surgung issue persists 340 4bbl - Moparts Forums

Register Log In Moparts Forums Moparts Question and Answer surgung issue persists 340 4bbl

Print Thread

Page 1 of 3

1

2

3

surgung issue persists 340 4bbl #325575 05/22/09 11:17 AM 05/22/09 11:17 AM
Joined: Feb 2003 Posts: 455 Ashburn, Virginia A ashburnmike OP mopar
ashburnmike OP mopar A Joined: Feb 2003 Posts: 455 Ashburn, Virginia	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

Re: surgung issue persists 340 4bbl DELETED DELETED [Re: ashburnmike] #325576 05/22/09 11:59 AM 05/22/09 11:59 AM
Joined: Jan 2003 Posts: 32,907 Grand Prairie,Texas stumpy I Win
stumpy I Win Joined: Jan 2003 Posts: 32,907 Grand Prairie,Texas	Post deleted by stumpy Last edited by stumpy; 05/22/09 12:01 PM.

Re: surgung issue persists 340 4bbl [Re: stumpy] #325577 05/22/09 12:03 PM 05/22/09 12:03 PM
Joined: Jan 2003 Posts: 24,562 Brookeville, Md Mr.Yuck Not enough dumb comments...yet
Mr.Yuck Not enough dumb comments...yet Joined: Jan 2003 Posts: 24,562 Brookeville, Md	lean.... fatten it up...or better yet get a DP. [IMG]http://i66.tinypic.com/pui5j.jpg[/IMG] Coming soon!!!!

Re: surgung issue persists 340 4bbl [Re: Mr.Yuck] #325578 05/22/09 12:14 PM 05/22/09 12:14 PM
Joined: Jan 2003 Posts: 16,123 Grand Haven, MI patrick I Live Here
patrick I Live Here Joined: Jan 2003 Posts: 16,123 Grand Haven, MI	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? Last edited by patrick; 05/22/09 12:16 PM. 1976 Spinnaker White Plymouth Duster, /6 A833OD 1986 Silver/Twilight Blue Chrysler 5th Ave HotRod SOLD!* 2011 Toxic Orange Dodge Charger R/T 2017 Grand Cherokee Overland 2014 Jeep Cherokee Latitude (holy crap, my daughter is driving)

Re: surgung issue persists 340 4bbl [Re: patrick] #325579 05/22/09 12:33 PM 05/22/09 12:33 PM
Joined: Oct 2007 Posts: 3,869 Oregon hooziewhatsit master
hooziewhatsit master Joined: Oct 2007 Posts: 3,869 Oregon	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 If you ever find yourself in a fair fight, your tactics suck.

Re: surgung issue persists 340 4bbl [Re: ashburnmike] #325580 05/22/09 03:12 PM 05/22/09 03:12 PM
Joined: May 2003 Posts: 1,603 germany 440sat72 top fuel
440sat72 top fuel Joined: May 2003 Posts: 1,603 germany	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. My car

Re: surgung issue persists 340 4bbl [Re: 440sat72] #325581 05/22/09 03:31 PM 05/22/09 03:31 PM
Joined: Jan 2003 Posts: 2,757 Gilbertsville, PA 19525 P Pntastar69 master
Pntastar69 master P Joined: Jan 2003 Posts: 2,757 Gilbertsville, PA 19525	Jet up a few on the primary.

Re: surgung issue persists 340 4bbl [Re: Pntastar69] #325582 05/22/09 03:34 PM 05/22/09 03:34 PM
Joined: Nov 2003 Posts: 36,040 Lincoln Nebraska R RapidRobert Circle Track
RapidRobert Circle Track R Joined: Nov 2003 Posts: 36,040 Lincoln Nebraska	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 Last edited by RapidRobert; 05/22/09 04:05 PM. live every 24 hour block of time like it's your last day on earth

Re: surgung issue persists 340 4bbl [Re: 440sat72] #325583 05/22/09 03:42 PM 05/22/09 03:42 PM
Joined: Jan 2003 Posts: 2,931 P Paul_Fancsali master
Paul_Fancsali master P Joined: Jan 2003 Posts: 2,931	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.

Re: surgung issue persists 340 4bbl [Re: ashburnmike] #325584 05/22/09 05:20 PM 05/22/09 05:20 PM
Joined: Nov 2003 Posts: 2,715 closer to Canadian beer! torkrules I'm neurotic
torkrules I'm neurotic Joined: Nov 2003 Posts: 2,715 closer to Canadian beer!	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.

Re: surgung issue persists 340 4bbl [Re: Paul_Fancsali] #325585 05/22/09 05:32 PM 05/22/09 05:32 PM
Joined: Feb 2003 Posts: 455 Ashburn, Virginia A ashburnmike OP mopar
ashburnmike OP mopar A Joined: Feb 2003 Posts: 455 Ashburn, Virginia	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

Re: surgung issue persists 340 4bbl [Re: ashburnmike] #325586 05/22/09 06:08 PM 05/22/09 06:08 PM
Joined: Nov 2006 Posts: 511 Jasper, Indiana fastnos mopar
fastnos mopar Joined: Nov 2006 Posts: 511 Jasper, Indiana	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... A True Hybrid: Burns Gas AND Rubber!

Re: surgung issue persists 340 4bbl [Re: ashburnmike] #325587 05/22/09 08:23 PM 05/22/09 08:23 PM
Joined: Nov 2003 Posts: 36,040 Lincoln Nebraska R RapidRobert Circle Track
RapidRobert Circle Track R Joined: Nov 2003 Posts: 36,040 Lincoln Nebraska	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. live every 24 hour block of time like it's your last day on earth

Re: surgung issue persists 340 4bbl [Re: ashburnmike] #325588 05/22/09 10:03 PM 05/22/09 10:03 PM
A Anonymous Unregistered
Anonymous Unregistered A	Try taking a ride with vacuum advance un-hooked.

Re: surgung issue persists 340 4bbl [Re: fastnos] #325589 05/22/09 11:09 PM 05/22/09 11:09 PM
Joined: Jul 2003 Posts: 6,167 Maryland GO_Fish master
GO_Fish master Joined: Jul 2003 Posts: 6,167 Maryland	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. Last edited by GO_Fish; 05/22/09 11:12 PM. Scott B. "I'm a self-made man... I started with nothing, and I still have most of it!" 68 360 rusty B'cuda 'vert (GO Fish)13.59@ 98.72 mph 69 340 GTS stock 14.18@ 95.60 mph 01 5.9L Ram 1500 Quad Cab 4x4 01 3.5L 300M 16.23@ 86.97 mph

Re: surgung issue persists 340 4bbl [Re: GO_Fish] #325590 05/22/09 11:35 PM 05/22/09 11:35 PM
Joined: Jan 2003 Posts: 14,470 renton, Washington ph23vo I Live Here
ph23vo I Live Here Joined: Jan 2003 Posts: 14,470 renton, Washington	as stated above unplug the vac advance and it will go away dan

Re: surgung issue persists 340 4bbl [Re: ph23vo] #325591 05/22/09 11:57 PM 05/22/09 11:57 PM
Joined: Nov 2003 Posts: 36,040 Lincoln Nebraska R RapidRobert Circle Track
RapidRobert Circle Track R Joined: Nov 2003 Posts: 36,040 Lincoln Nebraska	I hope it's not rotor phasing. I cant handle another rotor phasing thread. live every 24 hour block of time like it's your last day on earth

Re: surging issue persists 340 4bbl [Re: RapidRobert] #325592 05/23/09 12:04 AM 05/23/09 12:04 AM
Joined: Feb 2003 Posts: 455 Ashburn, Virginia A ashburnmike OP mopar
ashburnmike OP mopar A Joined: Feb 2003 Posts: 455 Ashburn, Virginia	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?

Re: surging issue persists 340 4bbl [Re: ashburnmike] #325593 05/23/09 12:28 AM 05/23/09 12:28 AM
Joined: Nov 2003 Posts: 36,040 Lincoln Nebraska R RapidRobert Circle Track
RapidRobert Circle Track R Joined: Nov 2003 Posts: 36,040 Lincoln Nebraska	always make (1) change at a time live every 24 hour block of time like it's your last day on earth

Re: surgung issue persists 340 4bbl [Re: Mr.Yuck] #325594 05/23/09 06:00 AM 05/23/09 06:00 AM
Joined: Jul 2008 Posts: 30,424 Florida STAYcation dOc ! The village idiot's idiot
dOc ! The village idiot's idiot Joined: Jul 2008 Posts: 30,424 Florida STAYcation	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.

Page 1 of 3

1

2

3

Moderated by Al_Alguire, Hotwheelsjr, moparts, not_a_charger, RangerDan440, tboomer

Hop To

Powered by UBB.threads™ PHP Forum Software 7.7.1