honing out the cylinders your not gonna remove that much metal.
Do it right and hone the cylinders.You won't see any difference.
How bad is the 1 cylinder?J

 

[sschefer]

Re: rebuilding V6 150 hp black max

With just honing out the cylinders your not gonna remove that much metal.
Do it right and hone the cylinders.You won't see any difference.
How bad is the 1 cylinder?J

Rings don't seat like some people think they do, they take a set in the ring lands on the pistons and tend not to move unless you dissasemble the engine and then you can't help but move them. You'd never get them back exactly in the same postion and the cylinder walls are worn to match the way the rings set.

Honing the cylinders removes that set and lets the new fresh rings find there own set.

A backyard hone job is when you don't have the right tools and just flip the rings over but that only works on straight cut rings and only lasts long enough to be able to blame the problem on the person you sold it to. Sort of like putting sawdust in a manual transmission.

 

[baja32]

Re: rebuilding V6 150 hp black max

the dead cylinder has 0 psi compression. I still have to take the heads off to get a better idea. However it may take time to remove the heads, the bolt heads are all rusted and probably have never been removed.

 

[baja32]

Re: rebuilding V6 150 hp black max

Im gonna take the block to a machine shop and have the bore out the dead cylinder and hone the rest.

 

[Faztbullet]

Re: rebuilding V6 150 hp black max

Compression really tells you nothing about a cylinder other than it has pressure to support combustion(leak down is better test). I have see old V-6's with 120 psi compression and have .010 wear at top of cylinder and half that at the bottom. Engine still ran but it was lazy on holeshots. Let the machine shop check the cylinders(taper) and bore all that are needed.

 

[sschefer]

Re: rebuilding V6 150 hp black max

As a side note to FB's advice. You can bore three without boring them all but if two are on one side and one is on the other you might as well bore them all to match since you're already paying for the setup of both sides. The only reason you wouldn't do it is if your short on cash for pistons.