Moparts
surgung issue persists 340 4bbl
Posted By: ashburnmike
surgung issue persists 340 4bbl - 05/22/09 03:17 PM
I am still experiencing a surging issue at a constant speed, in any gear on my car and looking for help to kill this problem.
this is a...just put back on the road, '70 Dart Swinger, rebuilt 340 (stock guts w/a P4452759 cam, rebuilt (by Edelbrock thru Year One) Carter AVS #4937 4bbl, no a/c 4-speed car.
It idles well
It accelerates well.
but it surges when i keep a steady petal.
I have:
replaced the plugs
replaced the wires
re-gapped the air gap on the distributor (I took the dual point out and installed a Mopar electronic ignition system)
have the car timed @ 5 degrees BTDC
retorqued the carburator
retorqued the intake manifold
sprayed starter fluid around the entire top of the motor looking for a vacuum leak- none found
Adjusted the A/F mix per the Edelbrock carb manual which says to: turn one screw counter clockwise (rich) until maximum rpms are acheived, if there is a change of 45 rpms adjust the idle screw accordingly, then back the screw clockwise in (lean) just a touch. Repeat on the other A/F screw.
I believe the vacuum hoses are all hooked up correctly.
One runs from the drivers side valve cover to the base of the carb (thick hose) and the other runs from the base of the carb to the advance on the distributor (thin hose). The carb on the car does have what appears to be a fitting for a hose on the pass side of the carb next to the fuel inlet fitting. There is nothing connected to this fitting.
The 4937 is not the correct carb for this cari It is for a '70 340 automatic w/ ECS. But it's all I have.
It has been suggested that something is out of adjustment inside the carburator that is causing this surge issue.
My weakest skill area.
Anyone have any thoughts or direction?
thanks
Mike
Posted By: stumpy
Re: surgung issue persists 340 4bbl *DELETED* *DELETED* - 05/22/09 03:59 PM
Post deleted by stumpy
Posted By: Mr.Yuck
Re: surgung issue persists 340 4bbl - 05/22/09 04:03 PM
lean.... fatten it up...or better yet get a DP.
Posted By: patrick
Re: surgung issue persists 340 4bbl - 05/22/09 04:14 PM
sheesh, not everything needs a frickin double pumper....
it's lean on the cruise circuit and/or too much advance on the cruise circut. on top of the carb, there should be 2 little metal plates held on by screws. are they flat or humped? if flat, they were changed to AFB parts, which will make finding replacement needles much easier. loosen the screws enough to rotate the cover out of the way and pull out the piston with the rods attached. if the rod does not have the dimensions stamped on it, take a caliper/mic and measure the diameter of the big diameter and the little diameter. if you have the humped covers, try calling some of the carb places (maybe demonsizzler on the board) and tell them you need a rod 1-2 sizes smaller on the big end and the same size little end for an AVS. or try buy some new flat rod covers (for an eddie AFB) or make your own out of some flat metal. now go look through the edelbrock catalog, find a rod with the same small diameter and 1-2 sizes smaller big diameter than your rod.
that will keep your power calibration the same, but richen up the cruise calibration slightly.
you could also try disconnecting and plugging the vaccuum advance from the distributor and see if that helps, but I doubt it, I think it's more that it's too lean at cruise with the upgraded cam.
another possibility, it could be the carb getting too hot. do you have a 3/8" thick insulator gasket between the carb and the intake?
Posted By: hooziewhatsit
Re: surgung issue persists 340 4bbl - 05/22/09 04:33 PM
I know you said you adjusted the Idle Mixture Screws, but I'd try doing it again, or, make them another 1/4 or 1/2 turn richer, and see if it changes.
On Edelbrocks site they list the cause of off-idle surging as the IMS screws being too rich or lean.
-Dave
Posted By: 440sat72
Re: surgung issue persists 340 4bbl - 05/22/09 07:12 PM
when excatly does the surge occur? just off idle? when driving? at which speeds? what happens if you accelerate hard?
from what you have described it sounds like you have a fuel delivery problem.
besides: i like to run a little more advance then 5° btc. i run 22° initial, but then again i have a low comp engine. with your engine i'd probably aim for 15° BTDC. you will get a better idle and better throttle response.
however, that might require adjusting the mechanical advance on your distributer.
Posted By: Pntastar69
Re: surgung issue persists 340 4bbl - 05/22/09 07:31 PM
Jet up a few on the primary.
Posted By: RapidRobert
Re: surgung issue persists 340 4bbl - 05/22/09 07:34 PM
Quote:
Jet up a few on the primary.
Try 4 sizes larger jets & take her back out & try it. EDIT I missed it that it was a carter as I saw double pumper somewhere down the line & that got me thinking holley but yes fatten the primaries up
Posted By: Paul_Fancsali
Re: surgung issue persists 340 4bbl - 05/22/09 07:42 PM
Try a bump to .120 needle and seats and jet primary to 101. That should fatten it up enough.By the way you may want to get the initial up as stated here to at least 15 and total of 38-41 as that cam is bleeding some cyl pressure Carters also have a tendency to get real funny with hot weather and the gas now days, I know it kills the leather accl pump plungers.
Posted By: torkrules
Re: surgung issue persists 340 4bbl - 05/22/09 09:20 PM
Quote:
I am still experiencing a surging issue at a constant speed, in any gear on my car and looking for help to kill this problem.
this is a...just put back on the road, '70 Dart Swinger, rebuilt 340 (stock guts w/a P4452759 cam, rebuilt (by Edelbrock thru Year One) Carter AVS #4937 4bbl, no a/c 4-speed car.
It idles well
It accelerates well.
but it surges when i keep a steady petal.
I have:
replaced the plugs
replaced the wires
re-gapped the air gap on the distributor (I took the dual point out and installed a Mopar electronic ignition system)
have the car timed @ 5 degrees BTDC
retorqued the carburator
retorqued the intake manifold
sprayed starter fluid around the entire top of the motor looking for a vacuum leak- none found
Adjusted the A/F mix per the Edelbrock carb manual which says to: turn one screw counter clockwise (rich) until maximum rpms are acheived, if there is a change of 45 rpms adjust the idle screw accordingly, then back the screw clockwise in (lean) just a touch. Repeat on the other A/F screw.
I believe the vacuum hoses are all hooked up correctly.
One runs from the drivers side valve cover to the base of the carb (thick hose) and the other runs from the base of the carb to the advance on the distributor (thin hose). The carb on the car does have what appears to be a fitting for a hose on the pass side of the carb next to the fuel inlet fitting. There is nothing connected to this fitting.
The 4937 is not the correct carb for this cari It is for a '70 340 automatic w/ ECS. But it's all I have.
It has been suggested that something is out of adjustment inside the carburator that is causing this surge issue.
My weakest skill area.
Anyone have any thoughts or direction?
thanks
Mike
Could be the curve is too quick. This happened to me last year and took me forever to figure it out. If all else fails, try some heavier springs in the dist.
Posted By: ashburnmike
Re: surgung issue persists 340 4bbl - 05/22/09 09:32 PM
Thanks guys. I printed your info off and am trying to correlate it to the Edelbrock manual pictures and descripitions. Would it be likely that the manual I have (for the Performer and Thunder Series)is similar to the carb I have.
I am weak in this area and don't want to rip open my carb without at least a vague understanding of what I'm ripping into.
Patrick:
1) The screws you mention I assume are the brass ones and they are humped. looks like a teardrop...sort of.
2) I will try the vacuum hose disconnect and see what happens
3) I just have a regular gasket under the carb.
Dave:
1)I will turn the screws a turn more clockwise (richer)
2) I think you and I are reading the same thing on the site.
440sat72:
1) The surge happens when I try to hold a steady petal, in any gear, at any rpm. If I mash the throttle, it takes off like a bandit and it idles fine too.
2) I replaced the fuel pump during the rebuild with a stock unit. replaced all of the fuel lines with stock replacement metal lines including the "correct" filter from Year One.
3) I timed the motor as if it had a stock cam in it. I will try timing it to 15 degrees and see what happens. the motor is has 10:1 pistons
Mark:
1) I need to study my diagrams and find out where exacly the jets are and how to get them out. I have no experience with internal carb components yet...other than pictures. Once I find them...will the jets have numbers on them? I don't have a micrometer...but looks like I will soon.
Robert:
Good to hear from you. I sent you an email about this yesterday, but it bounced back.
Paul:
I believe the needle is located under the hump cap that Patrick mentioned earlier. correct?
What about the floats. Could they be a factor?
You guys are the best.
Mike
Posted By: fastnos
Re: surgung issue persists 340 4bbl - 05/22/09 10:08 PM
One other thing to check. When sitting with a timing light on it, if you hold it @ (any RPM it acts up) does your timing mark jump around, or is it steady within 1-2 degrees? If it jumps excessively, might be worn timing chain/gears.
Just a thought...
Posted By: RapidRobert
Re: surgung issue persists 340 4bbl - 05/23/09 12:23 AM
Quote:
I am weak in this area and don't want to rip open my carb without at least a vague understanding of what I'm ripping into.
to change the mixture get a strip kit put in a set of rods w the thinnest "cruise" step & take it out & try it. It'll take you 4 minutes to change them & the top of the carb does not have to come off. A pair of rods may say ie(.070" X .037"). choose a pair that have the smallest dimention for the 1st step listed (ie the .070")which is the cruise step.
Posted By: Anonymous
Re: surgung issue persists 340 4bbl - 05/23/09 02:03 AM
Try taking a ride with vacuum advance un-hooked.
Posted By: GO_Fish
Re: surgung issue persists 340 4bbl - 05/23/09 03:09 AM
Quote:
One other thing to check. When sitting with a timing light on it, if you hold it @ (any RPM it acts up) does your timing mark jump around, or is it steady within 1-2 degrees? If it jumps excessively, might be worn timing chain/gears. Just a thought...
Same result could be worn distributor shaft and/or bushing.
I personally have had trouble with OEM fuel pumps on SB performance apps. Make sure you have good fuel pressure under all conditions...
All that said, I'd bet on lean carb conditions, need metering rod/ spring changes (easiest), possibly jetting changes.
Posted By: ph23vo
Re: surgung issue persists 340 4bbl - 05/23/09 03:35 AM
as stated above unplug the vac advance and it will go away dan
Posted By: RapidRobert
Re: surgung issue persists 340 4bbl - 05/23/09 03:57 AM
I hope it's not rotor phasing. I cant handle another rotor phasing thread.
Posted By: ashburnmike
Re: surging issue persists 340 4bbl - 05/23/09 04:04 AM
Tomorrow I'll be in the garage early. I'll unplug the vacuum advance hose first and see what happens. should I keep the timing @ 5 BTDC?
Posted By: RapidRobert
Re: surging issue persists 340 4bbl - 05/23/09 04:28 AM
always make (1) change at a time
Posted By: dOrk !
Re: surgung issue persists 340 4bbl - 05/23/09 10:00 AM
Quote:
lean.... fatten it up...or better yet get a DP.
A DP ? ... yeah "pump" this !! 
... 
The BESTer solution would be to put a PlasticFantastic on it ! 
With a TQ ... just a turn or so on the "tree" and you would be all set !! ..... and get LOTS better MPG to boot.
Posted By: Mopar73340
Re: surgung issue persists 340 4bbl - 05/23/09 12:11 PM
As already stated, if it's surging at steady cruise, it's to lean in the cruise mode. Find out what metering rods are in it and go 1 step richer in the cruise mode and your problem will dissapear.
Posted By: moper
Re: surgung issue persists 340 4bbl - 05/23/09 01:27 PM
Sounds to me like it might be lean, or it might be the vacuum pod adjustment. There is no reason to unplug the vacuum advance on this car except ignorance... So lets fix that. The vacuum advance only works at light throttle and cruise conditions. It add advance to the engine at these times because it gets much better milage and more power with less throttle. But, it's "tuned" for a certain level of vacuum. The cam change affected that. So now you need to adjust it. I believe what is happening is the timing is getting advanced too much at cruise. There should be a small allen wrend that will just fit inside the vacuum hose nipple on the vacuum advance dashpot on the distributor. Something like 11/32. In any event, unplug the hose, take that allen wrench and stick it into the nipple... It will go in and engage a screw in there. Turning clockwise will lower the vacuum required to advance. Counterclockwise will raise it. I go two full turns as one adjustment. Drive the car with the hose connected, disconnect and go two turns counterclockwise, reconnect and drive agin. When the surge is gone it's done. No reason to lose it entirely. Also, you may find that tuning the rest of the ignition curves will help it run better too.
Posted By: ashburnmike
Re: surgung issue persists 340 4bbl - 05/23/09 02:46 PM
Here is an update.
The vacuum hose remedy isn't working.
I moved the timing from 5 btdc to 10 btdc to see if that had any effect - it did not.
I'm going to try the vacuum pod idea and see what happends.
Hang in with me here guys. I really appreciate all these suggestions.
Mike
Posted By: RapidRobert
Re: surgung issue persists 340 4bbl - 05/23/09 04:39 PM
Quote:
Hang in with me here guys. I really appreciate all these suggestions.
Mike
I have more time than money
Posted By: ashburnmike
Re: surgung issue persists 340 4bbl - 05/23/09 05:01 PM
hahaha...Don't we all Robert.
I tried moper's suggestion about the vacuum advance pod. The hex key would turn counter clockwise @ will but was apparently maxed out clockwise as it wouldn't turn in that direction at all.
I made 2, 4 and 6 turn adjustments counter clockwise, road tested it each time and there was no difference. the problem is still there.
I drafted a '70 Chevy Z-28 guy from up the street and asked him to drive it and he felt the pulse/surge also with a steady petal...so I'm not imagining things.
It looks as though I need to attack the jets and rods next.
Any other suggestions to try before I pull the carb off the car?
Mike
Posted By: RapidRobert
Re: surgung issue persists 340 4bbl - 05/23/09 05:33 PM
Quote:
Any other suggestions to try before I pull the carb off the car? Mike
yes , dont need to take the carb off just change these rods on top
Posted By: ashburnmike
Re: surgung issue persists 340 4bbl - 05/23/09 06:01 PM
Quote:
Quote:
Any other suggestions to try before I pull the carb off the car? Mike
yes , dont need to take the carb off just change these rods on top
Thanks Robert, Paul Fancsali, in an earlier post, recommends going to a .120 needle and jet the primary to 101.
I'm not sure where all this stuff is inside my carb but we will soon find out.
Now the hunt is on to find someone locally who may have the parts.
Mike
Posted By: B5 GTX
Re: surgung issue persists 340 4bbl - 05/24/09 02:05 AM
What is the total timing and at what rpm does it come in at? I would bet it is to much or it is to much coming in to fast. Put a light on it and see how much it has at 2000 rpm them 3000 rpm. I never bother with initial timing on a performance motor, you are much better off setting the total timing.
good luck
scott
Posted By: ashburnmike
Re: surgung issue persists 340 4bbl - 05/24/09 02:50 AM
Quote:
What is the total timing and at what rpm does it come in at? I would bet it is to much or it is to much coming in to fast. Put a light on it and see how much it has at 2000 rpm them 3000 rpm. I never bother with initial timing on a performance motor, you are much better off setting the total timing.
good luck
scott
I moved the timing to about 12 btdc @ 2500rpm.
This didn't have much effect by itself...however...since there were many suggestions that I was too lean...I backed the A/F screws out as far as they would go without coming out of the carb.
This has reduced the surging alot but it still does it.
we are getting closer.
Posted By: GO_Fish
Re: surgung issue persists 340 4bbl - 05/24/09 03:09 AM
Obviously you shouldn't have to have the A/F screws out that far to make a difference. But at least you have found an improvement!
Carter AVS strip kits (metering rods, jets and springs) are scare and costly if you can find them at all.
It may be time to consider modifying your Carter AVS to Edelbrock AVS specs. The Edelbrock AVS uses Carter AFB style metering rods and jets, which are still available as an Edelbrock AVS strip kit. Edelbrock has their carb manuals all online in PDF format, complete with tuning graphs.
To change to the Eddy AVS style, you'll need to get (or fabricate) flat Carter AF
B style metering rod covers instead of the "humped" Carter AVS metering rod covers you have now. Then buy a Edelbrock AVS strip kit, and swap your Carter AVS metering rods and jets for the Edelbrock AVS equivalents. This is not nearly as hard as it sounds. The AVS is a very user friendly carb, well suited for beginners. You can do it!
BTW, while you have the carb off, you would be wise to install a 1/2" phenolic 4 hole spacer between the carb and the intake. The AVS carbs are well known for boiling all the fuel out of the bowl on hot days when you shut the motor down... the 1/2" spacer will cure the dreaded hot start problems...
Posted By: RapidRobert
Re: surgung issue persists 340 4bbl - 05/24/09 03:35 AM
Quote:
BTW, while you have the carb off,
Mike promise me you wont take the carb off(or the top off) until you put the richest pair("cruise" step) of rods in there(4 minutes) that are in the strip kit & take the car out for a spin 
Posted By: ashburnmike
Re: surgung issue persists 340 4bbl - 05/24/09 01:17 PM
I'm trying really hard to avoid getting into the guts of my carb with my limited experience.
I did take one of the humpback plates off carefully (you'd think I was defusing an landmine)
and familiarized myself with the step-up piston, step-up spring and the metering rod. Now I see what you are referring to.
I will search the internet for a vendor for the rods you recommend,Robert and also the phenolic spacer Scott recommended.
In my frustration last evening, I was looking at the Edelbrock site and considered taking this carb off and replacing it. Then study the one I have. I still have no idea where the jets are (lol)
If I can find the rods and it solves the issue...that was certainly be more cost effective
The '70 Z-28 guy up the street said to toss the Carter and get a Holley. "A real man's carburator".
I told him once this issue is squared away, my Moparts partners and I are going to take this little Dart to track and blow the doors off his little Holley fed, white striped, orange car.
Mike
EDELBROCK PERFORMER SERIES 600 CFM, ELECTRIC CHOKE CARBURETORS
CALIBRATED FOR FUEL ECONOMY
Designed for small-block and small displacement big-block engines, these carbs are recommended only for stock to Performer level applications. They are not recommended for use on RPM or Torker II intake manifolds. Match with an Edelbrock Performer or Performer EPS manifold and other brands of similar design. Calibrated 2% leaner than #1405. Includes both timed and full vacuum ports for ignition advance. Comes with: Metering Jets - Primary .098, Secondary .095; Metering Rods - .075 x .047; Step-Up Spring - yellow (4" Hg). Use our Carb Stud Kits #8008 or #8024 if needed, see Installation Items. For auto trans throttle lever adapters and more, see Tuning Accessories.
Posted By: RapidRobert
Re: surgung issue persists 340 4bbl - 05/24/09 01:39 PM
Quote:
and familiarized myself with the step-up piston, step-up spring and the metering rod.
I will search the internet for a vendor for the rods you recommend,Robert
The '70 Z-28 guy up the street said to toss the Carter and get a Holley. "A real man's carburator".I told him once this issue is squared away, my Moparts partners and I are going to take this little Dart to track and blow the doors off his little Holley fed, white striped, orange car.
Mike
Here's a pic of a strip kit $42.79 at O'reillys(they ordered it-2 days) though w your carb the kit # will be different. Only caveat is when you drop the rod assembly on top of the spring that you then wiggle it slightly till it finds its hole rather than forcing it. Sounds like your neighbor DOES need an attitude adjustment 
Posted By: ashburnmike
Re: surgung issue persists 340 4bbl - 05/24/09 01:53 PM
haha...he's a good guy and has helped me tremendously getting this car going..if fact when we come to a questionable area he always advises to get on "my board" and see "what do your guys say"
I'll order the appropriate strip kit for this carb with the rods you advise.
I see in my diagrams that the main jet is at the bottom of the hole where the rod goes down and the secondary jet seems to be at the bottom of the float chamber. Am I reading the picture correctly?
I assume you have to take the carb apart to get access.
Posted By: RapidRobert
Re: surgung issue persists 340 4bbl - 05/24/09 02:06 PM
Quote:
I see in my diagrams that the main jet is at the bottom of the hole where the rod goes down and the secondary jet seems to be at the bottom of the float chamber. Am I reading the picture correctly?
I assume you have to take the carb apart to get access.
(1) yes (2) yes but just slapping the richest rod in there real quick will tell you if you are on the right track which way richening the idle mix screws is already pointing to. then you will need an innovate LM-2 A/F ratio meter to mix/match the correct combo of rods/jets to get your mixtures correct in all areas, idle, cruise,part throttle, power and then you will need.... 
Posted By: ashburnmike
Re: surgung issue persists 340 4bbl - 05/24/09 02:26 PM
....yes....and those series of questions will be forthcoming....I assues you.
I'll report back with a different post when the strip kit arrives and I put them in.
Thanks to everyone who has taken me this far solving this issue with your comments and suggestions.
Have a great Memorial Day weekend.
Let us all take a minute to remember our fallen comrades who allow us the freedom to mess with these old cars in the first place.
Mike
Posted By: GO_Fish
Re: surgung issue persists 340 4bbl - 05/24/09 04:20 PM
Quote:
Here's a pic of a strip kit $42.79 at O'reillys(they ordered it-2 days) though w your carb the kit # will be different. Only caveat is when you drop the rod assembly on top of the spring that you then wiggle it slightly till it finds its hole rather than forcing it.
That I know of, nobody sells strip kits for the Carter AVS (occassionally you see a 30 year old used kit on Ebag). The kit above is designed for the Edelbrock AVS which uses Carter AFB style metering rods and jets. You cannot just install Eddy AVS metering rods in a Carter AVS without going inside the carb and changing the jets and metering rod covers also (so that everything is AFB style). The Carter AVS uses a longer 3 step metering rod, where the Eddy AVS uses shorter AFB 2 step rods.
Posted By: ashburnmike
Re: surgung issue persists 340 4bbl - 05/24/09 08:12 PM
Quote:
Quote:
Here's a pic of a strip kit $42.79 at O'reillys(they ordered it-2 days) though w your carb the kit # will be different. Only caveat is when you drop the rod assembly on top of the spring that you then wiggle it slightly till it finds its hole rather than forcing it.
That I know of, nobody sells strip kits for the Carter AVS (occassionally you see a 30 year old used kit on Ebag). The kit above is designed for the Edelbrock AVS which uses Carter AFB style metering rods and jets. You cannot just install Eddy AVS metering rods in a Carter AVS without going inside the carb and changing the jets and metering rod covers also (so that everything is AFB style). The Carter AVS uses a longer 3 step metering rod, where the Eddy AVS uses shorter AFB 2 step rods.
That is a bummer but good to know now.
I think my best option at this point is to invest in a new replacement carb, enjoy driving the car, and get the proper conversion parts for my old AVS.
I will look for a similar carb @ the Carlisle show and see if I can find one to practice on.
I will call Edelbrock Tuesday and get the recommendation, but what are your thoughts on which unit to go with.
Thanks
Mike
Posted By: RapidRobert
Re: surgung issue persists 340 4bbl - 05/24/09 08:23 PM
When he said AVS I thought he had an eddie AVS not an orig one but all is not lost. Just invest ~40 some dollars in a strip kit & cut a pair of metering rod covers out of a bean can lid(flat),drill a small hole in them & drop in the richest set of rods(the cruise step) in it & replace the domed covers w your new flat ones & take her out for a spin. You dont need a new carb & no need (for now) to even take the top off
Posted By: GO_Fish
Re: surgung issue persists 340 4bbl - 05/25/09 12:47 AM
Now you are on the right track!
As long as you change everything to AFB jets and metering rods (and flat cover), then you are good to buy the Edelbrock strip kit (actually, everything you need to swap ((except the flat metering rod covers))is in the Eddy kit). Just swap the new jets and rods in and put your Carter parts you remove on the shelf. Pretty simple conversion, then you have essentially an Eddy AVS. Edelbrock won't want to speak to you about converting your Carter, they are in business to sell you a new Eddy $$$$$. But the main difference between the Eddy AVS and the Carter AVS you have is AFB metering rods, jets and flat metering rod cover. It's not a hard swap, you can do it in an hour (even if you've not done it before).
Check the Eddy AVS PDF's on their website, it will be a big help in dialing the carb in.
Posted By: RapidRobert
Re: surgung issue persists 340 4bbl - 05/25/09 02:03 AM
I am going to send him a pair of my metering rods w the richest "cruise" step as they need to come out of my 1406 (they're killing my mileage
) but that will show if his surging is a main metering lean problem and I maintain that he does not even have to change his jets so the top does not have to come off.
Posted By: GO_Fish
Re: surgung issue persists 340 4bbl - 05/25/09 02:13 AM
As long as you are using Carter 3 step AVS rods, you are correct, the top does not need to come off the carb. As simple as different spring pressure could help solve the problem also. Stiffer springs (different color) will make it harder for his existing rods to get sucked fully down into the jet under high vacuum (making the mixture richer).
Posted By: aarlucas
Re: surgung issue persists 340 4bbl - 05/25/09 02:17 AM
Looks like everything thing is covered. However, when I had the same problem with my car it was due to the carb being to rich. So don't over look this too. How do your plugs look? If they are unreadable, replace one plug and drive it a few miles. This will give you and idea of which way to go as far as richer or leaner.
Posted By: surfman
Re: surgung issue persists 340 4bbl - 05/26/09 01:25 AM
My car did the same thing with the mopar small block electonic diatributor. I found that the advance shaft plate that was swedged at the factory underneath was loose and the centifical(?) advance was hunting or surging several degrees upon steady cruise conditions. You might try a new distributor or disassemble the advance mechanism to see if it is loose and maybe mig it up. I replaced my distributor and it fixed my problem.
Posted By: ashburnmike
Re: surgung issue persists 340 4bbl - 05/30/09 05:10 PM
Update:
Thank you again Robert for the rods and the caps.
I swapped out the existing rods with the ones you sent.
It now stumbles out of the hole and the surging is actually worse.
I went to re-time it and the coil I have is really hot to the touch. Don't know if this is could be a factor.
The strip kit hasn't arrived yet so I guess I'm stuck for the moment.
It's a beautiful day here in Northern Virginia and a perfect day for working on cars.
Mike
Posted By: RapidRobert
Re: surgung issue persists 340 4bbl - 05/30/09 05:49 PM
I was sure hoping that it would go the other way. I am wondering since the caps I sent didn't seal totally but were Ok for me as I am never(yet) into the power step & my pistons were always pulled down on the base & sealed & when you're into the power & the piston is up no more seal. dont know for sure if that is what is going on but I have an AFB coming & I will send you the stock flat covers from it & we'll see if things improve. we WILL get this resolved