318 won't rev past 3000 rpm

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rtgambit

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Just this past April my Dad decided he wasn't doing anything with his 67 Dart GT 2 door, so he gave it to me. It's sat in his garage for the past 14 years, getting started every 6 months or so. What's amazing is that it only needed the license plate light to pass the Ontario safety.

Cruise nights have been fun, but soon realized it was running into a brick wall at around 3000 rpm. Car would pull awesome to it, but act like it was hitting a rev limiter.

Just looking to get pointed in the right direction on this, and where I might start troubleshooting.

Known items:
Will do this in park or driving down the road, doesn't matter.
Electronic ignition, chrome box if I remember correctly.
Holly 600 cfm carb /w vacuum secondaries.
Full length headers, dual exhaust.
LA 727 auto.
Tuned to 14 deg. at 700 rpm idle. Good vacuum showing on gauge with no fluctuations.

Unknown items:
Cam specs
Head castings (guess it wouldn't be hard to pull a valve cover to check this).

Thoughts, gentlemen?
 
is there a throttle stop? is the carb opening all the way?
 
I would start with a basic tune up, including fuel filter and timing check (including operation of the advance mechanism).

I would replace the secondary vacuum diaphragm, just because, 14 years is a long time (while you are at it, poke the secondary butterflies with a screwdriver and make sure they aren't hung up).

You also have crap gas if it's 14 years old.
 
WELCOME aboard, first off,as said from above check to see if it is opening up full,next how long has it been since the spark plugs been change.My first car at 14, 62 Chev 250 did just what your saying.
 
magnumdart said:
I would guess the carb is a little gummed up.
Click to expand...

Should have mentioned that part. The carb was taken apart and cleaned up when I brought it home. Also changed out the fuel that was in the tank as well as the fuel filter. Fuel pump was replaced at the same time.
 
Are the weights etc free to move in distributor. They may have seized up from sitting. Also any chance of critters getting in exhaust and plugging it up.
 
1968FormulaS340 said:
I would start with a basic tune up, including fuel filter and timing check (including operation of the advance mechanism).

I would replace the secondary vacuum diaphragm, just because, 14 years is a long time (while you are at it, poke the secondary butterflies with a screwdriver and make sure they aren't hung up).

You also have crap gas if it's 14 years old.
Click to expand...

Fuel filter is new, but I'm not sure if/when the cap, rotor and wires were changed. If I remember correctly, can the vacuum diaphragm be checked with a vacuum pump? Good reason to go buy a pump, I guess.

Gas was also drained off when she got home.
 
Snake said:
WELCOME aboard, first off,as said from above check to see if it is opening up full,next how long has it been since the spark plugs been change.My first car at 14, 62 Chev 250 did just what your saying.
Click to expand...

:banghead: Completely forgot to check spark plugs.
 
Dubob said:
Are the weights etc free to move in distributor. They may have seized up from sitting. Also any chance of critters getting in exhaust and plugging it up.
Click to expand...

Will double-check the distributor weights as well. Come to think of it, I had checked the initial timing, but not the total timing.

I guess it would be hard to tell for sure about a plugged exhaust, but both exhaust tips seem to have the same amount of pressure coming out.
 
Coil/coil wire OK?
did you already slave in a different ignition box, just for S&G?
 
Total timing could definitely play a role-if it's too high, the engine has to "fight" against itself-didn't think about that...
 
If it revs to the same rpm in neutral as it done going down the road. I would be thinking valve spring are weak.

plunged exh could cause a simile reaction.Does the exh really hiss (no exh tone just fast sounding air rushing though?
 
KitCarlson said:
Also critters build nests in air cleaners.
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They also build em in mufflers. I started up a Barracuda that had been sitting for a dozen years. After revving the engine for a few minutes it blew a mouse nest half way out into the street. That's the first place I'd look. A mouse nest is not as effective as a Potato for stopping the engine, but it's close
 
txstang84 said:
Coil/coil wire OK?
did you already slave in a different ignition box, just for S&G?
Click to expand...

I agree with this possibility as well. I've seen control boxes go bad and act like a rev limiter. I just don't recall if it was OEM, aftermarket boxes or both. Yours is probably an OEM chrome box, not the Mopar Performnce version.
 
I bet it is the crome box..........If the exhaust is not full of critters.
 
I am guessing that you have run it long enough to blow out any debris in the exhaust, plus I assume it is dual exhaust and you would have noticed more exhaust on one side than the other (assuming only one side is restricted).

My 2 choices are

#1 - seized advance weights in the distributor - I have seen this before, pull off the cap and make sure you can twist the rotor to advance it, it should spring back when released

#2 - the factory sock on the fuel pick up (kind of like a filter) in the fuel tank is plugged / gummed up with varnish from the time sitting seriously restricting fuel flow.

Also, I hope that you do not have one of those silly 3" diameter air cleaners, or cheap foam and chrome edelbrock ones, try running it without the aircleaner.

Good luck!
 
if your running a msd that would be the first place I would look.and Im not even going to explan unless you know me and have read sum of my oid threds...............Artie
 
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