440 engine issues! Help Please

[Dart440]

Ok so I have a 1975 dodge dart sport with a 1971 440 auto727, my dad built the engine awhile back when he passed I got it and have been driving it ever since. It has had a new cams and lifters (not sure what or other work done) but I have set the timing at 36 on the spot at 2000rpms, it has no vaccum leaks, new cap, rotor, mopar perf distributer, champion plugs, Taylor 8.2wires, ignition module,new fuel pump and lines all the way back, gas tank. I had a 600 edlebrock it always ran lean but no major problems out of it. So I upgraded to a 800cfm edlebrock and it had an issue that no matter how I tuned it, even sent it to a shop, at 3500rpm it would backfire stumble and fall on its face and not push past it. So I got a brand new street avenger 770 holley i can romp into it at idle no problems at all revs fine and everything, but in drive it continues to have the same problem I put my foot down and stumbles hesitates wants to die out on me. I checked thefloats there spot on, set it everyway it says to by holley richted it up,leaned it out, checked the accel pump, i have done everything still has the same problem. Ithe also idles around 1500 park and 1250ish in drive if I go lower it wants to die. SORRY for the book but Im trying to give all the info I can. I don't wanna get rid of her and I want her to rip the streets apart.

 

[69Bee]

Mechanical advance springs in the distributor are too small (thin). The mechanical advance is all of the way out at idle, and when you try to lower the idle RPM, it dies since the weights come back, and the distributor cannot keep the engine running. You can't get over about 3500 RPM because you run out of timing also. More than likely, a set of "Razoo" Mr. Gasket lightweight advance springs were put in (bet you can't figure out how I know this). Put the original springs in, and it should work just fine.

 

[Dart440]

Ok so kinda novice to this all, it has a electronic distributer in it would that make a difference with the springs or no? Sorry for asking so much it is just driving me nuts

 

[440beep]

Here's a picture of the inside of the Mopar electronic dizzy and the two springs mentioned. These are the stock heavy springs.

Ok so kinda novice to this all, it has a electronic distributer in it would that make a difference with the springs or no? Sorry for asking so much it is just driving me nuts

 

[67 coronet]

if those are your minimum idle specs you must have a huge cam in that thing.you are not getting even close to the idle circuits of those carbs.wich,unless you are used to this problem,can cause some big tuning issues.was the "shop" you sent the car too used to adjusting race level setup's?or just an average shop?what is your timing at your current idle?

 

[Cranky]

I would think it should run ok past 3500 with 36 degrees total but it might be a little low if the engine isn't high compression and everything else is right. Thing is, it's not always easy to set up a carb when your timing isn't right. Does the timing pull back any at all at 1250? Do you have any idea what cam is in it or about what it is? Does it run smooth at idle? 1250 in gear is kinda high even for a fairly radical cam and for sure high at 1500 in neutral but at 1250, is the engine a little bit lumpy? What does it check out at for a compression test? Most engines like more timing if the cranking compression is fairly low....

 

[Dart440]

Just want ot start with saying thanks for all the help. Ok i will definatly look into getting the springs and try that, First i sent it to 3 local shops all of witch have a good reputation, two said it was, The carb was to big or that they dislike holleys for float issues (i live in the mountains apparently its harder on holleys), and the last one was actually somewhat of a speed shop not a huge one but they do have 1972 duster 440 drag car. Secondly it has always been fairly high, its a smooth idle with a little pop and sputter here and there (i have a lifter coming loose slightly) as of this exact moment i just got done rechecking everything with it warmed up 36 on the spot 2000 rpm the lowest i can set my curb idlke screw back is to 1500 Neutral and in gear 1000, But it rocks and shacks and stutters hard that low. Have yet to do a compression test dont have a tester but have a friend who does gotta ask him to use it. Any questions you guys have to help me figure this out just lemme know. Thank you again!

 

[khryslerkid]

I would like to hear more about "(I have a lifter coming loose slightly)"

 

[Dart440]

https://vimeo.com/148308601 this is what happens every time and the lifter on my passenger side is coming lose because when you stand behind the car you can hear it missing on the passenger side (it's a true duel exhaust all the way back) I can give video of anything else if it helps

 

[khryslerkid]

Are they hydrolic lifters?

If something on the valve train, to just one valve, isn't working properly, causing popping and backfiring, it's going to run bad. It would be running on 7 cylinders.

If its a noisy valve when listening under the hood on that side maybe you have a bent push rod?

 

[Dart440]

Like I said at the start I'm not sure never taken it apart to look I work two jobs and don't have to much time so.

 

[62 Dart Convertible]

I agree with kk that if you suspect something in the valvetrain isn't right, forget dizzy/carb until you are sure valvetrain is 100%! I had a pushrod punch an exhaust rocker on a sb years ago. It idled ok, but started to backfire as load/rpm increased...

 

[66Satellite47]

I agree completely with 62 Dart. Get a look at the valve train right away! The only motor I ever broke was from an adjuster backing off and the lifter popping out, no oil pressure during a run at the strip, destroyed crank & rods. A buddy of mine had a push rod poke through the rocker, it too resulted in spun rod bearing. Get a look under those valve covers.

 

[Cranky]

Yup, pull the valve covers off and take a look and see what's in there. I hope your dad didn't use the stamped stock style rockers with a high performance engine but MP does make (or did) a heavy duty stock style rocker which is better than stone stocker. Once you are inside that area, we can help figure out more about the engine and what kind of cam it may have. You can take some measurements on the rockers using a dial indictator and at least find out if it has a high lift or not. You can also plot out pretty much exactly what cam it is but that goes into a more detail and specialized tools. And I'm sorry for the loss of your dad.....

 

[Dart440]

Thank you cranky and everyone else! I will get it tore done asap, i will also take a bunch of photos to give you a guys a better look at everything! Never thought a forums would be so helpful!