ok this sounds really odd
I have been working on my truck for a while actually a long time. I have what i believe is a 1986 f150 with a 5.0. the problem is it runs like crap with the firing order of a 5.0 and a bit better withe the firing order of a 5.8 . since i have no idea what has been done to this engine how can i tell what i have?

 

did you check your VIN to see which motor it might be?

 

In 86 it is easy to tell the difference, if it has a big aluminum plenum that says fuel injection on it it is a 302 (5.0) , if it has a round air cleaner and a carburator it is a 351 (5.8).

 

the reason i am asking is the firing order is not what the manual says it should be. manual says 1-5-4-2-6-3-7-8 what is there is 1-3-7-2-6-5-4-8 my question is why or how do i tell what i have for a correct firing order. oh never heard the engine run when i pulled it from the donor truck

 

What year truck did the engine come out of? The did eventually switch the trucks to the HO/W firing order.

 

the donor truck was an 86 , not sure what if anything the previous owner might of done.

 

found that the number of bolts on the valve cover inicate the engine size. 6 bolt 289/302
8 bolts 351 and up

 

If you look around there is a diagram that shows the difference between the 302 and 351 via the location of the thermostat.

 

Quote:

Originally Posted by jd4300

found that the number of bolts on the valve cover inicate the engine size. 6 bolt 289/302
8 bolts 351 and up

You're misreading or are otherwise confused... The 351C & M engines (as well
as the 400) use 8 bolts on the valve covers, the W engines use 6 (as do the
302 & 289, all in the small block family).

Ford Windsor engine - Wikipedia, the free encyclopedia
Small Block V8 (221, 260, 289, 5.0/302, 5.8/351W) - Ford Truck Enthusiasts Forums

 

yeah my 302 has a more angled approach to the thermostat and the 351 I believe has a more vertical thermostat housing.. I could be wrong, it's happened before

 

It doesn't matter if you have a 302 or 351w in your truck, if someone has changed the camshaft you still won't know what you have. If you have a 302, and someone got the bright idea to put a 302 HO cam out of a mustang in it, then it will have the 351w firing order, even though it's still a 302. The camshafts interchange between the regular 302, the 302 ho, and the 351w. All you do is put the cam in, and then move the sparkplug wires around.

All you can do to really figure it out is take the sparkplugs out, and put your finger over the sparkplug hole wire turning the engine by hand. Start at number one cylinder, and after you feel air pressure pushing your finger off the hole, go to the next cylinder in the firing order and see if you feel pressure on that one. You should be able to go from one cylinder to another in the correct order.

 

Here's how to tell the difference between a 351w and a 302.

 

Also u can mesure the intake. The 351w I belive is 11 inches wide. The 302 is only 9 1/2 inches wide. Good luck on figureing out what u got.