Mopar flathead 6 motors- whats to be expected

Can I put a A-500 transmission on a 230 dodge flathead?
Do I need an adapter? ?

 

Yes you would need an adapter, go see "Wayfarer" on p15-d24.com, he is from Oregon, and builds adapter plates for flathead mopar 6s....

 

Put many miles on my old 55 dodge pickup with a flathead 6. The little low-side truck was light enough to be pretty peppy with that flathead.
I drove many, many miles in the Army with an M-37, 3/4 ton Dodge power wagon. Flathead 6, 4 speed and a governor to keep revs from killing the engine. We'd break off a pencil in the governor vacuum line to disable it and get 75 MPH from those things...never knew of one blowing up.
So, I get out of the military back to the states thinking I'll never have to drive one of those things again and my new mechanic's job came with my very own service-call truck ...yep, an old surplus M-37 complete with all the military stuff on the engine [snorkel kit, waterproof ignition, O.D. green paint, blackout lights etc etc]...it'd do 65 MPH. Drove it 'till 1987..
Those engines were reliable if not blindingly fast.

 

Question: I have a 55 Belvedere that has a 2 speed auto trans. Can I put a 318 in place of the 230 6 cylinder and use the same trans.?

 

Enjoyed your post, I have a 1955 Dodge pickup, with a 251 4 spd and mopar 8 1/4 diff with 3.23 gears. I have been thinking of going with a 318 automatic. But maybe I should keep the 6, and hop it up, and I know exactly where to get the speed parts too. These truly are great engines, and are super tough to boot. Mine is a little tired, probably could use a valve job, but has good oil pressure, and does not leak or burn any oil either.

Nope don't think so, you will need a 727 or 904 torqueflite trans..

 

Thanks flat six fix
Were can I get speed parts for this 230 flathead was thinking of making it turbo? Any idea you can share?

 

Go to this website for a lot of info, for general stuff and high perf flatties.
www.p15-d24.com

 

Minicadi and anyone else with a flathead six Chrysler product. Suggest you start by doing a compression test, checking the oil pressure and doing a tuneup. If you do not have good compression (over 100 PSI on all cylinders) and good oil pressure (35 PSI @ 30 in high) it is time for a rebuild or maybe just a ring and valve job.

Get it running right and see how you like it. You may be surprised you find you have all the power you need for everyday use. If not there are a few ways to get more power that don't cost a lot.

 

I was at a friends shop and we went to lunch in his ,51-52? Dodge pickup. He was telling me how simple the s-10 five speed went in it. I think he said he cut a little off the length of the shaft where it goes into the pilot bushing ,used a s-10 clutch disc with the Dodge pressure plate, he spot welded on four places of the housing that the throwout bearing sets on because it was too small , turned it to size in his lathe,drilled and bolted it on. I can get more info from him, he is not computerized.

 

The 251 is a pretty stout piece. The head can be cut to bring up compression, cam can be reground, electronic ignition is not difficult...bigger 2-bbl carb, better exhaust...all basic hot-rod stuff will make a huge difference. Just remember that you have a stroke about 8-feet long so it is not a hi-rpm engine.

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Thanks Rusty O'Toole
I'll do that compression text

 

Thanx 73RR, I am on the verge of a 318 LA smog motor swap in with 904 trans. But if I could get say 30-40 more hp, out of this engine, I may reconsider, if it doesn't bankrupt me.
I am also not that fond of my 4 spd trans, it's a T98 Acme built in Canada for the canadian market, so part are scarce.
I would like to do some kind of tranny swap, possibly if I keep the flattie, but need something to work with my mopar 8 1/4 diff with 3.23 gears....

 

You could easily be down 20 - 30 HP or more and never know it. The old flathead Chrysler products will continue to run without complaint in an advanced state of wear. They just get sluggish, hard to start and burn oil. Have seen them in use with 2 dead cylinders and the other 4 about half power. One owner showed me a broken piston, the mechanic was amazed the rod wasn't sticking thru the block but the motor didn't even knock.

 

Well yes, that statement is true, but hardly true in my case, at least i think.
Good oil pressure, half-way decent compression 100, does not burn oil, does not leak much oil, has some sticky or possibly a burnt valve.
But she most likely has miles, and the history like a lot of these is unknown.
I would say she has miles, but starts easy, but most likely has less power than a fresh engine.
My choice, is, drop in the 318 and 904 trans I have, or do a valve and ring job, or a rebuild, shave head, do a mild cam grind dual exhaust, maybe 3 carbs, or a deuce, that should liven her up a bit..

 

Mods like this should not break the bank and still produce respectable results. IIRC, the 25" head can be cut as much as 0.090". This, of course, depends on valve lift but these engines do not have much c/r to start with so any improvement will help.
Of course the 318-360 is a natural swap and the Magnum series are impressive in lighter trucks (as opposed to a 6,000lb Ram 1500).
If you want to look at an easy 5spd o/d for the L6 then check this out:
http://p15-d24.com/topic/17737-5-speed-not-t5/

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Yes and with these mods , what an increase of 30-40 hp. I also have wondered how well those 2 bbl carb adapters and a 2 bbl carb might work instead of multiple carbs?
Cam grind, how much lift and duration would be the outer limits for sane road operation and reliability?
Shaving the head, yes how much before issues with the chamber is diminished not allowing a good breathing and exhaling....thanx for your help

 

Just went to get gas for the truck. It is very cold here today, it actually snowed a bit last night, 45 f with a stiff 35-40 mph northwest wind.
I drove onto the highway, against this wind, very slow to get to speed once I shifted from 3rd to 4th, with the 3.23 gears in the diff.
Got to 60 mph, then had not trouble holding her their although the pedal was closer to the metal for this.
Now this is what I want to correct, I am not looking for big power or anything, but do want o cruise comfortably at 65-70 mph, which is good in thee parts, but do not want to spend the day getting there either.
So what do I do with this, speed parts and 5 spd, or swap into the V8 318 LA smogger

 

Smogger?
How about 477 hp from a stroked 318 (392 ci)? Engine Builder Magazine (www.enginebuildermag.com)
put a stroked 318 together for a charity auction and although they used a lot of non-stock parts the results were/are impressive. If a guy were to pick and choose from their list-o-parts a stout 318 should emerge.
However, a much more sane approach would be to just use a 360 with a warm cam since it starts with a lot more torque and that is what you are after.

As to the 251package, you probably do not want an o/d with the 3.23 rear gear.
I don't think you'll like the 2.26 final when in o/d.

choices...choices...choices......

 

Hmmmm, okay choice a), keep flattie and do the hop up, what can I expect over stock, for performance, highway cruising speeds and general 0-60 pickup speed.
Choice b) 318 with 904 trans.
3.23 rear diff, your right OD is not a good option, any suggestion on a modern 4 spd that may fit the bill?
With this stock LA 318, and say dual exhaust, would I notice a big difference in power and performance over my lfattie either stock or hopped up?
hey thanx again 73RR

 

Hey guys on my 230 I can start just fine,idles great very smooth then after a few minutes it shuts off and won't start it try to then it just turns over.
The next morning I put the key start just fine like nothing happen until a few minutes pass by then the same thing all over.
Could it be the fuel pump went bad???

 

need more info on this?
If your carb and fuel pump run dry, or the carb runs dry, and engine stalls. This may not start so easy unless the carb is primed, are you 12 volts?
How is the ignition coil, is it overheating and failing after running for a while, then is okay once it cools down again?

 

It's 12 volt and the coil not hot at all. Carb was rebuilt.
It turns on the next day like nothing

 

Actually I have carb and switch them out thing it was the carb but it's not that cause it happens with both carbs

 

well if you still have good spark, and no fuel, then it may be the fuel pump. When this happens, is your carb dry, pull the top off and have a look?
Install another fuel pump either another mechanical or an electric in line near the fuel tank pushing toward carb.
fuel and spark=fire, so which one is it, you need to do a process of elimination, from all components.

 

Yes it's drying, was thinking on a mr.gasket pump.

 

I think I would start by seeing if there is anything floating around in the gas tank, and be sure the fuel lines are good. Years ago, those big gas caps and large fill tubes were easy targets for kids putting all kinds of interesting stuff into the tanks. Some stuff can float around in the tank harmless until it gets sucked into the gas supply line and chokes off the fuel flow. Then after it sits a while, whatever was floating around floats away from the gas supply until it gets sucked in again. Been there, done that! Now I don't use old gas tanks, ever!

Flat Six Fix, what condition is the 318/904 in? Is it a used motor or a rebuilt motor? If your flathead is at 100 compression across the board, its ready for a rebuild! Back when these motors were built, very few of anything went very many miles, something with 100, 000 miles was very rare (even up into the early 70s). A 53 Dodge flathead 6 (230 CI car motor) had 7.1 : 1 compression from the factory. 103 hp @ 3600 rpm. An 85 Dodge (car) 318 is listed as 9.0:1 compression and 140 hp @ 3800 rpm and just for kicks, a 59 (Dodge car) flathead 6 (230 CI) has an 8.0:1 compression and is rated at 135 hp @ 3600. I don't know what changes, other then compression, were made between 52 and 59. Sounds to me like a fresh rebuild, a shaved head, a slight cam grind and a 2bbl carb will put that flathead 6 even (and maybe ahead of) a fresh unmodified 318. You can change out your current 4 speed with a made in USA 4 speed from the original time frame probably by bolting the other on in, but going modern will probably result in an adapter for the trans. If your buying an adapter, decide if to want an auto or a stick and buy accordingly. Gene

 

Thanx Gene, now regarding 100 psi compression, my engine was only 6.5:1 or 6.75:1, and the compression would not be a whole lot higher when new at 110 or so. 100 is not bad, but having said this, a fresh rebuild certainly may be the correct order of things.
The 318 is not rebuilt, to my knowledge, just a decent runner, so it might not be any damn good either. I love these 6s, and with a few more ponies and possibly a better trans, it would be a whole lot better.

 

Easiest answer is put in the V8. If you are comfortable driving your truck at 70 the V8 will make it a breeze. The six will always be straining unless you do some fairly extensive mods to engine and drive train.

 

I spent a few years pitting on a buddies sprint car and witnessed some real good racing and some real good parties and some real outrageous characters. One weekend we were at a distant track that I hadn't been to before. Walking through the pits I saw a cheesy old B class sprint with a dodge flattie, probably a 25" being in Canada. The floorboards were wire expanded mesh and the intake was a homemade affair that looked like it was made out of tomato cans. The carb, IIRC, was an ancient backdraft 2bbl off an early Olds or similar. Strictly low buck and back ally.

My old-timer buddy took offense at my smart ass remarks about the car, seems he knew the owner and had seen the thing in action many times. In former years he ran a pretty radical flattie Ford V8 and he said that tomato can Dodge more than held it's own. One night that car suddenly had a lot more power and in the main event he said if they both came out of the turn and booted it at the same time that old shitbox would accelerate away like his Ford was switched off.

Talking to the owner later he found out that he was a pro welder and a few days before that weekend he was sitting around with some buddies killing a few beers when the topic of rotating weight came up. Long and short of it, he whipped out the flattie, and then the crank and gas-axed all the counterweights off and did a real nice job of smoothing out the rough edges with an angle grinder. I don't know how long that crank lived, but she was unbeatable for that race.

 

To be honest she feels fine at 65 mph on good smooth highways, but the engine seems happiest at 55-60mph, even with the 3.23 diff. Most likely as been mentioned a tired engine, or my imagination..
Swap in V8 or hop up flathead,
318 swap,
-motor and trans mounts
-complete dual exhaust
-new rad and electric fan
-new carb and fuel pump
-new ignition parts, plugs wires etc
-driveshaft cut and balanced
-rad hoses
-lokar shifter and kick down cable
-gas pedal and linkage
-misc items, belts, fuel and trans lines etc

or 250 flathead freshen up and hop up,
-dual or tri carb intake, air breathers/filters
-split exhaust and exhaust system
-shave head
-ring and/or valve job possibly a complete rebuild
-possible trans upgrade

Well going to consider all of what may or may need doing, the wallet and time factors will dictate the situation...