Hi...
I need some tech info on the 90 model 5.0 truck engine with speed density.

I am faced with a tired 5.0 engine that needs at least several seals/gaskets, oil pan, exhaust manifolds, and some other repairs.
I was thinking I might just scare up a 5.8 (351w) long block and use a compatible oil pan, distributor, and intake lower... then just bolt on all the other stuff straight from the 5.0.
My concerns are:
Will the 5.0 injectors support the 5.8?
Will the 5.0 speed density system support the extra cubes?
Will the 5.0 upper bolt to the 5.8 lower?
Will the 5.0 accessories be a straight swap?
Will the 5.0 sensors be a straight swap?

If everything works together and the SD system won't mind the extra cubes, this should be a breeze of a swap.

Thanks much!
Dave

 

Okay...
Someone has to know if the Speed Density system for a 5.0 will support 49 more cubic inches or if it will 'freak out'...

 

you will have to use the 5.8L upper intake, they are different. The MAP sensors (speed density) are the same for both, no problem there. Also, all your current bracketry and accessories will bolt onto the 5.8. you may need to get a different belt, though. The exhaust may also have to be slightly reworked at the pipe under the oil pan. The 351 is wider at the manifolds than the 302. The firing order is different also. The engine wiring harness and computer would be needed from a donor. Even though the engine itself will bolt in directly to the trans and motor mounts, there is a little bit more involved when it comes to the EFI portion. It can still be done with all the right stuff. Hope this helps, Robbie

 

Thanks!
Good info.

Glad I know about the upper... I was about to buy a lower. Now I know to find them together.

If I use a 302 cam, could I then use my computer?
The cam swap would be simple and I would keep my FO.

Thanks again!
Dave

 

That's a good question. The 5.8 firing order is 1-3-7-2-6-5-4-8 The 5.0 is 1-5-4-2-6-3-7-8. I know the Mustangs switched to the 5.8 order with the H.O. motors. I'm not sure when the trucks did. Double check the firing order on the lower intake manifold it is stamped in the casting. If it is 1-3-7,etc, you can keep everything. If it is 1-5-4 etc, that would need the change. As for the cam swap, it sounds like it would work. Not sure if the wiring harness for the injectors would be wide enough due to the 5.8 intake being 1-2 inches wider than the 5.0. Also I have seen trucks having roller cams like the 5.0s in the later models. I don't think the 5.8 ever went roller.

Robbie