In a message dated 96-08-21 08:37:14 EDT, Will Zehring wrote:
<< I adjusted the timing down to about 12 btdc (from 15+) yesterday, and
frankly, I think it runs better at 15, so I may knock it up again (so to
speak). >>
OK Will,
I can't keep my $.02 out any longer. A couple of years ago at the NAMGAR
national meet Jokn Twist (UML) was doing a rolling tech session on the MGAs,
pulled out a timing light and set the timing on an MGA to 20 degrees BTDC at
idle, along with the statement, "I know that sounds like a lot for an MG, but
trust me, it works".
Just prior to that I was trying all kinds of settings to find a decent
compromise for idle, economy and performance at autocrosssing. 24 gave it
great top end performance, 20 gave it good economy, 12 made it idle smooth
but a bit slow, and 8 made everything suck. My problem was burning valves
once a year no matter what I did (drive and race a lot), running hot when I
tow the tire trailer at 75 MPH on a hot day, and pegging the temp gauge when
shut down after a hard run.
The valve problem was solved with hard seats, SiBz guides, and stellite
exhaust valves. While several itterations of radiator changes made little
difference, I finally ended up with a 4-row radiator with modified tank
solder joints pressure tested to 25 psi and a coolant recovery system, seems
to be reasonably good now.
On John's advise I set the timing to 20 degrees BTDC where it has been ever
since. Fuel economy is as good as any other MGA (trailer excluded), no
problems with valves of pistons in the last 40,000 miles, driveabiltiy is
great, and it screems like a banshee right up past 7000 rpm at the
autocrosses (stock carbs, cam and exhaust). I'll never set the timing back
below 20 again, it does work great, but I almost always have a hard time
convincing other LBC owners that 20 is OK for their car.
My advise is to go for what gives your LBC the best performance, you'll enjoy
it much more that way. If you're worried about burning the valves, stop
worrying. If the head is ever off for a valve job, install hard seats at
that time.
Barney Gaylord -- 1958 MGA
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