Do I need to bore or just hone

[jeremy1375]

I'm in the process of rebuilding a motor that a spun bearing. I've dealt with everything else and the last decision I need to make is whether or not to have the cylinders bored.

I measured the bores and found the max taper to be .0011" and max out of round to be .0017". The piston to wall clearance numbers for the turbo motor are .0012 to .0020". I am running stock bore and stock cast piston. The ptw clearance at the area of the number 4 cylinder where the out of round is the greatest is .0027".

I'm thinking I could run a rigid hone through the bores to correct the out of round and taper and end up with ptw clearances that approach .003". Would this be too loose and cause issues or would it likely be just fine?

 

[donniekak]

It needs bored.

 

[jeremy1375]

It needs bored.

What kind of problems I would expect at those ptw clearances?

 

[BogusSVO]

With a drill mounted ridged 3 stone hone, you may be able to hone about .001 out, but it will not correct the taper or out of round. They do not have enough force built into them.

Also they come loaded with coarse stones (IIRC) and that will leave to rough of a cross hatch for even the stock rings.

The PTW clearance will not be too bad, just a tad loose. .001 extra clearance will not kill the engine.

The down side is, the engine will not last as long as it would with a bore and new set of pistons.

Pistons & Rings, plus the extra machine work needed, bore and hone along with R&R the pistons will add about $250 or so to the build price.

 

[zedicus]

I'm in the process of rebuilding a motor that a spun bearing. I've dealt with everything else and the last decision I need to make is whether or not to have the cylinders bored.

I measured the bores and found the max taper to be .0011" and max out of round to be .0017". The piston to wall clearance numbers for the turbo motor are .0012 to .0020". I am running stock bore and stock cast piston. The ptw clearance at the area of the number 4 cylinder where the out of round is the greatest is .0027".

I'm thinking I could run a rigid hone through the bores to correct the out of round and taper and end up with ptw clearances that approach .003". Would this be too loose and cause issues or would it likely be just fine?

you are within tolerance of a running engine, are you doing any major performance mods to this car or is it a stock rebuild?

 

[jeremy1375]

Thanks for your replies!

With a drill mounted ridged 3 stone hone, you may be able to hone about .001 out, but it will not correct the taper or out of round. They do not have enough force built into them...

If I decide to go ahead with a hone and re-ring is there any point in me buying a something like a Lisle 15000 rigid hone for $140 or will a $25 glaze breaker do the job in getting the rings to seal?

Lisle Rigid Cylinder Hones and Stones

you are within tolerance of a running engine, are you doing any major performance mods to this car or is it a stock rebuild?

It's just a stock rebuild- 14b, stock boost levels, etc...

 

[zedicus]

the stock style rings are non hard faced. do not hone, do not bore, just assemble the engine with the new piston and rings. period.

when to NOT hone

like porting for flow vs velocity, and pretty much any thing else in this world everyone has an opinion. i have built motors with out any sort of hone or bore, PROVIDED the cylinders were in spec and glass smooth, and had really good results.

the only time to machine a cylinder is if it is out of spec or if you are going to use HARD FACED rings.