340 vs 360

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Realest said:
aww i love topics like these lol its kind of hard to tell how excited you boys get over engines and the quest for power. NOT . Aside from all the great knowledge i can gain from all of you. It sure is great to see i am not the only one so excited by this stuff. Most people involved in my daily life just roll their eyes when i start talking about the car. Given i may talk about it tons...

bob-how much $$ do you have invested in your awaiting engine?
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I have every bit of $2900.00 in it right now and I yet to buy a carb and motor mounts. I reused some parts off my 273. I sold my 273 block, timing chain cover, carb to John, aka lonegone, for his sweet looking red convertable and I sold the intake and the rockers and shafts to other members here. I sold the cam on e-bay. I got a little over $600.00 for my 273 parts. So I have $2300.00 of new money in it. Remember a 340 car will have a higher resale value than a 360 car, all things being equal. That's one of the reasons I spent $450.00 for a 340 block instead of going to a junkyard and picking up a 360 block for $125.00. Bob
 
stroker mike said:
here's a thought, 340 block, 360 crank turned down, 360 pistons .060 over, 372 cubic inches on the cheap. There's your 400 rwhp with the right cam and heads. Best of both, minus the forged crank. Assembly would have to be internally balanced like 340. External balance requires either a b&m flexplate with a neutral balance converter or the weight kit from mopar. also requires 360 damper.
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I wouldn't call that on the cheap! You are going to pay more for the 340 block than a 360 block. You are going to pay more to have the 360 crank turned down to 340 size than turned to a standard undersize (if it even needs it). You are going to pay a whole lot more to internally balance a cast 360 crank than to pick up an external balance b&m flexplate and damper. AND, you only gain about 5 cubes over a 30 over 360.
 
Excited???Who's excited?I'mnotexcited!!Ack!=P~ the pistons would be off the shelf, getting the crank cut would be about 150, and you'd have to balance it either way, if you upgrade said parts, so what's the dif? Count 225 for that, and the little monster would be ready to feed! As opposed to a kit, which would cost more. There are 340 block's on craigslist out here all the time!! But hey, I'm no expert. I just love this stuff!!
 
I am just saying you could build a 360 for less money than stroking a 340 to 372. The Mallory needed to do an internal balance is very very expensive and would likely double the cost of the balancing. Plus you can get a complete rebuildable 360 for $150. Unless you lucked out you will not find a 340 block that cheap.

All said an done you would have an engine that cost considerable more and would not provide any benefit.
 
A 360 crank into a 340 for a stroker is cost effective if you have the abilty to machine or a sugar daddy...er...sugar mommy.

The balanceing is the expensive part on this set up.
The best part id the possible larger bore and overboring of the 340.
But you know how I feel about overboreing. :bootysha:
 
cudaspaz said:
Good post.

I am at the point of what parts do I need to make my 3/30/70 360 block put out 500 ponies on the street and pump gas.

What would y'all recommend from carb to oil pan?

Keep in mind I'm no engine guy so acronyms will tilt my head like a dog.

It's going in a 67 barracuda notch with a cage, sub frame conectors, mini tubbed.
Built for the strip and street.
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I was just reading in the latest issue of Mopar Action that in answer to some tech Q, R. E. recommends 500 HP as the absolute upper limit on stock smallblock Mopars w/o getting into reliability issues ... cracked blocks, etc.

I am not at all knowledgeable in this area, just thought I share what I read.
 
Why would you use a 340 block if you are going to use .060 360 pistons. You would save the money on crank turning and the expense of a 340 block by using a 360 block to achieve the same bore and stroke. Is it just so you can say that it is a 340? or am I missing something?

Chuck
 
dartley said:
I was just reading in the latest issue of Mopar Action that in answer to some tech Q, R. E. recommends 500 HP as the absolute upper limit on stock smallblock Mopars w/o getting into reliability issues ... cracked blocks, etc.

I am not at all knowledgeable in this area, just thought I share what I read.
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Don't believe everything they print in magazines,my 416 stroker is based on a STOCK 340 block,and its putting out at least 520 h.p.,and has almost 2 seasons of racing on it,without any issues,its all in the prep work and using a good block...
 
I would ask what they mean by a stock block. If they mean stock fasteners than yes I wouldn't go any higher than 500hp, but then I wouldn't go any higher than stock hp with stock fasteners.

I have studs, both head and main and have my block half filled with hard blok so technically it isn't "stock" but then again it isn't a high dollar race block and it didn't take much work for it to handle the 550 I am putting thru it for 3 seasons.

Like 340srule is saying, it is all in the details.
Chuck
 
I don’t have the time, tools or place to build an engine properly. So I am looking to buy one already screwed together. Plus I don’t want be doing it with a learning curve.
I’ve seem people that actually knew what they were doing have to pull one back out to fix something.
So I’d appreciate help on the Chrysler crate engines relating to street reliability if anyone knows.

It seems to me that once the engine displacement is modified, it is technically neither a “340” or “360” anymore. It is something else.

Put another way; imagine if someone had no knowledge of what is being discussed here.
If all they understood were cubic inches, this would be very confusing.

Put even another way; how many time have we been ask if our car has a (fill in the blank engine) by someone that is clueless other than the reputation to that particular cubic inch engine?


So I suppose the question is which block is best to modify.
And that must involve a cost/availability/use discussion.
 
To answer the question - "what do they mean by a stock block?" ... The answer might be online @MA ... Q&A, did not check. Otherwise, it's in the latest issue in case you care to look. I don't want to take liberties with what R.E. wrote.

Nah, I just checked and it's not on the site. But it's under the title "BLO'D UP", and is the 1st Q&A in "Tech Topics", Dec '07.
 
turning a 360 crank and putting it into a 340 will give you the ability to use a substantially larger bore than you could with a 360. I have seen build with a 4.080 bore 340, but a 4.040 is about the most you want to push a 360 for street strip duty. The difference is about 12-14 cubic inches, my friend. There is no replacement for displacement, that's what my psychologist told me...LOL The reason you use 360 pistons off the shelf is the difference in compression height, or how close the pin is to the face of the piston. Off the shelf pistons are cheaper than stroker pistons. Right? 360 stroke, 3.58, 360 piston like KB's at an .060-.080 overbore, and you got a 372+ for less $$!!But you can't get a 360 block that will safely take an overbore of .080. Make sense? Thus, 340 block, $400, craigslist. Over all, still cheaper than a 408. Just my humble opinion, 340mopar, but it bears investigation. An extra 200 bucks for 12 more cubic inches? I think that's a good deal, myself.
 
But a 30 over 360 is 367 cubes so for all the additional expense of turning a 360 crank down and doing the balancing you gain 5 cubic inches. Not a a cost effective choice in my book.

Factor in a $400 340 block verse a $150-$200 complete 360, all the additional expense of machining a 360 crank to fit a 340, the mallory metal needed for the internal blance you mention it seems you are very close to the $900 you can can get a 408 stroker kit from folks like Hughes.
 
stroker mike said:
turning a 360 crank and putting it into a 340 will give you the ability to use a substantially larger bore than you could with a 360. I have seen build with a 4.080 bore 340, but a 4.040 is about the most you want to push a 360 for street strip duty. The difference is about 12-14 cubic inches, my friend. There is no replacement for displacement, that's what my psychologist told me...LOL The reason you use 360 pistons off the shelf is the difference in compression height, or how close the pin is to the face of the piston. Off the shelf pistons are cheaper than stroker pistons. Right? 360 stroke, 3.58, 360 piston like KB's at an .060-.080 overbore, and you got a 372+ for less $$!!But you can't get a 360 block that will safely take an overbore of .080. Make sense? Thus, 340 block, $400, craigslist. Over all, still cheaper than a 408. Just my humble opinion, 340mopar, but it bears investigation. An extra 200 bucks for 12 more cubic inches? I think that's a good deal, myself.
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He was talking about using off the shelf .060 360 pistons so the displacement would be the same. Sure the 360 would be .060 over and the 340 would be .020 over but that is of no issue other than it may be very difficult to find a 340 block that is a standard bore so it would clean up at .020. As for boring a 360 .060 over, it is of no issue. My 340 is .060 over and is just fine. I sonic check all of my blocks and haven't found one yet that couldn't go .060.

One other thing that hasn't been brought up is the 360 crank will be stronger with the 360 size mains than it will with 340 size mains.


Chuck
 
stroker mike said:
here's a thought, 340 block, 360 crank turned down, 360 pistons .060 over, 372 cubic inches on the cheap. There's your 400 rwhp with the right cam and heads. Best of both, minus the forged crank. Assembly would have to be internally balanced like 340.

Thats mine. 60 over 340. 3.58 crank=378 inch. BTW my enging guy says cast is softer and better for the twist. til you get up into the hi dollar forged cranks.

Been thinking bout selling mine. Over 125 guys looked at my post in parts for sale. No thoughts on its value..
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Here's what my buddy did. 340 .020 over for 4.060. 3.58 steel crank from MP. JE 360 .060 over flattop pistons. 11:1 at 371+ cubic inches. Eddie heads ported by Ray Barton, flow 275 on the intake side. Solid cam, 252/257 @.050, .550.557 lift. 340 victor gasket matched and a 750 mighty demon. 550+ hp, 510 tq. rev's to 6700-6800 no prob. In a 68 cuda fastback with A833 and 4.10's, we're expecting 11's.
 
The crank was $400, pistons were around 800, I can't remember. zero deck 9.5 Diamond, a couple sticks of mallory. I think Im into it around $4500, already owning the complete engine.
 
Sell the 340 block and use it to fund building the 360. You will get a lot more money than selling the 360 block.
 
At rock bottom, and understand the limitations of that choice, a 408 or 416 can be built for about $500 more than a 340 or 360. It's not how I like to build, but sometimes that's what the customer wants.

It breaks down like this: Scat 4" crank $300. Sonic test block $175. Clearance block $75. Redone factory rods $225. Hypereutectic pistons $300. Internal balance $450 w/Mallory. Total of $1525.

vs: factory crank redone $300. Recon'd factory rods $225. Hypereutectic pistons $280. Internal balance $300. Total of $1105

Both of these would obviously need the rest of what I consider "required" machining. Neither of these are crazy builds, but the hypers on a 4" crank run the risk of pulling apart over 6K rpm because the piston speeds go way up, and the cheap Scat crank is one of the weakest ones out there so it can flex at higher power levels. So I set a 5500rpm max rule on them. However, under 5500, these will far outpower a 360 or 340. The hypers will not reach the "fly apart" rpm threshold on a 3.58 crank until you get past 7K rpm. And it basically wont be reached on a 3.31 stroke. Sell the 340 block, build a 408 off that 360. A 408 turned to 5000rpm will last as long as a 360 that has to turn to 6K to get the same ETs.
 
340mopar said:
I would ask what they mean by a stock block. If they mean stock fasteners than yes I wouldn't go any higher than 500hp, but then I wouldn't go any higher than stock hp with stock fasteners.

I have studs, both head and main and have my block half filled with hard blok so technically it isn't "stock" but then again it isn't a high dollar race block and it didn't take much work for it to handle the 550 I am putting thru it for 3 seasons.

Like 340srule is saying, it is all in the details.
Chuck
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340mopar and 340srule - So it's clear that not everyone agrees with R. E. (MoparAction). I notice that it appears there is a lot of disagreement over his stand on brake fluid type too, as well as 8.75 wheel bearing choice - it seems according to the latest issue that I referred to, the Green bearings come into question, and yet I notice that most folks ... that's what they are using nowdays.

I am not attempting to create dissension at all - I am only interested in gaining the most useful knowledge available.
 
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