33 hp cylinder walls

Woodstock60 · Dec 27, 2008

I'm looking for peoples opinions on this subject. My 1968, 33 hp has a fair amount of criss cross scoring on the cylinder walls, however the compression is good and even, approx 110 psi on both. I want to know what the pros think, should I put a new head gasket on and just finish rebuilding from there or should I completely tear apart and resurface the walls and replace the rings. I don't want to open a can of worms if I don't have to. The motor is one of many that I enjoy fixing up and using myself, ( in a harsh saltwater environment), not for showpieces or to sell, I just want them to run good. Please tell me what you think. Thanks, Ronnie

HybridMX6 · Dec 27, 2008

Re: 33 hp cylinder walls

Are they scored or is it the cross-hatch markings from honing the cylinders? You say criss-cross scoring, which makes me thing of cross hatch, which is how they should look if I'm not mistaken. Scoring would be straight lines up and down the cylinder walls.

DJ · Dec 27, 2008

Re: 33 hp cylinder walls

Run it.

Woodstock60 · Dec 27, 2008

Re: 33 hp cylinder walls

I suppose that could be the case, but it just looks so crappy ( i'll open it up tommorro and take a pic and post it) I've honed auto cylinders before and they didn't look like that, but who knows what hack may have owned it before me. also I could feel very slight grooves with my finger. I guess a clear pic will be the way to go. Maybe my wife will let me do it now ( 8 pm on a saturday night)

jay_merrill · Dec 27, 2008

Re: 33 hp cylinder walls

Sorry, I goofed. Wrong area. I wondered where that response went.:redface:

jay_merrill · Dec 27, 2008

Re: 33 hp cylinder walls

jay_merrill said:
Sorry, I goofed. Wrong area. I wondered where that response went.:redface:

And what's even more fun is that the above is your response, not mine!

Hmmmmmmmmm ....... we have some digital gremlins in here!

DJ · Dec 27, 2008

Re: 33 hp cylinder walls

I am the ultimate digital Gremlin.

We are hijacking this guys thread all because of my mistakes.

jay_merrill · Dec 27, 2008

Re: 33 hp cylinder walls

True, dat.

Just to get back on topic, I just pulled the head on my 1972 Johnson 65hp motor, in order to install a tell tale nipple. I was surprised to see clearly visible honing marks on the walls of all three cylinders. That said, I suspect what the OP is seeing, if they are merely honing marks, isn't all that unusual.

What I would find to be of concern, however, is being able to feel surface imperfections. That doesn't sound like cylinder honing to me.

HybridMX6 · Dec 28, 2008

Re: 33 hp cylinder walls

jay_merrill said:
True, dat.

Just to get back on topic, I just pulled the head on my 1972 Johnson 65hp motor, in order to install a tell tale nipple. I was surprised to see clearly visible honing marks on the walls of all three cylinders. That said, I suspect what the OP is seeing, if they are merely honing marks, isn't all that unusual.

What I would find to be of concern, however, is being able to feel surface imperfections. That doesn't sound like cylinder honing to me.

I agree. If the OP can feel the grooves, then something isn't right. Honing marks should not be able to be felt by the fingers unless someone did it wrong.

Woodstock60 · Dec 28, 2008

Re: 33 hp cylinder walls

Here's a pic. of the lower cyl. looks a little worse than it is, I had to enhance to see it.

F_R · Dec 28, 2008

Re: 33 hp cylinder walls

I can't see the marks on my computer screen. But I do agree with what has already been said, the factory hone marks are a criss-cross pattern and not a defect. It is acheived by moving the hone in and out as it rotates. But you should not be able to feel it unless you have mighty sensitive nails. In fact, normal break-in and use results in a glaze forming over the crosshatch that should be removed with a re-hone when rebuilding an engine. That allows the new rings to seat.

DJ is right.....run it. That is assuming there are no other problems you are not mentioning. Your compression is good.

iwombat · Dec 28, 2008

Re: 33 hp cylinder walls

Those are hone marks that look bad because there's been some water intrusion and a little bit of rust. It doesn't look bad enough to warrant tearing it apart and rehoning though.

I agree with "run it".

Woodstock60 · Dec 30, 2008

Re: 33 hp cylinder walls

Just wanted to let those who replyed to me that I set this motor up with an electric starter and did a compresion test, both cyl. were 130 psi, don't know what to make of that , seems awful high for such an old, obviously heavily used engine.

1946Zephyr · Dec 30, 2008

Re: 33 hp cylinder walls

I'd say run it too. Hell....if the cylinders look bad, why not run it like ya stole it?

karlow1 · Dec 30, 2008

Re: 33 hp cylinder walls

@110, or 130 psig, you are good top go my man.
Don't sweat it

Woodstock60 · Dec 31, 2008

Re: 33 hp cylinder walls

Thanks much

33 hp cylinder walls

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