1989 5.0L or 5.8L how to tell apart?

[racechaser]

I have an 89 f250 4x4 project truck I'm fixing up. The owner told me it had a 302 in it when I bought it. While having the intake off I noticed my rocker arms weren't all lifting the same( I know the intakes and exhuast have different lifts). While looking around I just noticed a small sticker for belt routing that says 5.8L.

So I see that most all parts on upper engine are the same so I haven't run into any differences in locating used parts for the upper engine. I now want to replace the damaged cam to see if my cylinder pressures get more equal so I can decide whether it needs a rebuild or not.

So How can I tell if I have a 5.0L or 5.8L without pulling a head to check the stroke length. The bore is the same if I'm correct, so that is the only way to tell that I know of.

I was hoping the # of bolts on oil pan were different or maybe a casting # somewhere.

I really need help because the cams are diffeent between the two.


Scott

[mechhound]

Originally Posted by racechaser

I have an 89 f250 4x4 project truck I'm fixing up. The owner told me it had a 302 in it when I bought it. While having the intake off I noticed my rocker arms weren't all lifting the same( I know the intakes and exhuast have different lifts). While looking around I just noticed a small sticker for belt routing that says 5.8L.

So I see that most all parts on upper engine are the same so I haven't run into any differences in locating used parts for the upper engine. I now want to replace the damaged cam to see if my cylinder pressures get more equal so I can decide whether it needs a rebuild or not.

So How can I tell if I have a 5.0L or 5.8L without pulling a head to check the stroke length. The bore is the same if I'm correct, so that is the only way to tell that I know of.

I was hoping the # of bolts on oil pan were different or maybe a casting # somewhere.

I really need help because the cams are diffeent between the two.


Scott

The firing order is different. 5.0 firing order is 1-5-4-2-6-3-7-8, 5.8 firing order is 1-3-7-2-6-5-4-8. Follow the spark plug wire from the passenger side front spark plug to the distibutor cap, that is number one. Distributor shaft rotates counterclockwise. Cylinders are numbered from front passenger side 1-2-3-4, driver side from front 5-6-7-8. I believe the 5.8 is also 2 invhes wider at the head spacing, but that in itself won't tell you anything.

[racechaser]

There were no wires on it. Let's go with the distributor rotation are you saying one is counterclockwise and one is clockwise?

I guess watching the valve order lift would be next choice. If the third or fifth cylinder intake valve opens after # 1 cylinder intake that would determine firing order and answer question.

Am I on the right train of thought?

Scott

[mechhound]

Originally Posted by racechaser

There were no wires on it. Let's go with the distributor rotation are you saying one is counterclockwise and one is clockwise?

I guess watching the valve order lift would be next choice. If the third or fifth cylinder intake valve opens after # 1 cylinder intake that would determine firing order and answer question.

Am I on the right train of thought?

Scott

The 5.0 and the 5.8 distributors both rotate counterclockwise. You are right on about watching the intake valve order opening. I'm sure you already know this, but i'll mention it anyway. All engines turn clockwise from the front, in other words if you were using a ratchet to turn the engine over using the nut on the front of the engine, you would set the ratchet to tighten. Post back with which engine it is.

[mechhound]

Originally Posted by racechaser

I have an 89 f250 4x4 project truck I'm fixing up. The owner told me it had a 302 in it when I bought it. While having the intake off I noticed my rocker arms weren't all lifting the same( I know the intakes and exhuast have different lifts). While looking around I just noticed a small sticker for belt routing that says 5.8L.

So I see that most all parts on upper engine are the same so I haven't run into any differences in locating used parts for the upper engine. I now want to replace the damaged cam to see if my cylinder pressures get more equal so I can decide whether it needs a rebuild or not.

So How can I tell if I have a 5.0L or 5.8L without pulling a head to check the stroke length. The bore is the same if I'm correct, so that is the only way to tell that I know of.

I was hoping the # of bolts on oil pan were different or maybe a casting # somewhere.

I really need help because the cams are diffeent between the two.


Scott

I have to comment on your rocker arms not all lifting the same. As I'm sure you noticed there is no adjustment on these. You bleed down the lifters and then check the clearance between the rocker arm and the valve stem. If the clearance is not within the tolerance, you get either shorter or longer push rods. This may be why you have different cylinder pressures. Is this what makes you think you have a damaged camshaft? How much history do you know on the truck? Did the previous owner do any recent( in terms of when the engine last run) engine work?

[racechaser]

Originally Posted by mechhound

I have to comment on your rocker arms not all lifting the same. As I'm sure you noticed there is no adjustment on these. You bleed down the lifters and then check the clearance between the rocker arm and the valve stem. If the clearance is not within the tolerance, you get either shorter or longer push rods. This may be why you have different cylinder pressures. Is this what makes you think you have a damaged camshaft? How much history do you know on the truck? Did the previous owner do any recent( in terms of when the engine last run) engine work?

That is exactly why I think I have a worn cam. I never thought about checking clearnces like that, nor had I ever heard of longer pushrods. The engine had an engine fire and I stripped the from the intake up off. I have all parts now to fix, but I decided to change all the lifters when I had the intake off. It was after that I noticed the valves not opening and closing all the way. Some had much higher lift than the others. I swapped rocker arms, lifers, and pushrods from intake to exhaust valve on same cylinder. The same valve had the low lift as before.

The guy told me after I bought it(no reason to lie) that the previous owner had rebuilt the engine like 5-10K miles ago. The intake valley is clean and lifters I removed looked brand new. The intake ports look brand new no build up. But the outside of the motor is covered in oil. In fact the more I tore down to get to timing cover the worse it got. I have my doubts about a complete rebuild previously but maybe a valve job. It is a 4x4 and the pan is not readily accesible to rering it while still in vehicle so I doubt he did the lower end at all.

My cylinder pressured were from 60 PSI to 150 PSI and all over in between. The 60 and 150 both had cylinders with low lift. But I am leaning towards pulling it and just going through it and rebuild it. I was very turned off by all the oil leaks the further I got into it.

I will let you know what engine I have later.

Thanks
Scott

[racechaser]

Well as a follow up I wanted to let you know that I think I have a 5.0L based on the oil pan bolt configuration. The pics of the gaskets on autozone website made it pretty clear that I had a 5.0L.

I pulled the timing cover off and had plenty of slack in the chain. After pulling the camshaft I had three lobes that were completely gone, looked like perfect circular shapes. Anyone knows what caused that? The others looked worn but not gone like the others.

Scott

[unclebubbles]

Hey racechaser
If you have a 351, it should be stamped in the block in the lifter gallery, on the flat area toward the front of the block. The narrow flat area at the front where the intake manifold seals between the left and right deck surfaces(or between the heads if theyre on it) is 7 1/4 " on the 351, as mechhound said , the 351 is wider. Make sure before you buy the cam, the standard 302 and the 351/302 HO, have different crank configurations and firing orders, the cam has to match .