[Mgs] another oil question? really?

gordies garage mg_garage at comcast.net
Mon Jul 7 12:26:25 MDT 2014


I'm with you Max, I don't buy the oval story.
In fact, when I took my 1622 apart, my machinist said that my cylinders were 
not oval, and at .030 over, I didn't want to bore any more if not necessary. 
Honed cylinders and reassembled with same pistons and new rings.  After run 
in I discovered that my #3 cyl was registering 80psi compression (other 
three were 150).  Carefully removed #3 piston and found all rings with the 
gap at 9o'clock.  Presumed that this was the problem, and re-clocked the 
rings.  Re-assembled and compression was 150, just like other three. 
Checked again after first short drive and found it at 80psi.  My theory is 
that the cyl is slightly oval, enough that the rings 'center' themselves in 
a short time.
Current solution is a 3 main bearing 1800 sitting on a stand awaiting a 
rebuild, then I will look further into the 1622.

To the point of the thread.  In my '62 MGA, I have pretty much always used a 
qt of oil every 500 - 700 mi.  Latest oil change was with Redline 20w50 full 
synth and so far I haven't registered a noticeable loss (maybe an 8th qt) on 
the dipstick with about 500 mi.  I always have a drip or two on the ground 
when parked, and I assume at least a little when driving, so that accounts 
for a little loss.  I like the Redline, and it is packed full of the ZDDP 
that our flat tappet engines love.

Gordie Bird
'62 MGA (Ottawa bound with 80psi compression in #3)



--------------------------------------------------
From: "Max Heim" <mvheim at sonic.net>
Sent: Monday, July 07, 2014 12:53 PM
To: "MG List" <mgs at autox.team.net>
Subject: Re: [Mgs] another oil question? really?

> I don't buy that oval story. The whole idea is to keep the piston square 
> in
> the bore, so the rings seal. You oval out the bore, the rings are circular
> -- the only way they can seal is to cock the piston, which can't happen
> because there are 3 rings, not one.
>
>
> --
>
> Max Heim
> '66 MGB GHN3L76149
> If you're near Menlo Park, CA,
> it's the primer red one with chrome wires
>
>
> on 7/7/14 9:20 AM, Clayton Kirkwood at crk at godblessthe.us wrote:
>
>> Yes! Ok, I've had my 62 mga engine rebuilt 3 times by "experts". The 
>> current
>> iteration seems solid - put a couple thousand miles on her. But she sips 
>> oil
>> modestly. The guy who did the machine shop work for my 59 Land Rover told 
>> me
>> that most machine shops and rebuilders machine the cylinder walls wrong.
>> They make the cylinders round instead of slightly oval toward the bottom 
>> of
>> the stroke which considers the pull and push rotation of the driveshaft 
>> and
>> connector arm. Seems reasonable to me.
>>
>>
>>
>> So the question. Should I increase the viscosity of the oil to allow less
>> oil burn, and/or, go to synthetic which won't burn off?
>>
>>
>>
>> Also by now, I'm figuring she has finished running in and plan to change
>> oil/filter.
>>
>>
>>
>>
>>
>> "We live in the greatest nation in the history of the world," he pleaded. 
>> "I
>> hope you'll join with me as we try to change it." Barrie Obama
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