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.
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....
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.
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.....
You could also build a 412 ci stroker by replacing the crank rods pistons
It would be slightly less CI at std bore
Quote from: Chryco Psycho on June 30, 2018, 03:47:42 PM
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.....
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.......
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...
If you stroke it, bore it.
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.
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 .
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
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.
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
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.
Yup, looking at your bearing pictures that engines been run pretty hard to be showing copper & the pocking of the mains which looks like a fatigue failure.... I would be using a bore gauge to see what kind of roundness & taper your dealing with..... I might throw a set or rings & bearings at it if I had zero budget but I sure as hell wouldn't put a stroker kit in without at least measuring the bores... Be clear with the machinist you'd like to keep the stock bore but if it's to far outta spec it's gotta be bored....
As far as just dropping a stroker kit in place, some folks get away with that to a point, there may be grinding for clearance of the rods/bolts & crank ... Most of us also double & triple check clearances, file fit rings, sometimes bearings need scraping to clear a chamfer.... As you assemble keep a close eye on rotating torque as each piece is added... If it goes up significantly you need to go back & find out why.... If there's issue I like to assemble once without rings so I know whether it's just ring drag or a tight bearing...
Accidentally had this all in the post 1 Wild R / T shared.
Thank you Chryco that is correct, 1 Wild R/T thank you for thinking of me but like Chryco said I don't want to bore if I can help it. Honestly, with only 40,000 original miles on it I am quite disgusted that I have to do any of this to it but unfortunately replacing my main bearings and rod bearings did not make my lower end rattle go away it only quieted it down a little and bought me some time so I can still go to the Syracuse Nationals. Is there a specific stroker kit I should be looking for ? I would like to do as much of this myself as I can. I have means of honing the cylinders even though they don't look like they need it but it cant hurt to polish them as long as it is already apart. I live near Syracuse and we have a local place that turns cranks (Syracuse Crank and Machine) if I had to but by the sounds of things I can go with the stroker and it comes with a crank I believe. With all of that said, all I would need to do is have my block acid dipped and magnafluxed and put the stroker kit in and that would be it for my lower end and then all I need to do is get my heads done to oe specs correct ?
Quote from: RUNCHARGER on July 01, 2018, 09:08:49 AM
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.
I did not remove the engine to replace them so I could only mic half of the main journals as the crank was still in the motor and they all were within specs. The rod journals were also within spec so I went with the standard bearings. I had 2 excellent local mechanics tell me that it was my mains so I figured I would do the rod bearings while I was right there. My first thought was mains as well because of past experience. It only makes the rattle at a certain RPM (no tac yet) I'm guessing around 2500. I seriously hope I am wrong but fear I am not. If I get a chance later I will fire it up and post a video with the sound it is making and perhaps one of you can shed more light.
Hmm: Okay, If it was mine I would take it easy on it until winter and then pull it out and have a pro measure everything. Crank journals, piston diameters, cylinder walls, wrist pin clearance etc. before doing anything. I wouldn't spend a nickel on parts until finding the root cause of the noise. Unfortunately, 60,000 miles is enough to have lots of wear with an old carbureted engine that has probably had a ton of cold starts.
It all comes down to what are your goals. If you're just having it rebuilt and keeping it stock ( which I'm in the process now) I wouldn't buy a kit. Have the machine shop check the block to see if the bore is still good and you might get away with a hone and new rings. Of course cam bearings and freeze out plugs. I put in an Edelbrock performer cam in my other 340 and it runs great. Basically stock and trouble free. Now if you're looking for high performance then that's a whole different ballgame.
Quote from: Rich G. on July 01, 2018, 11:38:49 AM
It all comes down to what are your goals. If you're just having it rebuilt and keeping it stock ( which I'm in the process now) I wouldn't buy a kit. Have the machine shop check the block to see if the bore is still good and you might get away with a hone and new rings. Of course cam bearings and freeze out plugs. I put in an Edelbrock performer cam in my other 340 and it runs great. Basically stock and trouble free. Now if you're looking for high performance then that's a whole different ballgame.
Thing is he's got a 73 340 so low compression which really hurts it..... But clearly not ours to make choices so he's gotta decide.....
To the OP you say you've built engines, my question is how long ago? Cause there have been lots of problems with parts quality in recent years that in the past weren't much of an issue, cams going flat which in the past was some horror story you heard but virtually never experienced have become common & expensive to fix.... I'd rather warn you up front rather than hear you crying the blues later....
Probably about 20 years since I built a motor......... Chevy 350 so pretty common. I am no professional but dont want to spend a small fortune either. I know I have some decisions to make so I am trying to get the most and best possible guidance I can. To my original question and like
@Rich G. (https://forum.e-bodies.org/mlist/rich-g_641) stated can I use the 71 340 rebuild kit if everything is within spec to do so ?
Yup...
Thank you. Out of curiosity why in the hell is the kit only available for 68 - 71 ?
Quote from: tdwnilla1 on July 01, 2018, 02:36:57 PM
Thank you. Out of curiosity why in the hell is the kit only available for 68 - 71 ?
Because no one who's building a 340 wants to build a low compression dog..... The pistons you get in this kit are the early style high compression piston.... The block don't care what you put in it.... Back in the 80's all you could find easily were 72-73 low compression pistons....
Thank you.
Sorry if I keep asking the same questions but I have so many suggestions and responses it is difficult to keep track. No matter what I decide stroker like Chryco said, or what Rich G. Said about keeping it stock like I would like to with the exception that I have to at least have the crank turned I should be fine using my stock heads. Sorry to beat this all up but I don't want to screw anything up, these 340's are not very common and all Mopars are expensive to play with ...............not to mention it is an all original numbers matching car.
Your stock heads can work with a stroker. You should at least put 2.02 intake valves in them no matter which way you go. If you were to use the stock heads on a stroker with no port work and no headers the tendency of the engine would be to perform stronger in the low RPM ranges than a stock 340. Performance would drop off in the higher RPM ranges because of lack of airflow.
Thank you..........all of you for the great responses !! I have some homework to do
The factory 340 air cleaner on a stroker would also cut down some on power.
...Change one thing and you have to change others.
That is the way of the World once you go after market.
Still comes down to what are you doing with the car and how much do you want to spend. Just cruising and looking good is one thing. Going fast and making horsepower cost lots of money!