Moparts
340 or 360?
Posted By: OhioMopar
340 or 360? - 12/15/13 03:29 PM
I bought a Mirada over the summer with a cast crank '73 340 in it. It had 567 heads, TRW 4-vlave relief stock replacement pistons, cast crank, etc. Nothing spectacular.
I wanted to raise the compression, better heads, etc. Then I got to thinking that if I'm going to buy new pistons, rods, heads, whatever, would it be better to sell the 340 to someone that wants to restore something and find a 360?
The intent for the car is to race it for a while until I put together an overdrive conversion for it, then make it a fun street/strip car. With parts being the same, what would you think? After reading through the 360 stock crank thread, how does a 340 cast crank compare? The 340 is .030, I don't know anything about if it was sonic tested or not.
Any advice? Would you run a 340 over a 360 in a Mirada? (Clearly, originality isn't a huge concern).
The 340 is a larger bore shorter stroke and a 360 is a 4.00 bore with a 3.58 stroke. Sorry off the top of my head I remember the 360 but not the 340.The big question is how much you want to spend and how fast you want to go? Mirada is a cool car but very heavy. If your going to use either motor and replacing the whole rotating assembly I would price out a stroker kit.I run a Scat stroker (408) forged kit and love it in my 73 360 block. My Aspen is all steel with factory interior and runs a high 10.
Posted By: 471Magnum
Re: 340 or 360? - 12/15/13 05:08 PM
If you're starting over on the short block, the 360 is a much more economical starting point. 360 cores are cheap (around here anyway). Turn the 340 into cash and build what you want.
Posted By: A/MP
Re: 340 or 360? - 12/15/13 05:12 PM
Do a search for 360 proven combos. Streetable low buck 350-400HP 360 builds. Best bang for the buck.
In my humble opinion the only reason to run a 340 is if it is the original engine for the car, or if you are trying to build a high RPM engine from factory parts (and then I would want a forged crank version).
Otherwise the 360 is the way to go. Plenty of 360 LA cores still around, and just as many loose 5.9 magnums in junkyards. The heavy car will also appreciate the extra torque from the longer stroke.
Posted By: MR_P_BODY
Re: 340 or 360? - 12/15/13 05:21 PM
Quote:
In my humble opinion the only reason to run a 340 is if it is the original engine for the car, or if you are trying to build a high RPM engine from factory parts (and then I would want a forged crank version).
Otherwise the 360 is the way to go. Plenty of 360 LA cores still around, and just as many loose 5.9 magnums in junkyards. The heavy car will also appreciate the extra torque from the longer stroke.
You want all the torque you can find for that car..
its not light... 360 is better for low end torque
Posted By: dizuster
Re: 340 or 360? - 12/15/13 06:45 PM
100% agree. Make all the torque you can. If it were me I'd save my penny's and buy a $350 cast 4" strokes crank. In the grand scheme of things it will be the best bang for your buck. And who really wants a cast crank 340 motor? Might not be worth as much as you think.
Posted By: OhioMopar
Re: 340 or 360? - 12/15/13 06:55 PM
Thanks guys. To answer the first question, right now I would just like to put it together and run 12.99. More for later of course.
As for the cast crank 340 not being worth as much as I think... I don't expect to retire off of it. I'm not looking for a mint. Actually with a longer stroke, I would maybe think of using the 340 block for the bore advantage. But I'm thinking stock stroke, as fast as I can go without emptying my retirement account.
Posted By: dizuster
Re: 340 or 360? - 12/15/13 07:03 PM
No offense meant. I just mean a cast crank 340 is likely worth less then a 360. Might not be worth the hassle of selling if you go the stroker route. Like I said for $350 you could probably leave the heads alone, put a cam in it, and meet your goal for cheap.
Posted By: OhioMopar
Re: 340 or 360? - 12/15/13 07:20 PM
No offense taken! I was gonna shop it around a bit and if no serious takers, it will get stroked later. I've been on the lookout for a local 360.
Posted By: Leon441
Re: 340 or 360? - 12/15/13 07:31 PM
Quote:
100% agree. Make all the torque you can. If it were me I'd save my penny's and buy a $350 cast 4" strokes crank. In the grand scheme of things it will be the best bang for your buck. And who really wants a cast crank 340 motor? Might not be worth as much as you think.
This was pretty much my thoughts.
I would advertise the 73' 340. If I could make the sale for a decent amount of money, go for it. Otherwise your 340 is just as easy to do a 4" crank on as anything else, if you wanted to. That car could really use something with a 4" stroke crank. The smaller mains are good for high RPM if you ever decided to do so. In your case probably no difference whatsoever between the 340 block and 360. If you do not plan on installing a crank the 360 comes with more stroke which would make the choice to go 360. Just depends on your abilities, money and desires.
Leon
Yep, the only thing I can get for my cast 340 cranks is scrap price!
But I'll trade any/all of my 360 block(s) for any and all the 340 blocks a guy wants to let go.
I see 360 longblocks for as little as $100 up here on CL. Some even state that they "must sell". Sell the 340, buy a 360 AND the 4" stroker crank. Go 408 and don't look back.
Got a J-body here too. And I'm still not all that convinced that they are so heavy. It's basically a stretched F-body, and then look at how lightduty the rear framerails are.
Still looks lighter than a B-body to me. Mine is a low-option car. If there was a fiberglass hood out there it would certainly help.
For example........
http://flint.craigslist.org/pts/4197686399.htmlhttp://saginaw.craigslist.org/pts/4232483109.htmlhttp://saginaw.craigslist.org/pts/4165804889.html...."Make offer" ahead.....
http://detroit.craigslist.org/wyn/pts/4233368125.html
Posted By: RBDART1
Re: 340 or 360? - 12/15/13 09:03 PM
Guess I'm the only one to buck the system but give me the 340 anyday,anywhere even with the cast crank..just old school I guess but I am not a big fan of the 360 especially the mag 360...if 12.99 is what your after then stick with the 340 that would be an easy combo,have the shortblk assembly balanced and then you can run a reg covertor and balancer...yes the 360 has potential but you already have the 340 and dollar for dollar I'd put my money on the 340,I've been around for along time and the legends you hear about the 340 aint lies or fairytales even in a little heavier cars,technology with better tires,convertors,cam profiles and electronics has come a long ways since they 1st came out...remember who the real king of the street was and it wasnt a 360...I rate mopar engines as such...440 comes in 1st and the 340 comes in at 2nd only because there aint no 1 1/2...and the hemi..well it wasnt for the average street guy and there have been many and I say many a hemi smoked by a 440[street]and 340's on the street from stoplight to stoplight would eat up about anything out there..so my vote is run the 340 in stock stroke or stroker has the upper hand regardless of what you hear...
No brainer to me. You already own the 340.
This is the race forum, not the resto forum, we don't care if you blow up a 340 block. lol...
Posted By: OhioMopar
Re: 340 or 360? - 12/15/13 09:30 PM
Quote:
No brainer to me. You already own the 340.
This is the race forum, not the resto forum, we don't care if you blow up a 340 block. lol...
I guess it has to come out anyway...
Thanks for all the replies, guys.(and gal)
Still trying not to go to a stroker crank just yet.
Posted By: RSNOMO
Re: 340 or 360? - 12/15/13 10:49 PM
I'll 'buck the system', also...
No 1) If yer gonna puff something, puff the 360...
No 2) Your SuperBee would appreciate it if you'd pay less attention to the Mirada(as in, gone)and more attention to the business at hand...
Makin' that Bee pretty...
(Say 'No' to hoarding)...
Posted By: OhioMopar
Re: 340 or 360? - 12/15/13 11:11 PM
Now that's hitting below the belt!
Just remember Hoarders don't live any longer than anyone else. Somebody needs to store the old stuff for future needs of others!
W/o getting into the age old "340 vs 360" debate. Those legendary 340's that slayed on the street/strip scene were very likely in a light A-body with good gearing, conv., cfm, comp., cam.
It really comes down to the whole package, what you have to start with and where your budget best lets you throw your money at. I'd rather build a stroker ($) and run a milder gearset and converter.
ever read the story about the guy who sold his livestock farm to go diamond hunting?
the lady that bought the livestock farm found the worlds largest diamond one day while gardening.
I would have the 340 block sonic checked first and foremost before you go do anything. it might just check out better than any of the 360 you end up with.
cost after that to do what you want would be the same.
a stock bore 340 is 4.04" bore . 3.31" stroke (exact same as 318)
stock 360 is 4.00" and crank is 3.58" the crank journals on a 360 block are different so cranks wont swap..(common knowledge)
but to bore a 360 to 4.04 you have to remove material...and most likely end up with a thinner cyl wall..
Sonic check the 340 first..if its not good on the majors..then look for the 360..
but in any case i would source the best bore thickness block in the equation..
just my
Posted By: voigtspeed
Re: 340 or 360? - 12/16/13 05:00 AM
If the engine you have is still solid throw in a boost frendly cam and turbo it!
Best power for the price. The shorter stroke will help you hook the tires and when the boost comes on it will not feel like a little 340 anymore.........................
Posted By: OhioMopar
Re: 340 or 360? - 12/16/13 03:29 PM
Quote:
If the engine you have is still solid throw in a boost frendly cam and turbo it!
Best power for the price. The shorter stroke will help you hook the tires and when the boost comes on it will not feel like a little 340 anymore.........................
Not sure a turbo is in the budget. I've nnever really looked into it.
Posted By: J_BODY
Re: 340 or 360? - 12/16/13 03:52 PM
My Mirada was pretty much gutted. single race seat, full cage, still had the dash, factory door panels, glass, pwr windows, aluminum head RB, 727, D-60 rear and tipped the scales at 3380 with me in it
Posted By: fishy340
Re: 340 or 360? - 12/16/13 04:30 PM
my 340 w a 4" crank make 540+ tq,i use to shift it at 5800 to 6000rpm w eddie truly untouched heads.
Posted By: OhioMopar
Re: 340 or 360? - 12/16/13 06:44 PM
Quote:
My Mirada was pretty much gutted. single race seat, full cage, still had the dash, factory door panels, glass, pwr windows, aluminum head RB, 727, D-60 rear and tipped the scales at 3380 with me in it
I'm guessing mine is a bit more portly than that! Lol.
Quote:
Quote:
My Mirada was pretty much gutted. single race seat, full cage, still had the dash, factory door panels, glass, pwr windows, aluminum head RB, 727, D-60 rear and tipped the scales at 3380 with me in it
I'm guessing mine is a bit more portly than that! Lol.
A "full cage" and Dana 60 add a lot of weight over a stock 7&1/4. Alum head RB vs ironhead smallblock is probably/nearly neglible. Power windows didn't get lighter until most OEM's got away from the scissor style mechanism and went "tape/gear drive" in the mid80's. If the driver is in the 180+ range you're looking at 3200 for the vehicle. I'll assume gutted means no a/c & heater components, no wiper system, no p/s, no p/b and ?????
Posted By: SLOW67
Re: 340 or 360? - 12/17/13 02:38 AM
Quote:
Quote:
If the engine you have is still solid throw in a boost frendly cam and turbo it!
Best power for the price. The shorter stroke will help you hook the tires and when the boost comes on it will not feel like a little 340 anymore.........................
Not sure a turbo is in the budget. I've nnever really looked into it.
It's cheaper than building a motor To build a 400hp 360 it was going to cost me,machine work included, around 3k. Thats for decent parts and the only machine shop around here I trust isn't cheap. I probably have $1500 or less in my turbo system and that includes upgrading my fuel system at the same time.
Your going to need alot of motor or some kind of power adder to motivate a 4000lb car
Posted By: jyrki
Re: 340 or 360? - 12/17/13 10:42 AM
I would retain the 340, then later stroke it. You don't see much difference betweeb the budget 340 and budget 360. I built a .030" over 340 stroker a couple of years ago, stroker kit was 1200 at Muscle motors, adjusted the quench, homeported the heads and installed a comp cams flat tappet XE 285 cam and that's about it with some attention top details. Factory intake, factory exhaust manifolds etc. 416 cu in with very civilized manners, 9.5:1 CR, made 410 hp through original exhaust and 440 with 1 5/8" primary headers and 2.5" duals. Should relatively easily run sub 13 sec et's even with a compromise gearing and converter and look stock.
Posted By: OhioMopar
Re: 340 or 360? - 12/17/13 02:44 PM
Thanks again for all the replies. I still haven't decided, but I'm keeping my eyes and options open. Later 340's don't see to go for much and stick around for sale for quite a while.
I've had 340 and 360 short blocks in the same car, with the same heads, cam, intake, carb etc. and this was the difference. The 340 ran 10.44 and the 360 ran 10.46. The difference was the 340 was being twisted to 8,000 while the 360 was only twisted to 7200. The 360 left harder but didn't have the top end charge of the 340. I used a 4600 converter and 5.13 gears with the 340 and a 4200 converter and 4.86 gears with the 360. The 360 was certainly not as hard on the valvetrain as the 340 but being a bracket car running at the bottom of its class I really liked the top end charge of the 340. But the bottom line is if you are going to stroke it anyway it's not going to matter.
Posted By: OhioMopar
Re: 340 or 360? - 12/17/13 03:30 PM
Thanks! I really enjoy the experience and knowledge here.
Posted By: 11secdart
Re: 340 or 360? - 12/18/13 04:16 AM
I felt the opposite after running 340s for years , I went to a 360 ( crate short block) and felt like the 360 pulled better in high gear , using the same W2 heads I currently use., the 340 was 12.5 to 1 comp. with a 627 lift roller cam, my current 360 is 11 .5 to 1 comp with a 590 lift mechanical cam and it made more H.P. and torque. in the same car, same convertor and gears the 360 has gone about 3-4 tenths quicker.
Posted By: RobX4406
Re: 340 or 360? - 12/18/13 05:06 AM
Quote:
Later 340's don't see to go for much and stick around for sale for quite a while.
If the 340 runs it's a 1200-1500 engine. My friend just sold a 73 cast crank 340 with air gap and a 484 cam in it for 1600.
That one 360 with the aluminum intake/carb, looks like an LD4b, for 150ish is a steal.
Posted By: sportfury70
Re: 340 or 360? - 12/18/13 05:45 PM