[sam03v]

I've got a 1980 d-150 with a '82, 225 slant in it. I just swapped out the 1 bbl manifold and carb for a two bbl setup. It runs okay, but the idle is high and the throttle set screw is not even touching the stop on the carb, so the throttle plates should be completely closed. The idle is solid at 1100 rpm once warmed up.

THe timing is at ~18 btdc. I can slow the idle by changing the timing, but then the truck loses power on the road. The carb is a Carter BBD. Anyone have an idea what might be going on?

 

[Megunticook]

Just curious, why is your timing so far advanced? I had a '70 /6 years ago, as I recall the factory spec. was TDC.

I know you said you tried retarding the timing and lost power, but I'd just be curious what the original spec. is. If you're way off the mark, it's possible you won't get the curb idle you're looking for...and I'd also wonder whether you might risk some detonation or other potential issues.

 

[sam03v]

I had it set that far in advance because that's where it seemed to run best when I had the 1 bbl carb. I don't know what the factory spec is, the emission sticker doesn't say and neither does the shop manual(i have a real one). But I will try TDC.

Thanks for the comment.

 

[cribbs74]

Have a vacuum gauge? Sounds like you have a vacuum leak. Is the idle real smooth? or a little lumpy? Seeing as you just swapped manifolds and carb there's a good chance something didn't seal correctly. Try spraying starting fluid at the carb/ base of carb and intake manifold and see if the idle increases. Sometimes old carbs suck air at the throttle shaft. Hope you figure it out.

 

[sam03v]

Yeah, I have a vacuum gage. The idle is real smooth at 1100 rpm. I checked for leaks already same way as you mentioned. It took me about 3 tries of taking the manifolds on and off to get it leak tight so I'm pretty sure they are good to go.

 

[cribbs74]

Well,

If that's good then I would suspect timing as well. Since you have a vaccum gauge I would try setting the timing with it and see how it runs. Not sure where factory idle is supposed to be, I would assume well below 1K. You just may not be able to achieve that anymore while trying to time for best performance on today's gas. There are some good "how to's" on vacuum timing located within this forum. Do a quick search and something should come up.

 

[Megunticook]

As I recall from my '70 specs, timing was TDC plus or minus 2.5, and curb idle was 675. I used to run mine like that and it ran great. I tried "power-timing" it just for kicks (turned the distributor to attain max. rpm) once, against all the professional advice I'd read, and sure enough it created problems. So I always kept it at spec.

The /6 is a solid runner, unbelievably reliable, but not a fast acceleration kind of motor. I wouldn't try to achieve that.

 

[acton mike]

I saw the suggestion to spray starting fluid at carb base to look for leaks

for God's sake do not use starting fluid which is either; you will blow something to hell

use wd 40 or something like that but not ether

 

[Megunticook]

I saw the suggestion to spray starting fluid at carb base to look for leaks

for God's sake do not use starting fluid which is either; you will blow something to hell

use wd 40 or something like that but not ether

Straight oil would be even better, as WD40 is mostly solvent. Personally I would avoid any highly combustible liquids around the motor when it's running...

 

[Speed Dragon]

Lol, I knew somebody would pop in saying "Don't use starting fluid!" Always is. And yeah, if you're dumb and load it up w/ ether while running (which I'm sure some people are dumb enough to do) you could set something on fire or blow something up. But the fact is, I've done it for years, w/ both carb spray, ether, WD40, etc and never set anything on fire. All it take is a little squirt at a time, which is safe. Don't spray ether down the carb throat while cranking though, Dad had a can blown out of his hand once like that

 

[Megunticook]

But the fact is, I've done it for years, w/ both carb spray, ether, WD40, etc and never set anything on fire. All it take is a little squirt at a time, which is safe.

Just because you've gotten away with it so far doesn't necessarily mean it's "safe." Sure, chances are it'll never happen, but why take a chance when there's safer alternatives?

Remember when those firefighters died at the furniture store in Charleston a couple years ago? I talked to an FDNY veteran who was part of the post-incident assessment team--when they interviewed the Charleston chief and other officers in the department and asked why they were in a structure fire like that with small booster lines and insufficient water supplies established, the answer was basically, "because that's the way we always did it." They got away with it for a long time, so they figured it was safe, until eventually a situation occurred in which they paid a price...that kind of reasoning still exists in many fire departments even today ("we've always done it that way"), but it's a dangerous way of thinking.

I'm not trying to rag on you, Speed, I'm just making the point that just because you've never started a fire that way doesn't make it safe...

 

[sam03v]

I used "Sea Foam" to check for leaks. No explosions and it did work for finding the intake leak(s). Don't know if that was a good/safe idea or not...

I'm not trying to do anything fancy with this slant. I've read that the factory "Super Six" setup is the best way to go as far as getting a little more out of it so that's all I'm looking to do. As long as it has a little more umph than the 1 bbl setup I'll be happy.

After I get the idle/timing issue fixed I'll be taking the truck to an exhaust shop to get a 2 1/4" pipe run from the manifold out to the tail pipe. Any recommendations on mufflers? I just want as much flow as possible, sound doesn't matter a whole lot as long as its' not too loud.

Thanks!

 

[cribbs74]

I saw the suggestion to spray starting fluid at carb base to look for leaks

for God's sake do not use starting fluid which is either; you will blow something to hell

use wd 40 or something like that but not ether

To be honest I never really even considered this to be a safety issue. I had seen it done so often I assumed everyone did it.

Like Speed I have used ether many a time without issue. I'll probably still use it if that's all available, but it's good to know that there are alternatives. Thanks for pointing that out.

 

[Speed Dragon]

Hehe, well each to his own I guess. Starting fluid/ether and carb spray work the best IMO because they make a more noticeable difference when sucked in, but the other stuff works too. I guess it's like engineers torque their wheels on, the rest of us just zap them w/ an air gun or crank them down w/ a 4-way or breaker bar. Both ways work just as well, one is just the "certified correct" way to do it.

However, back on topic I'm having a similar problem w/ my '80 S6 w/ a 2-bbl swap. It came swapped, but the carb was junk (reman'd improperly). I'm running a V8 Holly 2280 on it, and I think it is too rich, and also the balancer may have slipped the outer ring. Tried setting the timing at 10-12, ran okay but stuttered bad when I gassed it. I just twisted the dizzy up till the idle sounded better, ran it around the yard (no tags) and got on it, spits back a time or two then goes. I think the timing is somewhere around 18-20, maybe 22 according to the timing tab, so I'm pretty sure the ring is slipped. I haven't tried disconnecting the accel pump yet, did disconnect the vac adv and it got worse. Also, when idling, it'll idle good for a while, then start missing, like a plug or wire died. Revving it will usually clear it up for a bit, then it'll go back to missing. If I let it idle for a long time, it'll sorta clear up a bit also. I've swapped ECU's (has an orange Mopar ECU now), dizzys, plug wires, caps, wiring harness, and has new Autolite copper core plugs gapped at .035".

 

[sam03v]

After all my grief it seems I only had a bad PCV valve! I never had one of those things give me trouble so I assumed it was okay after shaking it and hearing it rattle. I can get the idle as low as 500 rpm now (with a new PCV valve and hose), but it's rough that low. I set it at 750 with the timing ~5 BTDC. I'm still going to tweak the timing/idle a bit, but at least i'm heading in the right direction. :drink2:

 

[bherder]

Doncha just love simple fixes??

 

[Megunticook]

I can get the idle as low as 500 rpm now (with a new PCV valve and hose), but it's rough that low.:

Yeah, try turning on your brights and running the fan on high at that setting, think your lights would be about as bright as a candle!

Good job getting that figured out--did you dial in the carburetor mixture screw(s) yet?

 

[sam03v]

--did you dial in the carburetor mixture screw(s) yet?

I'll be tweaking the mixture/idle this weekend (hopefully). I drove the truck to work today, and it dieseled a tad when I shut it off so I'm gonna bump up the timing to 10 BTDC before I head home and see what happens.