I have a 440 that has a jerking motion while light cruising and when accelerating lightly/medium. I do have a wideband hooked up and i can see it fluctuate between 13.5-14.3 af. The car idles great at 13.8 af and has no stumbles any where. I just need to figure out what the bucking is all about. Could it be light distributor springs?

The specs on the build is:
440, 10.5 compression, 91 octane, ported iron heads, lunati voodoo solid roller(249/252 duration), 4500 stall, 3.23 gears, 950 double pumper.

As the Holley only has a full vacuum hook up, the factory distributor is hooked to that. The car is a full street car and hasnt seen the track yet as I have just got it fired up.

Thanks for the help!

Could be to much timing since its hooked to manifold vacuum. Did u try unhooking it and trying it?

I doubt it's too much timing, per se. What's likely happening is that as he opens the throttle the vacuum drops off and his timing retards. As the manifold vacuum bounces around, so does his timing. Simple test, pull and cap the vacuum line to the distributor and see if it goes away.

Normally bucking(AKA known as pinging) at light, part throttle in high gear is from being to lean, are you sure your wideban is calibrated corectly Make sure there are NO exhaust leaks also as well as the proper heat range spark plugs

I too think to much timing. Try backing out the vacuum adv 2turns to cure the light take off from a stop problem; and then limiting the total timing (this includes vacuum adv) to no more than 48 degrees to solve the highway problem.

I currently run 33 mech all in at 3k, and had to limit the vacuum adv to no more than 16 degress to stop highway cruising surge.

Hello Ori. you might block the rods up (eddy) or go 4 sizes richer on pri jets (holley) for a quick test & see if that is it. As said cap the can & see what that does. check rotor phasing. then if no luck I would get scientific & note the RPM that it does it at then back at home see what your total timing is at those (RPM) points and tape a vac gauge to your windshield & see what range of in hg it is in when it acts up. keep us posted!

Just got back from a nice cruise. I have some data to give you all!

I took the carb apart and low and behold I forgot I had a 0.019" wire in the primary only lower idle feed restrictors. I took that wire out and took it for a nice long cruise. With the wire in the AF was ranging from 14.0-15.3 afr. Now with the wire out of it, the afr 12.2-12.5 and it seems to have cleared up a lot of the stumbling. I didnt mess with the timing because it was dark and I forgot my light at home.
All of the above is taking place at 30mph@ a steady 12" vacuum.

Now I take it on a nice cruise at a steady 50mph. Now the afr's are in the 15.2-16.5 range and it acts like it used to in the 30mph test. Vacuum is at 10.5-11". How do I get this portion richer?

Last but not least I did a WOT test and it was lean as well, 14.8-15.2.

My jetting is:
78 front with a 6.5" PV
80 rear with a 6.5 PV

Im going to put 90 jets in the back and see how it does then at WOT.

Thanks!

I ain't a Holley guy but I would want to get the pri system dialed in first. If I'm reading that right that at 30 MPH the cruise is 12.5 & I'm thinking that is what you'd want at WOT. I'd play with the pri jets but that might be too simple an idea. See what the guys say

Make sure your timing is spot on also...

Exactly , lose the vacuum advance till you get everything squared away and them figure it out from there.

What altitude are you at and does your gas have Ethanol in it ?

Im at 5500ft and the 91 octane I use has 10% ethanol in it.

After some more cruising I found that if I plug off the manifold vac advanced on the distributor the car does not surge when accelerating or cruising. I think I need to hook the advanced up as PORTED but I do not have a ported port on my Holley. What do I need to make it ported?

Thanks!

Ori your sayin that the can is now capped? The can alters rotor phasing, it increases the reluctor gap, it adds timing. checkout the first two and note the RPM range you are cruising and accelerating in (that you mentioned) without the can (if I read that right) then plug in the can to manifold and back off the initial (turn the housing) till the timing total at your RPM range is the same as what it was earlier with the can capped (& no surging) (duplicate the amt in your driveway) & go out & see if the surging is still gone

Sounds lean...fatten it up some

Glad that this was it. Easy to check and correct. It is not uncommon for an engine to buck under these conditions due to too much timing.

None of you seem to realize that the only difference between ported and manifold vacuum occurs at or very near closed throttle.

I suggest you read up on how to adjust when the vacuum advance kicks in.

http://www.dodgecharger.com/forum/index.php?topic=14888.0

Not sure to whom you are referring.

Supercuda, it would appear to me (from the content of our posts) that both me and BSB67 are thinking that the can is adding too much adv not that it is a porting/manifold selection issue. & I'd like to see Ori check the reluctor gap and rotor phasing

I was trying to enlighten the OP. You can adjust at what vacuum level the advance kicks in, he may very well be right on the tipping point at cruise and it's cycling on him.