I did a motor swap, put all the old things that matter back on the truck. Only changed the long block. I have no replaced the injectors, computer, all the smog stuff, alt. battery cables. and nothing is changing a thing.

any clue as to why only cylinders 5 and 7 are the ones missing. I have new wires and plugs that I just put on. nothing seems to work.

 

What vehicle and wat motor are we talking about?

JMC

 

I did some more work on it today trying to get my 1990 F150 5.0 EFI to run on all 8 cylinders. It isn't running on 5 or 7 at idle and when you get it to go and it gets above 2000 rpm's it has a hesitation like it wants to run but then it don't. After all that I have replaced I am thinking that I may have a couple of bad lifters. Cause the motor I put in it came out of a 86 5.0 mustang. Same block but this one is a roller cam motor, with GT-40 heads. Thought I was going in the right direction for power, man was I mistaken. And if it isn't the lifters, I am thinking it may be valves. But I am going to go with the lifters first.

Any ideas?

 

Do you have the firing order correct?

 

15426378 I do have it in the right order I have checked it over and over again.

 

try the 351 w firing order
may have a cam that changed order
13726548
mitch

 

Yeah sounds like the firing order is different. You might have to find the computer out of the mustang at worst case.

 

With the dist cap off, which way does the distributor turn? Firing order is based on clockwise or counterclockwise rotation. 302 order is 15426378 clockwise; 351 order is 13726548 counterclockwise. Hope this helps.

Had the same problem on a 73 302, dual pont dist, etc, etc. I didn't think about cw and ccw. Good luck.

 

The 302 HO uses a different firing order than the standard 302. 1-3-7-2-6-5-4-8 for the HO vs. 1-5-4-2-6-3-7-8 for the regular 302 truck motor. You will need to rewire the distributer and the injectors to reflect this change.

 

Thanks to those who gave me the info on getting my truck to run. Now I am not stuck at home bumming rides back and forth to work. I am free because of those who gave me the info. My truck does have the fireing order 13726548. And boy does it run. Better than ever thanks to the donor 86 mustang gt that had a roller cam and GT-40 heads.