Engine misfires

[Kiwi Mal]

Hi everyone. I have recently bought a Sunbeam tiger which is powerd by a 289ci Ford. When I got the car it was not running as it had no spark. It has a later model motorcraft electronic distridutor from a 302 in it. the wiring was a mess and the ign module that had been used was not working and seemed a missmatch. I had an auto electrician tidy up all the wiring and replaced the ign module with a bosch 9 222 067 021 module and that got the engine running and he is happy by bench testing the unit we have good constant spark now.
The problem is as you are driving it at part throttle you can feel it surging a little, if you put your foot into it, it accelerates fine. Go back to cruise and it surges again. It will slowly get worse and start poping and back firing and adventually stop. Now the strange part. If you restart it , it will run as well as it does again, but the engine is getting hot by this time. I had it out today and once it started to run very roughly I switched the ign off and coasted, then before I came to a stop I crash stared it in gear and away it went ( well, as well as it does ).
It has a brand new Holley street avenger carb on it and I have made a wooden carb spacer to eliminate vapour lock as these cars have small engine bays which are very full of engine.
Any ideas anyone.
Thanks Mal

[MonzaRacer]

OK first of all you need to make sure the timing is ok, try for around 12 -16 initial, then hook the vacuum advance up to manifold vacuum.
Now make sure you get idle speed and mixture set with a handheld vacuum guage looking for highest vacuum reading.
If you still have a surge then your lean try upping the main jets 2 to 4 sizes. This means 64s go to 66s or 68s.
If its a 4bbl then its most likely been changed as most had 2bbl(I know a fella with one and the 4bbl was dealer installed.

Anyway also you may need to swap power valve(s) try sizing them around 1.5 to 2 in of mercury lower than at idle, in gear (if auto or in gear/clutch in ) you may then have to swap around.
ALSO keep richening up the secondaries only after getting everything else set up.
I keep the primary lean as I can.
NOW after reading this , SET THE FLOAT LEVEL FIRST!
Hot idling remove sight plug, fuel should just tip over hole at idle. if it does and tuning doesnt fix it you may have fuel delivery issues, ie filter, pump, lines etc.
Oh yeah takeout all the crap filters on/in the carb and install a good inline unit.

[Kiwi Mal]

Thanks for the reply MonzaRacer. The 570cfm carby is supposed to be set straight out of the box for a 289 ( I can now envis'age everyone rolling around on the floor laughing their buts off ). The float levels were ok anyway. I think using a vacuum gauge is a good idea. There may be a vacuum leak somewhere as it makes no difference if the vacuum advance is disconected and left unplugged to the engines running.
The stange part to me is when it starts running that bad it won't run, all you have to do is turn the ign off and then restart it and away you go again.
Cheers Mal