347 or 363, Preference and Why?

[Alan_C]

I am starting to plan my coupe build. I have used modular engines in my past builds but want to do something more traditional looking for the coupe.
I want to build up my engine from a short block. I am leaning toward a 363 with an aftermarket block to deal with the 500 plus HP the engine will produce. 347 cu in SBFs can produce nearly the same HP levels as the 363. I look at the 363 using an aftermarket short block as a better and more reliable option. What say those that have done both and why.

Thanks

[bobl]

The after market block wins in every category...except cost. Cubes won't make much difference between the 2 engines. buy a great cylinder head and you'll reach 500+ HP with either. If you are racing go with the aftermarket block. Normal spirited street driving the 302 block will hold up just fine. Ultimately it comes down to cost and intended use.

Bob

[GoDadGo]

Al,

I think the 363 is the best option if you are going with a Short Deck SBF.
The 4.125 bore really unshrouds the intake valves compared to a 4.030" bore.
Also, while I hate spending my money, I'd be happy to help you spend some of yours.

https://www.jegs.com/p/Ford-Performa...73244/10002/-1

Check out this video from Hot Rod Magazine from years gone by because the Daytona has a 363 SBF in it.
Strip at Las Vegas is nearly 2000 feet above sea level which eats up power compared to where I live.
That car really did very well for having really high rear end gears. (3.27 Ring & Pinion)

https://youtu.be/V96-AQ1FghI

Good Luck!

Steve

NOTE:..My 383 SBC is making 465-HP @ 6,000 and 465-TQ @ 5,200 makes for a very peppy MK-4 Roadster with 3.73 rear gears.

[PaulProe]

Just a word to the wise. I recently had to cancel an order for the M-6010-B302BB and convert to a M-6010-BOSS302. I placed the order for the Big Bore block the first part of January. They just pushed the delivery off another thirty days to April 11th. Discussion with the customer service rep, I learned their backorders go back over a year with no real solution in site. No input as to what the real problem is.

Fortunately they had a BOSS302 block in stock - Cancel one order, place another and I now have it in my hands.

Available inventory and lead times may make the decision for you

Paul

[Alan_C]

Al,

I think the 363 is the best option if you are going with a Short Deck SBF.
The 4.125 bore really unshrouds the intake valves compared to a 4.030" bore.
Also, while I hate spending my money, I'd be happy to help you spend some of yours.

https://www.jegs.com/p/Ford-Performa...73244/10002/-1

Check out this video from Hot Rod Magazine from years gone by because the Daytona has a 363 SBF in it.
Strip at Las Vegas is nearly 2000 feet above sea level which eats up power compared to where I live.
That car really did very well for having really high rear end gears. (3.27 Ring & Pinion)

https://youtu.be/V96-AQ1FghI

Good Luck!

Steve

NOTE:..My 383 SBC is making 465-HP @ 6,000 and 465-TQ @ 5,200 makes for a very peppy MK-4 Roadster with 3.73 rear gears.

Love the 2nd video, the 363 in the Daytona tested was perfect with one exception, I will be adding stack injection to mine for few more ponies. I am guesstimating about 550 HP at the crank as Ford Strokers rates their 363 with a single carb at 507 HP. The added looks and responsiveness of the stack injection is just icing on a already tasty cake!

[mrglaeser]

Just a word to the wise. I recently had to cancel an order for the M-6010-B302BB and convert to a M-6010-BOSS302. I placed the order for the Big Bore block the first part of January. They just pushed the delivery off another thirty days to April 11th. Discussion with the customer service rep, I learned their backorders go back over a year with no real solution in site. No input as to what the real problem is.

Fortunately they had a BOSS302 block in stock - Cancel one order, place another and I now have it in my hands.

Available inventory and lead times may make the decision for you

Paul

When I was at Build School I was told Ford Performance lost their foundry partner in 2021/2022. They had been working to replace them for a long time. I ordered a Boss 347 Short block in March of 2022 and it was delivered in November of 2023. I was not even close to needing an engine so I just left the order in. They are catching up, but really slowly. You can not get Boss 302 blocks you couldn't for almost 2 years prior to last fall. But yes I would consider inventory if you need it sooner rather than later.

[Alan_C]

Availability of the Boss blocks are a mute point for two reasons. One I never said I wanted an engine from Ford Performance, I referenced the short block at Ford Strokers, not the same place. Two, I am just now starting to put a plan together thus the questions about the engine. I get you guys went through long waits for what you wanted, but this is not the same time as it was a couple of years ago.

[Alan_C]

The guys over at the Vintage Mustang Forum really like the video of the Factory Five cars in the second link. There are a few of us over there like Dan Babb that had or have both Factory Fives and vintage Mustangs. What did not surprise me was that the feedback I received on VMF was far an away greater in numbers and value. Now I know that if I want engine build info, I will just go to the VMF site.
I will also note that the number of Cheby haters is about 10x greater on VMF than here. If you want to see someone get booed and maybe booted from the forum in record time, just start talking about putting a SBC in a vintage Mustang and stand back as the haters pile on!

[KDubU]

Both great engine choices, my preference would be the 363 ever since the FF video on engine choices.

[weendoggy]

I'm throwing in my own account. Started with mild build in 1999, worked on handling and suspension mods for 2yrs, moved to 331 learning how to handle and drive the car. I did a frame off in 2019 and put a new Boss Big Bore SB in after breaking a lifter. After discussing with my engine builder and my own reasoning (keeping it near 500hp) I opted to go 347. Few factors involved were keeping the bore stock, keeping more piston in the cylinder, gaining the torque and staying in the hp range. Thouroughly pleased with the results and have more than ample power in the little car. I've also open tracked the car for 24yrs so I know what my limits are, which are far less than the car itself. All the talk of HP is just that, "I have more than you", but, if you can't handle the hp, you have no business with more. jmo

[David Williamson]

I have a Dart block 363 in my Coupe. I decided to go with the aftermarket block and 363 ci because it is stronger with 4 bolt mains etc than the stock block 347. The way I use the car it likely will not matter but..... i went with the bigger engine because with the Dart block it is an easy extra few cubes. The Dart and Boss blocks are very similar but true or not I was told the Dart design was slightly better.
David W

[drewr]

I built my own 347 from a seasoned 302 SBF. I'm very happy with it. With a good cam, aluminum AFR heads, a good intake, you can have more power than you can use. There is is honestly little difference between the two choices. It all depends on what you want to do with it. If you are building a street/car show car, either choice is fine. If you are building a race car, I still think either choice is fine. There are plenty of successful racing Coupes with 347 blocks. There's one on BAT for auction right now. I think the only reason to have a 363 in this car is say you have a 363. I think it would be hard to show a difference on street or track.

[RoadRacer]

I know nothing about Ford motors, but perhaps this is relevant anyway - having a high-revving V8 is amazing. In the chevy world, I'd pick a 377 vs a 383 for the revs, horsepower being the same. Having a motor that can rev to 7500 is so much fun. Perhaps your 363 vs 347 is a similar thing.

[Alan_C]

I know nothing about Ford motors, but perhaps this is relevant anyway - having a high-revving V8 is amazing. In the chevy world, I'd pick a 377 vs a 383 for the revs, horsepower being the same. Having a motor that can rev to 7500 is so much fun. Perhaps your 363 vs 347 is a similar thing.

A good point to consider. The 70 Boss 302 tribute I am building now is powered by a 2nd Gen Coyote which can rev to 7200 according to Ford, but likely more like 7600 if you like taking chances. When it becomes time to order the short block, these kind of considerations will definitely be discussed with the engine vendor. I have wondered if there would be much real world difference between the 347 and the 363. Either way, I am going with an aftermarket block as the stories of split blocks on engines with HP exceeding 500 stick in my mind. The last thing I want to do is to nuke the engine should I take the car for a shake down at the track. So I figure, if I am going to buy an aftermarket block anyway, then why not stoke it more and go to a 363 while I am at it?

[drewr]

I think after a certain point you cannot get the horsepower to the asphalt, and any extra horses gets lost. Tires, overall weight, gears, driver skill matter more. These are light cars, way lighter than a vintage Mustang. The original was first in class at LeMans in 1964 with a 289! Maybe horses would matter with a drag car.

[Alan_C]

I think after a certain point you cannot get the horsepower to the asphalt, and any extra horses gets lost. Tires, overall weight, gears, driver skill matter more. These are light cars, way lighter than a vintage Mustang. The original was first in class at LeMans in 1964 with a 289! Maybe horses would matter with a drag car.

Agreed 100%, however we do have the option of buying 100 treadwear tires, but for street use too much money for too little gain. I am running NT05s on my Mustang and for street use I will do the same for the Daytona. My Mustang is limited to 295s since I did not tub it. I haven't asked the question yet, but I am wondering how much effort would it take to upsize to 335s on the back of the coupe? I already want to run 275s up front, doable I think as many are running them on their MK4s. How much and how sticky will determine how much HP is useful. I am going to do the late model Mustang IRS on the coupe build. Not sure that in a straight line that the IRS will hook up any better than the 3-link did on my MK4? What I can say with my MK4, unless I raised the revs way up and dropped the clutch, I could not do more than a short burn out with the 350 HP 4.6L DOHC engine in the car. That HP level was perfect for a first time owner/builder as Dave Smith suggested in the MK4 manual prologue. Adding nearly 200 HP in a car that weight just about 100 lbs more will be a different story, stay tuned.

[rich grsc]

On an episode of Engine Masters they discussed the 'split block' issue. Like most stories, the worst case stories always get passed around and around. They claimed it was very unlikely.

[GoDadGo]

I know nothing about Ford motors, but perhaps this is relevant anyway - having a high-revving V8 is amazing. In the chevy world, I'd pick a 377 vs a 383 for the revs, horsepower being the same. Having a motor that can rev to 7500 is so much fun. Perhaps your 363 vs 347 is a similar thing.

As you know the 347-SBF & 363-SBF share the same 3.40" stroke so I'm sure both would be Rev-Happy!
Regarding the 377 vs 383 I'm sure the 377 with its 3.48"-stoke and 4.125"-bore would be Rev-Happy too.
Hummmmm, maybe I'll one day build a Dark Side Daytona with a 377 in it.
Though my 383 can rev to 6,500 the limiter is set at 6,000.
No way would I spin it over 6,500.

[Alan_C]

Hummmmm, maybe I'll one day build a Dark Side Daytona with a 377 in it.

Don't you do it, please don't. The LS and LT are fine platforms, but as most of believe, they don't belong in a Ford. People who have seen my 70 Boss 302 tribute with a Coyote up front have thanked me for putting a Ford in a Ford. You will never have that pleasure. Just throwing you under the bus as many will should you do it.

[FF33rod]

On an episode of Engine Masters they discussed the 'split block' issue. Like most stories, the worst case stories always get passed around and around. They claimed it was very unlikely.

Agreed. That said, these days, quality used OEM blocks are getting quite difficult to come by. Many engine builders don't offer solutions based on them anymore, just after market blocks. My 347 suffered a crack in cylinder 1 very early on. Short block vendor offered some compensation but with me in Canada and them in California I ended up spending far more than I would have with a Dart block to begin with...

Alan says he's going aftermarket, good call...

Steve

[Jim1855]

Don't you do it, please don't. The LS and LT are fine platforms, but as most of believe, they don't belong in a Ford. People who have seen my 70 Boss 302 tribute with a Coyote up front have thanked me for putting a Ford in a Ford. You will never have that pleasure. Just throwing you under the bus as many will should you do it.

Peter Brock, perhaps you've heard of him, I think he knew something about Daytona Coupes, thought otherwise. He put a LS7 in his Superformance Brock Coupe. His comment was something to the effect of "it's a hotrod, do whatever you want".

But it's your car, do as YOU please. Trying to make others happy may be overrated.

Jim

[Alan_C]

Peter Brock, perhaps you've heard of him, I think he knew something about Daytona Coupes, thought otherwise. He put a LS7 in his Superformance Brock Coupe. His comment was something to the effect of "it's a hotrod, do whatever you want".

But it's your car, do as YOU please. Trying to make others happy may be overrated.

Jim

Cool your jets, it was a joke man. You are reading way too much into what I wrote or did I hurt your feelings?
I am doing a 5.3L LS2 V8 swap into my wife's Canyon. They're just engines, nothing more than that.

[Jeff Kleiner]

Don't you do it, please don't. The LS and LT are fine platforms, but as most of believe, they don't belong in a Ford.

But it's not a Ford. It's also not a Chevy. It's a Factory Five Type 65 Coupe. Just sayin'

And yanking your chain

Jeff

PS: Ask Dan Golub at FFR what he put in his.

[BRRT]

Don't you do it, please don't. The LS and LT are fine platforms, but as most of believe, they don't belong in a Ford. People who have seen my 70 Boss 302 tribute with a Coyote up front have thanked me for putting a Ford in a Ford. You will never have that pleasure. Just throwing you under the bus as many will should you do it.

Not much Ford in my Mk4 - Left/Right rear suspension knuckle and differential are the only things carrying Ford part numbers. Far more GM part numbers than Ford. Still, mostly Factory Five.

[Mike.Bray]

Don't you do it, please don't. The LS and LT are fine platforms, but as most of believe, they don't belong in a Ford.

What Ford?? These cars are replicas of Shelby Cobras which were cars made by AC. Putting a SBC in a 32 Ford 3 window does not make it a Chevy. Just saying.

[Alan_C]

But it's not a Ford. It's also not a Chevy. It's a Factory Five Type 65 Coupe. Just sayin'

And yanking your chain

Jeff

PS: Ask Dan Golub at FFR what he put in his.

Jeff I get it and I appreciate your understanding the humor in it all. However, a couple of guys here appear to have taken my comment, its a joke son, to literaly!