Questions and Answers

Ford Mustang And F-250 Pistons Q. Hello Vincent; I had a 1988 Ford Mustang LX with a 5.0 HO and a 5 speed manual transmission. I blew up the original motor racing, and built a new one for it. The only problem I had was that I used pistons from a 1986 ford F-250 with a 5.0 EFI.

Visually I noticed that the pistons from the truck have thicker skirts, but I had to use them as the stock 5.0 (not HO) has flat top pistons that my valves hit, and the trucks were notched for valve clearance. I am wondering what the red line (in RPM) is on a 1986 Ford F-250 with a 5.0 EFI is? It must be lower than my Mustang due to the extra mass in the pistons.

I do not want to over rev the new motor. Another question I have for you is this. My buddy borrowed my car ( when it was still running) and did a burnout in Reverse. Now reverse only works for about two feet, then it jumps out of gear, and it is a little difficult to put it in first. Could you please tell me what he has done??

Thank you, very much appreciated.
Ryan B

A. I did a little comparison in the parts books since I don't have a 1988 Mustang and 1986 F-250 5.0 engine torn down in front of me. What I found is this:

The part number for a 1988 Ford Mustang 5.0 HO piston is:
Piston and Pin (Standard) F2ZZ6108AB $41.22.

The part number for a 1986 Ford F-250 5.0 engine is:
Piston and Pin (Standard) F2ZZ6108AB $41.22

So as far as I can see, they are the same piston according to the Ford parts books.

As for what your buddy did to your transmission, only taking it apart will reveal exactly what he did, but he probably took out some bearings and the Reverse Idler Gear. It's not easy blowing up that Borg-Warner 5-speed. You're looking at about 10 hours labor to R&R and rebuild, plus parts. I hope he's going to do the right thing and have it repaired for you. If not, I'd find another friend.