I guess I will contribute since it looks like only Barney has replied, at
least on list.
It is to my understanding that a compression reading of 125-130 is typical
of the lower compression 8:1 engines that were produced starting with the
18V series or thereabouts (starting 1971 or 1972?). The 160 compression was
the range for the 9:1 compression engines, as in the 18G engines and UK
version of the 18V. But as Barney said, the key is evenness in the readings.
When I bought my 71BGT, it had consistent readings of 90 on all four
cylinders. It ran fine and power was good - it just liked to use a lot of
oil, a quart every 200-300 miles. I eventually rebuilt the engine when I
was ready.
As far as the hoses, you had it right the first time. Now you don't. The
hose from the crankcase should have a Y fitting that then has two hoses,
each connecting to each carb. I don't think your new connection would have
any effect to the running of the car unless the crankcase breather was
plugged. You could try connecting a clean hose to it and blowing into it to
see if there is any back pressure.
I had a problem with the crankcase breather on a 65B in which there was one
because it was a newer 18V engine - but with old SU carbs that do not have
those vent connections. Some listers suggested I just vent the crankcase
tubing rather than seal it, and it worked. So I don't see anything
detrimental to your hookup except that its not right (but the only people
who would know would be those who know their MGs and/or SU carbs).
David
72 B
67 BGT
At 05:45 PM 4/1/2002 -0600, Barney Gaylord wrote:
>At 10:56 AM 4/1/02 -0800, Zach Dorsch wrote:
> >.... I set up a page to show how I rerouted the hoses. ....
> >http://www.geocities.com/herr_dorsch//hoseroute.html?1017686907510
>
>I will plead innocent of any knowledge of emissions controls and leave that
>question to the late model folks.
>
> >.... I ran a compression test today, and all cylinders were at 125,
> >shouldn't they be ~160?
>
>Nah, stop worrying. These things run quite well with 125. A stock engine
>in excellent condition might be 140-145. 160-165 might be for a shaved
>head (or lots of carbon in the cylinders), and 175 would be for flat top
>pistons (and very high octane fuel rquirement). If all cylinders are
>within 10% and none less than 110 you should just drive it and enjoy
>it. If they vary more than 10% you can have a slightly rough idle. If any
>one cylinder falls below 100 it could be hard to start in cold weather.
>
>Barney Gaylord
>1958 MGA with an attitude (and 125-135 compression on a good day)
>http://www.ntsource.com/~barneymg
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