351 vs. 302

Spas · August 1, 2006

All right all you gearheads and engine swappers, this is a very serious question that directly concerns the future life of my '98 Sport. I've been bandied about by just about everybody on what type of engine I should be swapping into Blackjack... Lemmie just say that while streetability is a major concern, having the most powerful engine that I can cram in there (without modifying framerails!) is the bigger concern

This is a lowered truck btw, no body lift :nono:

I started out wanting a 347 so that someday I might be able to challenge the mighty Troll. But all I keep hearing is how 347's have such bad oil delivery problems and how the wrist arms cause premature cylinder wear. Theoretically a 331 would put out almost the same power and cause a lot less damage in the long run, but I'm having a hard time stepping down from that advertised 450 hp of the 347

Some coworkers have suggested using a fuel injected 351 and stroking it out instead, since dimensionally it's pretty much the same as a 302 block. But then there's problems with cramming an AOD trans in there...

This'll be a professionally built engine no matter what I decide on, but I'd like to keep the potential issues with wiring and trans choice/fitment to a minimum as I DO have a budget

NEED OPINIONS HERE!!!!

dreamr · August 1, 2006

The 351 is a good option!
As you said the dimensions are the same, but the swap will be a heck of a lot more custom than the 302 install.

There are several issues to address, but 410 should obviously jump in and give some feedback as well.

My first 3 concerns would be the the wiring and computer controls as there are not any 351's available in the late model explorer where a GT-40 302 is a direct replacement as it was an option.

The next concern will be in finding a oil pan the will work with the explorer chassis. In the 5.0 Mustangs this must be changed over to a conversion pan I assume it would be the same for an X though obviously a different pan that there is likely no aftermarket version of.

Then there is the whole front dress of the engine to consider for clearance issues as the Explorer 302 is quite a bit different than the EFI 351's.

my .o2 is to go with the 331 stroker and a supercharger system.

section525 · August 1, 2006

I was originally planning on 347 a while back. But I pretty much decided on a 351 platform instead. My plan is basically getting a 351 short block, using my current heads and headers, maybe even cam. I haven't looked into it a whole lot as I am still a project or two away. But this thread should be interesting.

prerunner02 · August 1, 2006

go with the 331 from dss. i have 1 in my 90 stang for 4 years now and no problems with streetability or smog issues. they also advertise their 331 as being able to produce (with the same equipment) 40 more horses then a 347 can although the 347 has about 20 more ft lbs of torque.

Spoofty · August 1, 2006

351 has a slightly higher deck than a 302. That means the exaust manifolds will be higher (about 3/4") than a 302. That also makes the block wider so a 302 Y pipe will have to be modified. The oil pan on a 351 is also different because on the larger main bearings. I don't know what pan would fit an X.

section525 I'm sure you are aware of this but 351's have larger head bolts and you will need to drill out you 302 heads to fit on the 351.

section525 · August 1, 2006

prerunner02 said:
go with the 331 from dss. i have 1 in my 90 stang for 4 years now and no problems with streetability or smog issues. they also advertise their 331 as being able to produce (with the same equipment) 40 more horses then a 347 can although the 347 has about 20 more ft lbs of torque.

Are you on cafords?

Spoofty said:
The oil pan on a 351 is also different because on the larger main bearings. I don't know what pan would fit an X.

It would if you don't have a crossmember anymore.

Dan Whitaker · August 1, 2006

How about a 331 stroker with a Vortec Super Charger

Spas · August 1, 2006

prerunner02 said:
go with the 331 from dss. i have 1 in my 90 stang for 4 years now and no problems with streetability or smog issues. they also advertise their 331 as being able to produce (with the same equipment) 40 more horses then a 347 can although the 347 has about 20 more ft lbs of torque.

Great minds think alike, LOL. I've been in touch with D.S.S. about building the level 10cnc 347 for me (AIN'T CHEAP, let me tell you!

) , but I'm waiting to hear back from them on the benefits and pitfalls of a 347 vs a 331... I'm glad to hear that you've had no probs with a motor from them!!

Dan, I was actually looking into a Procharger ps1

My goal is between 450-500 rwhp.

I've seen 351's done on this board- it'd be awesome to hear those members' thoughts on their swaps and if they would've done a 302 based conversion instead. I know the 351 is something like 3" wider than the 302... I'm assuming it'd need custom made mounts? Dreamr brings up a major concern with 351 wiring... What wiring harnesses would have to be spliced to get it to work? And could it be made to work with sayyyy, a 98 explorer 5.0 computer..?

BrianB31 · August 1, 2006

tmsoko and I have been working on this for our Rangers. He is going with a 351 in his 4x4, I'm going with a 347 in my 4x2. He's been fabricating a pan and exhaust for his setup becuase no 351 stock pans would work. When Ford did a 351 Explorer as a project we had to jack up the engine to get it to fit in a 4x4 frame.

The 4x2 is a different animal because the engine is closer to the body and the added width of a 351 plus exhaust would put it smack into the HVAC case and the steering column.

Also note the cam sensor for the Explorer 302 would have to be modified for the 351 height and oil pickup size difference. This also applies to the a.c lines.

Spoofty said:
351 has a slightly higher deck than a 302. That means the exaust manifolds will be higher (about 3/4") than a 302. That also makes the block wider so a 302 Y pipe will have to be modified. The oil pan on a 351 is also different because on the larger main bearings. I don't know what pan would fit an X.

section525 I'm sure you are aware of this but 351's have larger head bolts and you will need to drill out you 302 heads to fit on the 351.

Spas · August 1, 2006

BrianB31 said:
The 4x2 is a different animal because the engine is closer to the body and the added width of a 351 plus exhaust would put it smack into the HVAC case and the steering column.

Hrm. Is this true for Exploders as well or just Rangers, do you know?

BrianB31 said:
Also note the cam sensor for the Explorer 302 would have to be modified for the 351 height and oil pickup size difference. This also applies to the a.c lines.

No using a stock 351 sensor out of say, an F150, eh? Modified in what way, like reprogrammed or something? Pardon my ignorance, I'm learning as I go

Porter (my Mustang loving coworker who's agreed to do this swap, if not whole heartedly lol) seems to think that the wiring harness for a 302 will work for a 351.. thanks to the popularity of 351's being swapped into Stangs, if I heard him right the two harnesses are very similar. If that's the case then swapping a 351 into a second gen is more a matter of clearances than wiring, yes? Also, the AOD and 4r70w are very similar, so I don't see that being a problem. Unless the factory v8 computers won't agree with it? Yes the bolts and such are hard to get to, but Ford Techs all over manage to get by all the time

dreamr · August 1, 2006

Spas said:
Porter (my Mustang loving coworker who's agreed to do this swap, if not whole heartedly lol) seems to think that the wiring harness for a 302 will work for a 351.. thanks to the popularity of 351's being swapped into Stangs, if I heard him right the two harnesses are very similar. If that's the case then swapping a 351 into a second gen is more a matter of clearances than wiring, yes? Also, the AOD and 4r70w are very similar, so I don't see that being a problem. Unless the factory v8 computers won't agree with it? Yes the bolts and such are hard to get to, but Ford Techs all over manage to get by all the time

For the Tranny I would look into a custom built AOD-E to stand up to that much power in a heavy truck..... 4r70w would also work out as they are basically the same trans, I am just thinking that the 351 has never been coupled to a 4r70w from the factory so may be difficult to find an aftermarket adaptor for.....of course I could be wrong

Now the wiring.. The 302 was only run in the stangs up till the 95 model so the computer sytems are completely different. To my knowledge there are not any OBDII trucks that run the 351. That is where the issue is really going to start. However there is a guy on the board that could take your stock Explorer Harness and the harness from the 351 and integrate them for a Price. PM 410Fortune for his contact info. Look at Chief's Mustang 302 swap thread for an example of the wiring work that will need to be done.

JDraper · August 1, 2006

Dang shame a 5.4 won't fit in there.....

351W is a good choice for a motor. Not sure what mods you might have to do to make it fit (hood, custom motor mounts, massaged firewall??), but you can put a custom C-4 or C-6 behind it for a decent price. Performance Automatics makes a Competition C-4 that will handle well over 500 hp for about $1255.00

dreamr · August 1, 2006

^^^^Why didn't I think of that when I posted^^^^

Listen to him

Spas · August 1, 2006

dreamr said:
^^^^Why didn't I think of that when I posted^^^^

Listen to him

Yeahhh, but it's hard to take someone who calls himself 'Gronk' seriously

Spoofty · August 2, 2006

dreamr said:
For the Tranny I would look into a custom built AOD-E to stand up to that much power in a heavy truck..... 4r70w would also work out as they are basically the same trans, I am just thinking that the 351 has never been coupled to a 4r70w from the factory so may be difficult to find an aftermarket adaptor for.....of course I could be wrong

351's and 302's have the same bellhousing pattern so a 351 will bolt to any 302 tranny (and 300 straight 6). But the 351 needs a different flywheel to late model 302(different crank balance same as pre 1981 302's).

BrianB31 · August 2, 2006

Just for Rangers. The Explorer 4x2 and 4x4 and the Ranger 4x2 trailhead and 4x4 frames are the same for engine mounting. The Ranger 4x2 coil over suspesnion is different.

As for the sensor the Explorer 302 is the only V8 that used a cam sensor. The F150 and Mustang 302 and 351s had distributors. Now on this same subject there are several of these sensors used in 3.8, 4.0 OHV, 4.0 OHC and 4.2 engines but they all use the small oil pump hex.

Spas said:
Hrm. Is this true for Exploders as well or just Rangers, do you know?

No using a stock 351 sensor out of say, an F150, eh? Modified in what way, like reprogrammed or something? Pardon my ignorance, I'm learning as I go

Porter (my Mustang loving coworker who's agreed to do this swap, if not whole heartedly lol) seems to think that the wiring harness for a 302 will work for a 351.. thanks to the popularity of 351's being swapped into Stangs, if I heard him right the two harnesses are very similar. If that's the case then swapping a 351 into a second gen is more a matter of clearances than wiring, yes? Also, the AOD and 4r70w are very similar, so I don't see that being a problem. Unless the factory v8 computers won't agree with it? Yes the bolts and such are hard to get to, but Ford Techs all over manage to get by all the time

'97 V8 · August 2, 2006

Ohh im subsrcribing to this strictly for information purposes.

Spoofty · August 2, 2006

I have a 351 out of a truck and it has a distriduter with only a rotor in it. The ignition is crank triggered from the harmonic balancer. So it would probably be eazier to go with the wiring harness for the 351.

Dan Whitaker · August 2, 2006

Why not just carb the thing and not mess with all the damn computer BS!

Alot easier & cheaper.

Spoofty · August 2, 2006

Dan Whitaker said:
Why not just carb the thing and not mess with all the damn computer BS!

Alot easier & cheaper.

Amen to that

351 vs. 302

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