flathead back firing

M

mike d

Member
i have a 59ab that is backfiring on mild accelleration, crab dist with msd 6a box. i'm using only one set of point for a trigger. stock single carb with .051 jets. one wire alternator, idles at 450 rpm . should i have removed the condensor from the dist, or should i be looking somewhere else? thanks, mike
 
I would be looking to your builder and If it's a crab dist. talk to bubba's ign. It's prob. something very simple:eek:
 
When triggering with one set of points you should be using the set that normally opens last; the trailing set. The timing will be off some if using the other set; not sure if that would be the cause of the problem but something to check.
 
Are you using Resistor ignition wire's.
Ive heard that you can get "False" sparks if you use copper wires.

Check the MSD ignition manual and what it say's.
 
When you start throwing in non stock parts you kind of lose the stock guys ability to diagnose your problems,go to the HAM site,they would be better equipt to answer your ques. ken ct.
 
mike d said:
i have a 59ab that is backfiring on mild accelleration, crab dist with msd 6a box. i'm using only one set of point for a trigger. stock single carb with .051 jets. one wire alternator, idles at 450 rpm . should i have removed the condensor from the dist, or should i be looking somewhere else? thanks, mike
Click to expand...


I think BillM hit the nail on the head !!
He said :

When triggering with one set of points you should be using the set that normally opens last; the trailing set. The timing will be off some if using the other set; not sure if that would be the cause of the problem but something to check.

The spark timing would be way off the correct rotor phase if the wrong set of points were being used. Also the crab cap is pretty prone to jump spark when output is high. I assume its a pretty stock engine so theres no need for high spark output. The distance between the cap and the aluminum crab case will arc with high voltage. Plugs should be at .025.
 
BUBBAS IGN i offen woundered why ford switched in 46 to the other desine now after reading your post it makes cents ford must of had complants especaly on rainie days of spark jumping from cap to housing
 
Cannot think wny you would use the trailing set .The opsit is true .Trailing means last ?? You must use the points that open at 5 % in othere words its the set on the right facing the Grill

you must use the
BUBBAS IGNITION said:
I think BillM hit the nail on the head !!
He said :

When triggering with one set of points you should be using the set that normally opens last; the trailing set. The timing will be off some if using the other set; not sure if that would be the cause of the problem but something to check.

The spark timing would be way off the correct rotor phase if the wrong set of points were being used. Also the crab cap is pretty prone to jump spark when output is high. I assume its a pretty stock engine so theres no need for high spark output. The distance between the cap and the aluminum crab case will arc with high voltage. Plugs should be at .025.
Click to expand...
 
If FORD would have uses the rubber nipples on the caps 9 wires like i do the water would not have gotten in there.OMO. ken ct.
 
Cannot think wny you would use the trailing set .The opsit is true .Trailing means last ??
Click to expand...
The coil fires when the primary current is interrupted, so with a stock dual point setup both sets of points must be open; therefore ignition happens when the last set of points opens and this is where the timing should be set.
 
To answer the original question---no, you do not need the condenser when using the 6A MSD control box. Look at the carb accelerator pump, ignition timing, etc. For a quick test, apply some choke during the periods of back fire and see if that makes any difference.
 
You must log in or register to reply here.
Back
Top