Howdy, all; GSMullins here, northern Nevada. Glad to have found this forum, as it seems a treasure trove of information. I've an 82 Dodge D150 pickup w/4-speed manual that I recently picked up for a parts runner. Down the road, I'm probably going to lower it and add some beefier wheels/tires for cosmetics, and maybe do a few other mods.

Now here's my problem: it starts & idles fine, takes throttle fine with no load, 17" of vacuum at idle, no needle shake, but seems sluggish on acceleration and tops out at 55mph . All original Lean Burn devices and catalyst are in place, and it has what looks like a fairly recent set of silicone plug wires. I've verified that timing is at 12 btdc and seems to advance properly; I replaced the fuel filter and changed the fuel line to the carb to rubber; I set the idle speed to 600 and adjusted idle mix to get a smooth idle and no off-idle hesitation. So far, none of those things has effected the running problem.

I can see from the many threads on the subject of manifolds & carbs that changing the Lean Burn stuff out for a Super Six setup is the way many go, but for now, I'd like to see if I can get this running right in its present configuration before I invest in performance mods. Any help you folks can give me will be much appreciated.

mully

Hello, and welcome to the site!

I'm not the best at diagnosing these problems, but I have heard that a plugged catalytic converter might be causing this condition.

Although I agree with your "fix what you've got first" logic, I vote for doing away with your truck's lean-burn ignition in favor of the simpler electronic ignition when you can.

Other guys should chime in here. Good luck, and again, WELCOME!!!

_________________
"Ja, Ich fahre ein altes auto."
'78 Volare 225
'67 Charger 318

Freeing up the exhaust on a truck will help with top end power. You should be running at least 2.25" pipe all the way back. It does make a big difference.

If your running a one barrel carb (probably at 1945 Holley with the Lean Burn) a Super Six two barrel setup will give you more top end power. I used to pull a 19' fiberglass speed boat with mine.

Also check your rear end gear ratio. If you have a 4.10 rear end your going to top out quicker. If you have a 3.23 rear end it will scoot right along at 70 mph.

_________________
Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

Thanks for the replies, Ted & Wes.

Carb is a 6145; I think the final drive ratio is 3.23 (not certain).

I've had the carb apart; only thing I saw out of spec was float level was a little low (maybe 0.050"?). Will throw a rebuld kit in it when I can find one, just so I can cross that off the list.

mully

Not sure if you have one or two cat converters, but I'd wager that is the culprit. You can have a competent exhaust shop check the backpressure before and after cat to determine the level of suckitude. Or, do what I did and lop it off and go with dual Dutras and a single 2.5" exhaust. Mine topped out at 70 before, and now I can pull hills in overdrive at 75 where I used to be in third struggling to top 60.

_________________
If it was easy, everybody would be doing it.

Mully, sounds like it might be the cat, to me also. Just remember it you live in an emissions inspection state, they will fail your truck if you just remove the cat. Actually it is illegal to just remove the cat in any state, but the chances of getting caught are very slim in a non inspection state.

_________________
Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

Thanks, Charrlie & Coconuteater

Last night, I thumped the cat with a rubber mallet, which produced a tinny rattle that suggests it's damaged. I've got the carb apart awaiting a rebuild kit, and once it's running again, I'll put the vacuum gauge on it to confirm whether there's an exhaust restriction. No emissions test where I live, Charrlie, but I'll probably put a fresh catalyst back on it, since that's the right thing to do for air quality, and it'd help if I ever needed to sell the truck down the road.

Thanks for the suggestions!

mully

Again, thanks to all who offered help. Here's a quick update on the status of my problem.

After all the advice, I tried several different test to see if there was any indication of exhaust restriction, and found none. With that effectively eliminated, I decided to bump the initial ignition advance up from the stock setting to compensate for my altitiude here (4400 feet above sea level). When I got to 16BTDC initial advance, the performance got a lot better, but the truck still tops out around 60 mph, so nothing's conclusive yet.

Right now, I'm in the process of repairing a buggered clutch release bearing, and once things are back together (tomorrow?), I plan to go in search of a Holley 1920 and non- Lean Burn distributor. Stay tuned: film at eleven!

mully