Long/short block flatty trans mounts?

[40P10touring sedan]

I've kind of let the cat out of the bag around here, so I'll just step all the way out into the spot light now and start...I plan on installing a 265 long block flathead into my currently 201 powered short block 40 plymouth touring sedan. I toyed with V8 power for bigger displacement and HP, but that really wasn't what I wanted...I wanted a flathead but with more power since I plan on adding AC. When I found a 265 motor my problem was solved...of course, another problem is started with trying to fit it in easily enough, but everything in life is a trade off I guess.

Anyway, my questions;

-Is there a difference between trans bolt holes from a 23" short block to a 25" long block? I understand that between makes there were thicker crank bosses where the oem trans of choice for a given model and year was mounted, but what about bolt patterns? Are the adaptors for short blocks the same as for long blocks- bolt on wise?

-What's the accepted carb cfm for a 265..yes, stock was a single carb, but what's the max I should/could go- I plan on a head shave of roughly .020 or so, twin carbs{possibly 3}, dual exhaust{moose/langdon?} and forged pistons. Maybe a cam regrind. I also want the crank completely cross drilled for longivity sake and block off the lil oilers on the rods to keep pressure up.

-Is a langdon HEI dizzy worth it or should I do the pertronix conversion...I'd like to get away from points. I don't honestly know if the langdon dizzy will work on the long block since I've heard the LB and SB dizzys are different{probably in reach}..along also with his dual exhaust...I need to ask him.

-Alot of you gents here seem to prefer sticks when it comes to trans conversions, but I'm looking at the mopar A508 or A518 4 speed autos for my ride and most liekly a lokar floor shifter if I can' use the steering shifter as the sellect at that point. The 265 will be a 30ish% increase over the 201 and I can expect the auto trans will loose about 20-25% of that power thru it's process...I just wanted the bigger motor to run the AC better and some extra ponies never really hurts in other departments as well.

I want to get a new radiator...I'll need a slightly narrower rad anyway when I relocate it farther forward...like 1" narrower. I'm thinking about an all aluminum 2 or 3 row from an ebay source, http://www.ebay.com/itm/221014568473?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649, this one is just an idea for the low height filler, has bowtie outlets that closely match our mopar pattern{lower RH out tube-I can swing the inlet to the new upper LH tube rather than oem center}- I haven't checked size, like I said I'm just trying to get sources for ideas at the moment. Anyone use these guys with good success. With the auto trans route I will need some trans cooler hook ups in a radiator so I have to plan for that ahead of time.

That's all I can think of for now for questions...anyone wish to comment on any of this feel free please.

[40P10touring sedan]

Here's a pic of my current set up- a 23" 201 in my 40 plymouth.

I removed the nose access panel and see alot of room to move the radiator forward, but my big issue is that filler cap on the oem radiator, to move the rad 2" forward will be an interferance issue with that cap. Aside from more efficiant cooling this is why I see the need for a new rad...with a lower filler neck.

[40P10touring sedan]

Access panel removed shots...awhfully quiet around this thread...

Here you can see a 40 plymouth has a top cross bar that holds the hood support, the radiator can be moved in front of that.

In this bottom shot pic you can see the only real thing in the way is the splash apron and that can be replaced with a new piece thats shortened for a rad relocation.

Since I "plan" on AC being added I'm going to have to research what an AC condensor core size is going to be, or what's available, and see what kind of room I have for that too...when in rome....and planning ahead....

...Oh, and I now see that I could actually go a tad wider with a new rad, if need be, since the side aprons go wider as shown in the above pics...or stay I can stay stock sized.

Edited May 11, 2012 by 40P10touring sedan

[Plymouthy Adams]

the A5** series of tranmissions are designed to operate at 200 RPM less that of max torque to allow the fluxation of sligt inclines like overpasses not to knock the car out of OD. Now for the flattie that torque curve is at the 1600 RPM level..way way low for the optimum performance of the automatic. You will need to crunch the numbers to get your final rear gearing and tire size to obtain this. When torque runs out, HP must be available on tap to do the ork..This needed torque is the reason that the early 2.2 and 2.5 four cylinder cars did not get the automatic OD tranny but had the basic torqueflite that was reconfigured for FWD. Another thing is the loss of power that you will get with the use of the torque converter, AC compressor and the ultimate drag that the alternator will put on the engine as it feeds the AC inside fan, compressor clutch and hopefully your electric fan. A larger fixed position fan would be necessary for the flattie and again you looking at a great HP robber there also. The 4 speed auto will have to be from an earlier generation truck series and must have the suffix RH, Rear drive, Hydraulic shift. The A5** series tranmission were the first to break Mopar's golden rule that all trannies, auto or manual will fit the same same cross member as the distance was the same on all from housing to pad..but I amsure you know the corss member thing is going to be custom with any tranny change you do.

The 265 can be built quite to suit your purposes..added carburation, better cam etc will get you in the ball park. Don Coatney has a 265 DeSoto engine built to perform and be super reliable at the same time..his thread is here for the searching..you can glean a lot of info from the arcives. His built is documented pretty well here and has been repeated in various other article searchable with key words. Some may be on the earlier forum also..a disc with that info is available from GTK yet, I think ..

I am doing a P15 build now with swap components..the AC I just about have finished up..there 265 will have you forward mounting the radiator, your condenser will be just in front of that..you whave approx 7 inches to play with (P15) but only approx 20 inches without apron modification to install your components forward of the support

Edited May 12, 2012 by Tim Adams

[Robert Horne]

The radiator you mentioned on ebay, have very other radiators available that may be a good choice for your upgrades....

http://www.ebay.com/itm/1940-1952-Plymouth-Cars-Champion-Cooling-Systems-3-Row-Alum-Radiator-/320899362921?pt=Motors_Car_Truck_Parts_Accessories&hash=item4ab717b069

This one is listed as a 3 row, for 1940 to 1952 Plymouth.

[40P10touring sedan]

1}the A5** series of tranmissions are designed to operate at 200 RPM less that of max torque to allow the fluxation of sligt inclines like overpasses not to knock the car out of OD. Now for the flattie that torque curve is at the 1600 RPM level..way way low for the optimum performance of the automatic.

2} Another thing is the loss of power that you will get with the use of the torque converter, AC compressor and the ultimate drag that the alternator will put on the engine as it feeds the AC inside fan, compressor clutch and hopefully your electric fan.

3} A larger fixed position fan would be necessary for the flattie and again you looking at a great HP robber there also. The 4 speed auto will have to be from an earlier generation truck series and must have the suffix RH, Rear drive, Hydraulic shift.

4}The A5** series tranmission were the first to break Mopar's golden rule that all trannies, auto or manual will fit the same same cross member as the distance was the same on all from housing to pad..but I amsure you know the corss member thing is going to be custom with any tranny change you do.

5}I am doing a P15 build now with swap components..the AC I just about have finished up..there 265 will have you forward mounting the radiator, your condenser will be just in front of that..you whave approx 7 inches to play with (P15) but only approx 20 inches without apron modification to install your components forward of the support

1}Dang, the worst I was worried about was the hook up for the kickdown linkage...I hadn't honestly thought about "that".

2}I expected a 20-25% loss thru and auto and the accessories were a given as well- this is why I wanted a bigger flathead.

3}I planed on an electric fan given the needed room, I think I can do it.

4}Yeah, no oem rear "tail" mounts means a fabbed crossmember.

5}Just curious, what trans are you running? Honestly, for me being 6'4" with a 36" inseam, driving my car was tight for my legs when trying to steer{oem wheel}and clutch. Aside from trying to lower the seat alittle or moving it back{or both} that's why I liked the idea of an auto trans...add the wife said she would like to try driving it too{can't drive a stick to save her life-}.

[40P10touring sedan]

The radiator you mentioned on ebay, have very other radiators available that may be a good choice for your upgrades....

http://www.ebay.com/itm/1940-1952-Plymouth-Cars-Champion-Cooling-Systems-3-Row-Alum-Radiator-/320899362921?pt=Motors_Car_Truck_Parts_Accessories&hash=item4ab717b069

This one is listed as a 3 row, for 1940 to 1952 Plymouth.

Saw it - Got that one on the watch list too! The way the oem rad is made with that overhang and filler neck set way back would be an issue for moving that rad forward...this is why I'm looking for something easier to work with.

I PMed that company and asked if they have the "40" one with trans cooler fittings- no reply back yet. If they can come up with that rad with trans cooler fittings I'd pull the trigger on one.

[Don Coatney]

The bracket you mentioned was riveted to the radiator frame. I drilled out the rivets and bolted the bracket to the rear of the radiator. I forgot to mention that in the PM I sent you a few days ago. Here is a copy of that PM.

I installed a Desoto long block engine in my P-15 along with a Chevy T-5 overdrive transmission, Dodge Charger differential, GM alternator, dual carburetors, dual exhaust, dual point distributor, new driveshaft, disc brakes, dual chamber master cylinder, etc. This project took me about two years to get it on the road including a complete rebuild of the engine, transmission, and differential.

Fuel pump, water pump, carburetors, are interchangable. Distributor is not. I also have a full flow oil filter. Not sure if the engine you are getting is so equiped. If it is not I can tell you how to do it.

No firewall work necessary. I used a P-15 bellhousing that is a direct bolt up to the long block. I also used a P-15 flywheel. One issue I had with this combination of parts was the long block fluid drive crankshaft has a longer flange so the flywheel sat about 3/16" further back in the bellhousing. I had to machine some meat from the area of the starter motor mount on the bellhousing to obtain correct starter motor engagement with the flywheel.

I had to modify the oil pan as there was a clearance issue with the tie rod.

I had too modify the front crossmember to allow clearance for the vibration damper/pulley assembly.

I had to re drill the front "floating power" engine mount holes in the front crossmember.

I had to modify the lower radiator bracket in order to flip it and install the radiator two inches further forward. The original radiator is the same radiator used with the long block engine in the early Chryslers so no replacement was required. I did mount a thermostically controled pusher fan in front of the radiator and did not use the belt driven fan. I also had to trim the inner front fenders to allow clearance to install the repositioned radiator.

I am sure there are several more modifications I did that I forgot to mention. For pictures of all this visit my photobucket albums (Engine, T-5, radiator, oil pan, etc.) The link is below.

You must start this project with the attitude that "failure is not an option" as all of the problems you encounter can be addressed. Make sure you measure twice before doing anything that is not reversable. You may find that some of the things I had to do are not required on your car. And you may find a better way to do it. If so let me know so I can learn from your experiance.

I have driven my car over 40,000 miles and I am very happy with it.

Edited May 12, 2012 by Don Coatney

[Plymouthy Adams]

when I do upgrades I go all the way..I have a stock 54 Plymouth with the Powerflite..its very peppy even with the 3.73 gears..sometimes a 54 with good engine/tranny can be had for fair money..they have the 230 engine and will amaze you, mine will shift at about 53 mMPH into high just by holding the pedal down...according to the acceleration level you chose as tothe shift point...

for mods I have a few different setups here at the house..

383/727TF/2.72 ratio 8 3/4

360 police interceptor with 727 and 2.88 9 1/4 posi

3.9 Magnum/A500/2.94 8 1/4

3.7 Magnum/NV3500 close ratio 5 speed/3.55 8 1/4