In all the years I've been playing with these engines, I've only ever seen a
problem resulting from a cam being one tooth off. After all, one tooth on
the cam gear equates to a 9 degree difference of cam timing. I know people
use offset keys to vary the timing by a degree or so but 9 degrees is really
a lot, resulting in either a very "flat" engine with no top end when one
tooth retarded or one that's hard to start and rough at low revs if one
tooth advanced.
The engine of the car I was working on that happily ran with so much
ignition advance was an easy starter and strong throughout the rev range, so
I cannot believe it was a whole tooth off. Knowing the history of the
engine, it's also highly unlikely that anyone had ever fitted an offset key
to play with the cam timing.
Lawrie
-----Original Message-----
From: owner-mgs@autox.team.net [mailto:owner-mgs@autox.team.net]On
Behalf Of john c kahoon
Sent: Saturday, January 23, 1999 3:23 PM
To: mgs@autox.team.net
Subject: Re: 45 degrees advance at idle?
Do you think it COULD make a performance difference ? The valves have to
be
opening early relative to piston position, which could make a difference
in the
total mass flowing thru the head. Then the 45 degrees would fire it on
time with
the piston crank position. Hmmm does anyone know if this could benifit a
stock
engine . Any Engineers ?
john.kahoon@juno.com
71 Midget
On Sat, 23 Jan 1999 07:55:42 -0800 "Lawrence Alexander"
<lawrence@britcars.com> writes:
>No, I didn't check the valve timing, John. I did check the integrity
>of the
>harmonic balancer to make sure it hadn't separated - it hadn't - but
>the
>possibility of a car running that well with cam timing off a tooth or
>so
>didn't occur to me...........
>
>Lawrie
>
>-----Original Message-----
>From: john c kahoon [mailto:john.kahoon@juno.com]
>Sent: Saturday, January 23, 1999 3:04 AM
>To: lawrence@britcars.com
>Cc: mgs@autox.team.net
>Subject: Re: 45 degrees advance at idle?
>
>
>Do you know where the valve timing was ? Maybe they run a little
>better
>with a bit of
>" anticipation " in the valve timing and lottsa advance to go with it
>.
>Hmmmm
>
>john.kahoon@juno.com
>71 Midget
>
>On Fri, 22 Jan 1999 18:36:14 -0800 "Lawrence Alexander"
><lawrence@britcars.com> writes:
>>Rick...........
>>
>>If it's any consolation, one of my customers had a 73 B that was one
>>of the
>>fastest stock Bs that I had driven. On one occasion, when the car was
>>in for
>>service, I decided I had to find out what made it so quick. To my
>>surprise,
>>the needles in the carbs were stock, the ignition system was as
>>original
>>except that the timing at idle was 45 degrees btdc! It didn't ping,
>it
>>idled
>>smoothly and it went like the clappers. Probably had something to do
>>with it
>>being a low-compression engine, as other cars I've tried to "speed
>up"
>>by
>>giving lots of advance have let me know (by severe pinging) that they
>>don't
>>want anywhere near 45 degrees of advance. So, if you notice no
>>detrimental
>>effects from that much advance, just enjoy it and worry about
>>something
>>else!
>>
>>Lawrie
>>British Sportscar Center
>>
>>-----Original Message-----
>>From: owner-mgs@autox.team.net [mailto:owner-mgs@autox.team.net]On
>>Behalf Of Rick Guynn
>>Sent: Friday, January 22, 1999 4:16 PM
>>To: MG List
>>Subject: 45 degrees advance at idle?
>>
>>
>>Hi all,
>>
>>Well I finally got around to playing with the timing on the 'B again
>>and I
>>am
>>befuddled.
>>
>>short history:
>>'73 'B w/'79 engine and ignition. I cleaned evrything and set the
>>timing.
>>Car
>>would bog and backfire when 'snapping' the throttle.
>>
>>Update: after trying everything I could think of (including checking
>>the
>>valve
>>timing) I finally decided to try playing with the timing again. I
>>advanced
>>and
>>retarded it to no avail. The I REALLY advanced it. Now to my best
>>estimate
>>I
>>have the timing set at about 45 degrees BTDC at appx. 1000rpm. The
>>bog is
>>still there a bit, but not nearly as bad and it no longer backfires.
>>I
>>haven't dared
>>to advance it any further. I have in the past checked to make sure
>>that the
>>crank pulley mark and the actual position of the the No.1 cylinder
>>were in
>>sync,
>>and it appeared that they were. I may have to check again. There is
>>no
>>noticeable signs of pinging. SO I'm stuck... any suggestions?
>>
>>Thanks in advance (no pun intended),
>>Rick
>>
>>
>
>
>
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