Acceleration dead spot

[bdarcher]

Hello everyone newbie here.
My son bought a 1983 Dodge D150 fixer upper. Runs really good however when you step a little harder on the gas pedal or get a little aggressive with acceleration….it does a hiss, sputter and buck and then straightens back out. It does it from standing, rolling and high speed.
We have installed a new Holley 600 CFM carb, new ignition coil and ignition resistor, new distributor cap and rotor, new champion plugs, new fuel filters and timing has been adjusted. We are leaning towards looking into the vacuum advance canister next, thoughts??

 

[Dinky]

Adjust the carb at all? I would get rid of the holly and switch to edelbrock. Holly can be a bit finicky sometimes and hard to dial in.

 

[pacofortacos]

I prefer the Holley, might just need to adjust the accel pump setting or jetting, possibly a larger accel. pump.

What ignition system?

 

[Dinky]

I prefer the Holley

Nothing wrong with holley just harder to adjust on average. It's above most average people. @bdarcher could advance the timing a bit my 73 440ci never liked perfect timing.

 

[bdarcher]

Adjust the carb at all? I would get rid of the holly and switch to edelbrock. Holly can be a bit finicky sometimes and hard to dial in.

It’s been at the mechanic’s shop and he’s been adjusting it. Funny you mention Edelbrock, it had an older Edelbrock on it that he said was dated back to Carter days and that it was wore out and Holley would be better cause the Mopars didn’t like the adapter plate!? So he talked me into a new Holley! Oh well, I guess each mechanic has his preference!

 

[bdarcher]

I prefer the Holley, might just need to adjust the accel pump setting or jetting, possibly a larger accel. pump.

What ignition system?

Sorry, I’m not much of a mechanic….how would I determine which ignition system it has??

 

[bdarcher]

Nothing wrong with holley just harder to adjust on average. It's above most average people. @bdarcher could advance the timing a bit my 73 440ci never liked perfect timing.

Mechanic says he’s already a little more on the timing then it should be, so perhaps he’s already at your spot?!

 

[Dinky]

It’s been at the mechanic’s shop and he’s been adjusting it. Funny you mention Edelbrock, it had an older Edelbrock on it that he said was dated back to Carter days and that it was wore out and Holley would be better cause the Mopars didn’t like the adapter plate!? So he talked me into a new Holley! Oh well, I guess each mechanic has his preference!

Yeah I ran a Carter for years. Edelbrock did buy them out and Edelbrock rebuild kits fit then still. Nothing wrong with them and carburetor don't really wear out lol. You can fully rebuild them and make them as good as new. I would find a new mechanic as he said Mopar does not like spacers lol. Sounds like he does not know how to adjust a carb or know anything about spacers. To me it sounds like your getting too much fuel and it's taking min to process it. Pull out a plug and see if you have any signs of running rich. You can tell a lot on older trucks just by the plugs. Also what are the exact plugs you are running?

 

[turkeybird56]

Carburetor wear out: Hmmmm, heat riser may stick, clogged jets, worn springs, but wear out, hmmm, LOL. I ran friggin Rochester Quad junk on my Chevys, and my friend at a 300 New Yorker and also a 68 Coronet 440 with 3/4 factory cam (that beast never hold time well), ran Carters on the Mopar and with plates, we had a six pack manifold set up for the track. Just what I did, not a tell all, but checking plugs and conditions of same is a good indicator..

ADDED: Old thought, I being a BOIRD Brain. Gasket ref Carb to manifold may be bad, leaking in air, that cause hesitation also like a vacuum problem ,just another thought. We never had gauges and such, tuned most by ear and RPM, poor kids we were, LOL. (Kinda like adjust rockers by turn down till bind, then off 3/4 turn, ahhhh the old days).

 

[bdarcher]

Yeah I ran a Carter for years. Edelbrock did buy them out and Edelbrock rebuild kits fit then still. Nothing wrong with them and carburetor don't really wear out lol. You can fully rebuild them and make them as good as new. I would find a new mechanic as he said Mopar does not like spacers lol. Sounds like he does not know how to adjust a carb or know anything about spacers. To me it sounds like your getting too much fuel and it's taking min to process it. Pull out a plug and see if you have any signs of running rich. You can tell a lot on older trucks just by the plugs. Also what are the exact plugs you are running?

We just bought the truck a month ago and have been tinkering on it. The plugs that were in it were Autolite 65. This mechanic recommended Champion so the guy at NAPA crossed them over to a 905 Copper+ RN14YC. Which i actually just put in yesterday with a .35 gap. So, this dead spot was before and after new plugs and everything else we changed. The old plugs were definitely a little darker color but not so much wet at the contacts, more wet around the threads. Right now it just has old breather with rubber hose hanging out of it. I thought some of the residue on plugs might be from blow by.
I’m a grader operator and I love CAT and hate John Deere, it appears mechanics our the same when it comes to carbs, definitely have their preference!!

 

[Dinky]

We just bought the truck a month ago and have been tinkering on it. The plugs that were in it were Autolite 65. This mechanic recommended Champion so the guy at NAPA crossed them over to a 905 Copper+ RN14YC. Which i actually just put in yesterday with a .35 gap. So, this dead spot was before and after new plugs and everything else we changed. The old plugs were definitely a little darker color but not so much wet at the contacts, more wet around the threads. Right now it just has old breather with rubber hose hanging out of it. I thought some of the residue on plugs might be from blow by.
I’m a grader operator and I love CAT and hate John Deere, it appears mechanics our the same when it comes to carbs, definitely have their preference!!

I don't think Holley is bad just more temperamental as they have more adjustments and come out of adjustment eaiser imo.

 

[bdarcher]

Carburetor wear out: Hmmmm, heat riser may stick, clogged jets, worn springs, but wear out, hmmm, LOL. I ran friggin Rochester Quad junk on my Chevys, and my friend at a 300 New Yorker and also a 68 Coronet 440 with 3/4 factory cam (that beast never hold time well), ran Carters on the Mopar and with plates, we had a six pack manifold set up for the track. Just what I did, not a tell all, but checking plugs and conditions of same is a good indicator..

ADDED: Old thought, I being a BOIRD Brain. Gasket ref Carb to manifold may be bad, leaking in air, that cause hesitation also like a vacuum problem ,just another thought. We never had gauges and such, tuned most by ear and RPM, poor kids we were, LOL. (Kinda like adjust rockers by turn down till bind, then off 3/4 turn, ahhhh the old days).

So would that gasket be below the old spacer plate (adaptor plate)? Because the carb is brand new and I’d assume it had a new gasket to go on top of the spacer plate? But not so sure if the mechanic took the spacer plate off and inspected that gasket if there is one?

 

[turkeybird56]

Honestly, w/o looking, no way to tell. THAT was just a thought. We had gaskets on both under and on top of spacer, back in the "day". Just no way to tell wat is spec'd, required on what U have there, and wat brand, parts etc, just saying. But we in those days had "cork" gaskets, not neoprene. Reason 2 gaskets, the machines plates were not always as straight and level as one would think, but again we were just kids doing the best we can do. U would need a Good Mechanic to chime in here on thoughts, beyond my "turn" a wrench in the driveway experience.

 

[bdarcher]

I don't think Holley is bad just more temperamental as they have more adjustments and come out of adjustment eaiser imo.

Yeah, I was fine with the old Edelbrock on it, but again I’m no mechanic sk you have to put your faith in the local mechanic. So as soon as I talked to him and told him it was an Edelbrock, he was negative about it and suggested a Holley. So, I thought, well ok let’s do it if it’ll make it run right. After $800 still have a dead spot! Pretty frustrating but what can you do! And as for his comments about the adaptor plate and them bring finicky on mopars….I believe he fit that from the performance shop guy where we bought the carb….and I think that guy sells both kinds, so I assumed he was probably right?!

 

[Dinky]

Yeah, I was fine with the old Edelbrock on it, but again I’m no mechanic sk you have to put your faith in the local mechanic.

It is definitely hard to find a mechanic these days that can adjust a carb they are a dieing breed for sure. I have a buddy that has been in the race car scene for a very Long time. He rebuilds carburetors for a lot of people and helps adjust them. There is a art to them and a lot of people have lost the touch.

 

[turkeybird56]

It is definitely hard to find a mechanic these days that can adjust a carb they are a dieing breed for sure. I have a buddy that has been in the race car scene for a very Long time. He rebuilds carburetors for a lot of people and helps adjust them. There is a art to them and a lot of people have lost the touch.

I have an ancient Craftsman Analyzer, like 1972 model, which we used to "diagnose" issues. Usually checked/used ref dwell and RPM's.,. sometimes used to assist when playing with carb, besides the "ear" test. I know we neva got 100% OK, but got them pulled in close enuf to run well. POP hood these days, wonder if I need to invest $$$$ in ancient Sun Diagnostic machine, ahhhhhhhhhhhhhhh no, LOL. Now all the new ones plug into OBD, and U can spend a pretty penny on them too !!!

 

[Dinky]

I have an ancient Craftsman Analyzer, like 1972 model, which we used to "diagnose" issues. Usually checked/used ref dwell and RPM's.,. sometimes used to assist when playing with carb, besides the "ear" test. I know we neva got 100% OK, but got them pulled in close enuf to run well. POP hood these days, wonder if I need to invest $$$$ in ancient Sun Diagnostic machine, ahhhhhhhhhhhhhhh no, LOL. Now all the new ones plug into OBD, and U can spend a pretty penny on them too !!!View attachment 489053

Nice! Most don't have those anymore. That would come in handy trouble shooting more than the carb. I've always adjusted my trucks to sound and how they run. Than pull plugs after a 100 miles and take a peak. Yep now it's all obd scanner and tells you what's wrong. I miss old stuff somedays.

 

[pacofortacos]

The ignition back then was marginal at best, esp. if it was running a computer that sat on the air cleaner.
Since you mentioned vac. advance, I am going to assume that you have an old electronic ignition with a dual resistor block (possible single resistor) - which again was marginal at best.
I am very partial to OEM mopar cap and rotors on the old cars - some people like the caps with the brass inserts, personally I have seen nothing but problems with those.

Are you running ported or manifold vacuum to the distributor? Is the reluctor gap correct inside the distributor?
The RN14YC plug is a good plug for those engines.

Bullet proof ignition that I used is Mopar cap n rotor, summit 8 mm wires or better, hotter coil or MSD 6A with stock coil (MSD 5 should work also).

The carters are a decent carb, I just found that few people could get all of the adjustments correct - fortunately they ran decently way out of adjustment - and you can make a ton of adjustments externally which was nice.
Holley is usually just the jetting, float setting in the ball park, and maybe accell pump tweaking.

The Holley's with the emissions junk on were not very good unless you really knew how to play with them.
I can't remember when the cars went with O2 sensors, the early to mid 80's were challenging on some of the setups - and I have no clue when any or if any of that crap made it to the truck line.

Late 83 into 84, many of the Mopar 4 cyl. cars were fuel injection and were way ahead of most if not all automakers as far as that goes. The 1984 turbo fuel injection system was almost as advanced as the current Ram system.

 

[pacofortacos]

I have an ancient Craftsman Analyzer, like 1972 model, which we used to "diagnose" issues. Usually checked/used ref dwell and RPM's.,. sometimes used to assist when playing with carb, besides the "ear" test. I know we neva got 100% OK, but got them pulled in close enuf to run well. POP hood these days, wonder if I need to invest $$$$ in ancient Sun Diagnostic machine, ahhhhhhhhhhhhhhh no, LOL. Now all the new ones plug into OBD, and U can spend a pretty penny on them too !!!View attachment 489053

The old big blue Sun scope analyzer was a great tool - I used it everyday back in the day. Invaluable for checking out a distributor system.

 

[bdarcher]

The ignition back then was marginal at best, esp. if it was running a computer that sat on the air cleaner.
Since you mentioned vac. advance, I am going to assume that you have an old electronic ignition with a dual resistor block (possible single resistor) - which again was marginal at best.
I am very partial to OEM mopar cap and rotors on the old cars - some people like the caps with the brass inserts, personally I have seen nothing but problems with those.

Are you running ported or manifold vacuum to the distributor? Is the reluctor gap correct inside the distributor?
The RN14YC plug is a good plug for those engines.

Bullet proof ignition that I used is Mopar cap n rotor, summit 8 mm wires or better, hotter coil or MSD 6A with stock coil (MSD 5 should work also).

The carters are a decent carb, I just found that few people could get all of the adjustments correct - fortunately they ran decently way out of adjustment - and you can make a ton of adjustments externally which was nice.
Holley is usually just the jetting, float setting in the ball park, and maybe accell pump tweaking.

The Holley's with the emissions junk on were not very good unless you really knew how to play with them.
I can't remember when the cars went with O2 sensors, the early to mid 80's were challenging on some of the setups - and I have no clue when any or if any of that crap made it to the truck line.

Late 83 into 84, many of the Mopar 4 cyl. cars were fuel injection and were way ahead of most if not all automakers as far as that goes. The 1984 turbo fuel injection system was almost as advanced as the current Ram system.

Sorry, I’m no mechanic. I don’t know if it’s ported or manifold?? Tube come from vac adv and plugs in front of carb on the bottom. And i checked or know nothing of a gap on distributor…..just slapped a new rotor and cap on it.