The timing marks are inconveniently found under the engine. There is a notch
in the pulley and a toothed metal piece on the timing cover. Watching the
engine turn clockwise, the 0/tdc mark is the last one. Each pointer
represents 5 degrees earlier. John Twist, and others, recommend setting the
timing to 32 degrees BTDC at 3500 rpm or so. To do this, you will have to make
a 32 degree pointer, or at least a mark on the cover, to which you can refer.
You can do this with a piece of paper to measure, or just turn the pulley back
(remember 5 degrees per pointer) to establish the 32 degree point. If
Barney's method you cited was to drive up a hill at 2500 rpm and to turn the
distributor so engine just barely knocks, that's OK, but you do have some
hills in Gaineville area and you don't want to do excessive knocking. You
might check the valve clearances again. The erratic vacuum gauge may indicate
timing or valve issue. Valves should be OK but adjust again after a drive to
be sure. Barney's 90 degree method works well. Compression is not ideal. You
would like to have each cylinder pressure within 10 per cent, but for daily
driving it's fine. It may also get better as you use the car more. Twelve
years of slight use could have caused rings to take a slight set, maybe. Oil
pressure is a bit of a concern. You could stick a gauge of known accuracy
into the oil gauge line and see what this one reads. You would like to see 60+
at road speeds, though idle is OK. There was an article in MGB Driver this
month about a stuck oil pressure relief valve. That valve giving trouble is
rare. More likely is worn big-end bearings. How many miles do you believe
are on this engine? Has oil been changed regularly during its life? Has it
been changed annually even at 20 miles per year? Oil can acidify, and acid oil
does bearings no good. That can happen from time, heat and humidity. Back to
John Twist advice again, he wrote that big-end bearing changes at 60,000 miles
were cheap and easy to do, and if done before pressures dropped, the mains
would be good for 200,000 miles. If you have reason to suspect the rod
bearings, changing them is an afternoon's job.Bob
---------- Original Message ----------
From: <daybell7@aol.com>
To: "mgs@autox.team.net" <mgs@autox.team.net>
Subject: [Mgs] BGT Resurrected
Date: Fri, 19 Dec 2014 23:54:26 +0000
My 68b GT is running decently after resting in the garage for the twelve
years Ibve owned it.
Actually Ibve taken it for short drives each year but never got it dependable
enough to use
regularly. Right after I bought it I had new valves installed. In the last
week or so I adjusted the valves and ran compression tests using Edbs handy
form.
Readings hot and with three plugs are 160,155,140,165, with oil:
175,175,165,160.
Oil pressure is 25psi at idle and 48psi on the road. I changed the oil filter
when I first got the car and recently put Castrol 20-50 oil in the engine. I
intend to change the filter again and add Lucas oil additive to the motor,
probably two quarts. I see therebs a pressure valve to investigate, plus I
was just using the gage in the dash and want to get a more reliable reading.
I donbt see the markers to adjust timing, but used Barneybs method to time
the motor turning the distributor. I put in the Petronix electronic ignition
in the car.
The car has a 45DC Weber carb that I adjusted the best I could. When I put a
vacuum gage on the weber, the gage fluctuated wildly. An increase in RPM
steadied the needle somewhat, but still wasn't close to being steady.
My plan is to run it fairly hard & retest everything.
Anybody got any thoughts on this. BTW, I had a nice time driving the 30 miles
today.
Thanks,
Steve H
Gainesville, FL
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