vivivivivibration

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OK, good, and that piston info is appreciated; not sure how I missed that.... It is a 'leave no stone unturned' kind of a problem. L2316's should be stock weights.

As for the crank, I still have not seen definitive info on that, one way or another' the OP's post . Any crank can be in any year block. The response in post #4 is not clear to me, and the history of the engine is murky.

But the approach of 'fix 1 thing at a time and see if that cures it' may work as well. I just like to KNOW for sure on each part, as not knowing requires assumptions....
 
Assuming it’s a steel crank:
Not what you want to hear but.......

Remove the clutch and flywheel, bring it to a machine shop that does engine balancing....... have the flywheel balanced by itself, then have them install the pressure plate and zero it out on the flywheel.

Then you’ll know the back of the motor is definitively taken care of.
 
I have actually started up an External Balanced used 360 truck engine on the floor just to see if it would run before we made plans for it. We put a neutral balance converter and 1969 904 trans behind it so we could get a starter in it and fire it up . . it's the set we had at the time.

So this was a miss match right out of the gate, external balance 360 crank and balancer on a internal neutral balance torque converter. Started it up and warmed it up good. Had like an odd miss in it and was not smoothing out. Was playing with carb and timing to try and smooth it out, then we shut it down just knowing that it ran.

In hind sight, the rough running was the imbalance of the External Balance 360 and the Internal Balance 904 trans setup that we used to test fire it.

So knowing what that imbalance feels like first hand, I don't believe that is j.d. main problem here. JD was saying that it was a very minor vibration at first start up at an idle. Also he has taken it out and driven it for 8 blocks, so it certainly would have shaken a lot if the crank setup was out of balance.

He might have just needed some time for the lifters to pump up at first start up to get the valves working properly. Forgot to ask JD if he primed/pumped up the oil system with a drill before first start up, Having someone roll the engine over while priming the oil system with a drill is a good way to fill the lifters and get them pumped up before first start up.

Keep Digging . . .
 
Just keep in mind that the 360 external imbalance weight is larger than the 340 external imbalance weight. So any 360 mismatch is going to make a larger, more noticeable vibration; I'm not sure how good any comparison will be....
 
OK guys here we go.First off let me say I haven't done a compression test in about 30 years,so had a issue or two,no biggy.ran the right bank,turning motor over about 2 revs on each cyl.came up with some #'s the low 140's to 155.then moved to the left bank,thinking that my batt. might be getting low I put the charger on it and the spin increased noticeably,now I got readings from 155-164.so I went back and tried a new approach.spune the motor over about 4-5 revs,looking for highest reading,here's what I came up with.#1-161,#3-164,#5-155,#7-161 back to the right bank using same procedure #2-156,#4-170,#6-161'#8-155.I did go back and ck #4 a second time with same result.fixing to go back out and reinstall plugs,would appreciate recommendations on plug gap.I had set at .035,but there seems to be a lot of argument in the GM world about this when using different ignition than stock.the 1971 Plymouth scamp-for george jets,has a msd box,which I know absolutely nothing about,an electronice ign. dist.and a exterior coil.do you think .035 is all right to start with.running autolite 65 plugs.:realcrazy:
 
Assuming it’s a steel crank:
Not what you want to hear but.......

Remove the clutch and flywheel, bring it to a machine shop that does engine balancing....... have the flywheel balanced by itself, then have them install the pressure plate and zero it out on the flywheel.

Then you’ll know the back of the motor is definitively taken care of.
But it'll possibly/probably become worse if it is a cast crank..... then that work would be wasted. I'd rather pull the pan and be sure on the crank myself.
 
My engine is sitting at about 3-5 degrees slant in the engine bay,with car leveled,oil pan is off 1/4" in a 9" run.Is this a regular issue on these cars or a J.D. special?:BangHead:
 
OK guys here we go.First off let me say I haven't done a compression test in about 30 years,so had a issue or two,no biggy.ran the right bank,turning motor over about 2 revs on each cyl.came up with some #'s the low 140's to 155.then moved to the left bank,thinking that my batt. might be getting low I put the charger on it and the spin increased noticeably,now I got readings from 155-164.so I went back and tried a new approach.spune the motor over about 4-5 revs,looking for highest reading,here's what I came up with.#1-161,#3-164,#5-155,#7-161 back to the right bank using same procedure #2-156,#4-170,#6-161'#8-155.I did go back and ck #4 a second time with same result.fixing to go back out and reinstall plugs,would appreciate recommendations on plug gap.I had set at .035,but there seems to be a lot of argument in the GM world about this when using different ignition than stock.the 1971 Plymouth scamp-for george jets,has a msd box,which I know absolutely nothing about,an electronice ign. dist.and a exterior coil.do you think .035 is all right to start with.running autolite 65 plugs.:realcrazy:
Well, you did a very good job IMHO. 4-5 cranks per hole is what you want. Numbers are consistent; so there are no gross cylinder issues indicated from that.

The higher reading on #4 may be due to 1 or both of those lifters being a bit leaky, and opening the intake valve a tad less duration while cranking... or perhaps some other valvetrain anomoly there. Whether it/they are leaky when running/idling, and causing any uneven running, is another question; just put it on the list of possibilities. Is there any audible ticking at idle?

This just goes back to us not being there and trying to figure out what this vibration really sounds/feels like; hard (for me) to get a 100% sense over the internet.
 
Compression sounds, decent for less than 5 miles on the engine. I am sure the new rings will seat better after the first 100 miles, but yeah anything over 150 psi you are good for now.


This is one of my pet pevs and enjoy discussing how to break in a new engine:
There are 100s of theories about this. One good old time mechanic (who is passed away now) shared with me how he likes to see it done, made a lot of sense to me and have been doing this for some time now.

Paul the old time mechanic said this:
After pre-lubing and and assembling engine parts, special cam break in lube and some good sticky stuff on the rods and mains, prime the oil system with a drill, all basic stuff on a build. Zinc for cam too.

Here is what I like, he said to put in the thinnest oil possible like 5w30 or the likes, fire it up, run in the cam in for 20 minutes at 2,000 rpm and vary it a bit. Then he said take it out and warm it up, then run it hard and put a bit of a load on it but don't abuse it. This warms things up good, expands the rings out to push out against the cylinder walls and helps them to break in quickly. While the thin oil is flushing everything out and carrying away any fine fine debris to keep things breaking in clean.

After this first run in drop out the oil, change the filter, put in your favorite 10w 30 with zinc, rottella 10w 30 is good. Then finish out your break in for the next 200 miles driving it the way you normally would.

I am sure there are many many different opinions an experiences on this. Just wanted to share this as tribute to my friend Paul a great engine mechanic. Hope others can make use of this, as then his skill set will live on.

Thanks
 
Super Good Reply there MoparR&D. Thanks that is just we needed to hear, someone that knows.

Guess that's why they call you Mopar Research and Destroy !!!
 
Compression sounds, decent for less than 5 miles on the engine. I am sure the new rings will seat better after the first 100 miles, but yeah anything over 150 psi you are good for now.


This is one of my pet pevs and enjoy discussing how to break in a new engine:
There are 100s of theories about this. One good old time mechanic (who is passed away now) shared with me how he likes to see it done, made a lot of sense to me and have been doing this for some time now.

Paul the old time mechanic said this:
After pre-lubing and and assembling engine parts, special cam break in lube and some good sticky stuff on the rods and mains, prime the oil system with a drill, all basic stuff on a build. Zinc for cam too.

Here is what I like, he said to put in the thinnest oil possible like 5w30 or the likes, fire it up, run in the cam in for 20 minutes at 2,000 rpm and vary it a bit. Then he said take it out and warm it up, then run it hard and put a bit of a load on it but don't abuse it. This warms things up good, expands the rings out to push out against the cylinder walls and helps them to break in quickly. While the thin oil is flushing everything out and carrying away any fine fine debris to keep things breaking in clean.

After this first run in drop out the oil, change the filter, put in your favorite 10w 30 with zinc, rottella 10w 30 is good. Then finish out your break in for the next 200 miles driving it the way you normally would.

I am sure there are many many different opinions an experiences on this. Just wanted to share this as tribute to my friend Paul a great engine mechanic. Hope others can make use of this, as then his skill set will live on. Thanks
That's pretty much what I do... push it a bit after cam break in but not to the max to start the ring seal, then keep ushing it harder and harder for then next 50-100 miles. I hear arguments on how rings should seat in a minute or less, and I's sure a lot happens then, but if the bores are not done with torque plates, they are a bit out-of-round after torquing the heads bolts, and I suspect it takes some time for a 'regularly built' engine to get the bores 'rounded out'.
 
Super Good Reply there MoparR&D. Thanks that is just we needed to hear, someone that knows.

Guess that's why they call you Mopar Research and Destroy !!!

Oh shoot I just deleted the post because I only read the first page and figured I was repeating what someone else already said... sorry!

I basically just said that yes the tolerances for the factory K member are terrible and the flywheel shown in the pic is the one you (the OP) have but it's incorrect for your engine, you need an unbalanced one.
 
Yes, MoparR&D just posted that we got it right with our flywheel imbalance diagnostics. (then he deleted that post not knowing there was more pages to continue on this thread with)

Anyhow with this good experienced input if it were my 340, I would have no problem yanking out that 4 speed, Clutch and Bell Housing and swapping out that Drilled Flywheel for a Non-Drilled Neurtral Balanced one.

By the looks of JD's pictures that pressure plate looks like the 50 year old original yet. Good time to Replace Pressure Plate, Clutch Disc, and Throw Out Bearing, make it all new again. Check the bearing/bushing in the end of the crank too as long as into it that deep.

Thank You, Thank You . . .
 
j.d. Like the New High torque starter you have in there, my favorite.

Makes the Mopars spin over fast, does not steal anywhere near as much electricity away from the ignition system as the original mopar starters do. Makes the cars start like they have fuel injection, but they don't.
 
j.d. MoparR&D stated that your engine being in there at an angle and jacked up with the solid mount on the driver's side is pretty common for Header built A Body cars as there is just not much room on the A Bodies to get everything in there straight and neat, expecially going into the 3" exhaust.

Tight Fit . . .
 
Yes leave your engine sitting in there the way it is for now. Fix one thing at a time, get the minor vibration issue taken care of first.

I like to set the plugs at .035 ths with factor mopar ignitions. You are running the Hotter MSD box and Coil, you can still set them at .035 ths lots of guys are setting them at .040 ths with the hotter ignitions, your call.

We all like to get our personal preferences involved. Now that we have figured out to replace that original ignition power robbing mopar starter with the new Smaller High Toque Starters. It puts back more electricity to the small Factory Mopar Brain Box with ballast resistor set up and you really don't need the whole MSD setup unless you are super performance minded.

With your Stock Built 340 you can keep it looking nice and working nice with a mopar electronic ignition. Just my own ideas, I like the way Ma Mopar built things. Very high engineering standards for the day.
 
It was set up with the msd box when I got it.probably would;nt have been my personal choice but,it's there and working so,IF IT ANT BROKE DONT FIX IT.really messed with me on start-up day.guys were coming over about 2:00 to help,so I was trying to get everything ready and checked that I could do myself.that morning I got out to the shop about 5:00 and started on some of the last stuff to get ready,installed the plug wires,coil,grease back in tranny,few other things.when I got to checking if I was ready to fire it up I checked the coil hot wire to make sure I had power.notta.No power to coil,would not light test light.started checking wires,what could be loose,what did I screw up.everything was hooked up like I had taken it apart, couldn't find the problem.one of the guys coming over was a electrical guru so I gave him a ring and told him to bring some of his testing equipment. Luckily when he got there he was driving his nova.he looked at the same stuff I had and really couldn,t find any problem,No power to coil.I asked if mayby the coil only got power on crank position and then continued from the MSD box.Well lets test my nova and see what I,ve got.same thing no power to coil with swith on,off,start to crank,or when running.think when running it showed .01 ohms or something like that.so we decided to just try to start it and see what we got.fired in less than a full rev.Still don,t understand how it works, Thanks for all your help:thankyou:
 
Yes, you are welcome.

Yes that MSD has lots of wireing with them, think there is even a box under your dash. We were helping a guy get going at a cruise-in that had top coil tower cracked and the MSD was so powerful that it was jumping the spark back to the ground, kind of found that by stumbling onto it as we were looking it over with a test light trying to figure out why it would not start. My friend with a 69 Dart and MSD pulled his car up next to it to compare things, he still had to get under the the guys dash and futs with the box there. Then we took the coil off my friend's 69 Dart and got the guy going so he could get home;

We followed him home 15 miles away and got my buddy's coil back so he could get his Dart back home too. Lucky I had a small tool box along, I think we used every tool in there along with some electrican's tape.

Lol . . . All in good fun.
 
It was set up with the msd box when I got it.probably would;nt have been my personal choice but,it's there and working so,IF IT ANT BROKE DONT FIX IT.really messed with me on start-up day.guys were coming over about 2:00 to help,so I was trying to get everything ready and checked that I could do myself.that morning I got out to the shop about 5:00 and started on some of the last stuff to get ready,installed the plug wires,coil,grease back in tranny,few other things.when I got to checking if I was ready to fire it up I checked the coil hot wire to make sure I had power.notta.No power to coil,would not light test light.started checking wires,what could be loose,what did I screw up.everything was hooked up like I had taken it apart, couldn't find the problem.one of the guys coming over was a electrical guru so I gave him a ring and told him to bring some of his testing equipment. Luckily when he got there he was driving his nova.he looked at the same stuff I had and really couldn,t find any problem,No power to coil.I asked if mayby the coil only got power on crank position and then continued from the MSD box.Well lets test my nova and see what I,ve got.same thing no power to coil with swith on,off,start to crank,or when running.think when running it showed .01 ohms or something like that.so we decided to just try to start it and see what we got.fired in less than a full rev.Still don,t understand how it works, Thanks for all your help:thankyou:[/QUOTE


JD you were talking about wanting to get your engine sitting in there straight again. Quite sure that one down pipe on your headers by the starter is too close the the steering center link, that's why they have it jacked up on that side. Shimming up the passenger could push that pipe back down again, not good. So they probably just left it being they wanted headers in there real bad, and could not find a set of those nice 340 Performance HP factory cast large port exhaust manifolds.

Here is a picture of the 73 340 HP large port exhaust manifolds for the A Bodies. You can see the ones that have not been cleaned up, the HPs have much larger ports that the standard A Body V8 exhaust manifolds. Another project another time, but then you could get your engine back in there straight again and get the factory rubber engine mount in on the driver's side again too.



72.73 Exhaust.jpg
 
So leave it as is/doesn't sound right.any thoughts on the spark plug gap?

On the subject of your engine sitting in there at 3 to 5 degrees off level. Was looking at the picture from underneath your car looking forward at the headers. That Header Down Pipe by the starter is swooping down real close to the center link for the tie rods of the steering parts. This is probably why they jacked up the engine on the Driver's side and built that new raised solid mount engine mount.

Might be able to shim up passenger side engine mount to level it out, but in doing so that can push that left engine side header pipe back down making contact with the steering center link. You certainly don't want that to happen. They were probably stuck here when they first put the headers on and left it that way.

If you ever get tired of the headers, they made large port 340 HP factory exhaust manifolds that are kind of like a factory header in themselves. Pretty spendy if you can find them. They also made a set of 72 & 73 HP Large Port 340 cast exhaust manifolds that would work really nice too, just got a set of these at the last swap meet had to grab them. Saving them for my future builds.

Here is a picture of the 73 340 HP large port exhaust manifolds for the A Bodies. You can see the ones that have not been cleaned up, the HPs have much larger ports that the standard A Body V8 exhaust manifolds. Another project another time, but then you could get your engine back in there straight again and get the factory rubber engine mount in on the driver's side again too.


72.73 Exhaust.jpg
 
To bring people up to speed on our personal message conversation and back on to this post again:

JD said:

From something I read someplace on hear, I think the one steel mount and one rubber is a typical mounting system for a 6 to v8 change over. The headers have better clearance than it looks once its all in, sure is tight getting it all in there.


George Jet reply:

If it had a 6 in it originally, does it still have the 3 on the Tree steering column in it now that it is a 4 on the floor ? That will help tell me find out if it still has the original 6 cyl factory K member in it yet.
 
The Plot Thickens
JD's previous reply from PM:

It looks to me like they have changed out the column, vin showed it was orig.a 6 banger. might have just changed the color on column, not Sure. I have some pics of K member.


George Jet:
Always fun to search out the "History" on these cars and find out how they came to be !
I see someone was in there and put a universal joint in where the factory mopar flex coupler should be, so someone was probably in there switching out the columns in the last 50 years.

Nice Photos by the way JD, Thanks
 
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