ok, i built a 340 stoker engine.parts are eagle steel 4.00 crank,eagle 5140 rods,ross 9987 pistons ,total rings. I paid extra for external balencing, and the kit came with professional products harmonic damper with weight installed when received. i did mount the stock 1968 cast crank pulley from doner 318 engine on to damper .on the top end i installed mopar performance p4120233 hyd. cam .508 lift, set at tdc on sprocket. edelbrock heads 60767, edelbrock2176 air gap dual plane intake. i have an edelbrock carb on it. I installed harlan sharp roller rockers. The engine has 70 psi oil pressure at idle and 155 to 165 psi. in all 8 holes. i have pertronics electronic ignition from doner engine installed. firing order is correct and i have brand new spark plugs installed rn12yc champ. timing is set 20 degrees btdc. My problem is poor idle and only 11-12 inches of vacuum with a visible shaking at all rpm ranges or at least up to 3000 rpm ,that is as far as i have gone. if i hit the throttle their is no hesitation, and the centrifical advance does move on damper. but the shake remains. i did run the car down the street slowly and their seams to be surge in the engine under a slight load. I know this is a lot of info,I have tried to explain as clearly as possible. If anyone has any suggestions for trouble shooting or solutions , i would greatly appreciate advice...........thanks mark

 

Welcome to the site>>>>>>>>>>>

Do You think its a engine Vibration? or an Ignition miss ?
Have your readjusted the valves?

 

my guess would be engine not ignition. i did recheck valve adj. I went zero lash plus 1/2 turn. the distributor came from the doner 318 engine which ran nice..........mark

 

What about the rear of the engine? Weighted converter or flex plate? External balance flywheel? I'm a fan of internal balancing, but I'm pretty sure the external deal is more than just a damper.

 

Pull 1 plug and see if it's white....Could be just lean?

 

I have a rebuilt 904 with new converter and i used the flex plate off 318. I asked about balancing when i bought my rolling assembly and they said i could external balance at balencer only or internal, or at both ends. i opted for external balance at one end because cost and simplicity , since my engine was for street use . Is this true or not......mark

 

Straight vacuum going to the distributor? Should have NO vacuum to distributor when at Idle. Vacuum should kick in when given throttle.
Also did you set the fuel mixture with a vacuum gauge or rpm gauge?

have you played with the timing?

 

no vacuum to distributor,my engine has such poor idle it was hard to set idle air mixture,i have set timing in a number of different setting and it does not get any better.if i advance to much it gets a little better, will not start when shut off...........mark

 

did you check the intake manifold for vacuum leaks?
Also the carb gasket?

 

I will double check that , everything is fresh. what about cam tipping. does this mp cam work right at tdc. i am planning on talking to mopar performance Monday........mark

 

Thats about average for that cam.....

 

I've not heard of balancing a Chrysler engine on one end or the other. If it is externally balanced it will have weight on balancer and torque converter or flywheel, both ends.

 

Not sure how I skipped over the post.....
But this should help fit it if this the case????????

https://www.coperacingtrans.com/prod...f649794547862f

 

Geez, I was starting to think I'd lost it. So I am right here, both ends need weights?

 

IF it's a pulsating vibration while your driving.... You have a Assembly balancing problem.....

 

They balance the front, but they simulate the rear balance when doing the balance. Personally I would get a B&M flex plate with the weight built in, also SFI approved With that much cam, you need to add more air at idle. Open the primary just a fraction or better open the secondary a fraction. IF the primaries are open too far the mixture screws will not work

 

"Such poor idle". You cannot suspect other engine problems if you can't even get it tuned. The marks not moving MAY be that the distributor is stuck, or it might be that it has very light springs and IS ALREADY advanced at the point you are checking time.

Get a vacuum gauge on it and for the moment, ignore timing light. Adjust timing at lowest possible idle for max idle speed and vacuum. Adjust idle speed to keep RPM as low as possible. Adjust idle screws and RPM best you can, then either look down the throttle bore or pull the carb and examine the throttle butterflies to see if they are within the transition slots of the idle circuit. These will be where the butterflies close in the front against the bore.

You should be able to "spring" the rotor in the distributor to get some idea of whether the advance mechanism is stuck or no.

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Assuming you have improved things above, the next thing is to try to determine if the shake is due to a cylinder miss (one or more!!!) or not.

First, carefully examine the rotor and cap for damage, carbon, dirt, moisture, or other defects.

Then pull each plug wire and check with an ohmeter.

Last MAKE SURE that the firing order is correct!!!! Even us old guys sometimes sway 5 and 7, very easy to do "back there in the dark."

Next figure out a way to ground each cylinder. One way to do this is to loosen the dist. boots so you can pull the wires out with insulated pliers (fuse pullers)

Use your 12V test lamp as a probe, or just use a grounded clip lead and a screwdriver.

Pull each wire and as you pull the wire off, move your probe into position so that you ground that distributor tower. THIS IS IMPORTANT to prevent crossfire

LISTEN for each cylinder, WATCH the tach and vacuum gauge. Each cylinder should sound about the same and should drop about the same RPM.

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There seems to be a fair number of guys having valve train trouble on new engines for various reasons..............wrong length push rods, wrong adjustment, even new valves sticking. So run a compression and leak down test

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Once you get it better tuned, and determine the cylinder problem or not, if it still shakes, and you are convinced all cylinders are firing properly, it's time to look at engine balance

You need to contact whoever made this ?kit? assuming the entire rotating mass is from "their" source and find out exactly what the engine needs for balance.

There were several Mopars that were externally balanced, but for example a 5.9 (360 Magnum) uses DIFFERENT external weights than an LA 360. So you cannot just throw "some weight" on there and assume it's correct. And...........are you certain your supplier knows what they are talking about? Unless parts are made to factory original weight (as for a 360LA) I don't understand how bolt on parts can be "balanced," unless you bought this complete rotating assembly as "being balanced."

 

THANKS ALL, I am sending my balancing paper work to a machine shop to see if in fact i need a weighted flex plate or a different balancer. i was originally told it was not necessary to balance at rear .I called the jegs tech line and the man said that cam i chose would only draw 14 in. vacuum at idle.not nocking edelbrock, but i am putting my 750 cfm proform holley on and making a trip to the airport to get some 100 lo lead.I am sure the vacuum should pick up with the new carb. i will keep everyone posted on progress............mark

 

an added thought...I have been wondering about my compression. again, i was told with a .21 dish piston, 4.070 bore and a 62 cc chamber that i would have 9.2-5 compression ratio. my average psi is 155 per cylinder if you divide by 14.7 it comes out around 10.5 to 1. I know this is not perfect just a ball park figure...................mark

 

problem solved, cleggs machine shop1-888-471-2827 has set me straight. After reviewing my balancing paper work , Tyson said that he was sure my eagle crank was internally balanced. in fact that is the only way you can balance an eagle crank for 340 mopar , and should have no weights anywhere ei torque converter, flex plate or damper. the stock converter and flex plate are fine, but the after market damper had a weight in it which needed to be removed. Highly recommend this machine shop, ask for Tyson before you buy a stoker kit, he knows all years for sbmopar balancing issues...................mark

 

That will teach you to read the instructions....
I read them and thought... I could make that mistake....
Glad you got it figured out.... Fewwwww

 

that is part of the problem..... they do not give instructions. i just purchased 500.00 dollars or harlan sharp roller rockers, and not one instruction on installation or adjustment............i went to youtube and watched as many videos as i could...........mark

 

Make sure all the allen screw are tight.....

 

i was goung to ask why tge hell u would make it externaly balanced. thankgod its all fixed. no post dyno numbers

 

Keep us posted on the results....