3.6 V8 Cylinder/Piston/Head Condition - Opinions Needed!!!

[Dargo]

Pulled the heads off my motor last night to see what the condition of the cylinders, etc. were. To me, everything looked ok. Meaning, no holes in pistons, no cracks, no chunks of shrapnel floating around. The closer I looked, I noticed scoring above what I assume is the exhaust and intake ports. The pictures attached are of the #6 cylinder. Looked like the worst example to me. The motor is an ‘87 3.6 275. I have owned this for many years. I have never ran it. Was trying to get it up and going this summer for my Rally Sport. After closer inspection, the electrics are pretty well shot. I’ll need all new. Before I even think about investing that kind of $$ in this motor, I need to know if this is even runnable in its current condition. Motor has good compression. 100+/- lbs on each cylinder (cold). I have no clue what kind of hours are on this powerhead. I am no motor man by any means. To me, it doesn’t look good by any means. Do I throw $2k worth of electrics at this and hope for the best or scrap/part it out and look for something else?

PS-I will update my project thread soon. Boat is pretty well wrapped up. Motor on the other hand....FML.

[Dave S]

I have seen worse...…..hone and go...….. but the main issue is the head gasket crumble...….showing it's age......their are some that can help ????????belly up...….

[Instigator]

I have an identical 3.6 V-8 I just bought, also w/one bad hole.
Cant tell from you pixs if there’s damage on piston dome at the exhaust port or reflection??

If piston is good then you lost fuel/oil to that hole same as mine.
Fuel supply line pulled off that carb on previous owner on mine.

[Dargo]

Ok! That makes sense. No fuel, no oil, makes things not slide so nice. Pistons look to be in great shape minus the black color. No holes, etc. Heads seemed decent too. Not sure what the color is about. If pistons are good, what kind of work is needed to fix the cylinders? I would imagine honing. Is that something better left to a pro shop or can a guy at home do it? Are we talking new rings if it’s honed or new pistons? Just trying to weigh the cost vs. benefit of work I may need to do. I love working on my own stuff and would love to run this motor but I don’t want to sink a ridiculous amount of cash into it. At the same time, I like the idea of knowing what I have!

[racer]

IMO it should be pulled down for a good inspection and at minimum honed as the scratches look to be bad enough that you could feel them.

[Instigator]

I’m with Al.

No telling how much debri went where.
Only one way to know.

At min, that hole needs honed, probably alum removed from bore, one piston and ring set.

If compression was good on other 7, and you’re careful, you could resassemble those 7 as is but if you have it apart, honing all 8 and rings ain’t that much more than one.
Not much additional labor either.

Honing yourself can be done but if your not experienced, it’s a good way to screw one up.
Honing is cheap at most shops too.


IMO it should be pulled down for a good inspection and at minimum honed as the scratches look to be bad enough that you could feel them.

[FUJIMO]

...what racer suggested. complete teardown to go through it properly. any & all two strokes cylinder walls & pistons should always be made perfect in my opinion, unlike what you can "get away with" on a 4-stroke car engine. they're operation/use is much different. and then, of course, you need to fix what caused the issue in the first place. motor value? have no idea.

[V-bottom]

100# compression sounds low. The 275 should be around 120-130. The XP/GT 300 motors were usually 130-140.

[Instigator]

Correct.

I missed that part.


100# compression sounds low. The 275 should be around 120-130. The XP/GT 300 motors were usually 130-140.

[Dargo]

Sounds like a plan to me. I’ll keep going with tearing it down then. For what it’s worth, I still had compression on all 8. The number 6 cylinder that I posted pictures of was just the worst out of all 8. The scoring can be felt with your finger but it is pretty light. I’ll get this thing tore down and see what else is hiding inside. Am I safe to assume best case scenario is honing and new rings on all 8? No reason not to do them all if it is apart. Thank you everyone for your input so far. Kind of uncharted territory for me so I’m apprehensive to say the very least.

[keefallan]

Yeah, that is your BEST CASE scenario. The bottom line is this.....you will have peace of mind after you tear it down and put it back together that its all new. No one mentioned this. But.....you should rebuild the carbs. If you have done the block, go thru them too to make sure the floats are good and all the orifices are clean. When you are done, it'll be all new. Besides, you have a pretty cool motor there. :thumbsup: I would be keeping that one if it were me. Its worth it to make it like new....JMO

Take your time in the tear down. Get a factory manual. You NEED the factory manual. It will tell you how to overhaul(almost) that motor. When you remove a piston assembly, bag and tag. If you take your time, its not difficult. But its all in the details.....

Try and have fun too. This way, you will also learn your motor.........;)

[FUJIMO]

https://www.screamandfly.com/attachment.php?attachmentid=474525&d=1601837629

[FUJIMO]

https://www.screamandfly.com/attachment.php?attachmentid=474524&d=1601837629

[Dargo]

I was more than a little discouraged when I pulled the heads and saw the scoring. But the more I look at what needs to be done, I think it’s something I can handle. I’m sure there will be lots of questions along the way. I did rebuild the carbs over the winter hoping I wouldn’t have the issues I did with everything. Oh well, I’ll bag em and tag em with all the other parts. They were very clean already once I tore into them. I do have a factory manual already and that has made for lots of good reading. Here’s a question....if only a couple cylinders need boring, do you just do the ones needing it and oversize the piston to match or is it best to do all 8 so they are all the same? I don’t know what I would do without this site!

[keefallan]

https://www.screamandfly.com/attachment.php?attachmentid=474524&d=1601837629

Yeah, no hone is gonna fix that.:nonod: I couldnt see those pits before.................

[Merc 2.5]

I was gonna say earlier that someone gonna have to measure that bore and check for roundness, if u gotta send it to someone for that then all need be measured to make sure that it won't be out a spec (tolerance) after the hone. Then all new rings bearings and slug for 1 cyl

[Dargo]

I was afraid of that! I honestly didn’t see the pitting until you mentioned it now. I think we’ll get it apart and see where things are at. Looks like time to build my first motor. I even heard the little lady say, “Well, it makes sense”! Muahaha...oh does it!? I’ll update my hull resto thread and maybe it would be worth starting one for an engine build? Might be interesting for folks to see.

[Instigator]

The factory book on the 6’s says three over bored holes are acceptable.

My preference is them all being the same.
A +.020” piston weighs more than a standard putting the crank train out of balance.
The factory decided that at 4500 - 5500 rpm it was a non issue.

Your biggest change will be the coin you spend.
Honing is cheap and costs you a set of holes per hole.

Shops charge way more for bore work and now you’re buying pistons too.

[FMP]

Bore all 8 , new pistons, proper job on everything, deck and heads. You're doing the Ign , then you'll go through the carbs etc. Maybe need some bearings.
Good and fit for the long run.

[keefallan]

Chris, you will probably find that all the other cylinders are gonna be right on the edge with cylinder taper and wear. If you overhaul this thing, you have got a rare bird. I think the two stroke v8's are some of the coolest outboards of all time. It would be cool if you did a write up about the overhaul on here. There's not too many OMC v8 re-do's posted. There's always plenty of crossflow stuff..........much less looper stuff.......no v8 that I recall.....maybe in the search engine.

If you found that some bores were good and you wanted to keep the others stock, I highly recommend that you weigh all the pistons and make them the same.

But you already have guys saying that its best to do them all. I would let the bore gauge tell me what I need to know. But like I said, i expect the others to be on the edge of acceptable. If it were my motor, I would probably redo the whole thing, because I would want it to last as long as possible........... because of what it is.

[Instigator]

I am a huge fan of the V-8.
I have an identical powerhead w/the exact same issue.

Have built a bazillion V-6 loopers but never an 8.

They are a different bird.
Stock they are a tractor motor, modded properly, you add 1k - 1500 rpm and a 100hp, on pump gas.
(don’t remember reading what you’re putting it on?)

It has a gift for you.
If you choose to bore all 8, the 3.6 sleeves are thick enough (as was my 2.7 liter V-6) to bore to 4.0 specs (the 6 to 3 liters) as the later 4.0’s were.
All you pay for is the additional bore time.
Pistons cost the same.

The next tip is to add two finger (intake) ports per hole while its at the machine shop.
The 6’s all got this in ‘93 but never gave them to the 8’s.

Open the exhaust ports, clean up the rest of the internal castings, jet/tune properly, you’ll have a 400 hp, 7k+ beast that no one else does.

[FMP]

Cost per smiles , cheap.

[keefallan]

Cost per smiles , cheap.:D:D:D:D:D:D:D

Priceless...



I gotta admit, I love the sound of a v6 crossflow above 6000, but a v8's gotta sound ridiculous......... I never heard one to know...SAD!:nonod:

[Dargo]

You guys are killing my pocketbook! I love it! Lol. I think I’m beginning to understand a little more of the task at hand as time goes on. Now that I’ve had some time to digest this build a little, I think it needs to be done right or not at all. Dependability is very high on my list so cutting corners isn’t going to be in the program. Will certainly take some time but it will be right. Instigator...if I understand correctly, I can have this block bored to accept a stock 4.0 piston? That’s pretty awesome! Will these mate up with my current connecting rods? Machining the block...I live in BFE northern MN. There is a good machine shop about 80 miles away. Not a marine or outboard specific shop. Is this something any competent shop can handle? Is Wiseco a good piston option? Any other recommendations?

I am continuing to disassemble the block. It’s almost stripped minus the rotating assembly. I need to yank the powerhead off the mid still.

Can’t remember who asked what the motor was going on. It will be powering my Rally Sport. 21’ Shadow/Challenger knock off. It’s a nice hull but she’s no lightweight. Not sure if that changes anyone’s suggestions.

I can’t thank you all enough for your input so far!

[Chaz]

Keef , Here's gators daddy makin some music ... :)
Hear one once , you won't forget the sound .... :cheers:
Gator , i ain't forgot it's his turn to buy lunch, next time your down this way .. :rolleyes: :D

https://www.facebook.com/watch/?v=2244681879176658

https://www.facebook.com/watch/?v=588840651324194

https://www.facebook.com/watch/?v=588055168069409

https://www.facebook.com/watch/?v=858433461031577

There are two more dyno runs that are of a V-8 with both the slide and "extra hole E-tek intake. But I couldn't find them .. so here's a little one .. :o

https://www.facebook.com/watch/?v=223846748531541


https://www.youtube.com/watch?v=JOKbVlTuGCQ&t=59s

[Dargo]

Holy hell...that’s awesome!

[Instigator]

My daddy?
Bla, ha, ha.

That explains his lack of hair ��

As to lunch, you’re on!

Should be down in next 30 days.


Keef , Here's gators daddy :cheers:
Gator , i ain't forgot it's his turn to buy lunch, next time your down this way ..

[Instigator]

Dargo, yes on the 4 liter.
Nothing else changes, everything will bolt up.

I asked the question in hull.
Great answer.

I started a thread asking the S/F members what hull I should pick for my 8.
They picked yours.

On the machine work, yes and no.
A good auto machine shop can be a good OB machine shop if they understand 2 strokes which most do not.
What they miss is, after boring a 2 stroke block, the ports need to be chamfered so they do not snag a ring.
W/o this, it won’t make it through break in.

Another thing is “line boring”.
This aligns the boring machine, based on center line of crank as it should be.

Factory casts a bazillion blocks and pressed in sleeves after the fact.
Think they’re straight?

This corrects that.

[keefallan]

Chris, I think thats why Instigator was calling it a "Gift".......:thumbsup:

Chaz..............I have a new favorite sound. :D:D:D:D:D Had to press da rewind button a couple o' times!!! You wuz right!!! WHOOOOO DOGGEEY!!!

[Chaz]

My daddy?
Bla, ha, ha.

That explains his lack of hair ��

As to lunch, you’re on!

Should be down in next 30 days.

Chaz = thinkin it was meant as a compliment .. :thumbsup:

He's my daddy for the next couple months .. :eek: When ya get here , you'll see what I mean .. New year , new projects .. :)

Lunch .. heck yea. Since you were here last , he got a new smoker. Best ribs I ever had. I'm probably due another bribe ... :cheers: <---( I didn't mix much dry rub, and i don't remember which I gave you ) Sad part is it's true .. :o

Ya'll listen to gator , he knows them refrigerators .. :p

[keefallan]

Chris, as far as a machine shop goes, ask on here about anyone near you(adjacent states) if you cant find a reputable outboard machine shop. I have one horror story of a bad machinist in my area. At least I only have one and I learned. There arent any good one's in my area. I shipped my blocks south after that. I know there has got to be good machinists in the area near Wisconsin and Ohio if you cant find one where you are. But maybe I am wrong. I dont live there. Heck, I thought there was good one in my area too:eek::nonod:.......... But the one thing I DO know is this: If the block's not right............:thumbsup: and thats why I ship 'em out.

[Instigator]

Dargo, another (good) option for the block is to send it to Monty Racing in Fla.

He can work some magic on the ports for you (not for the beginner anyhow), bore it and send it back for you to assemble.
If you did that, he’d probably be willing to help guide you through the tuning process. Also, not for a newbie.

He did an 8 for a friend of mine that I have been lending moral support to and he now has it turning 7000 RPM!
And, couldn’t be happier.

I have another friend in Fla that did all my blocks and he’s very good.

Chaz, As in, if he’s my daddy, he pulled out all his hair due to raising me😂


Chaz = thinkin it was meant as a compliment .. :thumbsup:

[Merc 2.5]

^^^x2. Very good advice. Exactly what my machinist did for me on my 1st build. Saved me a ton of $$$$ on learning process

[Chaz]

Gary .. err .. I mean gator, I try to not tease anyone .. when I do , I usually wind up with the same thing I teased others about .. but for you I'll give it a shot ... :o

I think your daddy shaves his head, cuz his hair is the same color as ours .. :eek: :D

Not long ago , I said to the Mrs. : Honey my part is like an inch wide , look at this **** When did that happen .. ? She said if you think that's bad, you should see the back ... I held my phone over my head and took a selfie .. Jeezus WTF .. she walk away laughing .. Oh well , old age is deigned to many I reckon .. :thumbsup:

[Instigator]

Lucky for me I got my mom and dads hair gene.
(shot of me hauling my lil boy to the vet ��)

But, my dad only lived to one day from his 95th birthday.

If it wasn’t for me, he would have lived to be a 106!

Was fun in his final yrs, reliving some of **** I got in trouble for.

Sorry for the thread hijack Dargo.

Now back to your regularly scheduled programming.


Gary .. err .. I mean gator, I try to not tease anyone .. when I do , I usually wind up with the same thing I teased others about .. but for you I'll give it a shot ... :o

I think your daddy shaves his head, cuz his hair is the same color as ours .. :eek: :D

Not long ago , I said to the Mrs. : Honey my part is like an inch wide , look at this **** When did that happen .. ? She said if you think that's bad, you should see the back ... I held my phone over my head and took a selfie .. Jeezus WTF .. she walk away laughing .. Oh well , old age is deigned to many I reckon .. :thumbsup:

[FMP]

Member TomAprilsswitzers might know where in that region.

[Dargo]

I was actually kicking around calling Monty to get some prices for the bore and port work. Scares the crap out of me to have someone do it that may not be 100% familiar with these engines. I will certainly do my homework and make some calls locally but this kind of thing is pretty much nonexistent up here. Just pontoons and trolling motors. We’ll see what turns up. I’m pulling the rest of the intake side of the motor off tonight. Hopefully separate the halves early next week. Gotta work midnights all weekend...:-(

PS - I don’t mind the chit chat a bit! No worries!

[Instigator]

Do your homework but Gordon (Monty) has forgotten more about hot rod 8’s thank the rest of us know collectively.
Bore work is one thing but porting is a black art and those that know (spent tons to get there) ain’t talking.

A bit of advice about Monty though, he is old school (like a lot of us) and much prefers phone calls to texts, e-mails, pm’s etc.
A lot of us figure if you ain’t willing to put that effort into it, you ain’t willing to write a ck.

As the S/F board members become younger, it is becoming more frequent to see a member text one of the wizards one evening and when they don’t reply by morning, they come on here and bash them.
Thus ending and shot of help for them and risking it for us.

Most (Monty included) are one man shops and not sitting around their lap top/phone.

Chaz, as always, have Gordon send my commission check to...





I was actually kicking around calling Monty to get some prices for the bore and port work. Scares the crap out of me to have someone do it that may not be 100% familiar with these engines. I will certainly do my homework and make some calls locally but this kind of thing is pretty much nonexistent up here. Just pontoons and trolling motors. We’ll see what turns up. I’m pulling the rest of the intake side of the motor off tonight. Hopefully separate the halves early next week. Gotta work midnights all weekend...:-(

PS - I don’t mind the chit chat a bit! No worries!

[FMP]

If memory serves, TomAprilsswitzers has a monster or two. Perhaps PM him for a shop.

[Dargo]

I completely agree. I much prefer talking to someone on the phone. I will definitely remember that when it comes time to get in touch with him. Also, I’ll drop TomAprilsswitzers a note and see if he has any ideas.

[racer]

I agree if it needs boring make it a 4.0 how ever you need to have someone with the right equipment to bore to 4 as you will loose the recess at the bottom so tooling needs to be able to cut all the way down.

[Chaz]

That is correct ... I use the cutter on the left to "top" new sleeves . Center is for bike and car block / cylinder's .. And the "drop leg" on the right is for "blind holes" such as outboard blocks ... :thumbsup:


https://i.imgur.com/D03acxSl.jpg


Gator , not a problem brother .. I'll have him send the check to the hanger where you keep your stunt plane ... I think the pup in the back is sayin dad .. can we please fly right side up for a while ... I'm gettin sea sick .. :D


https://www.screamandfly.com/attachment.php?attachmentid=474699&d=1602077484

[keefallan]

I was gonna make a funny comment about being upside down, but couldnt think of anything.......DOH!;)

[Instigator]

Great point.

Forgot all about that Al.

What he’s referring to is, the sleeve doesn’t go to the bottom of the bore.
As is, the block is back cut at the bottom of the bore to prevent the block from growing (from heat) under load and making contact w/the piston.

When you cut the bore that far, it puts the I.D. of the sleeve the same as the block bellow it.
So now the piston makes contact to the aluminum block bellow the bottom of the sleeve.

I had a huge auto/truck machine shop shot peen a set of rods for me and they told me they bored OB blocks too. When I asked him about the above, he wrote and sent a company memo on the spot, saying they no longer bore OB blocks ��



I agree if it needs boring make it a 4.0 how ever you need to have someone with the right equipment to bore to 4 as you will loose the recess at the bottom so tooling needs to be able to cut all the way down.

[keefallan]

And that's why you need a reputable machinist..............my story still gets me shakin' my head. How in the heck do you bore the wrong hole? On my v4, I needed #3 done and I got #2 done by accident. So, he needed to resleeve that one:eek:..........and then #3 got done(I only needed it .010 by the way, there was a teenie tiny fingernail catch on one side from the piston contact). BUUUTT #3 came back to me @ .064:eek:!!! He said it was because he didn't have a piston in hand!! I know what happened.........he didn't align the block up right and it took him that much to get it right. So my barely scratched block got punched out to .064. So CHRIS, learn from my mistake.

[mrichartz]

I was actually kicking around calling Monty to get some prices for the bore and port work. Scares the crap out of me to have someone do it that may not be 100% familiar with these engines. I will certainly do my homework and make some calls locally but this kind of thing is pretty much nonexistent up here. Just pontoons and trolling motors. We’ll see what turns up. I’m pulling the rest of the intake side of the motor off tonight. Hopefully separate the halves early next week. Gotta work midnights all weekend...:-(

PS - I don’t mind the chit chat a bit! No worries!

Spending the extra time and money sending it out to someone who knows 2 strokes is worth a whole lot more than it costs worth every penny.. especially Monty
Post #45 is a perfect example

[FMP]

https://www.screamandfly.com/showthread.php?291792-V-8-questions-Can-anyone-help&highlight=

[Dargo]

Beginning to think that sending the block out to Monty just needs to be the plan. What does he need for his end of things? Bare block and a set of pistons? Great tips that I would have never had any idea about! Man you guys know an awful lot about this stuff!!!

[mrichartz]

Call him and talk to him about what you want to do.
Can go on his site first too to get an idea and you will probably end up with more questions after looking at his site to ask too.
There's a whole range depending on what you decide to do.

[Dargo]

Will do! I'll call down there next week after I get work wrapped up for the weekend.

[Dargo]

Well, I’d hoped to have more of an update on my progress by now but I can’t for the life of me get this powerhead to break free from the midsection. I got all 15 nuts/bolts off. I had to cut the head off of two of the long bolts that go through the exhaust housing. They were rusty and stripped as soon as I put a wrench on them. Any advice to loosen the death grip this thing has? I’m hearing propane isn’t hot enough to heat things up. That explains why that didn’t work.

[Brokemercury]

Check out piston coatings, I'm doing a rebuild and this piston coating brings old pistons back to life, up to a 5 inch hope going .006 is 38 bucks, they can go up to .015, I've found no bad reviews on it, sounds awesome to me

[Dave S]

Before ya cut the heads off..... try shocking the bolts sideways.... to see where they are stuck. I use a 0 to 1/4 inch wedge...... it will pull the threads out. Of the block....... a nudda trick is drill sideways to cut the bolt....thru the adator plate.....Ruff stuff working on salt motors.........