Lycoming 4cyl

[MaxxForce]

I am looking at buying a boat with a 4 cylinder Lycoming on it but it has no data plate on it and I have no idea what engine it is I have pics on my phone but don't know how to post them can I send them to someone to post for me and figure out what engine it is?

 

[Slidin Gator]

This recent thread should help.

https://southernairboat.com/phpBB3/viewtopic.php?f=47&t=72134

 

[MaxxForce]

I saw that thread but I don't think it's a 0320 or 0360 I think it's a 0290 I'm just not for sure .

 

[John Fenner]

Go to full editor&preview button, scroll down click on attachments and click add files choose the picture from the folder you have it in, the bar will light green if file isn't too big, if it says too big in red, just crop the picture and save it, try again.

 

[John Fenner]

Ok, that said, the cylinder hold down nuts, internal or external hex, plates under internal hex, or just nuts to flange, 4 =1/2 and 4 =3/8 studs?

 

[MaxxForce]

Trying to add pics thanks for the help .

 

[MaxxForce]

External hex, 4-3/8, 4-1/2"

 

[John Fenner]

O-290 GPU, has a flange under the flywheel I'm sure.

 

[MaxxForce]

Thanks for the info, what horsepower is it 125?

 

[John Fenner]

Yes

 

[MaxxForce]

I bought this boat with a 0290 on it and it came with some extra parts like cylinders and pistons but the cylinders are different than my 0290 cylinders can anyone tell me what they are?

 

[Slidin Gator]

O-290 GPU, has a flange under the flywheel I'm sure.

John,
I'm curious, what are you seeing in the pics that say this is a 290? Valve covers and external hex nuts look like a wide flange 320 or 360 to me. I'm not sure about the oil pan.

The valve cover on the spare cylinder matches the O-435/290 style.

 

[twister69z]

The 90 degree fitting on the oil drain back line is only on 235-290-435 cylinders.
So it is 290

 

[Slidin Gator]

Thanks Twister.

 

[MaxxForce]

So do y'all think the spare cylinders I got are 435 cylinders, if so what is involved in putting them on my 290 ?

 

[John Fenner]

Flange under flywheel, or belhousing flange for a better term.

 

[Slidin Gator]

Flange under flywheel, or belhousing flange for a better term.

You got the eye for sure! I see it now.

So do y'all think the spare cylinders I got are 435 cylinders, if so what is involved in putting them on my 290 ?

Maxx, 435 is the 6 cylinder version of the 290. Chances are that the cylinders are interchangeable. The pistons may not be, depending on compression ratio. Note that the valve covers are my only basis for the 290/435 diagnosis on the spare cylinders, so take this with a grain of salt, but it is very likely the guy you bought it all from had those as spares for a reason.

Since valve covers are interchangeable, Ignore the different valve covers and compare them otherwise to determine if they are the same. The first two items to compare are the hole pattern diameter on the flange and the cylinder height. Measure the cylinder bore and post what you find.

 

[MaxxForce]

Cylinder height is the same , I don't have a way to accurately measure the bore but they appear to be the same cylinders that are on my 290 so I believe you are right they are just a set of extra cylinders, I appreciate the help.

 

[Slidin Gator]

Standard bore is 4.875" I believe. The cylinders may be over bored or chrome'd back to spec, all of which drives piston and ring selection. You will need to confirm what you have to know what to do with it.

Good luck!