Author Topic: Is my carb too big for my 383?  (Read 22553 times)

Offline Chryco Psycho

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Re: Is my carb too big for my 383?
« Reply #30 on: August 15, 2015 - 05:09:28 PM »
use the eddy carb as a boat anchor,grab a holley, quick fuel,some jets and a vac guage.I pulled a 750 eddy pile off my old 440,pu on a holley 850,tweaked it.It was atleast a 50hp gain I swear.Them 2 carbs are easy to tune and have many jets with 4 corner adjuster screws.
Can't argue with that , I have had similar results numerous times

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Offline Bluemonster71RT

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Re: Is my carb too big for my 383?
« Reply #31 on: August 15, 2015 - 05:43:35 PM »
use the eddy carb as a boat anchor,grab a holley, quick fuel,some jets and a vac guage.I pulled a 750 eddy pile off my old 440,pu on a holley 850,tweaked it.It was atleast a 50hp gain I swear.Them 2 carbs are easy to tune and have many jets with 4 corner adjuster screws.

Thats the plan, but until I get mine rebuilt I have to tinker.  Driving today I figured timing was the easiest to do so I moved to 20*btdc and the popping got better so I came back and brought it to 18*. It was so bad I had to turn back home. I put it back at 20*.
It mostly drove ok but seemed better after 2000 rpms. Prior to the drive I chose the springs for the timing curve to be all in at 2500. It felt to me like that curve was to fast so I readjusted the springs to get a slower curve and be all in at 3500.
I definitely gained some speed the car seemed much more responsive there. Then it started popping after just normal driving and giving it some pedal. Then I noticed that if I clutched it and gave it a rev before going in the next gear it would be ok. I assume that its a fuel issue then. I guess I'll do the bigger jets and see. Unless this info helps with another thought.       
1971 Challenger RT 383 4spd

Offline Strawdawg

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Re: Is my carb too big for my 383?
« Reply #32 on: August 16, 2015 - 09:35:39 AM »
sounds more like fuel to me....be sure you have adequate fuel pressure, increase the jet size, or a smaller rod at cruise...also, could it be getting hot and boiling the fuel?

Offline Bluemonster71RT

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Re: Is my carb too big for my 383?
« Reply #33 on: August 16, 2015 - 06:50:44 PM »
Ok, jets and rods added to go one step richer on both the power and cruise mode. I'ts worse now. Backfiring and popping increased. This has to be timing right? I can't seem to find a cure for this issue. If it pops because of too much advance and the more I bring it toward tdc the worse it idles, whats the next plan of attack here. Will the car pop if it is too rich? Maybe I have to go the other way. It's going to take a week to clean the 40 years of black out of my Holley so this is it for now.
1971 Challenger RT 383 4spd

Offline Chryco Psycho

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Re: Is my carb too big for my 383?
« Reply #34 on: August 16, 2015 - 07:33:19 PM »
if it is getting worse go the other way

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Offline Bluemonster71RT

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Re: Is my carb too big for my 383?
« Reply #35 on: August 17, 2015 - 12:56:35 PM »
I seem to have made something better. I only have minor bog now. What I did was with the vacuum gauge hooked up I advanced until the needle was the most steady. Now I don't know if I'm using the timing light wrong or its off but with it at 0* on the dial I don't know what # it is at (my take blew off already). So I assume that you can turn the knob until the timing mark lines up with 0*  and that tells you where you are no? :clueless: If that is correct then something is way off because it says I'm at 44*. That can't be right? I checked twice to see if I was off a tooth and it looks real close and I'm not sure it works like that anyway. 1 is where 1 is. Not like a Chevy where you can drop it in off a tooth or 2. 1 time it started a little hard but 2 times it didn't so I must be in the ball park.  I'm just afraid of braking parts now.  I have read that MSD boxes can toss your timing light off,  the Mac guy said this one works with it. :dunno:
1971 Challenger RT 383 4spd

Offline Strawdawg

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Re: Is my carb too big for my 383?
« Reply #36 on: August 17, 2015 - 02:30:07 PM »
When using a dial back timing light, you set the knob so the arrow points at zero and then set your initial timing to say 16 degs.  If your timing tab does not go to 16, guess where it would be.  Then turn the knob until the line comes back to zero on the tab.  read the dial and see if says 16 when the mark lines up with zero.  (if you are using vacuum advance, be sure it is disconnected while setting the distributor)

Now, you can do the opposite of this and set the knob to 16 and rotate the distributor until the timing line is at zero on the tab.

The distributor should be in the same place whether you took my first comment, or the second.  :)


Then, increase the rpm until the line stops advancing, then dial it back to zero and you will the total mechanical advance.

Offline Bluemonster71RT

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Re: Is my carb too big for my 383?
« Reply #37 on: August 17, 2015 - 02:53:04 PM »
When using a dial back timing light, you set the knob so the arrow points at zero and then set your initial timing to say 16 degs.  If your timing tab does not go to 16, guess where it would be.  Then turn the knob until the line comes back to zero on the tab.  read the dial and see if says 16 when the mark lines up with zero.  (if you are using vacuum advance, be sure it is disconnected while setting the distributor)

Now, you can do the opposite of this and set the knob to 16 and rotate the distributor until the timing line is at zero on the tab.

The distributor should be in the same place whether you took my first comment, or the second.  :)


Then, increase the rpm until the line stops advancing, then dial it back to zero and you will the total mechanical advance.

Then something is wrong with the light when using the dial because its not lining up the same. I have a mechanical advance distributor. I just got bach from an hour drive and the only issues were a few dead spots in the carb. So at the very least the timing seems right though I dont know exactly what it is. I'm guessing about 22*. So I can mess with the carb now and know that it's not timing.
Thanks to everyone helping so far.  I couldn't do this without your help.  Now on with more test and tune. I will post results and findings  :burnout: 
1971 Challenger RT 383 4spd

Offline Bluemonster71RT

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Re: Is my carb too big for my 383?
« Reply #38 on: September 13, 2015 - 06:25:21 PM »
UPDATE.. I have been still chasing some popping and hesitation. I was getting frustrated to no end as I'd keep changing jets and rods and springs and nothing would make it all better. Some changes made it slightly better and then going a step further would make it worse. I went 2 steps rich in sequence and nothing got better. So I changed to lighter springs and it go somewhat better but I assume because the secondaries opened sooner and allowed more fuel. Thats when I went to stage 2 rich and still no better. So I thought maybe it's too rich and went back to stock and one leaner. Worse. So I was thinking it's still a timing issue. No matter where I put it it was no good. Same issues. So for my last option was to go max rich.  Low and behold no more popping. So I guess it needed more fuel on the primaries. But I did notice that I lost some low end power. Maybe its timing still but if I put it were it "sounds" best it doesn't start nice. Like the battery is week for cranking. This setup should be able to melt the tires off and I can't even get much of a squeak but it does pull real hard after the initial get go.
1971 Challenger RT 383 4spd

Offline Chryco Psycho

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Re: Is my carb too big for my 383?
« Reply #39 on: September 13, 2015 - 09:55:19 PM »
can you reduce the pump squirt to get more low end response now

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Offline Bluemonster71RT

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Re: Is my carb too big for my 383?
« Reply #40 on: September 13, 2015 - 10:13:33 PM »
Yes. Matter of fact I can. It's in the hole closest to the carb for the largest pump shot. I'll try the next one down. I just figured that it needed the larger shot.
1971 Challenger RT 383 4spd

Offline Chryco Psycho

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Re: Is my carb too big for my 383?
« Reply #41 on: September 13, 2015 - 11:19:04 PM »
if the responce has deteriorated then it could be too much fuel initially now that you have enough fuel supplied through the jetting

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Offline 734406pk

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Re: Is my carb too big for my 383?
« Reply #42 on: September 14, 2015 - 02:44:38 PM »
Something else to check is your ignition rotor phasing. Your engine seems to have some of the symptoms (hard staring, misfire etc.).
Here is a link to MSD instructions:
http://www.msdignition.com/uploadedFiles/MSDIgnitioncom/Support/frm28392_tech_bulletin_rotor_phasing.pdf
And a Video:
https://www.youtube.com/watch?v=aWMlNwGW0tM
Good luck!
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1973 Challenger 318 2bbl auto 2.73 rear 22.5 mpg RIP
1970 Challenger TA 340 4bbl auto-Sold and sad
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Offline Bluemonster71RT

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Re: Is my carb too big for my 383?
« Reply #43 on: September 14, 2015 - 06:59:26 PM »
I'll check into rotor phasing after I do my next move.  I changed the pump shot lever to the middle and the performance was right back to pop city. I'm thinking I need even more fuel. I might have to get the larger squirters.
I had another thought. I put a 90* fitting at the out put of the fuel pump so the fuel hose wouldn't run so close to the alternator. Could that restrict enough fuel to cause an issue? Other than that I'll keep working on getting this Holley clean and back together. What a dirt ball it is.
1971 Challenger RT 383 4spd

Offline Chryco Psycho

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Re: Is my carb too big for my 383?
« Reply #44 on: September 14, 2015 - 08:23:33 PM »
Your hesitation is instantanious so fuel supply is not the issue at all so the 90* fitting is not the issue . but if the float level is low that could be causing issues , I would try raising it 1/16" or so

Challenger - You`ll wish You Hadn`t