complete explorer engine replacement or simple explorer efi conversion

[Bronco DLight]

Ok. So suppose you had a stock '74 302 (with new bcd headers and exhaust w O2 bungs installed) and had decided to go explorer EFI. You bought a donor vehicle (?'97-'01) in running condition. (I don't currently have the donor). The Current engine was fairly strong but unmodified and had an unknown amount of miles on it.

-What are the pros and cons of simply pulling the EFI and associated parts for a conversion vs completely pulling and replacing the entire engine with the explorer one?

-Would the decision change if the explorer engine had 80,000 vs 150,000 miles on it but both seemed to run fine?

-what would be the expected differences in power?

My uneducated thought is that were I to go for the complete swap, the it may be worth the $ and effort to look for a lower mileage one, but for just the electronics, the miles may not be quite so important.

Thoughts?

thx

 

[bronconut73]

Roller cam engines do not have to make more peak power to feel more powerful since they have a broader torque curve.
The roller cam allows the valve to be open longer and close quicker and gentler.
I wouldn't be worried about a 150 k Explorer motor if it looks like it was maintained well.
You could learn alot from a compression test.
Maybe pull the pan and check a couple bearings.

 

[73azbronco]

Get yourself a mechanics video probe tool like they sell at harbor freight for around $80, stick the camera into the cylinder via the spark plug hole, and look at the cylinder walls. Still see the factory cross hatching from the honing? No other vertical scratches? I'd say keep it all one peace, maybe replace the front and rear seals, valve cover gaskets, oil pan gasket only if it looks bad, and run it.

I bought an explorer motor with about 90000 miles, and when I pulled it apart it looked new, thanks to owner using synthetic and or following oil change guidance.

Just be careful, I found a good well maintained one. I know explorers have mostly fallen into the hands of folks who seem to care little for their vehicles other than it was the cheapest thing they could buy at the time, and they treat it as such. I comment on them on the road so much even the wife now says "look, future bronco parts".....

 

[strokers]

i would put the motor in that was designed and built 20 years newer. if the original engines would have lasted hundreds of thousands of miles the current ones do we wouldnt be swapping them

 

[Bronco DLight]

power

what would be the difference in power bt what I could get from a stock 97-... explorer vs fuel injecting a stock 302? I'm at high altitude and need more power. should I spend the $$$ converting original to efi and adding performance parts or going all explorer engine ...?

 

[bronconut73]

In a perfect world you would get a '96 351 Windsor roller motor and put the Explorer injection system and serpentine system on it.

If not the 351 W, then yes the Explorer engine is an improvement over your low compression smog era sbf.