Hot Rods building HP out of a 46 ford flathead

im looking at a '46 ford tomorrow that a friend owns. its a running truck, and the engine is good. its a 3spd manual and flathead v8. i know very little about performance with flatheads, so im wanting to reach out to those who know more. i'd like to rebuild this engine to somewhere around 300-400hp. more like 300-350hp. no super charging, no juice, i want to do this like they did way back when. id like any tips, tricks, places for parts, etc on building this engine. i will probably change the trans to a t5 from a camaro so that its better geared for cruising and change the rearend to a 9". this is going to be a budget build, i dont have a set budget but im trying to do it as cheap as possible since i have a part time job, and college. i thought about swapping in a sbc, but i really like the flathead sound and the nostalgia of it. thanks in advance.

 

Flatheads and cheap just are not two words that go together. If your looking to get over 300hp you will be spending a lot of money to get there. You can get over 300hp in a flattie, but you need to look at a supercharger to get there. Doing that right now myself. Good luck with the truck.

 

For your info:
A bored and stroked flathead 3 3/8 x 4 with cam, high compression, multiple carbs, porting, headers, ignition, etc, etc, is not even gonna make 200hp, in fact someone reported just recently their engine of similar specs dyno'd at around 135hp. Now I find that a little low for those specs, I would have expected maybe 150-160hp.
Flatheads are not about high horsepower, they're about torque and cool.
If you want gobs of hp, go for a SBC. If you want to have a nice cruiser, a mild flathead with a modern trans with o/d is the way. Forget the 9", an 8" will do the job and look better.

 

+1 to what's already been said, pulling those kind of horses from a flatty is an expensive proposition.....that being said they're cool as hell

run a search on here there is a ton of good performance tips for that engine

 

300HP and flathead ain't terms that go together. I do not think those of us who drive flatheads put that kind of crap together. Drove mine home last nite, in the dark, listening to the clap out of the laker style headers that comes from each cylinder. I was amazed out how the old gal pulled up and down the hills on a very curvy road in 4th with a 3.00 rearend. Sometimes down to 1600 to 1800 rpm but she just chugged along. I was mesmerized with the nostalgia of it all.

 

I would say go for a drive in a well built flathead powered roadster, and see how much of a grin it puts on your face, and once you go "i want MINE to go just as good as this one" then ask the owner how many horses it makes, you'll be suprised at the tiny answer you get..
sure, in a heavy truck you need all you can get..I think an honest 150-160hp at the flywheel isnt too hard to achieve on a tight budget if you research a LOT.ten hours selective reading of searches this site over a week of evenings would be a good start.

 

Hahaha!

Seriously, you could spend 20k on a bored/stroked/blown full house flathead and barely kiss the 200 mark.

 

really? wow, i mean ive been reading up and at first i didnt want to mess with it, but the sound of a flathead, its catchy and just of what it is makes me want to keep it. i found a isky 400jr cam, how hard and what all would i have to do in order to run that? im thinking headers, triple duece intake, port and polish. and the cam. id like a good cruising truck. something that people turn and look at and admire as i cruise down the freeway or around town. thanks to everyone who has replied, big help
i found this video on youtube of this guy who has a sick sounding flathead. i want mine to sound like this. http://www.youtube.com/watch?v=eDL9iGvS43U
what size cam would make mine sound like this?

 

A guy could almost build 2 for kinda cash …. there’s enough misinformation on this site already get clue or don’t talk.

 

Do you realise that an Isky 400jr is not going to give you a comfortable around-town cruise? In fact there is no cam, except maybe an L100, that's going to be better than a stock cam for around-town cruising. Remember that performance cams are usually down on hp and torque until they get to certain revs.... usually in the 2500-3000 area.
Considering your lack of knowledge (I'm not being a prick, I mean that in a helpful way) of flatheads, my recommendation would be to get the truck running and driving first with stock running gear. Then gather the trans, rear end, trans adapter and any other bits you need. Once you've got all the stuff together, do the transplant. Get it on the road again and see how it goes. Then, and only then, look at some mild mods on the flathead.... skim the heads, twin carbs, headers, ignition and if you still want a cam, go for an L100 and Johnson cam followers.

 

300 plus NOPE

Tig

 

here's how I'm gonna max out....200HP if I'm lucky....lol

 

Say what? get a clue or don't talk? That's pretty uncalled for, man.

I'm not saying you HAVE to spend that much, but it sure wouldn't be hard. I'm not just talking out of my backside here... By the time you price out all the new internals, stroker crank setup, heads, intake, carbs, blower, dist/mag, machine work (which tends to get exhorbitantly pricey when trying to make a bunch of HP with an en bloc engine), assembly, balancing, blueprinting, etc. You could easily be in that neighborhood. Notice I said "could"... just like in my original post.

One of my friends just put together a naturally aspirated 304 ci, he says had over 12k in parts alone prior to any machining or assembly. Granted, some of the suff he chose was pretty exotic...

 

Call H and H and ask them to build you a full on flathead and see what dollar figure you get quoted. You could spend $ 20K (I know people who have) and still not be making 300HP. But you would have a very cool motor that makes maybe 200.

Tony DiCosta built the flathead that went in the pink Total Performance car and had $ 9K in it, and that was 20 years ago.

Don

 

I can't believe what I'm reading, the truth about flathead performance.

 

The OP didn’t say he would have to just pay up to have it done so I assumed he could / would do some work himself.

Yes … sure someone that knows nothing other than how to read a magazine - put gas in it and turn the key would need to pay dearly but there’s no reason to jump to the most expensive option there is …. Like that’s all there is.
Many a nice V8 was built before there was a H&H.
Iv built a couple of nice stoker flatheads (un blown) for under 5 grand and that’s including everything / turn key.

 

Well the next time I need a stroker built, I'm calling you!

I agree, if you're a resourceful guy with some experience, knowledge, and some tools you can pare that figure down a LOT. A machinist friend who's familiar with old engines doesn't hurt either.

I was just making the point that it's entirely possible to spend a boatload of cash on these things and not be anywhere close to what the OP is expecting.

 

There is a reason why they quit making them in 53....

 

I apologize for helping to take this thread off course a little. I guess what we were trying to stress to the OP is that a 300 HP (and beyond) can be built, but it ain't gonna be cheap, or be an engine you could readily jump in and drive a lot. As with most engines, as HP goes up so does the stress on parts.

But a reasonably priced build with some good block work, some crank work, good heads and compression, a decent cam, and a good intake and exhaust system would probably make 180-200 and be a very good running, dependable motor. I read one time that a really good flathead will put out about the same performance as a well tuned 283 sbc, and that seems about right to me.

Don

 

Get the book "how to build a flathead ford v-8" by Gearge McNicholl. He builds 3 engines ranging from street performance to Ardun conversion. He list all the costs involved very realistically. The build costs range from $9500 (2003 vintage) to $15000 for the blown street engine to $20000 for the Ardun build. Horsepower figures were 208, 307 and 300 respectively.
A total stock rebuild will probably run you $3-4000. I stuck all my receipts in an envelope and I don't want to ever add them all up...

 

We're talking about engines with 60 years!! think it's not cheap!!
"Speed costs money... how fast do you want to go"

 

In the June 1951 Hot Rod Magazine is a report on a dyno test of a full race 296" flathead. On straight alcohol it produced 218 hp and with 25% nitro 236 hp. On pump gas I think a flathead would be doing very well to dyno at 185 to 190 hp in racing tune and maybe 170 in a street motor.

Jerome

 

ok. well ive concluded that if the truck fires up and runs consistently to drive it, and while im driving it, ill buy the trans and adapters, headers, intake n carbs, cam,and when im ready, like this winter, ill do all the work at one time like the earlier mentioned post. i guess my lack of knowledge with flatheads has shown, i think that if i want hp, ill go sbc. but for cruisability, authenticity, and nostalgia ill use the flathead. so next opinion, whats the best sounding exhaust on one? i like the sound of the one that i attached the vid link to my earlier post. and yes as far as work goes, i work in a small aviation shop so i have access to alot of tools, if i bore it or any kinda block work ill have a pro do it. but any other the other stuff i can handle. and how hard/ what all do i change to convert it to 12v? i know like solenoids, fuses, battery, starter, and replace the generator with an alt.

 

It's simple, if you like the flathead, do it, I enjoy every time I touch one of his pieces, because I like what I do, and learn , notice that in my country there's not a speed shop to buy parts, but still I do , I always predispose to the old, because it has more soul than the other in my opinion...
cheap, is expensive! SBC What is this?

 

I'd highly recommend getting a book from Roadrunner Engineering. Joe Abbin is THE authority on dyno proven power from flatheads. Dyno proven 335 hp with a blower.

I'd say others may be equal to his experience and knowledge, but it would be hard to say anyone is better.

 

I've been privy to seeing 3 flatheads on the same dyno here in Northern Cal.
First was 284 CI, traditional build 202 HP. Customer unhappy.
Second was 313 CI, very high dollar, Hilborn injected 192 HP. Customer happy
Third was another 280 CI, 177 HP. Customer unhappy.
IMO, the highest horse power naturally aspirated flathead was built by Ken Kloth. It made about 280 HP on 267 CI. BUT, you wouldn't want to try to drive it to the store. It really was a race only engine, idling at about 1600 rpm. His record has stood for more than 20 yrs.

 

Those engines, if that should be hot, I do not think that they are stable to drive on the streets

 

Visit Billben Flatheader Forum. Guys dedicated to all things flathead. A few have books out that will tell you what works and what's a waste of time and $$, especially for a street motor. My '52 8BA (.040) with 4 bbl, Red's Headers, 252d cam, Edelbrock heads, MSD plug and play dizzie probably gained about 20-30 hp, but I'm not counting. Fires right up, goes anywhere, 19mpg on a trip (t-5 and 3.55 8" rear) and the only thing that gets mor attention in the cruise ins are other flatheads.
Dual exhausts help a lot with glasspacs for the sound, headers too. You can shave the original heads a bit to increase compression, stay around 8.5 to 1 max and save on aluminum heads that only increase water capacity.
Best advice is to ask what books to read for flathead building. If power is what you want, keep it all Ford, they fit in there too.
RB

 

sbc- small block chevrolet. sorry i never thought about people from other countries. its a real big thing over here, if you want cheap, simple and reliable stuff a chevy in it. nothing against small block chevys, because they are great engines, but people get carried away with sticking them in anything. and i mean everything. go carts,old fords, old mopar, jaguars, airplanes( yes im not kidding people have used them in small airplanes) shoot they even stick them in motorcycles.

 

well i drove down to stuttgart,Ar where its located and looked at it in person. its more than i can handle with college and work. its an awesome builder. complete truck, in good shape for its age. he wants $800 without the flathead or $1000 with it. new gas and new plugs and he said it would run. there is rust, but nothing that someone couldnt fix. amazingly the cab was in really good shape, with everything intact. and the floorboards were solid. i honestly think it would be too much for me to handle. if i can sell it for him without the engine i get to keep the engine.