340 Engine rebuild kit

[tdwnilla1]

Hi everyone, I have another question that hopefully one of you knowledgeable people can assist me with. I have been trolling the internet for a rebuild kit for my 1973 Plymouth Cuda and I am having no luck finding a kit for it. I am finding plenty of kits for anything from 1968 - 1971 but that's it !! What could have changed so drastically in two years that would be different ? Is it because of smog regulations so the kit "does not apply" or do I just have one of those bastard situations ? As always any suggestions would be greatly appreciated.

[1 Wild R/T]

In 72 they dropped the compression ratio two points.... And went to a cast crankshaft... You probably would be happier with those extra two points of compression so use the early kit....  Your gonna need machine work, boring, decking, turn the crank... And you'll need to talk with your machinist about how far the parts need to be machined anyway so you should probably talk with him about parts..... Yes you'll pay a little more but at least he should  warranty any parts failures....  You supply the parts & something goes wrong you own it....

[tdwnilla1]

Thank you for the response however, if I could pick your brain a little more ? My car has 40,000 original miles on it, my crank needs to be turned however, the cylinder walls appear to be in great shape. Could I go with the 71' kit, re-ring my pistons (if I can find them) and turn the crank ? There is nothing wrong with the block so I would rather not bore it out if I can help it as it is an all original numbers matching car.

[1 Wild R/T]

If the bore stays standard you could just replace the rings & bearings....

I would still take it to the machinist, have it hot tanked & replace the cam bearings...  Have him measure the bores & if they are within spec have him hone the bores.....

[Chryco Psycho]

You could also build a 412 ci stroker by replacing the crank rods  pistons
It would be slightly less CI at std bore

[1 Wild R/T]

You could also build a 412 ci stroker by replacing the crank rods  pistons
It would be slightly less CI at std bore

More money but allot more fun.....

[tdwnilla1]

Thank you guys. I appreciate all of the information, I am by far a professional mechanic but I have worked on and rebuilt my fair share of engines so all of this information is most helpful. Not too familiar with stroking (a motor anyway lol ) what exactly would it entail and could I keep it mostly stock meaning no boring ext.......

[1 Wild R/T]

Stroking means you replace the original crank with it's 3.31 stroke with an aftermarket crank with a 4.00 stroke.....  Also the pistons & rods get swapped but they don't effect the displacement, they just make all the parts to work together...

With proper parts selection & assembly you turn your 240 horsepower smog era 340 into a very mild 375 horsepower docile cruiser or with less street manners a 500 plus horsepower monster...

[GY3R/T]

   If you stroke it, bore it.

[nsmall]

How much more would it cost to stroke a 340 vs just rebuild it to 68-71 standards?

Another vote to stroke the 340 if you can afford the costs as I wish my mild built 340 was stroked.

I have 73 340 with 10:1 and heads worked on and this and that, yes it is not pathetic, but those strokers are nasty.

[Chryco Psycho]

Stroking is not usually a lot more , by the time you machine the crank & rods & replace the brgs , rings  pistons & rod bolts  maybe a $1000 extra usually less .
Boring the block really adds nothing , , 4-5 ci but it thgins the cylinder walls so if the block is good as is do not bore an engine ever , I know some of the SS racers used to bore the blocks just enough to get the cylinders perfect & would custom order pistons @ .004 over for example .

[1 Wild R/T]

Thing is, once you start down the path it's hard to stop.... Build the bottom end & now if it's gonna reach it's potential you need better heads.....   And really you need to chose heads before you buy pistons cause chamber volume is a big factor in hitting a good compression ratio.....  If you can really stick to a strong cruiser build you might be happy with a set of 308 heads with some mild port work... Hell even stock 308 heads on a stroker bottom end will make great torque up to 4,000 rpm's where it wants to come alive but the heads say your done.... But still a lot of fun on the street.... 

Rings & bearings with a little machine work & a valve job....   $800-$1200

Stroker short block probably $3500 but even on the cheap (reuse stock heads) plan on another $1000 plus on a cam, lifters & a valve job...


Good heads                 $1800-$2200
Rockers, Ductile? Harlen Sharp? $300-$600
Cam & Lifters flat tappet or roller?   $300-$1500

[RUNCHARGER]

If it was mine I couldn't leave the original pistons in it. I would have to put the 68-71 pistons in it and maybe just fix the rest of it. As Wild says if you stroke it it wouldn't be maximized without better heads and exhaust so it starts to cost a lot more. A 68-71 340 is a pretty lively beast all stock and it will wake it up.

[1 Wild R/T]

Another member in Ohio is thinking of selling a rotating assembly that could save you some money if your nterested....    Forged pistons with two points more compression, still a stock stroke but a forged crank which is a definite upgrade....

https://forum.e-bodies.org/whats-it-worth/15/are-speed-pro-340-forged-2332-pistons-and-oem-rods-worth-anything/7510/msg104160;topicseen#new

[RUNCHARGER]

In the other post you state you have replaced the bearings already and have bottom end noise. Did you check clearances? I'm just curious if you have wrist pin noise or cylinder to wall noise. Just because the engine hasn't been bored doesn't mean the cylinder walls are straight all the way down either.
I do believe in leaving the cylinder walls as thick as possible but sometimes a bore is required for proper results.