Three motor options

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Newf

Newf

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Hi all,

This is my first Mopar and I have a few options that I wanted to run by you. I have a 72' Demon that I got with no power train and it came with some nice options. I'm missing the second fender tag for one and I would like to know what was on it. If you could tell me whats missing I would have a place to start. You probably would need to see the car but is there anything obviously missing?? Here's the first tag:

6 LM29:
Dodge Dart,Demon
Medium
2 Door Sports Hardtop

H2B: 340 240HP(net) 1-4BBL 8 CYL
1972
Dodge Main, Hamtramck, MI, USA

464627: Sequence number

E55: 340 cid 4 barrel V8 275hp
D34: Light Duty Automatic Transmission
EV2: Hemi Orange Exterior Color
F6XW: Trim - Luxury, Vinyl Bucket Seats, Black/White
TX9: Black Diamond Int. Door Frames
602: Build Date: June 02
C35507: Order number

EV2: Hemi Orange Top Color
C: Canada Specifications
A88: Interior Decor Group
B51: Power Brakes
C16: Console w/Woodgrain Panel
C56: Bucket Seats

G37: OS Dual Racing Mirrors
H31: Rear Window Defogger
J25: 3 Speed Wipers
J52: Inside Hood Release
J54: Sport Hood
L25: Trunk Lamp

L31: Hood/Fender Mounted Turn Signals
M21: Roof drip rail moldings
M25: Wide sill moldings
M31: Belt Moldings
M43: Grille Trim Moldings

N23: Electronic Ignition System
N41: Dual Exhaust
N42: Chrome Exhaust Tips
R11: Radio Solid State AM (2 Watts)
V21: Performance Hood Treatment
CTD: Codes Continued on 2nd Fender Tag

I have 3 motors to choose from but all need a full rebuild so it will probably cost the same or there abouts for all of them. A 340, 400 and a 440. The 340 is date correct but was detuned as I've been told to 8.5:1. I was thinking big block originally as that was the first motor that was given to me, and then I came across the 400 and was thinking 451 stroker, now I have come across this 72' 340 and I feel that it would be the right thing to re-unite this car with the motor it was born with (not matching #'s). I just want to build a daily driver so I'm not looking for monster torque or 600hp. Just a nice fast ride with a little jam under the hood. I know that ultimately it's my decision because I have to live with and drive it in the end. I am asking because I appreciate your opinions and I have options on the table. Your thoughts??

Cheers, Joe
 
Given those choices I would sell the 340 to fund putting the 440 crank in the 400.
 
Since the car was a factory 340 car I would put a 340 back in it. If it started out as a /6 I would say big block it, but given the fact that it did start out as a H code then I would personally put it back that way
 
Thanks for the responses guys, there is one more piece of information that I haven't shared. I haven't actually picked up the 340 yet or paid for it. He's asking $1000 firm and that's for a disassembled motor. That's where my doubts are. If I buy a de-tuned 340 just for the date correct motor and it needs to be rebuilt anyways, probably with new heads, that is one expensive block I'm thinking. Sell the 440 and 67' 440 crank, take the grand on top that i was going to spend on the 340 and put towards a stroker kit for the 400??
 
Well if you dont have the 340 already and it is a grand to get, I would go with a Big Block. As for which one, what are you trying to get out of the car, the guys on here can help steer you in the right direction. Also I wouldn't rule out a 451 yet, I always thought it would be cool to have a low deck stroker.
 
Do you really want the car to be a daily driver? A small block car will get better mileage, handle better, and be easier to work on (more space!) than a big block car.

I'd keep a small block in it. Talk to the guy with the 340, maybe you can talk him down a little. Heck maybe you can work out a partial trade with the 440.

There's a lot of extra expenses with going to a big block. You need a new transmission and driveshaft first off. Then, you'll want to upgrade your suspension for the extra weight and power- bigger torsion bars, sway bars if you don't have them, etc. Depending on how your car is set up, you may want to convert to disk brakes (no mention on your tag if your car has them) or even put bigger drums in the back. An all drum brake A body with a 451 would be pretty interesting to stop.

Even once everything is done, it'll cost more to drive the car- gas, insurance, tires, etc.

I'd sell the 400 and the 440 and buy the 340. Less money to spend on the rest of the car, less money to spend at the pump, and the added bonus of it being a date correct engine for the car. Since you seem to have a pretty highly optioned car, that might actually matter down the road if you sell the car at some point. Also, since the 340 is disassembled, the fact that it's a later "detuned" 340 won't matter. You'll be building it anyway, so you can up the compression when you install new pistons. No reason you couldn't have a 400 hp 340 (or more, but the price starts to go up), and it wouldn't cost anymore to build that than a 451 other than the cost of buying the 340. But even that you could offset some by selling the big blocks.
 
Well I don't know much about building them but I was thinking I would like to build the best streetable car as possible maybe 10:1 compression? I would definitely support the body some more with subframe connectors, lower rad support and maybe torque straps. I'm doing everything myself and although not a budget car I don't want to spend more than I have to not including paint i'm thinking 7-10K$. I would like to get into high 12's or low 13's. No juice though. If anyone got a quick formula for that with a stroked low deck
I would appreciate any info. Thanks again and since I haven't forked over the coin yet for the 340 I think I may just put that $$ to better use.

Thanks again,

Joe Welder
 
72bluNblu said:
Do you really want the car to be a daily driver? A small block car will get better mileage, handle better, and be easier to work on (more space!) than a big block car.

I'd keep a small block in it. Talk to the guy with the 340, maybe you can talk him down a little. Heck maybe you can work out a partial trade with the 440.

There's a lot of extra expenses with going to a big block. You need a new transmission and driveshaft first off. Then, you'll want to upgrade your suspension for the extra weight and power- bigger torsion bars, sway bars if you don't have them, etc. Depending on how your car is set up, you may want to convert to disk brakes (no mention on your tag if your car has them) or even put bigger drums in the back. An all drum brake A body with a 451 would be pretty interesting to stop.

Even once everything is done, it'll cost more to drive the car- gas, insurance, tires, etc.

I'd sell the 400 and the 440 and buy the 340. Less money to spend on the rest of the car, less money to spend at the pump, and the added bonus of it being a date correct engine for the car. Since you seem to have a pretty highly optioned car, that might actually matter down the road if you sell the car at some point. Also, since the 340 is disassembled, the fact that it's a later "detuned" 340 won't matter. You'll be building it anyway, so you can up the compression when you install new pistons. No reason you couldn't have a 400 hp 340 (or more, but the price starts to go up), and it wouldn't cost anymore to build that than a 451 other than the cost of buying the 340. But even that you could offset some by selling the big blocks.
Click to expand...

I did try to talk him down a bit, I couldn't get him to go down to even $800. That said, I like your reasoning as far as a daily driver with the 340 Gas up here in Canada is more than $4/Gallon. I like the idea of being able to work on it with room as well. And to top it off I have a buyer for both BB's if I decide to sell them, although its basically core block prices of $250 each. All the same, they cost me nothing so it would offset the 340 by $500.

To get 400Hp out of a 340 would I need to stroke it?? Also he says that he doesn't think its been punched out so if I go with that option should I go .060 or do just the minimun needed to clean up? Like I said I appreciate any and all info you guys share and it is much appreciated. I can do the work, i have the tools and mechanical inclination, just missing the knowledge base. I'm 35 and my parents didn't even own a car when I was growing up believe it or not. lol.

p.s. the Demon was factory front disks.

Joe Welder
 
400 hp out of a 340 isn't a big deal really, you could do it with a stock stroke engine. A 400 hp small block A-body will put you solidly in the 12's on the quarter mile. If you check out the racer's forum and look a the sticky for 12 second small block combo's you'll see plenty of ~400 hp small blocks with cars in the low 12's.

Although I have yet to fire the darn thing, I would guess the 340 I built for my Challenger will be good for close to 450 hp. I wouldn't worry about the bore either, the minimum needed to clean it up would be fine. My 340 is .060", but that really only gives you an extra 10 cubic inches. Since you're probably going to have to bore whatever you get, you're only talking about a couple of cubes between .030" over or .060" over, not worth the ability to rebuild the engine later.

This is what I would suggest:

Find yourself a 360. The 340 is nice, and date year correct would be cool, but you'll have to decide if its worth the extra money to you. 360's are usually a few hundred bucks for a core. Heck I've got one I'd sell you cheap but shipping to Canada would likely make it less than worthwhile. I do have a shipper though, so if you're really interested I'll call them.

Have the engine square decked and bored/honed with torque plates. Get a set of flat top pistons and set them up at zero deck for a 360 or a later 340. (Early 340's will end up with their pistons proud of the deck, that's the way they were set up.)

Set your compression ratio up at 10:1 by playing around with the chamber size and head gasket. Much more than that and you won't be able to run pump gas without worrying about it, too much less will hurt your horsepower.

For 400 hp you'll want 2.02/1.60 valves, and maybe a little clean up on the ports for stock heads. Porting really isn't needed for 400 hp even with stock 360 heads, just a good valve job, a little port matching, and maybe knocking off the big edges. If you've got extra money to spend, either have the stock heads ported, or pick up a set of the Indy small block heads.

Run a good intake, I like the Edelbrock Air Gap RPM, but the regular RPM would be fine and it'll give you a heat crossover. Probably 750 on the carb, it'll work with a smaller one but you might give up a little top end. Headers. And a good cam. I like Lunati's, but anything that's rated as a moderate to hot street cam will fit the bill. For the Lunati, that would be a 60403 (minimally) or 60404.

If you do stay with the 340, all of the same applies, you'll just be down a few cubes, so you'll have to go with a little more cam, or porting the heads, or both. But it can still be done with just basic stuff.

Check out all of the dynoed 360 builds listed here-
http://www.mopar1.us/dyno.html

They'll give you a pretty decent idea of what certain combo's will make. My 340 is set up with KB 243's, .018" over the deck ('68 340). Compression is 9.8:1, with 308 heads opened up for 2.02/1.60 valves and ported to flow 264 cfm at .500" lift. Stock forged crank, reconditioned rods, stock windage tray, Eddy Air Gap RPM intake, 1 3/4" headers, and a Lunati 60404. Pretty similar to "package 8" on that build list, the lunati has a little less duration, but more lift. Since my 340 (well, 349 now at .060") is down a few cubes I'm guessing it will be short of that dyno, but I'd still guess between 430 and 450 hp.
 
Another dyno run for a 360.

78 360 .040"
linehoned/decked, stock stroke cast crankshaft cut .010"/.020"
Eagle SIR rods, KB 107's, pocket ported 'J heads 1.94"/1.60" (flowed 231 at .480")
Professional Products Crosswind intake
Lunati VooDoo hydraulic cam #60404,
stock stamped rockers, Holley 750 dbl, 1 5/8" street style headers, Magnaflow mufflers, etc...

-440 hp, 460 ft lbs torque

Thread is over on Moparts, just search Lunati 60404 dyno.
 
Thank you very much for the info, I think a 360 would be a good candidate for my build. This helps me out big time. I found a 74' in a fury that would make a good donor. All he wants for it is $500 and its running.

I went to look at the 340 motor the other night and what a dreamer:violent1: this guy is. OK Mopars are pretty new to me and I hear 340's are rare but tell me what you think. First, motor is missing carb, intake, distributor, Cam, pushrods, lifters, two main bearing caps and half the rod caps and he wouldn't budge from $1000CAD. It was a 72' to boot with low comp pistons and a rusty cast crank.

So I have one more question about the 360, will it bolt right in without any changes to the K member?? Thanks again for the responses. Much appreciated.:cheers:

Joe Welder
 
For that price for a torn down 340, I would demand that he allows me to take it to a reputable machinist to have everything mic's and checked., but then again myself I don't think I would even consider buying at that price.
 
X2
72dart_swinger said:
since the car was a factory 340 car i would put a 340 back in it. If it started out as a /6 i would say big block it, but given the fact that it did start out as a h code then i would personally put it back that way
Click to expand...
 
A 360 will need a new engine mount on the passenger side, but no changes to the K member.

The seller of the 340 is dreaming. The missing carb, intake, cam etc. wouldn't bother me, all that is probably going to get replaced anyway. But the missing main caps are a problem, that adds a line bore to the price of your rebuild, and of course you'll have to buy the caps. And then you'd still need new rods too. Plus it kinda sounds like the engine isn't in the best condition, and that could come back and bite you somewhere else in the rebuild.

It'd be cool to get a date correct 340, but the 360 sounds like a way better deal.
 
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