340 vs 360?

[wyrmrider]

A .040 over 360 is just a stroked 340
some pay big bucks for a stroker and you already own one
put the money in the heads ( at least magnums)
YOU should not spend money on stock J or X or whatever iron heads-
(I have some with new guides and exhaust seats but I do not recommend them today unless you are doing some matching number deal)
(unless you need to buy a rotating assembly)
get pistons that will give you a tight quench at the compression you are looking for
get a cam that uses a .904 master not a chevy grind that works with the compression and heads and exhaust and intake and the rpm range you want
There are several recent series specially for MOPAR
for street I use one that's only 256 @.006 204 @.050 but has .305 lobe lift- compare that with some one size fits all chevy lobe

 

[rumblefish360]

I need spacers and the motor mounts are different? I thought I just needed the B and M weighted flex plate and everything else would match up?

The engine mount difference is a small potato issue, but yes, the 340/360 share engine mounts and the 273/318 share engine mounts. Do worry about it. Washers can take up the space.

put the money in the heads ( at least magnums)

Disagree! Unless you already have a Magnum engine. If your going to use after market heads, 2 choice scream.
Aluminum Edelbrocks or
Iron EQ heads.
Don't bother with OE Magnums for an "Upgrade"

YOU should not spend money on stock J or X or whatever iron heads-

Only if you can get them done cheap!!!

get pistons that will give you a tight quench at the compression you are looking for

KB-107's can do this with a block decking.
BUT, with a 72cc chamber head (AKA, OE X, J, O, U, etc....) & a .038 head gasket, your compression ratio is 9.8-1. That's 93 octane with a small cam. If your limited to 91 octane, you may not be happy and might have to retard timing in order not the ping. Regarding the timing is a huge HP loss.

get a cam that uses a .904 master not a chevy grind that works with the compression and heads and exhaust and intake and the rpm range you want
There are several recent series specially for MOPAR
for street I use one that's only 256 @.006 204 @.050 but has .305 lobe lift- compare that with some one size fits all chevy lobe

In low performance applications, this advice is over rated. It is more stress on the valve train than the intended power is worth.

 

[wyrmrider]

Don't bother with OE Magnums for an "Upgrade" agree I was thinking magnum chamber Iron or AL, however I used to use the MP Magnum heads and never had any problems with them

Only if you can get them done cheap!!!
Sorry- you cant fix the lousy combustion chamber

In low performance applications, IT actually makes more difference, you want to keep overlap as short as possible and get the intake closed early, etc

tough to make stock heads work, I've got a pile of them you can make them not ping with good gas and high rpm but not on a street build on regular gas

 

[moper]

Given the family situation, and the options and inferred cost limit of $1200... I'd find a 5.9L Magnum runner, buy the intake and carb, re-use your distributor, and buy the Magnum conversion flex plate. You can shim the mount and re-use what you have. That will get you the equivalent of a 300hp MP Crate engine for under $1K. I don't think you'll have the 340 or 360 anywhere near running and in your car for near that.
Fallback plan would be to just find a 318 long block or complete someone's removing to upgrade and buy that and drop it in.

 

[wyrmrider]

I agree
360 Magnums are available on half price day at pick a part, grab the od trans FI and computer and never look back
I have both 318 Dakota and 360 Magnum pick up I also have a 360 block all detailed with balanced crank all ready to put together and a couple of sets of ported 360 heads with hard sintered Dura Bond Seats and bronze guides all done on a SERDI Project is on hold while I do some Magnum style heads- there is just no way to get optimal performance with open chamber heads - the ping vs timing vs gas quality problem
don't get me wrong- you can use the stock heads when racing in a class that requires them as your rpm never drops- no fun on the street

 

[J. Cower]

Okay so I found an 86 360 with a 727 on it already for pretty cheap. So I know a need a new driveshaft and oil pan since it was a truck motor but would the new tranny fit right in or not?

 

[J. Cower]

Or would I be better off just mounting my 904 to the 360 with the $80 b and m flex plate?

 

[rumblefish360]

That's what I would do.

 

[Christopher]

Google "Double Take 360 Mopar" and read about the whole build. It was done over several issues. You could build the same shortblock and add better heads.

http://www.hotrod.com/articles/mopp-0003-360-engine-build-top-end-part-4/

Or, 360/408. Easy, strait forward, cheap power. A balanced eagle rotating assembly with cast crank is right at $1300 for 408. Add in a machined block, and do the math. You really can't beat the cost of this small block combo.

 

[rumblefish360]

Your 408 here --> https://www.summitracing.com/parts/sca-1-98011bi

 

[joemish]

Okay so my 318 in my 71 SSP is worn out. I'd rather not throw money at it when I want a bigger motor anyway. So I have a 79 360 someone gave to me all apart and sitting in the barn or I can buy a 73 340 that says it was running when pulled but no carb or distributor. The 360 is also needs a carb and distributor and haven't gotten block checked yet even. So is it worth the $1200 for the 340 or just build the 360 I have and throw a Mancini weighted flywheel on to change from external balancing. I'm kinda of new to this and money is somewhat tight as I have small children.

most people that say it "was running" are selling it for a reason and it's not because they are a nice guy. And 1200 is way too high....if he said 350$ i'd say maybe

 

[joemish]

Okay so my 318 in my 71 SSP is worn out. I'd rather not throw money at it when I want a bigger motor anyway. So I have a 79 360 someone gave to me all apart and sitting in the barn or I can buy a 73 340 that says it was running when pulled but no carb or distributor. The 360 is also needs a carb and distributor and haven't gotten block checked yet even. So is it worth the $1200 for the 340 or just build the 360 I have and throw a Mancini weighted flywheel on to change from external balancing. I'm kinda of new to this and money is somewhat tight as I have small children.

your 318 block is the same as 340-360... Get yours rebuilt with a better cam intake manifold and carb. that might not cost you 1200 to do and you know the block is good.

 

[rumblefish360]

I wish I could do all that for $1200!!!!

 

[Bighead440]

I had a blast with my first performance SBM (I had always been a BBM guy except for trucks before), which was a .030" over 360 with KB107 pistons and a .528" solid PurpleShaft. With 340 "J" heads (2.02x1.60 valves), double springs and ductile iron adjustable rockers it ran 12.60s/12.50s with a 3000 stall and 3.91 gears. Really streetable, pulled 15" vacuum and would pull to 7000rpm. I figure 400hp easy-peasy with no blueprinting/balancing etc.

 

[ir3333]

Wow...i bet you're even more confused now!

 

[dvw]

We run 2 360s. #1 ported stock smog heads, [email protected], .540/.560 hyd roller, LD340, 650 Holley, 9.0-1, TTI 2.5 exh, 4 speed. Runs mid to high 12's in a street Challenger. 6500 rpm shifts since 2006. Never had a valve cover off. #2 Turbocharged Stock block and crank. Makes 850hp. Going on year 5. Been 9.55@142 3750lbs in street legal trim. No reason to use a 340. I have a supercharged 340 as well.
Doug

 

[MrJLR]

360 stroke it

318...stroke it

 

[Moparfiend]

Hey Cower ....So what did you end up doing?

 

[J. Cower]

Got a 71 340 short block that needs a rebuild. It's at a machine shop now.... Dropped it off 2 1/2 months ago and they haven't gotten to it yet but hoping for something soon. Hoping the block is good. I'll let y'all know how it goes. Thanks for all the replies.