Technical Flathead performance expectations?

From my other threads of looking for 46-48 Ford sedan. So I have found some that are bone stock and some that have had "upgrades". Most have Offy heads, 4 barrel intake, maybe a different cam. If I end up with a good running stock engine and decide I want to swap to Offy heads and a different intake (4 barrel or 2-2 barrels) what should I expect? Is it like a 10-20 hp improvement? Or is it mostly a cool factor that you gain?

 

Just a cool factor. You may see little difference but the cost isn’t worth the gain.
But smiles on a cool looking engine is priceless.
Concentrate on buying a car with a flathead that has good compression and doesn’t leak and smoke.
That is a good start.

 

So would the added value just kinda be the value of the parts?

 

If you are buying new speed equipment, you will never get that money back once installed.

 

I replaced a weak (90-100 lbs of compression) but good running stock flathead in my '51 Ford coupe with a '51 Merc that ran even better. I added a set of custom fitted (.050 "squish") Edmunds heads, a Rochester 2G carburetor on a bored out aluminum Merc manifold, and a Mallory dual-point. I considered installing an Iskenderian MAX-1 cam and kit, but after doing some research and having discussions here and on "The Ford Barn", I decided to keep the stock Merc cam. The difference was like night and day. The car was kind of a slug before, but now it accelerates well and will cruise all day at 70.

That engine has been in the car for 10 years now and is starting to blow a little smoke. My plan is to pull it and bore it out .125 (giving me 276 ci) and giving it a valve job. I expect another substantial increase in performance.

One thing to keep in mind is that adding "Speed Equipment" is more than a matter of just bolting it on and GO. The Rochester carb wouldn't have been much of an improvement had I not properly bored out the intake manifold. Similarly, the heads wouldn't have yielded the benefit they did without fine tuning the quench. The Mallory also needed it's advance curve optimized.

As the old Alka-Seltzer commercial used to say : "Try iy, you'll like it".

 

One car I am looking at has a 51 Mercury engine with heads, Holley 4 barrel, cam and Mallory distributor. I don’t know how well it was tuned, but seems to run well.

Another car just had heads and a 4 barrel carb installed. Everything else looked stock.

For the first one would you add a premium $$ value for the engine? Like it’s worth an extra $1000 or more? The second one isn’t as nice and I am guessing the parts where just bolted on at some point during its life.

 

On any engine. Performance parts will make you mildly wealthy, if you start out a millionaire.

If you throw enough money at a flathead, you can easily triple the factory HP and have a good running, dependable engine. It won't be cheap. A set of heads, manifold and a couple of carbs will look cool but negligible gain.

 

Unless they are running in a car or on a stand, they are just parts. If it is running and you buy one, take it home that instant. A friend bought one running, the guy took it out of the car the next day and my buddy returned to take it home. The guy switched engines for a cracked one. I just helped him do the burn in on a fresh flathead he had built to replace the tired, cracked one he got sandbagged on.

An engine on a stand, no matter how pretty is a parts engine. Pay accordingly.

 

Well, coming from my minor background in classic car appraisals, I can tell you that I would never equate "speed-parts" with value. Let's move this analogy to a more universal hypothetical.

You have 2 55 Chevy Bel Air Hardtops, identical, except one has after market aluminum heads, intake, and a big Holley Double Pumper carb on the otherwise stock 265ci V8. Now, that might add value to the less than 10% of buyers who think that's cool, but the average buyer of a 1955 Chevrolet actually would expect to see the original engine in it's proper well-maintained and presentable condition, and thus, it would typically bring LESS money than a car restored to exact original specs.

Obviously, if you have a car with an engine swap, upgraded with modern features and comforts, then it's a different story, but Speed Parts on an otherwise stock car don't immediately make a car worth that much more. You bolt a $25k Blown Ardun Flathead in a 32 Ford and you won't automatically get $25k more than before.

 

$25k for a blown Ardun flathead? Sold!

 

The “H” series Ford flathead 6 pulls almost as hard as a flathead V8. I always thought of putting one in a roadster, but speed parts are hard to find and very expensive.

 

I am looking at running driving cars in good condition. I am not necessarily looking for a “hi performance “ flathead in the car. Some of the cars are completely stock and some of upgrades. The 47 I am looking at has the 51 Mercury engine swapped in with all those upgrades. It also has other mods and definitely isn’t a museum piece but more of a hot rod.

Others are mostly stock.

 

"There is no replacement for displacement". A 4" stroke Scat crank goes for over $800, so a car with a good running late Merc engine is probably worth the extra grand.

And c'mon Billy, "easily triple the factory HP"? It took Joe Abbin a supercharger (and a lot more) to get 335 HP, and there are a lot of people that don't believe it. A regular guy (like most of us here) will never get a 50% increase over the claimed stock HP out of a flathead without resorting to significant and expensive large displacement increases or supercharging. Most stock engines rarely make the factory rating, so significantly improving over that requires careful modifications and fine tuning.

 

A flathead motor is worth about $50 with the heads on. The price could go up or down wiyh the heads removed depending where the cracks are. My experiance has been 4 out of 5 have bad cracks

 

Flathead Jack told me one time, that no matter how much you bore, stroke, port or cam a Flathead, that N/A it won't make much over 200 HP. The secret is how to spend the least to make that....

 

"gregsmy"; from what I've seen on this thread, we live in the same world. We both want a nice car we can jump in, hit the starter and go. And go a bit better than the average guy, while we're at it. With that in mind, the car with the Merc sounds ideal. Given the cost of aftermarket "stroker" crankshafts, the $1000 price premium doesn't seem out of line. The big problem is determining whether or not it really is a Mercury engine, since the main identifiers (heads and intake manifold) have been replaced. There are a couple if minor indicators I can give you, but nothing short of pulling a head and measuring will tell for sure.

But that may be in the cards anyway, because the "speed parts" may not have been installed in the proper manner. If it were mine, I'd pull the heads and make sure the quench over the piston was in the optimal range. I'd also check the carb for he proper mixture and jets and recurve the ignition advance while I was at it. All of these things are cheap to do and necessary to get the maximum performance from those shiny aluminum bits.

It's also a lot of fun and very self-satisfying. Good luck with whatever you decide to do,

 

What is a good compression number for a stock 8BA? I know that the lowest is supposed to be within 10 or 15% of the highest, but what does a stock flathead in good condition have for cranking compression?

 

"Flathead Jack" has been out of business for years, but he was right. To get the proper slant on all of this you should read John W. Lawson's book "Flathead Facts". In it, he took a properly rebuilt late flathead (making all of 87 HP BTW) and added the regular speed stuff incrementally while making dynamometer runs after each change. It was so long ago that I don't remember the exact numbers, but they were far from impressive.

 

Off the top of my head, '49-'51 should be 110 psi, the '52-'53 higher, maybe 120? After doing the modifications on the Edmunds heads on my car, I got between 145-150 psi.

 

Spot on for what I am looking for. Anything I can look for on the outside to determine if it’s a Mercury engine swapped in?

 

The first thing is to try to determine the original color of the engine. The Mercury's of that era were a greenish turquoise, while the Fords were dark green, blue, bronze, or tangerine. Try to find an obscure out of the way place on the engine and try to get down to the first layer of paint. Also, on the engines I have had (admittedly not many, maybe 10 or 12), the restrictor fitting on the oil filter was "blocky" on the Fords while it was "rounded" on the Merc's. Last, on engines I have disassembled, the oil pump drive gear housing cover inside the bell have been cast on the Merc's, while they were stamped steel on the Fords. Now, these last two may be random or even a plant by plant (or year by year) variation, but it's what I have observed.

 

I made 330 HP on an engine dyno. It can be done but it cost me $17,500 to pull it off. That was with a 4 bbl 650 on top of my 471 blower, it now runs 3 Stromberg's. 8 pounds of boost, 8.5 CR. .125 over bore. Heavily ported, Merc crank, custom grind cam, MSD and BTM-6, almost all of the parts came from H&H. I sold a 71 LT-1 vette to build my roadster, this is faster. Joe only used that little B&M forced air unit that Roadrunner was marketing at the time. I used his "cookbook" to the letter other than that. I have heard of 200hp being achieved normally aspirated. The flatheads biggest challenge is breathing. A 471 or maybe the big SCoT is required to achieve big numbers.

 

I came across a Mercury that has a Road Runner 284ci 49 Mercury with the 471 Weiand.

 

The engine has been repainted red. I am guessing without pulling a head I couldn’t be sure. It has this style of bell housing.

 

I've never owned anything with a flathead V8. But I've always assumed that anyone who's driven one in fair condition for any length of time with a decent tune-up, and then bolted on some basic hop-up parts, will be pleasantly surprised by the improvement. But the rest of us who are only used to driving 260+ cubic inch overhead valve V8's will be left wondering what all the fuss is about.

 

It looks like it was originally a 6 cylinder car since the vin starts with 7GA.

 

On a chassis dyno with my 97's I would be kinda happy with that number. I didn't know Weiand made a 471, the ones my friends run are much smaller units. It has such a good tune I am afraid to disturb it and the guy that tuned it passed away unfortunately. Point is, flatheads can make big numbers (big for what they are) without falling apart. Is it worth the price? Probably not unless you are racing it. But I sure like driving mine. Twisting up a pair of drag tires with a flatty? Priceless.

 

That's a pressed steel bell that originally came on '49-'early '51 Mercury's which is a positive indicator. The truck bell housings that can also be used to mate a late V8 to an early transmission are made of cast iron.

Just out of curiosity, what does the restrictor fitting on the oil filter housing look like?

 

The ever common 471 on a flathead is now the thing of the past with the low drag pro charger style when looking for hp. Massive improvements were made with welding in new porting on the top of the engine if it’s hp you want. Look to Bonneville racers/builders for inspiration. May not be traditional now but fast none the less.

 

This is what its supposed to be.