Evinrude 300xp info needed

[capteliminator]

Picked me up a Superboat with an Evinrude 300 XP. Previous owner was selling the boat or his deceased brother and very little about the boat. My question is what size is it? The serial tag on the clamp bracket is not legible. I did some searching online and came up with checking piston tops for slight domes. I have a cheap bore scope and it is hard to tell but I think it has slight domes. Motor sounds great on the hose but I doubt I'll have time to run this year. Seller says motor is good. Appears to be stock with vro still intact. Any info appreciated!
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[powerabout]

top port side of carbs might have a omc number molded in which might help to identify it
check if under the plastic cover behind the flywheel has one or 2 packs and or post a photo

[capteliminator]

Cool thanks. Ill check it out tonight and post up some pics.

[STV_Keith]

Single power pack, which is the later style. Look at the tab of the head gasket that sticks up above the head and block...is it flat on top or does it have a half circle notch cut in it? Flat is 3.6, notched is 4.0.

[racer]

Block has bosses for finger ports so it should be a 4.0 from 91 to late 93 as before that no bosses and after different air box.

[capteliminator]

Head gaskets have a notch, looks like single power pack. Thanks for the info guys. So i guess it is a 4.0L. Are these motors fairly reliable? Should I leave the vro alone or go pretty mix? I have a nice Mercury 300x but if this thing is reliable and could push the Superboat to around 80 I'd love to keep it on the boat.has a 26P chopper style prop.
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[MattGreen]

The V8 was not OMC's most reliable engine. The folks that live with them most successfully are either handy themselves or have a good local Bombardier technician (preferable a great haired OMC Master Tech :D). Parts availability is poor for the gear case, which is also prone to problems. Don't get me wrong, they have a major cool factor which is why I'm pursuing putting one on my SOB as well, they are just realistically not as reliable as a newer 300 model. Many have blown up.

Matt

[racer]

Grey hair?

[MattGreen]

Ha ha, well considering they haven't really been sold since 1995 ish, my take on this is you want a Master Tech that was around during the V8 "heydays" if you will of the mid to late 80s .....and would therefore probably have grey hair now :D. Not directed at you Al, was actually thinking of my old shop mates when I wrote that ;) Hope all is well in semi-retirement,

Matt

[powerabout]

Ps Al hasnt got any grey hair

[racer]

Things are good Matt just giving you a little grief. Hoping my hair stays like dad's he hardly has any grey at 81.

I do agree a tech that has history with these engines helps but a GOOD tech should be able to repair them correctly.

[Instigator]

Things are good Matt just giving you a little grief. Hoping my hair stays like dad's he hardly has any grey at 81.

It depends on the women you keep company with ��
Last one I hung out with greyed ALL my hair!
Brother, 10 yrs older than me has none!

[rude tim]

Matt,

I beg to differ with you about V8 reliability. The engine is just as reliable as any OMC of that generation. The V8 uses the same pistons, rings, rods and bearings as the V6. The V8 is basicly 2 V4 engines made into one. It is just like anything, with proper maintenance they will go for hundreds of hours.

[Instigator]

Matt,

I beg to differ with you about V8 reliability. The engine is just as reliable as any OMC of that generation. The V8 uses the same pistons, rings, rods and bearings as the V6. The V8 is basicly 2 V4 engines made into one. It is just like anything, with proper maintenance they will go for hundreds of hours.
Agreed. Seen them in the keys still running with 1800 hrs. plus on them. Like anything else it depends on what you start with.

[MattGreen]

Matt,

I beg to differ with you about V8 reliability. The engine is just as reliable as any OMC of that generation. The V8 uses the same pistons, rings, rods and bearings as the V6. The V8 is basicly 2 V4 engines made into one. It is just like anything, with proper maintenance they will go for hundreds of hours.

Hey Tim,

I know you have a lot of looper experience and I remember your big-bore V8 project so I know you speak from experience that a V8 can be built to be reliable. I agree with much of what you said, but let me elaborate a little so you can see where I'm coming from.

Yes, it's basically 2 V4s on top of one another. It shares a lot of components with V4 and V6s. But there are differences that negatively affect reliability:

- 2 VRO pumps, neither of which alone can supply enough fuel at WOT, despite the funky balance valve thingamajig.
- Known deceleration-leaning issues, hence why some models (especially later ones) were fitted with a vacuum-enrichment switch as a Band-Aid to keep them alive. V4s and V6s don't need this.
- a known weak gearcase (well, weak for the torque the V8s made anyway)
- a lot of motor to cool considering it's the same water pump as V4 and V6 and may also be cooling a power steering system
- due to it's massive appetite for fuel, they will not tolerate boat fuel system restrictions a V4 or V6 might tolerate. Restrictive anti-siphon valve ? Too many small-ID fittings in the system ? Rigging tech doesn't check this stuff....go a little lean....squeeq...if you're lucky, perhaps kaboom.

I used to work for a busy Bombardier dealership that had sold a number of V8s over the years. I was there after V8s were discontinued but the Master Techs I worked with had been there for decades. Many of these V8s blew while under warranty, some multiple times. In the heydays of OMC piss-poor quality control, the dealership eventually started disassembling the factory replacement powerheads to make sure all was good inside before installing on the customer's midsection. As time went along, customers have managed to blow up all of them except one - coincidentally, one that Al originally rigged is still running as of August, and it's owner does have it religiously maintained. So that's where I agree with you Tim (and Gary) - with especially diligent attention to detail during rigging and annual maintenance, they can be reliable. But that's where the V8s differ from the little brother looper V4s for example. We had many, many customers with V4 and V6 loopers from the same era as the V8s that were still running strong. The 90 degree V4 looper in particular is a remarkably reliable and tolerant engine. Yes, I've of course seen those blow up too. But if you look at it on a percentage-wise basis, the V4 is less failure prone than the V8. Many years ago Bill Gohr posted on here that OMC saw the smallest percentage of warranty claims on that V4.

This is not an isolated example; here's some more. I bought one of my V8s from a defunct dealership in Ontario. The former shop owner had a similar tale of problematic V8s. He had one customer with 5 V8s (one set of twins, one triples), and they were a fantastic source of revenue - always problems until the customer gave up and went to car motors (I bought the last of the 5). Similarly, I was on a parts-scrounging trip this summer, and stopped at another long-time OMC dealer that I had not met before. Low and behold, similar story - all blown up in his area. If you talk to the Long Island SOB boys, they have lots of stories of grenaded gearcases from offshore use. You don't hear about V4 gearcases doing that for example. If I recall correctly, STV Keith gave up on the stock gearcases and went to CLEs for a similar reason.

So that's where I'm coming from. I don't hate on V8s, I just want people with limited background knowledge to know what they're getting into. The OP's motor looks pretty clean, I wish him the best.

I am still (and always be) an OMC guy. I will also still always like V8s, and when I get the GD stringers back into my Scarab a 4+ liter V8 will go on the back - with a lot of fore-thought into how it was assembled and rigged to make it as trouble-free as possible. :cool: But I'll still have a stock-pile of spare parts in the basement just in case :thumbsup:

Anyway, ramble over, sorry to the OP for getting off-track.
Matt

[powerabout]

so its gearcase ( who can keep a 300x box alive running high) and lean decel being the 2 design faults?
The rest was owner/dealer/boat builder blow ups

[MattGreen]

so its gearcase ( who can keep a 300x box alive running high) and lean decel being the 2 design faults?
The rest was owner/dealer/boat builder blow ups

Ultimately I hope Al will chime in with his experience. The gearcase problem is made worse by the fact that many of its components are now NLA from Bombardier and limited aftermarket options.

Matt

[Instigator]

I have been watching the used V8 market in FLA for 10 years.
A Franken eight is on my bucket list. Up until about the last year you could buy still running lightly or non-molested versions for $25-$3500.
You could buy nonrunning lightly or non molested versions for seven to $1500. All with OEM gearcases. In my opinion they're fine in normal use.
Remember too this is in salt water and a 12 month boating season and there ain't nothing, nowhere, worse!

[racer]

We sold a lot of V8's over the years, the 3.6 were an issue if not run on good 91 octane due to the amount of compression. In fact I believe a lot of engine issues for all outboards is poor quality fuel even locating pin issues as better fuel reduces crown temp. The 4.0 was not nearly as fuel sensitive but I still had my customers running them on 91. I have/had customers with our 22 that are V8 powered with well over 1000 hours and still running. One thing that I feel helped was we put 1 hour on everyone prior to delivery and gave the customer a written break in schedule.

Now the gear case is the weak link if not set up correctly and properly broke in, yes I believe gear case break in to be very important. We also found that 4 blade propellers help with durability especially since we were running 20 inch engines on boats with 26 inch transoms. When building one from scratch gear prep is very important, taking all the gear edges and putting a slight radius really helps as the gear does not peel the oil off the mating surface. Proper shimming, bolting the carrier and good oil with regular changes will keep them together. Tim can vouch for how we did lower units.

Due to the limited number of unit parts the last couple years we were in business we converted the SLE e-tec unit. Found them to hold up really well but at the cost of a 1.85 ratio.

[rude tim]

Matt,

No arguments. People can brake anything and more power and torque makes it much easier.

The big mistakes people make with respect to reliability is jetting and fuel. I have burnt my fair share of pistons trying to get that last hundred rpm. Was it worth it? I can tell you that my deck boat is on the fat side. I burnt one piston on my 4.4 V8 I believe that it was from having a lower unit nose cone that could not feed enough water at 50mph. It was the number 1 cylinder and the complete piston out grew the cylinder. As for lower units, Al hit it. Proper set up and the best oil available is key. I use Royal Purple and change it as soon as it smells different. Another big thing is starting the engine in gear, now with stainless props with solid hubs you can kill a gear set quick just from the shock of putting it in gear. In saying that I finally split a V8 pinion gear, I have no idea how many hours it had on it but I know that I have had it on my boat for 10 years and for the past few it has had 428hp put to it. Also V6 gear cases, I have ran them with the prop surfaced with 389hp and never broke a gear. I have lost one pinion bearing and broke a few bearing carriers which can split the back of the case.

[capteliminator]

Thanks for all the replies and info. I would like to run this motor and dont mind maintenance. The motor appears to be stock and I will leave it this way. Can anyone confirm if my lower is the original style V8? It appears to have a nosecone added but no low water pickup, still had the side inlets. I was hoping to be able to shift it as it eases coming in to the docks. Should i not?

[BUZZIN' DOZEN]

I had a V8 and it actually shifted very smooth because of the shift interrupter, even with a 32" prop.

[powerabout]

Thanks for all the replies and info. I would like to run this motor and dont mind maintenance. The motor appears to be stock and I will leave it this way. Can anyone confirm if my lower is the original style V8? It appears to have a nosecone added but no low water pickup, still had the side inlets. I was hoping to be able to shift it as it eases coming in to the docks. Should i not?
looks later model to me?

[capteliminator]

Looked at the lower a little closer it looks like the top half of the side water inlets are blocked off or filled in and it has a drain plug in the bottom of the carrier like a merc spormaster.

[STV_Keith]

But there are differences that negatively affect reliability:

- 2 VRO pumps, neither of which alone can supply enough fuel at WOT, despite the funky balance valve thingamajig.
- Known deceleration-leaning issues, hence why some models (especially later ones) were fitted with a vacuum-enrichment switch as a Band-Aid to keep them alive. V4s and V6s don't need this.
- a known weak gearcase (well, weak for the torque the V8s made anyway)
- a lot of motor to cool considering it's the same water pump as V4 and V6 and may also be cooling a power steering system
- due to it's massive appetite for fuel, they will not tolerate boat fuel system restrictions a V4 or V6 might tolerate. Restrictive anti-siphon valve ? Too many small-ID fittings in the system ? Rigging tech doesn't check this stuff....go a little lean....squeeq...if you're lucky, perhaps kaboom.
Matt

Sounds like a V8 that is pre-mixed (VRO-removed), with a Merc gearcase and aux water pump is the ticket. :) Hmmm, the same setup I've had on my Scarab for 8 seasons (and now for sale). :) I've never changed the jetting as given to me by Gordon, never burned anything up (except a regulator or two) and run pump 91 octane. 200+ hours and runs harder now (in FL) than it ever has. Magic air I tell ya!

[MattGreen]

Keith I always liked your boat, and you've reinforced the points made above - when rigged with attention to detail and cared for by knowledgeable people, V8s can be reliable :cheers:
It's a small world too - some of the V8 spare parts in my basement came from your dad !

Matt

[STV_Keith]

Keith I always liked your boat, and you've reinforced the points made above - when rigged with attention to detail and cared for by knowledgeable people, V8s can be reliable :cheers:
It's a small world too - some of the V8 spare parts in my basement came from your dad !

Matt

Yup, small world. I think he's liquidating all his V8 stuff finally as well. There may be more available soon. :)