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Possible to lessen choppy idle due to cam? #1662739 08/23/14 09:36 PM 08/23/14 09:36 PM
Joined: Jan 2011 Posts: 15,879 Central Florida larrymopar360 OP Stud Muffin
larrymopar360 OP Stud Muffin Joined: Jan 2011 Posts: 15,879 Central Florida	Love the power my 410 smallblock makes, but the idle is pretty choppy and I'd prefer it be as smooth as possible (kind of a sleeper car). Assuming the carb is set properly, and I believe mechanic has it spot on, are there ways to smooth it out? Adding a vacuum canister (I don't know the proper terminology but I have seen them) that holds vacuum help? The power brakes are fine. The pedal does get a little hard after back to back use, but I can live with that. This engine is in my '89 Diplomat Police car so choppy idle isn't exactly "appropriate". Now if it were a Duster or Demon, etc...... It is a brand new engine so I don't want to change out the cam. Just wondering if there is a simpler solution that might lessen the choppiness. Thanks. Facts are stubborn things.

Re: Possible to lessen choppy idle due to cam? [Re: larrymopar360] #1662740 08/23/14 10:04 PM 08/23/14 10:04 PM
Joined: Jan 2003 Posts: 9,826 las vegas 70AARcuda master
70AARcuda master Joined: Jan 2003 Posts: 9,826 las vegas	More initial timing you can crank into to it the smoother it will idle...and then you have to limit the mechanical advance in the distributor to keep total around 35 degrees... Tony 70 AARCuda Vitamin C 71 Dart Swinger 360 10.318 @ 128.22(10-04-14 Bakersfield) 71 Demon 360 10.666 @122.41 (01-29-17 @ Las Vegas) 71 Duster 408 (10.29 @ 127.86 3/16/19 Las Vegas)

Re: Possible to lessen choppy idle due to cam? [Re: larrymopar360] #1662741 08/23/14 10:05 PM 08/23/14 10:05 PM
Joined: Sep 2004 Posts: 6,906 IL, Aurora A ademon master
ademon master A Joined: Sep 2004 Posts: 6,906 IL, Aurora	Rhodes lifters,

Re: Possible to lessen choppy idle due to cam? [Re: ademon] #1662742 08/23/14 11:31 PM 08/23/14 11:31 PM
Joined: Jul 2007 Posts: 1,682 Philadelphia R radar top fuel
radar top fuel R Joined: Jul 2007 Posts: 1,682 Philadelphia	Turn up the idle to a slightly higher rpm and keep it quiet with good mufflers

Re: Possible to lessen choppy idle due to cam? [Re: radar] #1662743 08/23/14 11:52 PM 08/23/14 11:52 PM
Joined: Jan 2003 Posts: 1,030 JAX FLA Curt super stock
Curt super stock Joined: Jan 2003 Posts: 1,030 JAX FLA	I ran crane variable duration lifters over 2 decades ago...... Doubled my idle vacuum from 2" to 4" and helped smooth out off idle running as well. Curt Oh yeah...THAT'S gonna leave a mark!

Re: Possible to lessen choppy idle due to cam? [Re: Curt] #1662744 08/24/14 04:21 AM 08/24/14 04:21 AM
Joined: Feb 2010 Posts: 18,493 Granite Bay CA Kern Dog Striving for excellence
Kern Dog Striving for excellence Joined: Feb 2010 Posts: 18,493 Granite Bay CA	Holy crap ! TWO inches of idle vacuum???

Re: Possible to lessen choppy idle due to cam? [Re: larrymopar360] #1662745 08/24/14 06:04 AM 08/24/14 06:04 AM
Joined: May 2008 Posts: 5,399 Aurora, Colorado 451Mopar master
451Mopar master Joined: May 2008 Posts: 5,399 Aurora, Colorado	More timing at idle really helps. I found that out when I installed the EFI system. You might be able to adjust the vacuum advance to pull in at a lower vacuum level and then connect the vacuum advance to full time vacuum source. Another option could use an ignition retard module triggered with a microswitch on the carb, like a nitrous setup. At idle you could run alot of ignition advance, then when you hit the throttle, the ignition would retard and advance with the distrubitors advance curve.

Re: Possible to lessen choppy idle due to cam? [Re: larrymopar360] #1662746 08/24/14 10:21 AM 08/24/14 10:21 AM
Joined: Jul 2014 Posts: 72 Pennsylvania R Red 79 member
Red 79 member R Joined: Jul 2014 Posts: 72 Pennsylvania	The more initial timing you can run the better it will idle. I used to run 12 degrees at idle with a choppy solid lifter in 360 cu and since have changed to 19 degree at idle (still 35 total). The difference in idle quality is much better and still starts just as easy as before. For me it was worth the effort and time it took to modify to mechanical advance.

Re: Possible to lessen choppy idle due to cam? [Re: Red 79] #1662747 08/24/14 07:38 PM 08/24/14 07:38 PM
Joined: Jan 2011 Posts: 15,879 Central Florida larrymopar360 OP Stud Muffin
larrymopar360 OP Stud Muffin Joined: Jan 2011 Posts: 15,879 Central Florida	I did bring up the idle setting just a bit and that helped a little. Still very choppy though. I noticed install mechanic has the vacuum advance plugged. I know total timing is set at 36 per the engine builder. I will check with him on initial timing, thanks. I don't want to change out anything right now. It is a brand new internally balanced engine, and I sprung for the roller cam upgrade and other goodies, so I really can't afford nor want to start unbolting and replacing parts. Hoping for a simpler solution but am ignorant on the subject of choppy idling cams. I know there may not be a simple one, but I will definitely talk with mechanic about initial timing. Thanks again. Facts are stubborn things.

Re: Possible to lessen choppy idle due to cam? [Re: larrymopar360] #1662748 08/24/14 07:48 PM 08/24/14 07:48 PM
Joined: Apr 2005 Posts: 12,271 Overpriced Housing Central RobX4406 I Live Here
RobX4406 I Live Here Joined: Apr 2005 Posts: 12,271 Overpriced Housing Central	Total might be OK at 36, but if that dist has 28* of mechanical in it, it's going to idle like bullcrap. Total timing method is horrible way to time a car that's street driven and good idle quality is desired. Put a distributor out of the box that isn't set up for the engine and you'll get junky idle and low speed manners. Put a light on it at idle and see where it's timed. I wouldn't have any less than 15 minimum in most any case. It may take some work to get it right.

Re: Possible to lessen choppy idle due to cam? [Re: radar] #1662749 08/24/14 08:56 PM 08/24/14 08:56 PM
Joined: Nov 2004 Posts: 7,274 s.w.fl B bonefish master
bonefish master B Joined: Nov 2004 Posts: 7,274 s.w.fl	Quote: Turn up the idle to a slightly higher rpm and keep it quiet with good mufflers thats all thats going to help without changing parts.i usually just tell people when they say somthing about the cam."naw,i just need to get that carb dialed in and it,ll smooth rite out"

Re: Possible to lessen choppy idle due to cam? [Re: bonefish] #1662750 08/24/14 09:07 PM 08/24/14 09:07 PM
Joined: Jan 2003 Posts: 9,826 las vegas 70AARcuda master
70AARcuda master Joined: Jan 2003 Posts: 9,826 las vegas	turn up the idle speed...then lose your mixture screws adjustifiability....fix the timing...then adjust carb... Tony 70 AARCuda Vitamin C 71 Dart Swinger 360 10.318 @ 128.22(10-04-14 Bakersfield) 71 Demon 360 10.666 @122.41 (01-29-17 @ Las Vegas) 71 Duster 408 (10.29 @ 127.86 3/16/19 Las Vegas)

Re: Possible to lessen choppy idle due to cam? [Re: RobX4406] #1662751 08/24/14 09:32 PM 08/24/14 09:32 PM
Joined: Jan 2011 Posts: 15,879 Central Florida larrymopar360 OP Stud Muffin
larrymopar360 OP Stud Muffin Joined: Jan 2011 Posts: 15,879 Central Florida	I will definitely discuss all the timing settings with install mechanic. He is a great mechanic...not a Mopar guy, but still great mechanic. I am certain he had a light on it and vacuum gauge, but this distributor is a Mopar performance with the orange box, so maybe other changes will help? I would be willing to spring for new ignition if it would help alot, and at least that wouldn't require getting into internals of new engine. I'd love it if tweaking the carb adjustments brought it down some! I think maybe the timing is a little off of the suggestions of builder. We shall see! Last edited by larrymopar360; 08/24/14 09:36 PM.

Re: Possible to lessen choppy idle due to cam? [Re: larrymopar360] #1662752 08/24/14 11:06 PM 08/24/14 11:06 PM
Joined: Oct 2003 Posts: 21,345 Marysville, O-H-I-O 70Cuda383 Too Many Posts
70Cuda383 Too Many Posts Joined: Oct 2003 Posts: 21,345 Marysville, O-H-I-O	The only way you'll smooth out the idle, is to increase the RPM. Even the choppiest of race engines 'smooth out' in sound as RPM goes up, and the tamest if engines will sound like wild race motors if you dial the rpm down to 350 at idle. Now, don't cheat and just turn your idle speed screw. Need to tune for max vacuum at idle by increasing timing. Then set dustributir to limit total timing to 36-38. If its still too choppy, get a big, single exhaust snd large muffler. Combining exhaust into 1 system helps mellow out the pulses from each other. And finally, if its still not enough, bump RPM by 150 via idle speed screw. Photobucket sucks

Re: Possible to lessen choppy idle due to cam? [Re: 70Cuda383] #1662753 08/24/14 11:29 PM 08/24/14 11:29 PM
Joined: Jan 2011 Posts: 15,879 Central Florida larrymopar360 OP Stud Muffin
larrymopar360 OP Stud Muffin Joined: Jan 2011 Posts: 15,879 Central Florida	Quote: The only way you'll smooth out the idle, is to increase the RPM. Even the choppiest of race engines 'smooth out' in sound as RPM goes up, and the tamest if engines will sound like wild race motors if you dial the rpm down to 350 at idle. Now, don't cheat and just turn your idle speed screw. Need to tune for max vacuum at idle by increasing timing. Then set dustributir to limit total timing to 36-38. If its still too choppy, get a big, single exhaust snd large muffler. Combining exhaust into 1 system helps mellow out the pulses from each other. And finally, if its still not enough, bump RPM by 150 via idle speed screw. I am taking notes. I just spent big on the exhaust too though. Mandrel bent 2.5 dual exhausts. H or X pipe make a considerable difference? I did turn up idle a bit and it helped a bit but not enough. Thanks. Facts are stubborn things.

Re: Possible to lessen choppy idle due to cam? [Re: larrymopar360] #1662754 08/25/14 10:03 AM 08/25/14 10:03 AM
Joined: Nov 2004 Posts: 7,274 s.w.fl B bonefish master
bonefish master B Joined: Nov 2004 Posts: 7,274 s.w.fl	it sounds like the motor you built,SOUNDS like the motor you built.it needs to breath and thats going to keep it choppy.

Re: Possible to lessen choppy idle due to cam? [Re: bonefish] #1662755 08/25/14 11:20 AM 08/25/14 11:20 AM
Joined: Jun 2005 Posts: 5,105 Western Md. skicker "The Champ"
skicker "The Champ" Joined: Jun 2005 Posts: 5,105 Western Md.	Installing an X pipe will smooth it out a lot. Its not a cheap solution but it does work well and will add performance. I just went through some of this with my 340. I run an MSD ignition and after changing the bushings to limit the advance my motor sounded a little tamer than before. My initial timing is now advanced to 20* with total being right at 38*. Your distributor can be modified to do what you want, it's just so much easier with the MSD because the adjustments were built in when it was designed. ...FAFO...

Re: Possible to lessen choppy idle due to cam? [Re: skicker] #1662756 08/25/14 12:40 PM 08/25/14 12:40 PM
Joined: Jan 2003 Posts: 16,376 D dogdays I Live Here
dogdays I Live Here D Joined: Jan 2003 Posts: 16,376	Wht's the duration at 50 lift and the lobe separation angle? Where is the intake centerline? These questions MUST be answered before any kind of intelligent answer can be found. I have a feeling you and your mechanic have different ideas of what a "streetable" cam is. Eventually you're going to replace or regrind the cam , is my bet. You may be able to advance the cam, which closes the intake valve sooner, which can cut down somewhat on the choppy idle. But answer the questions first. And if your mechanic can't tell you where he installed the cam, he's not much of a mechanic. And "lined up the dots" doesn't count as an answer. R.

Re: Possible to lessen choppy idle due to cam? [Re: skicker] #1662757 08/25/14 06:17 PM 08/25/14 06:17 PM
Joined: Jan 2011 Posts: 15,879 Central Florida larrymopar360 OP Stud Muffin
larrymopar360 OP Stud Muffin Joined: Jan 2011 Posts: 15,879 Central Florida	Quote: Installing an X pipe will smooth it out a lot. Its not a cheap solution but it does work well and will add performance. I just went through some of this with my 340. I run an MSD ignition and after changing the bushings to limit the advance my motor sounded a little tamer than before. My initial timing is now advanced to 20* with total being right at 38*. Your distributor can be modified to do what you want, it's just so much easier with the MSD because the adjustments were built in when it was designed. Thanks for the tips. Facts are stubborn things.

Re: Possible to lessen choppy idle due to cam? [Re: dogdays] #1662758 08/25/14 06:25 PM 08/25/14 06:25 PM
Joined: Jan 2011 Posts: 15,879 Central Florida larrymopar360 OP Stud Muffin
larrymopar360 OP Stud Muffin Joined: Jan 2011 Posts: 15,879 Central Florida	It is possible "streetable" has different definition to me. A lot of people like a choppy idle on their street cars. I did explain to engine builder the use of the car, weight, rear gear, trans, tire size, etc. In their defense, it does have enough vacuum to run power brakes. The builder was Muscle Motors, who came very recommended on this forum when I was asking around. The dyno run sheet shows total timing of 36. I don't think it has initial timing. My mechanic did the install, and I have as much confidence in him and his abilities as I do in any mechanic. He does excellent work and is very knowledgable. That doesn't mean the timing or something else doesn't need to be tweaked though, or that the addition of something like an X pipe as suggested wouldn't help. I hadn't thought of an X pipe. I want to have some info written down when I talked to him so I don't waste any of his time. I will see what he has to say. Today I checked the firing order just to be sure. there wasn't a loose wire or crossed wires (I doubted it but easy to check). I figured it runs too good to have that issue, but it idles like it might have. Thx. Facts are stubborn things.

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