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Hi Bill, don't let them grind the cam journals, it seems undersize cam
bearings are not obtainable. King bearings had a problem many years ago
but I believe there are no problems with them now. Vandervell did make
bearings for the 100 years ago but they would be hard to find these
days. The 100 block is very soft iron, my car had a massive ring groove
even though the engine had only done 8000 miles from new. I had it bored
to 3 5/8 and sleeved it back to 3 1/2 using good quality iron liners
from LA Sleeve. I used semi dished plus 0.060 pistons from JP pistons
here in Australia. They give a final compression ratio of about 9.5 to
1. I would see no problem with machining the top of the pistons back
flush as it would only be a very small amount. My head gasket is 0.040
thick composite material with steel rings around the bores. As long as
the pistons are no more than flush with the top of the bore you should
have no problem.
Hope it all works out
Regards
Larry Varley
On 26/06/2015 2:33 PM, WILLIAM B LAWRENCE wrote:
> Thanks for the advise Larry,
>
> Yeah, I was wondering about the piston clearance since I don't really
> know what the stock deck height is supposed to be or how much it has
> been cut before. I'm planning on using Denis Welch's 100M pistons and
> their MLS head gasket. I suppose I could use a shim to clear the
> pistons if they are too close, but that would defeat the purpose of
> the MLS gasket. Instead of that I've been thinking of having the top
> of the piston (ring around the pocket) cut back enough to clear the
> head if necessary. The metal seems to be plenty thick there.
>
> I'm planning to do several fit ups with an old gasket (assuming the
> new gasket will crush to the near the same dimension) and check for
> interference and clearances with some modeling clay. I've heard there
> is an optimal piston to head dimension to reduce the squish area while
> still allowing clearance for rod thermal expansion. If you have any
> information on that or on any other tricks or rules of thumb I could
> use the info.
>
> I'm sending my camshaft back to Iskendarian to have it freshened up. I
> really liked their grind so don't feel the need to change.
>
> Checking over the engine while I was disassembling it, a lot of the
> grime I thought was coming from gasketed joints was actually from the
> copious amounts of oil running out of the head joint. Most of my
> joints seemed to be successfully sealed although I may have had a
> problem with the rear lip seal. I think I overextended the garter
> spring while I was assembling it. Not a lot of room for my big clumsy
> fingers to manipulate the spring. I think I'll assemble it on the
> crank before I lay it in the block this time. I'm always amazed when I
> think about the rear cam journal being sealed by a gasket on the end
> plate. It's a miracle it doesn't leak, but I guess most don't. Extra
> support there would be a good thing.
>
> Right now I'm working on sourcing parts and I'm running into a blank
> wall when I look for good quality engine bearings. Moss has some
> trimetal rod bearings by King, but I don't know anything about them
> and I would want the same for the mains too. I'd like to find some
> Vandervells or similar quality bearings, but all their parts lists
> I've seen don't include the A90 engine.
>
> Again, thanks for your input. I'm going to need all the help I can get.
>
> Oh, and while the engine is down I'm going to be working on the body
> and interior too. A Healey has an image to uphold and so far mine is
> falling short.
>
> Bill Lawrence
> BN1 #554
>
>
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Hi Bill, don't let them grind the cam journals, it seems undersize
cam bearings are not obtainable. King bearings had a problem many
years ago but I believe there are no problems with them now.
Vandervell did make bearings for the 100 years ago but they would
be hard to find these days. The 100 block is very soft iron, my car
had a massive ring groove even though the engine had only done 8000
miles from new. I had it bored to 3 5/8 and sleeved it back to 3 1/2
using good quality iron liners from LA Sleeve. I used semi dished
plus 0.060 pistons from JP pistons here in Australia. They give a
final compression ratio of about 9.5 to 1. I would see no problem
with machining the top of the pistons back flush as it would only be
a very small amount. My head gasket is 0.040 thick composite
material with steel rings around the bores. As long as the pistons
are no more than flush with the top of the bore you should have no
problem.<br>
Hope it all works out<br>
Regards<br>
Larry Varley<br>
<br>
<br>
<div class="moz-cite-prefix">On 26/06/2015 2:33 PM, WILLIAM B
LAWRENCE wrote:<br>
</div>
<blockquote cite="mid:SNT149-W3632149F2DC0C17E3610B0A5AD0@phx.gbl"
type="cite">
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<div dir="ltr">Thanks for the advise Larry,
<div><br>
</div>
<div>Yeah, I was wondering about the piston clearance since I
don't really know what the stock deck height is supposed to be
or how much it has been cut before. I'm planning on using
Denis Welch's 100M pistons and their MLS head gasket. I
suppose I could use a shim to clear the pistons if they are
too close, but that would defeat the purpose of the MLS
gasket. Instead of that I've been thinking of having the top
of the piston (ring around the pocket) cut back enough to
clear the head if necessary. The metal seems to be plenty
thick there.</div>
<div><br>
</div>
<div>I'm planning to do several fit ups with an old gasket
(assuming the new gasket will crush to the near the same
dimension) and check for interference and clearances with some
modeling clay. I've heard there is an optimal piston to head
dimension to reduce the squish area while still allowing
clearance for rod thermal expansion. If you have any
information on that or on any other tricks or rules of thumb I
could use the info.</div>
<div><br>
</div>
<div>I'm sending my camshaft back to Iskendarian to have it
freshened up. I really liked their grind so don't feel the
need to change.</div>
<div><br>
</div>
<div>Checking over the engine while I was disassembling it, a
lot of the grime I thought was coming from gasketed joints was
actually from the copious amounts of oil running out of the
head joint. Most of my joints seemed to be successfully sealed
although I may have had a problem with the rear lip seal. I
think I overextended the garter spring while I was assembling
it. Not a lot of room for my big clumsy fingers to manipulate
the spring. I think I'll assemble it on the crank before I lay
it in the block this time. I'm always amazed when I think
about the rear cam journal being sealed by a gasket on the end
plate. It's a miracle it doesn't leak, but I guess most don't.
Extra support there would be a good thing.</div>
<div><br>
</div>
<div>Right now I'm working on sourcing parts and I'm running
into a blank wall when I look for good quality engine
bearings. Moss has some trimetal rod bearings by King, but I
don't know anything about them and I would want the same for
the mains too. I'd like to find some Vandervells or similar
quality bearings, but all their parts lists I've seen don't
include the A90 engine.</div>
<div><br>
</div>
<div>Again, thanks for your input. I'm going to need all the
help I can get.</div>
<div><br>
</div>
<div>Oh, and while the engine is down I'm going to be working on
the body and interior too. A Healey has an image to uphold and
so far mine is falling short.</div>
<div><br>
</div>
<div>Bill Lawrence</div>
<div>BN1 #554</div>
<div><br>
</div>
<br>
</div>
</blockquote>
<br>
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