Projects 302 vs 351W 1950 Custom

Looking for some input on my decision making process. Me and the wife recently got a project car, a 1950 Custom Coupe. It currently has a 1951 mercury flathead, if I recall correctly. At the moment it runs fine, still have some body work to do and what not, but we plan on replacing the old flathead with something with a little more go. Ideally, I'd like to get 350hp out of it, with as little work as possible. I have experience working on motors, but I'm not an expert on anything performance. So I've got a few questions and if anyone has any advice or tips that could help, we'd appreciate it!

351w vs 302, would either of them be harder to mount? Need any special body work/welding/etc for it to fit?
Which one would be the better choice for bolt on performance? What are my priorities for bolt on?
Would swapping the 3speed manual for a 5speed manual require much work aside from cutting a hole for the shifter, and changing the transmission mount?

Thanks, I'm not looking to do anything real soon, but trying to get my options lined up so I can start planning out parts, build options, etc.

 

The 351W has a longer stroke which makes the oil pan deeper.
You may have to cut into the front cross member to get it in.
As far as I know, the 302 does not have this problem.
Motor mount kits are available.

 

I think the deck height is actually higher not the oil pan, makes it a little wider than a 302

 

The 351 and 302 mount the same but the 351 is a little wider at the top, so the intake isn't interchangable. The heads are the same I think the oil pan is a little different. The accessories are the same but you need adapters. And I think there was something with the 302 harmonic balancer and flex plate weights being different

Sent from my moto z4 using The H.A.M.B. mobile app

 

Check 5.0 mustang boards, but I think the 302 and 351 are pretty much interchangeable from a bolting in stand point. I think the 351 is either taller or wider, but I can’t remember.

 

It's actually both, but to put that in perspective, a 351 is the same width as a SBC, just a bit taller. A 351 will be easier to get to 350 HP and have much better street grunt, and whichever engine you use, don't re-use the OEM trans....

The oil pan limit is due to the oil pump, and both SBFs use the same pump. Stroke has nothing to do with it.

 

The 351w is a tall deck version of the 302. So, it (351) is taller and wider than the 302 but not by a lot. You will need a rear sump pan along with the longer oil pump pick up tube to match the pan. The 302 and the 351 share the same 28oz external balance until the end of 1981 then the 302 went to a 50oz balance, the 351 stayed the same at 28oz. You can make 350 HP fairly easy with both engines with a decent set of heads but the 351W with it's 1/2 in longer stroke tends to make more torque down low. The problem with installation of these engines is usually the overall length from flywheel to fan, they are longer than a flathead or small block Chevy. This engine family started out to go in the Falcon/Fairlane engine compartment designed for a 6 cylinder, so replacing a long 6 cylinder length was not an issue, width was. There are combinations of front cover, water pumps, belt drives used over the years that can shave inches off the length if that's a problem for you. Has been done hundreds of times before so it can be done.

 

So it sounds like either one will have some.minor issues due to length. Changing out the radiator, fan, etc for the length isn't an issue. As long as I'm not needing to frame or body work for either of them. The oil pan sounds like the hang up for the 351w. I'd have to grind down the crossmember or I can replace the pan. Where are the best places to look for a replacement pan? I appreciate all the input. I never had an issue with space doing this sort of thing in my old f150s.

 

Some Bronco's, Econoline Vans, and Trucks had 351's with rear sump pans. There are several places to get new pans with everything for cheap like this one from Speedway. https://www.speedwaymotors.com/Ford-Performance-M-6675-A58-351W-SBF-Rear-Sump-Oil-Pan,49713.html

 

While definitely not the hardest, a Shoebox Ford is not that easy of a car to modify. It's much better than say a Chevrolet or Mopar of the same period but they do have their quirks.

Think long and hard about this. A flathead V8 pushes these cars around very well and if it indeed is a Mercury engine, you have the 4" stroke. That stuff is very desirable. Personally I would keep the Mercury in it.

What I'm saying is....
This is not a simple project. It's not just a engine/transmission swap. You'll basically have to redesign/rebuild the whole car. It's a lot of frustrating aggravating work especially with a SBF. If you want fun and simple....keep the flathead.

 

Here are some HAMB people that have done it and shown what they did to make it fit. 302 is easier. I replaced the Y Block in my 55 with a 302/C4 combo and it is about 240 pounds lighter (with an aluminum intake) and it drags the 55 down the road pretty well! A 302 is just 63 cubic inches bigger than the flatty and easy triple the horsepower.
https://www.jalopyjournal.com/forum/threads/351w-into-a-50-shoe.664882/

 

I did the 289/302 swap in my 53, which is the same platform as the 50. Most of the previous comments are dead on. The 351 does present an additional challenge though- because the engine is slightly wider, you will have clearance issues with the steering box if you plan to run headers. I am running headers, a manual 3 speed top loader transmission, and a mechanical fan.

 

I would definitely go with the 351w and a small street blower. Lots of easy horsepower and very reliable and smooth running and it's not a gas hog and it's pretty.

 

Because of the shorter stroke and lower deck height, the 302 is narrower
And more compact around the steering gear. That alone is a good reason to choose it over a 351 for your swap.

Also, as much as I like a five speed, remember that all the common applications used a cable clutch linkage and hung, rather than through the floor pedals, so that’s another thing to figure out.

There’s a reason so many of these swaps use an automatic transmission.

 

I was thinking the 351W had a larger drive shaft and not interchangeable with a 302?

 

The 302 is going to go in easier, and you can always do a 331 or 347 stroker setup for extra grunt. That said, a good, streetable heads/cam/intake setup on a 302 will make 350hp easily.

 

I suspect a 302 will be a lot easier to find, and stroker kits for them are pretty widely available these days.

 

I'm also for keeping the flathead, but if I did swap it out, I'd be a 351. If you ditch the flathead hmu, I'll take it! Lol...

 

The W used 351 heads through '77, 78 & up are 302 heads with bigger bolt holes. The early intake/heads have more intake bolts than the 302 based heads, so there are 2 different intakes for the W.

 

^^^
If I was going to go through all the trouble of an engine swap....This.
The Early Cadillac...can be found if you look.

 

One other item I don't think was mentioned yet is the Oil Filter. They can be an issue if you don't know about this little item.
I don't have much more to add than pointed out above. No matter the choice it will be a little more involved than you expect just because it sounds like it's just a bit out of your normal range of knowledge. That said it isn't all that tough.

 

I've had both, in vehicles of similar size and weight. The 302 got 20MPG or more, the 351 struggled to get as high as 15. So if economy counts, I would take a 302. But if you really want 350HP in a heavy street driven car, go with the 351.
Having said that, I would do everything possible to keep the flathead. Even rebuilding it if necessary, before I threw in a modern engine.
Incidentally the newer 4.6 V8 out of Crown Vic etc is a better engine, don't know why no one uses them, is it because they are scared of fuel injection and the wiring that goes with it?

 

I know for a fact the 4.6 is getting used in the 49 up Fords. It just don't get talked about here due to our Old School program. New generation F.I. is Taboo.

 

You are correct for the oil pump drive shaft, 5/16" for the 351 and 1/4" for the 302.

 

Now the serious question. Where do you live and what are you going to do with the flathead?

 

There's trade-offs with each choice. The 302 will be easiest to find, and late-model roller cam motors are still relatively common to find. A late-model Explorer would make a good donor (engine and rear axle, the EAOD trans not so much), if sticking with a 'traditional' carb set-up as all you need is a different intake and distributor as these have 'good' cylinder heads. The later motors have a block-mounted oil dipstick, but lost the clutch pivot boss on the block. But a 302 just won't have the same torque delivery as a 351 unless you do a stroker, and that opens a whole 'nother can of worms.

The 351W will in almost all cases fit anyplace a 302 will. Yes, it's taller/wider than a 302, but not by that much. It's as narrow or narrower as any 'traditional' choice (SBC, early Olds or Caddy, all common swaps 'back in the day'), so that shouldn't be a deal-breaker. Oil pans choices aren't quite the same; Ford never installed the 351W into a production rear-sump car (with the exception of the very limited production GT-R Mustangs) so you're limited to truck/van/Bronco rear sump pans which aren't quite the same. Most have a 5-quart capacity, one more than the cars. Some sheet metal and a mig welder can usually address any issues. A tip: if you use a pan with a riveted-on 'adaptor' for the dipstick, braze it to the pan as these tend to seep oil.

Like the 302, there's multiple versions of the 351W block. Ford played with the deck height over the years although that can be ignored as a rule. Unlike the 302, Ford never 'lightened' the 351W block; all 2-bolt blocks are equal strength-wise. Up until the late '80s, all rear-sump applications used a pan-mount dipstick, then Ford modified the block for a block-mounted stick like the 302. The block lost the clutch pivot boss in this change, but this can be fixed with the same aftermarket bracket used on the late 302 blocks. Roller cam blocks started appearing in '94 (although the cams didn't appear until a year later); these are prized by builders and not easy to find. Aftermarket roller cam conversions are readily available if desired.

As noted, the 351W used 351W-specific heads until '77, Ford then switched to 'plain' 302 heads. GT40 heads can be drilled to fit and are an inexpensive upgrade, or there's plenty of aftermarket choices. If looking for a factory iron head, the C9 and D0 351 heads are the ones you want.

Engine length/front dress. Ford used two mounting positions for their radiators all through the '50s, back for the V8 cars, forward for the 6 cars. Use the 6-style mounting and you'll have all sorts of room. Both the 302 and 351W used essentially the same front dress, with sometimes different brackets to account for the heads being higher. Most of what you'll find these days will be serpentine, get one for the engine size you have and you should be OK. Same rules apply if you want a v-belt drive. To be honest, I don't care for most of their brackets or the aftermarket stuff and have been building my own.

You won't be re-using the OEM manual trans with either motor as the bolt pattern won't match up with the bellhousing. Now Ford did build a limited number of dual-pattern bells for service replacements in the mid-'60s that would work but these are as rare as hens teeth today. The only current bell with the dual-pattern is the Lakewood ****tershield but you can get a better, different trans for the same money. Stay away from the C6 automatic, it's a mileage killer. You can get mileage out of a 351W, my OT F250 4WD knocks down 17-18 highway with a manual trans.

 

You can get 350 hp out of either engine w/o a supercharger, but you'll need aftermarket heads. A smaller engine of equal hp should give better mpg until you put your foot into it-less m*** and less friction to overcome.

 

50 Fords weight approx. 2959 lbs.
66 Mustang approx. 3000lbs. ( "MOM!........he said the M-word!")
So you'll be 50 pounds lighter with the swap. (5.0/302/289)
Replace the heads and intake with after market Alum stuff and that another 100 pounds!
(see where I'm going here?!)
Replace the ****** with a T-5 and your gas mileage will jump over the old flattie too!
Sell the flattie to Billy Bandit (or others) and 1/2 your expense of the swap will disappear!
Find a new(er-ish) wrecked M-word car or Exploder and the FI parts are an easy sell to Ford guys($$)
Other parts could be salvaged from the donor car for even more ($)
Clutch pivot boss is an EZ fab job that attaches to 2 of the bellhousing bolts.(Cable clutch may be an even better option also from the donor car)
Money you save could easily go toward a rebuild and a hotter/snotty camshaft and heads. (replace the rod bolts with ARP's and have the big end of the rods re-sized.) You'll be good to 6500+RPM if you so desire.
600cfm Eddy carb and a nice set of headers....Alum after market heads...machine work to zero deck the block....9.5:1 CR pistons(swap the pistons from side-to-side) and your EZ 350+ HP that you can cruise Route 66 & back no prob.
6sally6

 

Good lord the knowledge on here is unbelievable... I have no technical knowledge on this particular subject to add, but I will say there would be no shame in keeping the current "period correct" combo. Someone back in the day (I ***ume it was back in the day) put the "hot" Mercury motor in there and IMHO would be almost sac-religious to yank it, and if it were mine I'd keep it. My '55 Merc has a '60 Ford 352 that someone in the '70s took the time to do and although it's blowing smoke and oil out of the breather now, and there are plenty of other higher HP options out there, this one will get rebuilt and continue to power the car it knows and loves. She won't be the fastest car on the road but she will sound awesome, be fun to drive, and be a piece of history. All that being said, no shame in taking on the challenge of the swap if you're up for it! Keep us posted! Having fun with it is what matters most!

 

Get what ever get you driving the car sooner. If you get a deal on either. Go for it.
If you actually have one in it just rebuild that. Maybe just add headers and a multi carb setup. And a new rear with a better ratio
My reco would be to get the running gear out of a 60’s fairlane or Mustang that being parted out.
The main thing is keep a running project.

Don’t send it away to get worked on, etc... keep it running and do the work while you can enjoy it.

I would say also if you get another engine make sure to get the whole thing all the front engine parts, if the ****** is there take all of it all the wait to the column even. Driveshaft and rear.