I have my engine back together, but it is only firing on 4 cylinders and I do get flame out of the exhaust. (looks neat, but totally useless) From the heat on the headers, it is 5 7 3 and 4 that are firing. 1,2,6 & 8 are cold. I have rechecked the plug wires and I am getting spark on each plug and the order appears correct. My first guess was reversed wires,but the order matchs the diagram and firing order. Any ideas ?
Only firing on 4 cylinders
- Thread starter acm57
- Start date
Did you install a new ignition/distributor? If it fires consistantly on 4 but misses the other4 you may only have a 4 cylinder "cam" on the distributor.
Sounds like the distributor is 180 degrees out of phase.
Pull # 1 spark plug and put your thumb over the hole, have someone bump the engine over until your thumb pops off the hole then check the dustributor rotor position - it should be very close to the nbr 1 plug wire lug.
Pull # 1 spark plug and put your thumb over the hole, have someone bump the engine over until your thumb pops off the hole then check the dustributor rotor position - it should be very close to the nbr 1 plug wire lug.
If you had the engine all apart, installed the cam and sprockets with the alignment marks and the engine at TDC, then installed the distributor with the rotor pointing to nbr 1 spark plug lug in the distributor cap, then your ignition timing is out of phase. Rotate the crankshaft one more full revolution (which is 180 degrees of the camshaft) and then align your rotor to the nbr 1 in the cap.
This is actually a lot more common than you might think and it has bitten me more than once in years past...
This is actually a lot more common than you might think and it has bitten me more than once in years past...
Dimi Terleckyj
Lifetime Supporter
Years ago I had the same problem when I upgraded my cam in a 351 to a higher performance cam but wasn't told that the firing order reverts back to the firing order in a 302.
I ended up pulling off the rocker covers and turning the motor over by hand with the plugs out and watching the valves open and close in conjunction with the piston position in each cylinder to confirm the firing order.
Dimi
I ended up pulling off the rocker covers and turning the motor over by hand with the plugs out and watching the valves open and close in conjunction with the piston position in each cylinder to confirm the firing order.
Dimi
Hi Tony
As Wally said If you mix up the two firing orders the engine will run on 4 cylinders.
302 firing order is 15426378.
and 351 13726548.
the common cylinders are 1,2,6,8 The engine will run on these cylinders with either firing order. However you said these were the cold ones:huh:
May be recheck your valve lash.
As Wally said If you mix up the two firing orders the engine will run on 4 cylinders.
302 firing order is 15426378.
and 351 13726548.
the common cylinders are 1,2,6,8 The engine will run on these cylinders with either firing order. However you said these were the cold ones:huh:
May be recheck your valve lash.
It certainly seems like you've switched from a 302 firing-order cam to a 351 (or vice-versa). Try switching the plug wires to the other order.
Ford Windsor (289, 302, 5.0, 5.0HO, 351) Firing Order & Cylinder numbers
Ford Windsor (289, 302, 5.0, 5.0HO, 351) Firing Order & Cylinder numbers
Do you have a dual plane manifold or open plenum ??? If dual plane one side of your carb may be plugged up, VERY VERY carefully just dust one side then the other with starting ether and see if you get the other cylinders to pickup, If so fix the carb. I would also try this around the intake and see if you had a gasket fall out of place and have an air leak. Wally
Not to add further fuel to the fire, but IIRC doesn't the 302 have a different firing order than the 5.0 HO Ford engine? I remember something akin to that being different....but at my age, the memory is foggy and I've slept since then...:shocked:
I could be totally wrong...hope someone will correct me if that is the case.
[EDIT--just read the info in Bob Putnam's link....looks like the 5.0 engine has 2 different firing orders, with the HO version being different from the general service 5.0 and the truck model....who would have thought?]
Cheers!
Doug
Last edited:
I changed the firing order to the 351 (13726548) and no cylinders fired so I went back to the 302's (15426378) and I am back to firing on 3 4 on the right bank and 5 and 7 on the left bank. The compression is 1 (165), 2 (160), 3 (155), 4 (125), 6 (165), 6 (145), 7 (170), 8 (150). I do get spark on all cylinders. It is an Edlebrock preformer rpm intake. I am trying to find the flow pattern to see if there is a common link to the dead cylinders. It has an EZ FAST fuel injection The front 2 injectors do spray the prestart spray. The motor is from The Engine Factory (www.fordcobraengines.com) I do appreciate all the help.
You say this is not firing on cylinder 1, That would indicate that the distributor is not installed correctly ??? Recheck it's location As I agree with Randy that if you don't have # 1 firing where it should there is something wrong with the setup of the Distributor and if all else fails. You can thank Dimi for this solution. Wally
Success, firing on 8 cylinders:thumbsup::thumbsup:. I called The Engine Factory and got the correct firing order which is the 351 pattern. Since 3,4,5, & 7 were running instead of 1,2,6, & 8 the distributor was 180 off. Now it is a matter of tightening the headers after a heat cycle, retuning the fuel injection, checking fluids and final timing and valve adjustment refinement, it should be back on the road. Thank you for all of your help as this a great way of bouncing ideas literally from around the world.
Similar threads
