351 Swap...

I am trying to decide if i should swap out my 302 for a 351. What are the major complications that coulod occur if i did the swap. (cooling, not enough space, etc..) Anyone make this swap and regret it? Thanks for your help.

justinpangelle said:

I am trying to decide if i should swap out my 302 for a 351. What are the major complications that coulod occur if i did the swap. (cooling, not enough space, etc..) Anyone make this swap and regret it? Thanks for your help.

Click to expand...

I forgot to say i have a 74 Bronco. Thanks.

Cooling is going to be your biggest concern. The other thing, are you going to be putting in a 351W, 351C or 351M? The 351W will slide right in because it is basically the same block as the 302/289 block. I think the C & M blocks are bigger, based off of the big block line.

I did my 351W conversion in 1977. Changed the oil pan and bolted it in.. Never experienced any cooling problems.

I don't think you will regret the extra cubic inches

More cubic inches are great, but is the cost and gas worth it? Enless you have a free motor and heads and proper cam and carb or efi system, maybe a cam for your driving style (rocks,mud,sand)and bigger exhaust and or carb system , might be cheaper and faster!

i really wanna do this....

how do u guys think a 351w (used out of bronco, or truck etc.) with:

-mild to medium cam

-rollor rocker arms

-4 bbl eddie manifold performer

-650 cfm truck avenger by holley

...thats what i have for it.

but would there be anything else you guys sugest for good quick power? or reliability? thanks

Eric

Y'know,

i pretty much have that set up.

its strong as **** - guzzles gas like an inferno (10mpg at BEST!)

the only downer is all that fat torque and power is being scrubbed off somewhere

i think i am going to have to upgrade my trans / converters / clutch to get the benefit of the 351, perf intake and 670 holley - out to the wheels quickly.

you might want to factor in a contingency cost for getting the extra bang to the wheels fast - rather than ever so painfully g r a d u a l y !

oh yeh - and brakes

once you get her movin, she dont like to stop.

at least 2 disks, with booster.

you might want to ramp up the suspension and tidy up yr front end joints and links.

theres gonna be heavier iron out front.

Monza.

justinpangelle said:

I am trying to decide if i should swap out my 302 for a 351. What are the major complications that coulod occur if i did the swap. (cooling, not enough space, etc..) Anyone make this swap and regret it? Thanks for your help.

Click to expand...

If you're talking about carbureted, "old style" motors, DO NOT DO IT!! There is no reason to do this. I have an older Windsor in mine. From overheating, to custom made brackets to HORRIBLE mileage, I would not do it again. If it's power you want, there are 302's with more power than you can use. A windsor just brings up too many potential problems. If you ever thing of adding a/c, you basically can forget it with a windsor. I had to have all the brackets and pullies fabricated. NIGHTMARE. There's also a hood clearance issue. Again, why do it? Go get a 400 hp 302 and bolt it in.

My 70 with the 302 SMOKES my buddies 95 f-250 with the 351. Now I know he has a heavier truck, but his is injected and all I have are headers and a big carb. Plus I get better gas mileage. The 351 is all torque, the 302 is horsepower.

LOL you know what seperates these 2 motors ? 1/2 inch of stroke /emoticons/[email protected] 2x" width="20" height="20" />

y'know

this is a great topic.

My EB arrived with a 351 swap - i often wonder about swapping back to a 302 - esp with a manual trans, but then wonder what i might be losing....

If i had a 302 i would be neeeeeding to know how much extra muscle a 351 would give me...

the grass is always greener - right?

great thread

someone should promote it to an open discussion.

Monza.

monza said:

Y'know,i pretty much have that set up.

its strong as **** - guzzles gas like an inferno (10mpg at BEST!)

the only downer is all that fat torque and power is being scrubbed off somewhere

i think i am going to have to upgrade my trans / converters / clutch to get the benefit of the 351, perf intake and 670 holley - out to the wheels quickly.

you might want to factor in a contingency cost for getting the extra bang to the wheels fast - rather than ever so painfully g r a d u a l y !

oh yeh - and brakes

once you get her movin, she dont like to stop.

at least 2 disks, with booster.

you might want to ramp up the suspension and tidy up yr front end joints and links.

theres gonna be heavier iron out front.

Monza.

Click to expand...

You got it. "power being scrubbed off somewhere". I figure the drivetrain itself is rather inefficient, and thus, absorbs energy. This would be the same with a 351 or a 302 or 502 for that matter. However, the 351w (old school, like carbureted from the '60s or '70s) are grossly inefficient. I mean, I'd say only 20% of the energy from the burnt fuel actually reaches the rear tires and makes the rig go forward. I figure the rest:

1) exits the tail pipe in the form of heat

2) exits the tail pipe in the form of unburnt fuel

3) is absorbed by the cooling system as heat

4) frictional losses at any point

My 351W powered Bronco gets 7 MPG average yet was beaten in a stoplight race by a Scion XB. True story. The modern 5.8 liter motors are reasonably good. That would be from about '90 on. The old school, carbureted ones are total garbage. This is why I say "just get a 302 and be done with it. If it's real, raw grunt you want, get the modern 5.8 or any stroked 351 or BB. Plan on spending real $$ though.

Some of you guys mentioned using the EFI 5.8. I have a 91 pickup that I kept just for that reason. But I've measured and measured, and even with a ProFlow hood I can't see how it'll fit. Am I wrong here? (I have no body lift and I won't put one on)

I would never put injection on mine (even though I have laid awake at night think about how that would be). When it comes down to it, I think a carbureted 302 is the only way to go. I don

I'm new to the forum. I joined for the good exchange of info. I have a '73 Bronco that I purchased off Ebay 2 yrs. ago. I drove the slightly modified Bronc for a while, until the Bronco bug bit me. So, the frame-off has begun. My wife shakes her head since I spent 6 yrs. on our 67 Stang. Which by the way we have enjoyed racing and showing. Anyway, the question to ask for the engine swap (which I can't answer myself) is, "what are you using the Bronco for?" Sand drags, dune-running=mad torque and some revs. Rock crawling, trails=mad torque, low revs. For most folks the Bronco is a recreational vehicle, however if your's is the primary vehicle or needed transportation; I would suggest a crate motor. Looking for some more low-end grunt the 351w is a good bolt-in choice in my opinion. You can purchase a long block 351w from Kragen or the like for about $1200. The added hp & torgue far out-weigh the added weight. Wild Horses Bronco is a wealth of info on engine swaps, and they have the parts to do it. Just my 2-cents. Here is what I am doing, and if I can help, don't hesitate to contact me.

I am installing a 351w stroked to 408 into the Bronc. Cast stroker crank, Probe forged pistons, RHS heads, Comp Xtreme 4x4 cam, Holley carb (for now) and eventually when I save my pennies AffordableFuelInjection.com for a complete SEFI kit. I am going to use a Extreme radiator I purchased off Ebay along with an electric fan. Also installing a C4 W/ 2500 stall, forged rear axles in 9 inch, Dana 44, 4;10 gears, 35 inch Procomps, full Cage Offroad Suspension, Wild Horses cowl induction hood, Painless wiring, custom 8 pt. cage, etc. I completed the body work and the Bronc is primed. I used Hippo liner on the tub. Hippo liner is tintable to ANY color you want. About $70 per qt. it took 3 qt's for the interior tub. Looks great! The spray gun is about 25 bucks. I used a 5 gal WalMart special air-compressor and it worked fine. I cut out the glovebox and flipped it over so it can be used without hitting the cage. I am fabricating the seat brackets and welding them in today. I will then remove the body and strip the frame so I can paint it with Por-15 chassis black. I have painted everything with Por-15, and I swear by it. The backside of the dash received Por-15, the underside of the dash, etc. Wear gloves when painting with it. The Mustang received por-15 on the entire underside. High gloss and very durable years later.

Well, I've rambled enough. Keep the rubber side down and enjoy the journey.

Go Tac said:

View attachment 5183I'm new to the forum. I joined for the good exchange of info.

Click to expand...

hey Go Tac

i just PM'd you -

i dont want to hijack this thread with my own selfish needs.

thx,

Monza.

Interesting discussion.. I spend most of my time on another Bronco forum and on occasion check out this site. I am also contemplating the switch to a 351 from a 302. The general opinion on the other site is the 351 is the way to go. I am working with a custom engine builder in San Diego and he also is of the opinion a 351 is the way to go,more cubes. And yes if not designed and built correctly cooling can be an issue, however if you understand this going in and make the necessary adjustments cooling issues are avoided. I plan use a serpentine belt setup so as to avoid pulley issues. Another issue is clearance again I am using a 1" body lift on account of my new NV3550. Also using a raised hood open in the rear to help exhaust heat from the engine bay...