383 Surging / Missing below 2000 RPM

[dburnett6263]

There have been several posts on this topic but I'm going to throw mine out and see if anyone has some thoughts.
68 RR 383 .040 over comp XE cam, duration @.050-.230 / .236
valve lift .488 / .491, lobe lift .325 / .327, range 1800-6000.
Heads stock 440 with machine work and porting, Edelbrock alum. intake, Holley 770 Street Avenger, Carter Muscle car Mech. fuel pump w / reg. and gauge (5psi), MSD billet distributor (no vac. adv.), 6AL box. A833 4 speed 3:23 gears.
Engine was on dyno after build and ran strong, no issues. (35* total timing)
Engine now in the car and 1000+ miles on it and it will get with the program when asked.
I live in a rural area so, country roads 35-45 MPH. But at the lower RPMs and light load surging / missing begins, even in neutral as I bring the RPMs up from idle you can here it.
I've had the initial timing all over from 5* to 25* advanced, being careful not to detonate. I have not touched the carb as Holley is adamant about how it is factory set. But it is quite rich. I have the blue springs in the distributor, starts at 1500 RPM, all in at 2800 and the advance stop bushing is at 21*. Initial timing is now back to 14*. Doesn't seem to make any difference where it's set. I was fighting a cold start issue early on which turned out to be 17psi fuel pressure, hence the reg. and gauge, also new plugs. Don't know if it's cam, carb, timing, or all 3.
Any thoughts or suggestions would be greatly appreciated.
Thanks
Dale :eusa_wall:

 

[Xp29h]

D... Sounds familiar! My 383 does the same thing! Very similar set up, initial timing been set in same ranges. Now at 21 degrees. Running same msd dizzy. Blue springs and I've tried the other combos of springs. No difference. The only thing I didn't do is lock the dizzy out. Didn't think it would work.

Now, after a long trial and error period, I found out I have very low compression due to bad rings? I won't know for sure until I take it apart. I think that is my issue. I wouldn't look there for you. Unfortunately, I don't have a great answer for you. Carb maybe. I've tried different ones. 600 to 850 holleys. 850 on it now. I just thought I would let you know I've tried many different things and it still misses in the low range but once it gets going, it's great 2500+.

Hopefully someone will be able to give the great answer! My answer is stroking a 400!

Good luck!

 

[miller]

As Xp29h says on compression...suggest a good compression check on all 8 holes. At least that will tell you what shape the motor is in.
I'm not a Holley guy. But with that said, how can Holley say leave at 'factory settings'? I don't care if two same motors are built side-by-side, there will be differences on carb/ignition settings, cam, etc. Don't believe in slap on carbs. Mixture setting needs to be at least checked, to give the motor what it wants. You can always put the mixture back at the 'factory settings', if you need to.

 

[ODZKing]

I have a 67 Charger 383 which was originally a 2bbl. I had the surging issue that drove me crazy. I am not saying this is your solution but simply telling you what I did to eventually solve it and with this information if it gets you to look in a place where you haven't looked previously, great.
When I bought it no matter how well I adjusted the 2 bbl it had the surging, bad. So I changed the points, no change. Went to electronic ignition, NC.
Tried timing here, there and everywhere ... nothing. Tried different gas, hotter plugs, different wires, fuel pump, sender, changed filters, nothing took care of the surging.
So at one point, I went to the parts book and found that the 67 383 4bbl (non HP) has all the same components as a 2 bbl. Nothing to change except linkage to trans. Then a friend gave me his stock 4 bbl intake which I cleaned, painted and put on the car. Then I found a correct AFB and installed THAT on the car. Initially I did this because I wanted a 4 bbl, not because of the surging issue but the outcome was excellent. Overall the car ran better and the best part - Surging gone!!!!!
If the info helps you, great. But my guess is it is fuel related.

 

[dburnett6263]

Thanks ODZ, I am going to look into the fuel thing as I have exhausted the timing experiments. Will check compression but it's a new engine built by one of the best in the area so I don't suspect any surprises. I'm still open to thoughts and ideas. Thanks Dale

 

[miller]

Satisfaction is a good compression test, and matching numbers. It will tell you the story.

 

[PP1RT]

Any vacuum leaks? Maybe not noticable at idle but off idle up to 2000 rpm?

 

[Lets Roll]

In the old days they would spray some carb cleaner around the base of the carb and the intake gaskets and listen for a change to find vacuum leak. I wouldn't suggest it. But definitely look closely for vacuum leaks.

 

[bm02tj]

Maybe wrong power valve or a bad one
but carb has to be adjusted for your motor it will not be perfect out of the box

 

[dburnett6263]

I have a 67 Charger 383 which was originally a 2bbl. I had the surging issue that drove me crazy. I am not saying this is your solution but simply telling you what I did to eventually solve it and with this information if it gets you to look in a place where you haven't looked previously, great.
When I bought it no matter how well I adjusted the 2 bbl it had the surging, bad. So I changed the points, no change. Went to electronic ignition, NC.
Tried timing here, there and everywhere ... nothing. Tried different gas, hotter plugs, different wires, fuel pump, sender, changed filters, nothing took care of the surging.
So at one point, I went to the parts book and found that the 67 383 4bbl (non HP) has all the same components as a 2 bbl. Nothing to change except linkage to trans. Then a friend gave me his stock 4 bbl intake which I cleaned, painted and put on the car. Then I found a correct AFB and installed THAT on the car. Initially I did this because I wanted a 4 bbl, not because of the surging issue but the outcome was excellent. Overall the car ran better and the best part - Surging gone!!!!!
If the info helps you, great. But my guess is it is fuel related.

Sounds like your problem might have been a vacuum leak. The new manifold, carb, and especially gaskets may have done the trick.

 

[GTX MATT]

Is it on throttle tip in?

 

[GTX MATT]

If you're still having the issue, I'd try some different squirters. The 25 in those carbs stock is pretty small, a 28 or 31 would work alot better.