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MG MG Y Type - YT timing

hi,
PUZZLE for the day.
I have a weird scenario with getting my YT running. The photo shows the timing chain position. I have timed the distributor to TDC, adjusted the rocker clearance to 0.19", and have both rockers on piston one (front of engine) down, ie you cannot move them by hand), and piston 4's rockers are loose. I also used the rule of 9 to check the sequence of the rockers.
The issue is, when I crank the engine, it kicks a little and then stalls when it should fire on the next piston, turns another cycle and does the same thing again. If I turn the distributor to 4 o'clock, it backfires at the muffler end, if I turn it to 7 o'clock, it backfires through the carburetors (maybe vice versa??).
I have applied a dab of white paint where the timing marks are on the cam and crank shafts. There are 13 links on the left side, and 15 on the right side (engine upright).
Thanks.

andrew sorouni

Andrew, Check through the plug hole that piston 1 is at the top of it's stroke and the exhaust valve is about to open and that the points have opened opposite the No1 lead.
Peter
P W Vielvoye

Hi Andrew,

Have you got the plug leads set up 1 3 4 2 for the distributor rotating the correct way? (anticlockwise)

Bob Schapel
R L Schapel

Hi Peter,
when Piston 1 is at TDC, both rockers are hard to move.
What do you mean by 'the points have opened opposite the No 1 lead? By points you mean the distributor!

Hi Bob,

yes timing order is 1 3 4 2 anticlockwise.

regards

Andrew
andrew sorouni

Hi Andrew,

Your dizzy could be 180 degrees out?
With piston 1 at TDC and its rockers hard to move, piston 4 should be at TDC and its rockers loose. In that situation you should set the timing with the rotor pointing towards plug lead 4.

If you turn the engine one revolution it should be the opposite .... i.e. with pistons 1 & 4 at TDC the rockers belonging to no. 1 piston should be loose and the rotor should point to no. 1 plug lead.

In other words the piston at TDC and firing should have the loose rockers and rotor pointing to its lead.

Bob
R L Schapel

Andrew
You saying the rockers were hard to move at TDC didn't sound right to me both valves should be firmly closed with the rockers at full 0.19 as this is the start of the firing stroke.
As Bob says the rotor pointing to No 1 lead as the points open. Also the pointer on the crank case should be in line with the notch in the crank pulley.
Peter
P W Vielvoye

Hi Andrew, Sorry I have missed your phone calls.

It does sound like you have timed it on #4 piston.

When the timing mark on the front pulley is near the pointer on the timing cover, the following must be aligned:-

1 - Piston No. 1 should be at the top of the bore
2 - Valves for No.1 should be rocking & not touching the valve stems
3 - The rotor arm in the distributor should be pointing to the No.1 plug lead

Keep turning the engine over till you get 1 & 2 happening together, then adjust the distributor to get it aligned properly & you should be OK to go....

Cheers

Tony



A L SLATTERY

Thanks everyone. Will try these suggestions and let you know.

Regards

Andrew
andrew sorouni

This thread was discussed between 20/07/2015 and 21/07/2015

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