I NEED HELP. I HAVE A STOCK 302 CLEVELAND IN A 1977 F100 2WD AUTO UTE. IT HAS NO MODS EXCEPT FOR STANDARD FORD ELECTRONIC IGNITION. IT HAS A LOW DOWN MISS. I HAVE CHANGED PLUGS, LEADS, DONE A COMPRESSION TEST (110-120 PSI IN ALL 8 POTS) SWAPPED PLUGS AND LEADS AROUND, CHECKED TIMING, PULLED OFF A ROCKER COVER TO SEE IF ALL THE ROCKERS WERE MOVING (THEY WERE) AND DONE ALLOT OF HEAD SCRATCHING. I THEN STARTED PULLING LEADS OFF ONE BY ONE AND THIS IS WHAT I CAME UP WITH. NUMBER 1,4,6 AND 7 NO CHANGE. 2,3,5 AND 8 ENGINE RAN ROUGH. I THEN PULLED 1,4,6 AND7 ALL OFF AT ONCE AND THE ENGING DID NOT CHANGE. THIS TEST WAS CARRIED OUT AT IDLE IN PARK. I DONT KNOW MUCH HISTORY ABOUT THE ENGINE BUT IT LOOKS LIKE IT HAS BEEN REBUILT IN THE LAST FEW YEARS, IT BLOWS NO SMOKE AND IT STILL DRIVES AROUND OK. I CANT GET IN TOUCH WITH THE PREVIOUS OWNER TO SEE IF HE HAD THE SAME PROBLEM.


ANY IDEAS AT ALL WOULD BE GREAT.

THANKS bundy351

 

What is the firing order you see on the intake manifold. I'm going to make this up as an example (but I think its close); 302, 1-5-4-2-6-3-7-8. I was replacing an engine in a mustang and had about the same problem but I found that the cam was different (it had the firing order from a Cobra's cam of the same year) and that the firing order had changed to; 1-5-6-3-4-2-7-8, you see the 4 number in the middle changed places.

 

THE FIRING ORDER ID 1 - 3 - 7 - 2 - 6 - 5 - 4 - 8. BUT IF THE FIRING ORDER IS OUT WOULD IT BE BACK-FIRING? I THINK IT MIGHT BE A FUEL PROBLEM, WHEN YOU LOOK AT THE FIRING ORDER IS IS EVERY SECOND CYLINDER THAT IS NOT FIRING BUT WHEN I ARC OUT THE LEAD IT SPARKS A BRIGHT BLUE COLOUR ON THE BODY. I AM THINKING IT MUGHT BE A BLOCKAGE SOMEWHERE. THE MANIFOLD IS A DUEL PLANE 2 BARELL SET UP. I HAVENT LOOKED YET BUT IT MIGHT BE THE LOW PLANE THAT FEEDS THE CYLINDERS THAT ARNT FIRING. I WILL HAVE A GOOD LOOK THIS WEEKEND AND LET YOU KNOW.

bundy351

 

Let us know what you find

 

I AM 99.99% SURE IT IS THE CARBIE. I HAD A LOOK AT THE MANIFOLD AND THE 4 CYLINDERS THAT ARE NOT FIRING ARE FED BY ONE SIDE IF THE CARBIE AND THE ONES THAT ARE FIRING ARE FED BY THE OTHER SIDE. I SCREWED IN THE IDLE MIXTURE ON THE SIDE THAT IS FIRING AND THE ENGING RAN ROUGH AS EXPECTED (LEANED OFF). I THEN SCREWED IN THE OTHER SIDE AND NOTHING HAPPENED. I SCREWED IT IN ALL THE WAY AND NOTHING HAPPENED. I MUST HAVE A BLOCKED IDLE PORT ON THAT SIDE IF THE CARBIE.

BUNDY351

 

mate if i was you, i would drop a efi donk in her and go from there cause it is the fuel that makes it run rough

 

Bundy,
Good throbbleshooting!