Original engine a good candidate for a stroker?

[Chuck Leeper]

^^^^ True!
I had Jim Ruggles do my first 109.
He and the Sunnen rep had a special way to line hone the mains.
He explained it as the short length of the block can cause hone wobble and kill the end bores.
He had a procedure to prevent that. He never went into "detail".

 

[TIMINATOR]

One way is to remove the stones from the holder, leaving the holders in place, on each LAST of each end stones and grind down the shoes on both the end ones too, this allows a shorter effective arbor, and keeps it "balanced" in the block so there isnt as much hang out at each end of the stroke...
TIMINATOR

 

[SCOOBY DOO]

You align bore a block...not hone it. The bar goes through straight. A top notch machinist when he cuts the caps will take the bare minumum from the block and the rest from the caps to keep the the distance from the crank and the cam the same or as close as possible. Guys are always wondering why their cam chains don't fit...that's why...and that's why cam chains can be bought in different lengths. A hone should only be used if the mains have a few slightly tight spots.

 

[TIMINATOR]

Main saddles can move up and down, or side to side. With a saddle that has moved "deeper" into the block, the cap gets cut less than one that hasn't gone as deep. Like EVERY machining process, whether sleeving, line honing, decking, balancing, or honing, the experience of the machinist is as important as the process. In some cases more.
I have seen MANY cases where folks buy all of the latest whiz-bang, expensive equipment, and are out of business in a year or so. They didn't have the expertise or experience to build anything but hand grenades with the pin hanging out!
I have had a few dozen employees in my 45+ years in business, and about half found backers or loans and went into business for themselves. All failed within a few years. Everyone here was a specialist in what I paid them for. In many cases, I taught them everything they know, I just never teach ANYONE, everything that I know. I have taught all of my employees a LOT! But that is NOT my main business.
Sunnen and others make both line hones, and line bore machines for a reason.
TIMINATOR

 

[TIMINATOR]

A "tight spot" while rotating the crank, means the crank is bent, or ground incorrectly.
If you are referring to a dial bore gauge reading while rotating it in the main bore, a "tight spot" in one direction, typically corresponds to a "loose spot" 90 degrees from it.
A main cap can stretch from detonation, resulting in a loose reading top to bottom, usually without pulling in the sides of the block, in that case, the cap is cut slightly more when line honing to maintain roundness.
Severe detonation can cause the main bearing bores to widen. At that point, line boring or honing the mains is needed, and a shorter timing chain will be required.
A small "shadow" about a quarter inch down in the block from the parting line is acceptable, as modern bearings are "delta wall" constructed. The bearing is thinner near the parting line to allow for a slight side to side cap mismatch so the sharp edge at the parting line does not scrape the oil off of the crank.
Get old catalogues from your machineshop or speedshop, and READ the tech section! All of this info is in there in performance catalogues. Knowlege is power, or E.T.!
TIMINATOR