Hi guys! Long time lurker, new poster.

I picked up a '71 Duster from a friend of mine about 4 months ago and she's got some problems. Some I've already solved and some I need some help on.

When I got the car it was already modified. The 225 already had a Clifford intake, Edelbrock 1404 carb and Clifford 6 into 2 headers with dual exhaust. He also installed electronic ignition from a later model Duster. I've also got paperwork that shows the motor was rebuilt about 8500 miles ago. He spent a good amount on a 30 over rebuild, with whats described as a new "Factory Spec. Cam" and a completely rebuilt head.

When I first got it, it ran terrible. It wouldn't idle, she was rich as hell and had a bad miss through the entire rev range. After going through everything, I found the coil was going bad. So I swapped the ignitor and coil out with a Summit Street/Strip CD Box and coil I had in the garage. Did a cap & rotor change, plugs and wires. Then tuned the carb. NOW, she runs and idles fine. No misses, only a slight off idle stumble and still a little rich. I just checked the valves yesterday and they're within spec.

The problem I'm having now, is that the car seems like it has no power on the highway when I romp on it and it drops into passing gear. City driving is fine. Shes got decent throttle response and good pick-up on city streets. It's just on the highway, it takes forever to get from 50 or so up to 70. She makes alotta noise and spins up (slowly), but doesn't pull as hard as it should. Especially for a new motor. What things should I be looking for? Possible ignition advance problem? or Cam timing problem?

The SECOND problem I've got is when the outside temps are above 75 degrees and I'm sitting in traffic. If I sit for more than 8 or so minutes, it'll vapor lock and/or percolate. All it takes is a minute or 2, then a full throttle start and she fires right up. I'm thinking that the heat from the headers is cooking the intake manifold and percolating the carb. Should I be running water through the manifold? Right now, the water passages are plugged and not plumbed in.

I'll be eliminating the mechanical fuel pump this weekend and going to an electric with a bypass regulator and rubber lines. So hopefully the vapor locking will go away.

Anyway, sorry for the long post guys!!! I figured I'd ask in one post rather than 3 or 4 separate ones.

Before you go to an electric fuel pump, look up the fuel line mod SlantSixDan put up. for a street driven car, the mechanical is a very reliable device. Depending on which electric fuel pump you've chosen, they can be maddeningly loud.
You may be getting excess heat from the headers, but generally the better thing to do is to coat them or wrap them. You won't want a lot of rubber hose. It can be a failure point. I have perhaps four inches of rubber hose in my entire fuel system. Makes the tech inspectors very happy.

I went with wrapping, and have been very pleased with the results. After making a full on pass at the drag strip, I can touch the head pipes.

The water system for the manifold is designed to add heat to the plenum. It will also keep the heat more even. It's real purpose is to improve cold weather driveability.

I run a 2" aluminum spacer under my AFB. The type with the four holes, not the big square one. This lessens heat from the stack getting to the carburetor. Zero problems with hot starts. (I do run a Holley Red pump into a secondary regulator though.) The Red pump is perhaps four decibles quieter than the average weedeater.

Look into the fuel line mod. The way the stock fuel line is routed, it goes across the front of the block. I've never had any problems with this, but I moved the fuel line back over the valve cover directly to the carburetor from the Holley regulator.

What thermostat is in the car? Any tendancy to overheat?

Normally, headers won't be the root cause of a vapor lock.

2¢

CJ

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Part of Tyrde-Browne Racing

Thanks for the reply CJ

The fuel line mod has already been done. It runs over the top of the valve cover straight to the Carb.

Shortly after I got the car I changed out the water pump and put in a Stant 195* thermostat. She doesn't overheat, but I do get big temp swings once its warmed up. The gauge will read around 200, state opens then shortly after it'll drop to around 165-170. Then everything starts over again. I think I may have gotten a bum thermostat.

I plan on wrapping the headers once my new manifold gasket comes in, and I may try a phenolic Carb spacer I have in my parts bin this weekend (its supposed to be hot, perfect time for a test!)

THANKS AGAIN!

Flat performance on highway could be result of a timing problem. Too much mechanical advance or not enough, or wrong vacuum pod, or wrong advance curve for build, or stuck governor weights, or cam not properly timed may contribute to lazy acceleration.

Get a timing light, and conduct an rpm vs. degrees of advance study and graph engine’s advance curve from idle to 3000 rpm in 100 rpm increments. This information will be helpful.

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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

Vote #2 for reviewing the distributor's advance curve.
It sure sounds like a "throw parts at it" car...
My bet is that there is one of those single light spring "performance" MP distributors in it... those never did work well, sepecially on the street.
DD

Thanks again for the replies.
Looks like I'll be getting my timing light back from my brother in law and taking acloser
look t the distributor and timing.

I would check the timing mark also, mine was 8* retarded.

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The surgeon general never said that smoking the competition was bad for your health.

Found it!

The vacuum advance pod is bad. No one local (kragen, autozone, Napa, pep boys) has one in stock. I spent about 4 hours on the phone yesterday calling around trying to find it. So I ended up ordering one from Napa. They said it should be in on Tuesday.

I also put in a new thermostat. I did the boiling water test on the old one it would go clear up to 215 degrees and pop open instead of slowly opening at 195.