Will it work

[aaron88]

So I have been stock piling most of the parts I need to build a na ohv 4.0 for my prerunner for some time now. but some things happen in life and I won't be able to do the build for at least another year. I don't want to wait that long to drive the truck. I have a 1993 ranger with the stock 4.0 blew a head gasket before I started building the cage yanked the engine out and checked the lower end and it's completely fine had a cracked head when I inspected it. I have a set of 96tm heads that are bone stock 0 miles on rebuild I know that will bump compression almost a full point with the 4.0 I have. now my question do you think the factory computer will handle that other then the head change it will have headers and be stock. I'm fine with running 91 octane just don't want to mess anything up so I can get some fun out of it will I save for the fuel system to run the built engine.

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[adsm08]

You have to be careful running post 95 heads on a pre-95 short block. The pistons and heads were redished for 95, and putting late heads on an early block changes the compression ratio. It can cause overheating and head cracking.

 

[RonD]

+1 ^^^

The computer will be fine to use, compression doesn't change air flow, but it is a MAF system in any case so could handle air flow changes up to a point.

4.0l OHV head castings have weak spots between valve seats, if overheated the metal expands too much and the heads can crack at that spot.
No do-overs for these heads, one overheating and they will crack, so make sure cooling system is MORE than adequate.