I will be acquiring a 5.8L from a 1991 Bronco to install in my 77 F150 EFI and all. I would like to know what to expect for longevity of this engine. Mileage is unknown. My main question is does this engine have cast pistons? I thought the first year for hyperutectic (spelling?) pistons was 1992, anyone know for sure? The reason I ask is if I mod this engine ie GT40 heads and a cam, non-roller I assume, can I expect the pistons to live through it?

Thanks
Matt

 

It doesnt matter what the piston is made of, itll be fine with the combo you list. Its only when you start throwin a good bit of boost or nitrous at em that the cast and hyper pistons start havin issues. For a HCI motor you can rest assured that itll be ok. As for the rest, the rods are STOUT from the factory. Im almost down puttin together a 12:1 compression 393 stroker for my 90 mustang that is using stock truck 351 rods with ARP studs and im not loosin any sleep. Tear the motor down, inspect it for odd wear patterns and if you have time and $, rebuild it while its out using the stock parts and itll be ready to rock!!! Good luck with it!
Matt

 

You should be fine with the cast pistons , i think your thinking about the 302 HO , they had forged pistons till 93 then they went to hyper & the 91 351 will have a flat tappet cam....Lew

 

Yeah the mustangs had forged pistons till 93 for sure. Dunno bout truck motors and 351s but either way you will be just fine!
Matt

 

As far as I know the only 5.8 to get anything but cast pistons was the Lightning and even then they was only hypereutectic. Even so there is nothing to worry about in this motor at lower power levels(under 450hp) unless you get into boost or wind it up past 6500 rpm.

 

Thanks for the replies. I will probably use it in stock form for a while. I forgot about the head bolt side differences from 5.0 to 5.8, my plan of getting junkyard Gt-40s from an explorer is foiled without paying to have the bolt holes enlarged.

Anyone have any experience with an Explorer roller cam added in an otherwise stock 5.8?

 

You could do the work yourself on enlarging the holes, or find someone local with a drill press and pay them...sometimes all it takes is a good meal or a case of beer!
Matt

 

dont jump to this conclusion to quick. i got some GT40s off a 96 explorer and my bolts for a 351W fit perfect.

and besides having someone drill out the bold holes shouldnt cost much.

 

Have done this myself on my drill press.. it's not difficult at all since the holes are perpendicular to the head gasket surface..

That's what is in the '94+ 5.8 motors, but you'll need some expensive linkbar lifters to put in it the older non-roller block. Besides the Crane 444232 flat tappet is much better suited to the 5.8 and yes it is SD friendly.