Bill, I spoke to my machinist about the differences between align
boring and align honing. When they do an align bore, it is done on
each individual bearing, with a separate set up for each bearing.
They would take very little material off of the flat of the block, and
most off of the cap. The block should still be align honed after the
boring to get all three bearings lined up and finished off. the
boring is more of a rough in operation. This would generally need to
be done if using bearing caps that did not come originally with your
block. Since each bearing is done with a separate set-up in the
boring operation, it is impossible to get them all lined up perfectly.
If you are trying to get your original caps lined up, you can
save a step by not doing the boring. When honing, you have to make
sure that your machinist takes the minimum amount off of the block and
cap flat surfaces, and that will prevent the crank from being pushed
too far up into the block. My machinist says that he typically will
take 1/1000 off each of the block and cap surfaces as a starting
point. So it will only move the crank up about 1/1000. If the holes
were far off, he would sometime have to take more, but he would do it
in stages. This is more time consuming, but you don't end up with big
changes in the crank height. Many machinists tend to get in a rush
and just take 5/1000 off the surfaces and then hone it. That way they
know that they only have to do the honing once, but in this case it
will push the crank up into the block considerably. Joe (B)
----- Original Message -----
From: <WEmery7451@aol.com>
To: <jaboruch@netzero.net>
Sent: Tuesday, June 27, 2000 6:16 PM
Subject: Re: Line Boring the TR-3/4 Three Main Engine Blocks
> In a message dated 6/27/00 5:40:00 PM Pacific Daylight Time,
> jaboruch@netzero.net writes:
>
> << When I built my latest engine I had it align honed. >>
>
> I appreciate the response, Joe. Jerry Barr seems to make a
distinction
> between align bore and align hone. I will try to copy and paste in
his
> message:
>
> >>Subj: Align boring engine blocks
> Date: 6/26/00 8:00:00 AM Pacific Daylight Time
> From: jbarr@itol.com (Jerry Barr)
> To: WEmery7451@aol.com
>
> Bill,
>
> I still think that to build a proper race engine you must start by
align
> boring the block and yes the bearing bore will be round, not egg
shaped. The
> machine that causes all the problems is the "Sunnen Align Hone". To
use this
> machine the machinist must first cut the caps .010", then the hone
will cut
> an equal amount off of the block and caps, which will move the
center line of
> the crankshaft up into the block about .005". That's the problem! Be
sure
> when talking to a machinist about align boring that he/she is
referring to
> boring with a single point tool, not a hone. As I said before,
Align boring
> will only move the centerline up about .0005" to .00075" which is
well within
> the tolerance set up by the manufacturer. Depending on how the seal
is set
> around the crankshaft, it may be necessary to recut the seal bore.
By the
> way, I have never had a seal leak caused by align boring the block.
A problem
> with the thrust bearing can occur if the caps are not set up
perfectly
> straight when cutting the cap parting line. This will cause the
thrust cap
> if used ) to be at an angle to the block and cause reduced end
thrust for the
> crankshaft.
>
> Well I have rambled on long enough. I hope this helps. My first love
has
> always been building engines that go fast or in the case of Diesels,
last a
> long time, although I have built some for modified class Diesel
tractors of
> the type tractor pull series that you see on TNN. Jerry<<
>
> I received several more messages on this subject, many of which
advise me
> against doing aligning boring or honing, but I am saving all the
messages
> including yours. I think the block of my last engine which locked
up on the
> fourth weekend may be slightly out of line, and I may try to align
it. I
> change out the bearings after every four weekends. In the mean
time, I am
> putting together another milder engine to try to finish some races
this
> summer. Thanks again. Bill Emery
>
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