340 long block or 360 short block

[George G. Leverette]

Had a post looking for suggestions on going with the 340 long block from Autozone or the 360 short block from MP. Well I got the 360 short block and the following expense and experience.
P4876908 Engine $1.500.00
P3690715 oil pump drive shaft $32.70
P4120613 bolt pkg oil pan $9.50
P4286589 oil pump $63.40
P5249559 water pump $67.15
P5249059 oil pan $132.45
P5007301 damper $210.00
P4007040 fuel pump $36.60
left motor mount $43.00
P4120692 overhaul gsket set $78.50
P3614321 lifters $94.40

Afraid to do the math because the 340 long block without me having a core would cost $1.800.00.

Most of the parts are here getting the engine ready for assembly and noticed the 360 block was stamped made in Mexico, no problem the damper stamped made in Canada, could accept that
turned the engine over to attach the oil pan a tag on the drain plug read made in Tiawan? maybe thats why the dip stick that came with the pan will not fit in the tube, a slight amount of overspray on the milled surface probably accounts for the parts of the block partically covered.

This is a used block milled to the maximum of 20 over with this information should I have:
Purchased the 340 long block
Purchased the 360 short block
Purchased the 360 300HP Magnum which was not available.

[pishta]

wow, 132 for an oil pan. MP I guess? I wonder if the 94.40 lifters are the same in a purple cam pack? 340 long block sounds sweet for 1800.

[451Mopar]

Have you ever looked at mail order (Jegs or Summit racing?)
360 Short Block $1,239.99
Crane or Comp Cams Performance Hydraulic lifters $69.95
Mopar oil pan package $99.95
Mopar oil pump $41.95 or Melling HV $39.95
Fel-Pro Gasket set FEL-KS2109 $59.69


I got a Stock 360 Dampner from the dealer and it was $120 (with my MOPAR car club discount.)

These price differences would have saved over $420, even with the order processing charge, but I'm not sure about shipping charges on the shortblock? Did you pay shipping charges on top the $1,500 for the engine?

[1972roadrunner]

$1,800 sounds VERY good for a 340!! i dumped over $4,000 into mine and DIDN'T get:

crank
rods
dist.
ignition
coil
fuel pump
intake
heads
carb
all fuel lines etc.
timing cover
headers
valve covers
any head work...

the only things we DID do was:

bore to .040 over
new pistons (full float rated @ 12.5:1 cr)
new piston rings
honed the cylinders
cam
lifters
roller rocker arms (adjustable aluminum)
pushrods (male-female)
bearings
water pump
home-made left motor mount bracket (less than $5)
oil pump
air cleaner cover
new breathers
new flex plate

heck, most things was small stuffs.... i'd personally go with the 340, but its your choice!! good luck with your new motor - which ever one you get!!

[Fast_Eddie]

This is a used block milled to the maximum of 20 over with this information should I have:

On what block??

340 block can easily go 40 over.

[George G. Leverette]

Fast Eddie the 20 over is for the 360 block which is the maximum recommended. the 340 blocks from Kragen, Pep Boys, Autozone are from the same source and could be 60 over which is the max for the 340. The 360 Crate is an all new engine.

[Doug Wilson]

I think you're into the 360 for around $2250... so far. I think $1800 for a 340 long block is a screamin' deal. I put over $7,000 into the 340 for the HELLFISH.

[George G. Leverette]

Doug you got the message, The best deal of all is the crate engines but availability is a problem.

[Doug Wilson]

I have no experience with the MOPAR crate engines, but am not a fan of them. Lots of comments in the different forums about very poor machining and parts installation. Also, I don't think that they are precision balanced. I like the 340 a lot more than the 360, and in your shoes would go for the 340 long block. Do you know what heads they use?

[Openroadracer]

I've got the same short block as you with about 4000 miles on it. Be sure to check it out real good before you install it. I didn't and wish I had.

[George G. Leverette]

Road Racer you got my attention, I havent installed the engine yet other than the dirty screw holes that needed tapping, the overspray on the milled surface and the lack of spray in some areas, what else should I be looking for?

[Openroadracer]

I'd check all the clearances on the bearings. The MP book on small block A engines P4876826 has a section on using Plastiguage. My engine has never had very good oil pressure, which I imagine is a result of too much clearance on the bearings. I've heard some horror stories of blocks missing bearings and others only making it 100-200 miles or so. I'll be pulling my engine this weekend because of low oil pressure and I've found way too much metal in the oil filter and a few little pieces in the bottom of the pan. Not what I hoped for with only 4000 miles.

[moparman318]

In your shoes I would have got the 340 simply because of price. But I would have checked out the source for info on quality though. If I was really wanting power I would have got a 360 short block. That way I could get some W2 heads and done the whole port polish thing. Then you also have more options. Heads and intake is where all the power is made anyways.

[Doug Wilson]

Originally posted by moparman318
If I was really wanting power I would have got a 360 short block. That way I could get some W2 heads and done the whole port polish thing. Then you also have more options. Heads and intake is where all the power is made anyways.

A 340 in a similar configuration, will out power a 360.

The bottom end can make lots of power also. And after all, the bottom end pretty much determines how long the engine will live. You can put all the trick stuff on top and if the engine only lasts a second and a half at full throttle, then what you did on the top is rather pointless.

W-2s also fit on 340s.

I'm not trying to pick a fight, it's just true. It's kinda like building a chebbie or a MOPAR - the MOPAR is going to cost more in most cases for the same power level. The 340 will usually cost more than the 360 - but with the same build will make more power.

[1972roadrunner]

isn't a 340 basically a stroker?? seein how its got a bigger bore than the 360, and a shorter stroke, thats the impression i get... basically its a stroker...

just sumthin to chew on...if i'm wrong sombody please correct me!!

is it possible to stroke a stroker??

[72Challenger]

You've got it backwards. "Stroker" implies that the stroke has been increased over stock - so if anything the 360 is a stroker 340 (after you punch it out 40 thou of course).

Doug, this is one of the few times I have to disagree with you. A 360 will respond to mods just the same as a 340, with more cubes (see above). The advantage to the 340 is the shorter stroke can wind higher at the absolute top end. Even at the track, the time spent at lower RPMs will give the advantage, if any, to the 360.

Obviously not all will agree...

[1972roadrunner]

? ok, so does a 350 chebby have more stroke than a 400 chebby? my dad builds 400 strokers that have 350 cranks in them.... if you don't know chebbies i understand....but i'm really confused

[Dart]

Hey George...

We have had three of those MP 360 Short Blocks. You had better check eveything - Rings, bearings, etc.

My first had std. bearings and a .010 under crank. The second was labled as a 10 to 1 but was a 9 to 1. The third lasted 5k miles before throwing a rod.

Those are cheap rebuilds. Some have new stuff, others don't. Those are basically re-manned warranty blocks with some new parts (maybe).

[Doug Wilson]

There you go.

[Doug Wilson]

RE: 340 vs 360 - Identical mods on both, in the same car and the 340 will trailer the 360. Identical dollars spent on both, in the same car and the 360 wins.

Race car - 340. 4X4 - 360. Tow rig - 360. Street car - 360.

The 340 is a bored 318. The 360 is a stroked 318. All 3 can be stroked and/or bored more than stock specs.

I was trying to compare sort-of-stock engines. I can see that is futile, as it always is, attempting to do this kinda thing.

My OPINION is that any small block I do will be a 340 base engine, and anything else will be a 400 or 440.

I will likely eat these words in the next 12 months or so. Oh, well...

You guys are starting to treat me like my wife does - or at least, one of them, did...

[Mopardad]

Built at the same compression ratio & all other pieces the same the 360 will kill the 340 every time ,don't matter street or race

[Doug Wilson]

You will put stock 360 rods through the block before the 340 starts to breathe hard.

[Mopardad]

And just why will that happen?? My son has been twisting his 360s over 7000 on a regular basis. You do know that the rod is the same as the 340 or do you mean because of the longer stroke. If its because of the longer stroke & cast crank that has never been a problem. The 360s like to run some RPMs too.

[1972roadrunner]

Originally posted by Mopardad
Built at the same compression ratio & all other pieces the same the 360 will kill the 340 every time ,don't matter street or race

doesn't a 340 have more cubes?? isn't a 360 more for RV/towing?? i just tend to disagree...

Originally posted by Doug Wilson
You will put stock 360 rods through the block before the 340 starts to breathe hard.

i agree with you...

Originally posted by Mopardad
You do know that the rod is the same as the 340 or do you mean because of the longer stroke.

thats what i would think...but then again, i'm only 16 and have a lot to learn yet...

[72Challenger]

72RR,

First of all, let me say I respect that you admit what you don't know and are willing to learn. I have a lot to learn myself, even though I've been working on Mopars more than twice as long as you've been alive.

To answer some of your questions:

First let's get the Chevy crap out of the way. A 350 has a 4" bore and a 3.48" stroke. A 400 has a 4.125" bore and a 3.75" stroke. To make a 383 Chevy stroker, you put a 400 crank in a 350 block. If you're dad is putting 350 cranks in 400 blocks he's a magician, because the journal sizes are larger in the 400, the cranks have to be turned down to fit in a 350 block. That would be like putting a 340 crank in a 360 block, can't be done.

Now for the real car stuff - MOPARS!

doesn't a 340 have more cubes??

Please just think about what you wrote. A 340 has 20 less cubes than a 360, it's just simple arithmetic.

As for the 360 throwing rods, a longer stroke means faster piston speeds at any given RPM. So yes, in equally prepared engines, the 360 will fail at a lower RPM than the 340. But up to that point, the 360 is making more power at any RPM than the 340 will. That's why in EQUALLY PREPARED engines, the 360 will win every time, unless you've figured out how to launch at 7000 RPM.

Doug, I'm puzzled by the statement you made.

"Identical mods on both, in the same car and the 340 will trailer the 360. Identical dollars spent on both, in the same car and the 360 wins."

How do you do identical mods to both, without spending identical $? It seems like you're saying 340 parts cost more than 360 parts. Except for the pistons and crank, they're identical parts. And if you use an early 360 block, you can bore it the same as the 340, so even the pistons can be the same (well, except for the pin height). Could you please clarify this?

I completely agree with you when comparing "sort-of stock engines" the 340 will win handily. There are other reasons for considering a 340. The smaller main journal size means less drag. It also means more material in the web area for a potentially stronger bottom end. But if you're making so much power you risk breaking the block, it's probably time to step up to an R3.

On the subject of strokers and R3 blocks, my dream engine is a 440 small block. Use the siamese bore R3 and a 4 3/16" piston with a 4" stroker crank. Put 318 badges on the fenders, the Chevy guys won't know the difference. ULTIMATE SLEEPER!

[Dart]

Guys,

The 360 was designed for truck/towing and has 8 to 1 pistons stock. If the 360 were built to early 340 standards (10.5 to 1 etc.) the 360 will outperform the 340 because of more cubes. I agree that the block on the 360 isn't quite as good as the 340 casting, but the early 360 can be over bored .060 (same as early 340). The webbing is not as strong and most racers will tell you if you are around 450-500hp with a stock block (340 or 360) you are risking an explosion. The way to go (if making or wanting to make over 450 hp) is with the R3 block, but (if I remember correctly) it does not have a full water jacket so that is kind of limiting for the street.

Has anyone seen (not just in the catalog - I mean in person) the new 340 block from Mopar? I think I read somewhere that the block was strengthened and that can handle some serious power (over 500hp). Granted they want an arm and a left one for it (~$1500) but that may be a good medium level entry for a serious 340 without having to go full race with the R3.

[Dart]

Ok, I looked up the new 340 block in my catalog and it states that the block has 4 bolt mains, stronger webbing, thicker deck, not a thinwall casting, high nickel content cast iron etc.

Sounds like a winner...

Anyone seen one of these blocks???

[Doug Wilson]

I rest my case. On to greener pastures.

"Let those who ride decide"

[1972roadrunner]

Originally posted by 72Challenger
If you're dad is putting 350 cranks in 400 blocks he's a magician

ok, my bad...i think i got the 2 mixed up...i'm sure he was going the other way around.

Originally posted by 72Challenger

Please just think about what you wrote. A 340 has 20 less cubes than a 360, it's just simple arithmetic.

actually...i was referring to the stock bore.... but yeah, that does make sense...

Originally posted by 72Challenger

unless you've figured out how to launch at 7000 RPM.

thats easy!! its called a 4speed... course, i don't have one, but i really want one!

[George G. Leverette]

The 2780930-340 was produced from 1968-1973 with the ability to blow off big blocks, the 3418496-360 produced from 1971-1974 was a direct replaement for the 340 and had the same features including the ability to be over bored .060. the 3870230
360 engines manufactured in Mexice 1975- were thin walll castings that could be over bored .020. Then comes the Magnum which are presumeably not a part of this conversation. The 1968-1971 340s had a copmression ratio of 10.5-1 and even with the change in the rating system were the most powerful compared to the later 8.5-1 compression small blocks, therefore the 340s are and were more powerful than any 360 in factory trim. When modifications are considered the 340 with the same crank will yeild more cubic inches than the 360 when they are stroked. The 340 maintains its position as the most powerful small block engine produced by the manufacturer.