Explorer 302 or 289?

Av8r37

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Dec 19, 2020
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Hey guys, I have recently acquired a 1964.5 mustang! I am currently in process of rebuilding it and am balancing my options for motors. What I have is my roller without an engine
and a totaled 1966 with a stock 289. My plan is to swap over all the driveline and interior to my solid roller. I am just building a toy car and not planning on ever taking it to the drag strip or even the track. However, I still would like it not to be sluggish! What I don't know is whether I should pull a local 302 out of an explorer or mountaineer at a parts yard. I know they have the gt40p heads and intakes. Should I just chuck in a cam and put an explorer 302 in the car? Would it be better to take the gt40p heads and put them on my 289? I bought the 66 from Copart and have got the 289 to run seemingly well but don't know its full history. Is pulling gt40p heads or the whole engine even a good idea or should I keep it stock? What do you guys think? Also, from browsing forums I have learned most exhaust headers don't fit the gt40p heads because of the spark plug positioning, I heard 90-degree sparkplug boots can alleviate this issue, is that true? Also what HP numbers am I looking at with a performance cammed 289 with gt40p heads vs a cammed Explorer 302? Anyway,I would appreciate any feedback on how I should proceed with my build without emptying my bank account! Thanks!
 
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65ShelbyClone

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"Better" is subjective and all you're really said is that you don't want the car to be sluggish. It's not going to be sluggish with either engine in good running order. Nothing was said about transmission type, gear ratios, etc.

There is going to be a lot of nuances to using the 5.0. You'll need a distributor with a steel gear, a 50oz flywheel and damper, a decent intake that won't choke the heads and cam, and headers to work around the heads. On that topic, an Explorer 5.0 is not guaranteed to have GT40P heads; the early production ('96 to maybe halfway through '97) ones had regular GT40s. The roller 5.0 block won't have a place to mount the z-bar if you use a clutch and will need an adapter bracket. You'll also need springs for whatever cam you get. That's just off the top of my head.
 

02 281 GT

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In regards to the Explorer swap, I would only caution that it’s not 2005 anymore. A lot of Mustang guys still tout the Explorer swap without realizing that any Explorer/Mountaineer you come across in a yard will likely have a tired, 200K+ engine in it. I wouldn’t drop one into my car without at least giving it a thorough look over and compression check, if not disassembling completely to have it checked by a machine shop.
 
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MustangIIMatt

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In regards to the Explorer swap, I would only caution that it’s not 2005 anymore. A lot of Mustang guys still tout the Explorer swap without realizing that any Explorer/Mountaineer you come across in a yard will likely have a tired, 200K+ engine in it. I wouldn’t drop one into my car without at least giving it a thorough look over and compression check, if not disassembling completely to have it checked by a machine shop.
There's also the other downside to using an Explorer donor...

Soccer moms are notorious for not maintaining their vehicles.
 

7991LXnSHO

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There's also the other downside to using an Explorer donor...

Soccer moms are notorious for not maintaining their vehicles.
I had no idea how true this is until we went to replace the bandwagon. No wonder insurance did not believe me as to it’s pre-accident condition without pictures and receipts and a recent inspection report.
If I knew the 289 was good with your goals, I’d transfer it over, making sure it had a 4bbl intake or looked stock. You can be driving it while working up something peppier if it is not fast enough.