Main Bearing Caps

[Brian Crombie]

Greetings All,
I am rebuilding my 1147 and have a very knowledgeable friend standing by for any
problems. The following problem has even him scratching his head.
When I took the motor apart, I didn't mark the main bearing caps (I will next
time!) but do know that the center one was marked 44 twice. Problem is there
are two caps with the same double mark. Adding to the dilema, one is narrow and
the other is wide. So out of three cap I'm looking at this:

#1 Wide : Stamped 44 twice


#2 Narrow : Stamped 44 twice


#3 Narrow : Stamped 44 once

According to the maintenance manual, stamped below the oil pan gasket (on the
block) are corresponding numbers. I only have one spot stamped. It's the center
one showing a 44.
I spoke to a guy who builds engines for a living and he told me to bolt them on
where I think they should go, tourque to spec and make sure the crank spins
freely. With the manual telling me that they are not interchangeable, I won't
heed his advise. Any suggestions from you guys/gals that have been down this
road before me?

Many thanks in advance!

Brian Crombie
Faribault, Mn.



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[rogtwo@aol.com]

I've never had one of these engines open, or any British engine for that
mater. But, based on my work on American and German engines, I will make
these comments.

Three bearing caps, means you have 6 potential combinations (12 if the caps
can be turned end-for-end). But (if I understand you correctly) one cap has
a wider bearing width. This wide cap should be easy to locate. That is, if
the cap is wider look for the crank journal that is also wider. This leaves
you with just 2 caps, and thus only two combinations (4 if they can be turned
end-for-end). You already did away with 66% of the possibilities!

Put the two remaining caps on randomly for now. Do NOT install the bearings.
Install the bolts and tighten the caps snugly (you don't need to use a
torque wrench, just make the bolts tight). Now check the joint between the
cap and block very carefully. Run your fingernail across the joint to check
for an "edge". Now swap the caps and check the fit again. If the caps can
be rotated end-for-end, then rotate them and do repeat the checks again.

NOTE: If you have an inside micrometer, you could also check the "diameter"
from the block to the cap. You can see if this varies with cap location, and
pick the location that gives the most appropriate diameter.

If they seem to fit best in one location, then you are all set. I suspect
you could detect as little as half of a thousandth of an inch of mismatch
(0.0005 inches). Since bearing clearances are probably 3 to 4 times this
big, if you can't detect a mismatch, you are likely OK.

However, if you want to be sure, then put the caps on, mark their location,
and have the block line-bored -- if oversize bearings are available.


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[tommyintpa@aol.com]

Re: Re: Main Bearing Caps

In a message dated 4/28/03 4:50:03 PM Eastern Daylight Time,
minnow@amphicar.net writes:


> One solution may be to replace the bearings and have your crank
> turned a reliable machine shop.
>
> John
>

Brain,
Captain John is correct and your friend, although trying to be helpful, IS
WRONG -WRONG - WRONG.
If you reassemble it and your crank is bound up then you have scored it and
if it turns freely it may well start to knock. Then you killed it for sure.
The bearings don't cost that much, and get that crank turned anyway. If it
were mine I would take it to the NAPA machine shop I deal with and have them
do the following. Bore the block a little, turn the crank, have them measure
and install the correct rings and insert the pistons, install the new rod
bearings and main bearings and replace the oil pump. If the bottom end of the
motor is complete have them install the oil pan too. You can do it yourself
but it will be easier to keep the inside clean with the pan on.
You will have a rebuilt short block, a smoke free, easy to start, strong
running, happy Amphicar - and life will be good

Good luck - Tommy in Tampa

Just think how nice a valve job would be about now, with some hardened valve
seats wow baby and a NOS carburetor and maybe a new distributor and you could
use...


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[a_colo_native]

> I spoke to a guy who builds engines for a living and he told me to
bolt them on where I think they should go, tourque to spec and make
sure the crank spins freely. With the manual telling me that they
are not interchangeable, I won't heed his advise. Any suggestions
from you guys/gals that have been down this road before me?

Brian,

I'm not sure I can help you out on the initial problem. But I can
tell you to avoid this guy! The crank spinning freely is no
indication it will continue to do so. This looks like a guy who
should not be building engines, or at least anything I want to be
reliable.

One solution may be to replace the bearings and have your crank
turned a reliable machine shop.

John

 

[Brian Crombie]

Re: Re: Main Bearing Caps

John,
New bearings are in place, crank polished and specs checked by Napa with myself
present.
Thanks for your input!

Brian
----- Original Message -----



One solution may be to replace the bearings and have your crank
turned a reliable machine shop.

John


Yahoo! Groups Sponsor





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[bomby74]

Roger,
Your on the right track. I spoke to a local mechanic this morning
and he said the only way to do it is to look at the marks that line
boring produced. Line boring leaves cross hatch marks that one
should be able to match (block to cap). He described it like a
forensic person matching bore marks on bullets. Can't wait to play
CSI when I get home.
Thanks guy's for your words of wisdom!

Brian
--------------------------------------------------------------------


> However, if you want to be sure, then put the caps on, mark their
location.
> and have the block line-bored -- if oversize bearings are available.