Engine Builders Question

[Russ/40]

I have run into a problem on an engine I am currently building. The block is a '41 with the sleeves pulled and bored to std. 3 3/16." The problem is when it was bored, no chamfer was made to remove the portion of the top most bore area that the original sleeve sat upon. With my spring compressor when I try to run the piston down, the lower steel ring portion of the oil ring snaps into this small depression around the bore preventing me from getting the piston fully down the bore.

I'm using the spring steel type of compressor. Any ideas to bypass this obstruction and get the piston and rod down the bore without damaging the rings?

My pistons are 4 ring. The bottom oil ring is no problem, but the upper oil ring with the expander setup is the problem.

 

[flatheadmurre]

The compressors that is a steelband sometimes can go down into the notch...

 

[Russ/40]

I just can't get mine to set that well.

 

[Ronnieroadster]

On the few blocks i did like yours remove sleeves and bore to 3-3/16 a slight chamfer was added at the top of the bore this eliminated that step. The chamfer was accomplished by using a cone shaped sanding drum in a hand drill. The machine shop that bored the block should have a similar sanding drum most shops do this to the cylinders after the bore to help guide the rings in.
Ronnieroadster

 

[JSeery]

Not sure how much trouble you want to go to, but you could have a tapered sleeve machined to install the pistons/rings and machine a lip into the bottom of it to fit the block. Might be able to use one of these type of installer and just add the lip to the bottom of it somehow.

Or maybe something like this: https://www.prlog.org/12641500-ipd-...tool-promotion-for-cummins-isx15-engines.html

 

[Russ/40]

On the few blocks i did like yours remove sleeves and bore to 3-3/16 a slight chamfer was added at the top of the bore this eliminated that step. The chamfer was accomplished by using a cone shaped sanding drum in a hand drill. The machine shop that bored the block should have a similar sanding drum most shops do this to the cylinders after the bore to help guide the rings in.
Ronnieroadster

I agree with what you say, but, I have a valve train and crank in place and don't intend to start grinding on bores now. Looking for a better ring compressor. I have ordered one of the taper ring compressors I will modify if necessary. Would be nice if someone that has tried this would come forward and fill me in on their experience.

 

[JSeery]

I agree with what you say, but, I have a valve train and crank in place and don't intend to start grinding on bores now. Looking for a better ring compressor. I have ordered one of the taper ring compressors I will modify if necessary. Would be nice if someone that has tried this would come forward and fill me in on their experience.

Think you are on the right track.

 

[Fordestes]

Will there be any sharp edges to worry about causing a hot spot if left not chamfered ?

 

[rotorwrench]

I don't know what the step dimensions are but I would find something hard to fill the step but still have the same ID as the cylinder wall. It could be made from wire but it would have to be soft enough to not damage the rings and hard enough to let them pass over it. I've had to do this on hydraulic cylinders before.

A lathe would be handy to make a guide sleeve but a person would have to have one to fabricate a specific sized guide sleeve. A cylinder sleeve could be used to speed up the process.

 

[Russ/40]

Will there be any sharp edges to worry about causing a hot spot if left not chamfered ?

Interesting thought, but I don't think there is enough meat there to matter. The step is probably .025 x .025" approximated.

 

[Russ/40]

I don't know what the step dimensions are but I would find something hard to fill the step but still have the same ID as the cylinder wall. It could be made from wire but it would have to be soft enough to not damage the rings and hard enough to let them pass over it. I've had to do this on hydraulic cylinders before.

A lathe would be handy to make a guide sleeve but a person would have to have one to fabricate a specific sized guide sleeve. A cylinder sleeve could be used to speed up the process.

GREAT ! Point rotor wrench !

I didn't think of that. Forgot I actually have a few 3 3/16 sleeves, and I have a lathe if I need it. Good info !
I knew a few extra brains would help.

 

[deuce_roadster]

Would stuffing a rag down in the cylinder and using a ridge reamer take that sharp edge away? You could vacuum out any filings created. You might be able to taper the cutter to make a chamfer. Just a thought.

 

[Russ/40]

A cylinder sleeve could be used to speed up the process.

Took the 3 3/16" sleeve and ground the bottom to a knife edge all the way around. It made the perfect ring compressor to slide the loaded piston past the offending notch that was grabbing the 3rd ring. That comment did the trick. Thanks rotorwrench!