71 Bronco 302 into an 84 Ranger

I have a 71 Bronco 302, I plan on swapping it into an 84 Ranger....ive got some general questions about these old 302's, and what works.....i would search them but the Search feature keeps messing up on my phone.

Will the GT40 Explorer heads work on this motor?
Are these the best "junkyard" head for it?
Are there head studs i can use for this? What is the ARP#?
What kind of redline can i expect with this block/internals (theoretically) without breaking it?


Goals: somewhere in the neighborhood of 350-376hp (motor) and around 350 ft lbs+....the focus is more on torque. I just want a fun street truck, and there are a lot of hills around where i live. So theres no room to wind it up really, just short, quick stretches and meandering turns.

I think they were still using the small chamber heads then, you might check more in the classic Mustang arena to see how they do it. I am leaning towards ending up with really low compression.

85_Ranger4x4 said:

I think they were still using the small chamber heads then, you might check more in the classic Mustang arena to see how they do it. I am leaning towards ending up with really low compression.

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Been reading the stock heads are something like 58cc chambers, but im not sure what the GT40 or GT40P heads are...

LoneRanger3O2 said:

Been reading the stock heads are something like 58cc chambers, but im not sure what the GT40 or GT40P heads are...

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EDIT: looked it up, GT40 heads have larger chambers like 63-66cc.....gt40-P heads however, have 58-61cc chambers which are closer to stock.

The question is....what compression #'s am i starting with? Because ive read it is around 9.5:1 and ive been told its 10:1 also.....so which is it? Haha.

Theoretically even if the motor had 9:1 compression after the addition of the GT40P heads, wouldnt i still be ok?

Well if you want torque I'd stroke it, so that will change your compression numbers anyway.

adsm08 said:

Well if you want torque I'd stroke it, so that will change your compression numbers anyway.

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Yeah i dont have that kind of budget unless you have a junkyard suggestion on internals?

Ive looked into it and my money is gonna hafta be spent more on the top end for now, ill get more bang for my buck from what ive seen?

Any particular ideas? Im open. Just dont have a generous wallet at the moment. Lol

why are you using it? because you have a complete fan to transfer case setup?

is this a 2wd or 4x4 application?


does the 84 have a c5 and your just gonna bell swap???



what is the condition of the engine? is it stock?


that is a weak engine on a good day brand new... but with some plates and spacers its pretty easy to get in there


not sure what your budget is but the 302 does have reasonable performance capacity in the 1500 dollar range if its not needing machine work....

how well does it run now? you need a proper compression check and leak down and then make decisions from there.


summit and jegs have pretty good deals on packages..

bobbywalter said:

why are you using it? because you have a complete fan to transfer case setup?

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Im going to use the motor (currently bone stock, i would like to build a motor off the short block) because it is what i have and i feel like i could build what i need out of it. The motor has 93,000 miles on it.

bobbywalter said:

is this a 2wd or 4x4 application?

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2wd....likely staying 2wd as well. Not really many places to go with a 4wd where i live, unless a guy knows someone with land to play around on. And i dont. Haha.

bobbywalter said:

does the 84 have a c5 and your just gonna bell swap???

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Not sure what type of trans currently but it is a manual. I plan on using a different trans entirely. Possibly a Borg Warner T5. Many people have suggested a C4, but i dont want an auto.

bobbywalter said:

what is the condition of the engine? is it stock?

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Yes! The engine is in great shape, it is stock with 93,000 miles on it when pulled. Pulled by a restoration company for a customer that wanted a modern engine in their Bronco. The Bronco came from California.

bobbywalter said:

that is a weak engine on a good day brand new... but with some plates and spacers its pretty easy to get in there

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Not sure what you mean here?

bobbywalter said:

not sure what your budget is but the 302 does have reasonable performance capacity in the 1500 dollar range if its not needing machine work....

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I dont think the short block will need anything (was thinking of putting all new bearings in though) however i plan on having work done and doing some work myself on the heads and intake. I work 2 jobs so i havent had much time to mess with it. Wedding in 2 weeks. Haha.

What is your suggestion on modifications? $1500 sounds like mostly top end to me. I havent looked too much into a stroker kit, it doesnt have to br forged because i dont plan on revving it too high or racing, but i would want quality stuff.

bobbywalter said:

how well does it run now? you need a proper compression check and leak down and then make decisions from there.

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As far as i know it ran well when pulled. Havent had time to do any tests, but the engine is pulled and stripped down to just long block with intake and w/p, timing stuff on it etc.

bobbywalter said:

summit and jegs have pretty good deals on packages..

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What do they include??? What do you mean?

Keep in mind in that era 100k miles and generally everything was shot on a vehicle. As mentioned, check compression, leak down and pull the heads and see for sure what you have.

IMO especially on a budget a 351W is a better investment than a stroker kit.

85_Ranger4x4 said:

Keep in mind in that era 100k miles and generally everything was shot on a vehicle. As mentioned, check compression, leak down and pull the heads and see for sure what you have.

IMO especially on a budget a 351W is a better investment than a stroker kit.

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You might be right on that. Ill need to check the inside of the motor. Worst comes to worst i could trade it for other parts or sell it in favor of a 351W if those are better.

LoneRanger3O2 said:

You might be right on that. Ill need to check the inside of the motor. Worst comes to worst i could trade it for other parts or sell it in favor of a 351W if those are better.

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302 can be plenty torquy too, just if you are going to go stroker in your place I would be looking into just going with a W and skipping all the stroker expense.

i guess low power is relative...if someone looks up the specs for 1971 they might get 1 or two ratings....71 going into 72 was a crossover forpower ratings...in 71 they were rated around 200-210gross hp and 300 or so ft pounds... pretty much what any 9.5 to 1 302 will make. or close to that with most styles of heads. but that is not necessarily true as that was gross hp.


with current ratings, it would rate at 140 hp and 240#'s of axle twist.... so its weak compared to a modern 302 from say a explorer which run 200-215 hp and 300#ish feet of torque....


93 k on a carb engine is like 180 k on a efi engine all things being equal in maintenance.


yes, i was referring to a quality hci combo on your bottom end.

even with the somewhat restrictive oem exhaust manifolds...or a set of drakes, it would be pretty good.


if its in good shape, your staying 2wd, and its a hot rod...... i would just install it with a t5 or m5od r2 and a good fresh holley and dui ignition and drive it.


the manual trans will make it fun.

if you want more power, build a replacement engine over time. taking your time it can be built to the power levels you want and not kill the budget at the house...

hopefully by the time this engines whooped the rest of the way, the fresh unit will be ready to shred tires.

85_Ranger4x4 said:

302 can be plenty torquy too, just if you are going to go stroker in your place I would be looking into just going with a W and skipping all the stroker expense.

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Gotcha. I think the trouble will be finding one that hasnt been beat to hell. Lol

bobbywalter said:

i guess low power is relative...if someone looks up the specs for 1971 they might get 1 or two ratings....71 going into 72 was a crossover forpower ratings...in 71 they were rated around 200-210gross hp and 300 or so ft pounds... pretty much what any 9.5 to 1 302 will make. or close to that with most styles of heads. but that is not necessarily true as that was gross hp.
with current ratings, it would rate at 140 hp and 240#'s of axle twist.... so its weak compared to a modern 302 from say a explorer which run 200-215 hp and 300#ish feet of torque....

93 k on a carb engine is like 180 k on a efi engine all things being equal in maintenance.

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I see what youre saying here...so what did the Cologne 2.8 make power wise that is in the truck now? Just for comparison?

bobbywalter said:

yes, i was referring to a quality hci combo on your bottom end.
even with the somewhat restrictive oem exhaust manifolds...or a set of drakes, it would be pretty good.

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I see....well, i will have to be on the lookout for deals then.

bobbywalter said:

if its in good shape, your staying 2wd, and its a hot rod...... i would just install it with a t5 or m5od r2 and a good fresh holley and dui ignition and drive it.

the manual trans will make it fun.

if you want more power, build a replacement engine over time. taking your time it can be built to the power levels you want and not kill the budget at the house...

hopefully by the time this engines whooped the rest of the way, the fresh unit will be ready to shred tires.

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Youre not wrong there, the v6 that is in it still runs ok but im sure it is tired with as many miles as it has on it.

M5OD R2 is from the 90s F150s correct?
I dont really like the M5ODs but if thats what i find i might use it anyway.
Usually T5 World Class have been shredded on.

In either case i may just have to put shifter refresh kits on them and just slap it in the way it is.

What are you referring to when you say dui ignition? Like MSD?

Building a motor over time is what i was planning on doingvanyway, but i may consider doing the swap with the 302 and finding a 351W or like a better 302, a roller motor, etc.