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By DANIEL TINDER - 16 Years Ago
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Something just occurred to me (a bit late now), but when bolting up a line-bored engine to a stock/orig. bellhousing/trans. assembly, since the crank/flywheel/clutch center is now likely a bit higher in the block (?), would this minor misalignment be significant? If so, what is the standard procedure to compensate?
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By Rono - 16 Years Ago
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Daniel; I line honed my block and used the stock bellhousing with a Centerfo Force clutch and pressure plate. I just used a clutch allignment tool and standard procedure and everything was fine. Line honing the block shouldn't cause you any problems. Rono.
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By Duck - 16 Years Ago
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I seriously doubt that very small amount of offset would ever be any kind of an issue... /Duck
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By crenwelge - 16 Years Ago
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I don't think the line bore would upset anything, but I like to put a dial indicator to the clutch housing. Warped clutch housings are not that uncommon and can usually be corrected with a little shimming. Misalignment puts stress on the input shaft bearing. If its really off, it can even cause a transmission to jump out of high gear.
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By DANIEL TINDER - 16 Years Ago
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I seriously doubt that very small amount of offset would ever be any kind of an issue... /Duck
Regardless, I'm thinking it still could be wise if I invested the extra labor to remove the bellhousing, install it on the new block and measure crank center runout (I HAVE an engine stand adapter that allows turning the motor nose down). If any factory misalignment AND the align hone boring change should stack up, even if I don't experience any obvious transmission problems down the road, the research I've done indicates it might still shorten input shaft, clutch & bearing life. I should likely make sure offset dowels that fit the Y-Block bellhousing are available first, though.
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By aussiebill - 16 Years Ago
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Daniel, why put yourself through it? .003 or 004 thou wouldnt even show up, never mind the twisting of the bellhousing over the years, ball race clearances and gearbox face alignment due to years of normal flexing and load. if you put anything under a microscope you,ll come up with something and guess what, make no difference to anything, as for offset dowels, you,ll be first to do it! Sorry to seem so direct but just cant see why? Best regards bill.
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By DANIEL TINDER - 16 Years Ago
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Bill,
Pro: 1. With bellhousing removed, it would likely be easier to clean/repaint.
2. A certain "peace-of-mind" from knowing what your crank center/face runout really is. I would kick myself if the trans. failed in a couple years due to misalignment (I typically drive it around 8K miles a year), since the old guy who rebuilt it has retired, and chasing down rare NOS parts is a real pain.
3. I live in a remote rural area, where the penalties of aggressive driving are moot (more or less), and thus thrash it routinely. The stress of misalignment would catch up to me sooner than most.
Con:
1. 3/8" offset dowels apparently not generally available. May have to contact the manufacturers.
If no easy way to correct the problem, then I wouldn't want to know about it.
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By Hoosier Hurricane - 16 Years Ago
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Daniel: Since you seem inclined to check, I have a suggestion. Take the dowels out, bolt the bellhousing to the block, indicate it, and when the concentricity suits you, tighten the bolts. Then drill/ream the dowel holes to the next bigger size, either metric or fractional. I know it makes your engine/trans a mongrel for interchangeability, but at least you would know.
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By ejstith - 16 Years Ago
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Rono (12/9/2009)
Daniel;
I line honed my block and used the stock bellhousing with a Centerfo Force clutch and pressure plate. I just used a clutch allignment tool and standard procedure and everything was fine. Line honing the block shouldn't cause you any problems.
Rono.
Good lookin' Customline Vicky you've got there .. like the color .. 
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By John Mummert - 16 Years Ago
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The factory manual has a proceedure to check run-out between the crank and bore of the bellhousing. I'd have to look it up but I think the acceptable number is around .015". JohnF's idea makes a lot of sense (no surprise). You could get it perfect and make it permanent. I regularly surface truck bellhousings and they are so out of whack you wouldn't believe they would even run!
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By DANIEL TINDER - 16 Years Ago
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John,
55 shop manual spec. is .010 max. indicator variation (.005" concentricity). Same standard recommended by everyone.
If runout proves really excessive, and 3/8" offset dowels cannot be located, I may try Hoosier's idea. Locking in a specific block/bellhousing combo must be considered anathema though, as that suggestion never came up on any of the many clutch-tech sites I visited.
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By aussiebill - 16 Years Ago
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John, sorry to cut in, received the rocker setup today, they are nice! and fast post also!. thanks again. Regards bill.
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By crenwelge - 16 Years Ago
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The way we center clutch housings on 855 Cummins engines is to dial them in, tighten it up, and drill out the dowels to the next oversize. This was the recommended way to do it for 50 years. Their newer engines are said to not require dialing in, but we do it anyway. I use the same procedure on my jalopies.
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By DANIEL TINDER - 15 Years Ago
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John Mummert (12/10/2009)
The factory manual has a proceedure to check run-out between the crank and bore of the bellhousing. I'd have to look it up but I think the acceptable number is around .015".
JohnF's idea makes a lot of sense (no surprise). You could get it perfect and make it permanent.
I regularly surface truck bellhousings and they are so out of whack you wouldn't believe they would even run!
John,
Finally torqued down & measured that NOS bellhousing on the align-honed block. Surprisingly, the bore center is .006" HIGHER than the new crank center (shop manual max. spec. is .005"). It also needs a shim. Parallel face runout is .012" at the 6.25" bore/diameter. Ford spec. is .007" max. measured at 8" diameter (with dealership service tool).
Though the crank center is not that far off, I might pull the dowels anyway & drill for oversize (1/2" FoMoCo) pins, but I wonder how hard it will be to remove the orig. 3/8" dowels? (don't want to chew them up, and have to drill them out).
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By crenwelge - 15 Years Ago
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I would shim it first and get the parallel right first and check the runout again. The shims will move the hole a little and a thou or two isn't much. Dowels will usually come out with a vice grip, but I would sure try the shims before I went to all that trouble.
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By DANIEL TINDER - 15 Years Ago
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crenwelge (6/6/2010)
I would shim it first and get the parallel right first and check the runout again. The shims will move the hole a little and a thou or two isn't much. Dowels will usually come out with a vice grip, but I would sure try the shims before I went to all that trouble.
Thanks Ken, good advice.
Will have to locate some shim stock. Have a washer the perfect size, but made from aluminum. Can't predict compressibility over time, so will go with steel.
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By charliemccraney - 15 Years Ago
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All but the softest aluminum should work. Even then it can take years for it to be compressed any measurable amount. Do you have any idea which alloy the washer is? Many bellhousings are aluminum. If it didn't work, it wouldn't be used.
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By DANIEL TINDER - 15 Years Ago
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Interesting. Halving the parallel face runout with shims doubled the bore runout. This could get complicated.
I noticed the manual describes the face shim procedure first, and then, when the next test shows the bore is out of spec., their only remedy is replacing the bellhousing! I'm starting to think the original measurements may not be so far out of spec. after all for my mildly spirited driving style. With my luck, once the bore is trued and the dowels are drilled oversize, the face runout will change, and more shim juggling will move the bore center again, and on and on.
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By DANIEL TINDER - 15 Years Ago
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charliemccraney (6/7/2010)
All but the softest aluminum should work. Even then it can take years for it to be compressed any measurable amount. Do you have any idea which alloy the washer is? Many bellhousings are aluminum. If it didn't work, it wouldn't be used.
Washer was ID plate from an old toggle switch.
Re: shop manual shim/alignment procedure: If your block was out of whack (casting shift) I could see where shims might prevent bearing failures, but it's a bit disconcerting when a brittle cast iron housing designed for 360 degree contact ends up touching the block only at the 4 bolt bosses after leveling!
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By DANIEL TINDER - 15 Years Ago
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[b]DANIEL TINDER (6/8/2010)style. With my luck, once the bore is trued and the dowels are drilled oversize, the face runout will change, and more shim juggling will move the bore center again, and on and on.
I can see where (if perfect alignment was absolutely necessary) the best approach might be drilling for aftermarket oversized adjustable eccentric dowels. As long as the bolt holes allowed enough movement, you could dial in the bore runout after shimming.
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By pegleg - 15 Years Ago
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Dan, The center of the crank may not necessarily be moved from factory, if it's done with care. The ALIGNMENT of the bearings should improve though. Of course we don't really know that the factory machining was all that accurate, do we?! Ask Mummert about deck heights and how parallel the deck planes are to the crank center if you want to scare yourself! Also, any misalignment won't be caused by a casting "shift". the casting will be machined wrong because of worn out machine tooling, or a sloppy setup, loose fixturing, blah, blah. "Casting Shifts" will produce erratic casting features, but not (usually) machining errors. Although, typically, the machine shop will try to blame any problem on the casting.
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By John Mummert - 15 Years Ago
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Frank, are you trying to say that Detroit wasn't putting out precision race engines back in the 50's???
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By pegleg - 15 Years Ago
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Mebbie!!
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