Need Info On An Engine Swap (302)

[Comfortjp]

Guy's, I just bought an 89' Bronco and I love it, but the guy I bought it from put a 90 mustang 5.0 motor in it. Well the rod is knocking and getting worse!!! My question is, can I put an older 302, say a 70 model with low miles and still be efficient?? Also, will the fuel injection or computer cause any problems??? Thankyou for any input, I've never replaced a fuel injected motor with an older carb model, and don't want to get over my head!!!

 

[Broncoholics]

I believe a engine block is an engine block so I don't see any problems doing the conversion. You might be able to replace the bearings, rods, pistons and rings and be ok. Have a machine shop bore out the cyliners, machine the heads and have the valves checked.

 

[Comfortjp]

Thanks, that was pretty much my opinion, but I wanted some more input. I just wanted something I could drop in and drive, while I rebuilt the 90' motor like I want it..

 

[Toby the Dancing Bronco]

Putting an older block might be a problem for 2 reasons, I think, but maybe someone can correct me if I am mistaken. First, I believe the crank on newer 302's is lighter than on older ones, and this may be problem your ECU will not forgive you for. (This is the one I am not sure about.) There may be issues, too, regarding the transmission type, but that is just a thought. The thing I am reasonably sure about, though, at least in the Peoples' Republik of Kalifornia, you can't go older, due to smog laws. If the visual inspection looks the same, ignition, vacuum, exhaust, emmision stickers in their proper place, it might not be an issue, but sometimes the tech's crawl under and check the numbers for things like this. Ford numbers are no secret to figure out, so it might be an expensive lesson. It wouldn't matter if you passed the sniff check if the motor has been altered to an earlier version. Check with your local emmission shop and learn what your options are for your area. I don't know what ever happened to the "don't ask, don't tell" mentality, but ... I hope it works for you, and I would do as suggested eariler, drop in the spare, then rebuild the Fuel Injected motor the way I want it then swap it. Before I got married, I used to have a spare engine and transmission in the garage, "just in case." My friends did, too, then as we had kids, well, spare parts became the "new parts" and the old ones became "core charges". Oh well.

 

[BLADE262US]

Hello Yes you can put the older block in your truck . Yes the flywheel is lighter and no the computer doesnt care about this . You just have to use an older flywheel too so its weighted corectly . The harmonic balancer is also weighted different so as far as this goes if its old it has to stay old and if its new it has to stay new . Use all your 70,s parts and you will be fine . Now heres the tricky part . Yes the old motor will go in there and work but........ Your broncos fuel injection system is more than likely a speed density system what this means is that the computer is programmed with known things happening . It doesnt know how much air is going into the motor like a mustang motor which most were mass air . So the cam timing events such as how long the valves are open and how long there open are programmed into the computer that is how it knows how long to fire the injectors and such things . So if you use your 70,s motor with your trucks existing fuel injection manifold you will more than likely have to change the cam to a cam that is very close to the existing cam in the injected motor such as duration and amount of lift or the computer will more than likely freak out and it will run like shit . You also cant take the cam out of the efi motor and use it in the older block as it is a steel cam meant to be used with roller lifters which most all efi 302,s were also cant use the ditributor out of the efi in the older block . because the length of the oil pump drive is different . Just some things to think about /emoticons/[email protected] 2x" width="20" height="20" />