I was thinking about adjusting the timing by engine vacuum. I did that on my RV with a 318 and it purrs.
How can I tell if the carb is a lean burn carb??? I know that the van I pulled it and the 2bbl intake out of in the junkyard was a 77 or 78 I think with lots of stupid hoses connected to it. lol I found a vacuum diagram telling me everything it did have hooked up to it. It went something like, vacuum amplifier, EGR, choke diaphragm, distributer, PCV, air pump and the CCEGR valve.
I plugged everything except the PCV, distributer and the choke diaphragm. I tested the choke diaphragm with my vacuum tester and it works great with no leaking.
ALSO I did mention that my vacuum advance on my dist. is totally shot and I have the line plugged until I can replace it. But that would not effect/cause the rough idle issue I am having.

GOD GOD.. .thank you everyone for the help.

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1965 D100 225 slant 6, NP435 Utiline.

I very well might just bite it and get the Holly 2280... Unless I can get this set-up to work decently. I would like to spend my money on upgrading my exhaust... but I suppose I could just cut the pipe before the muffler and let my neighbors deal with it... lol

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1965 D100 225 slant 6, NP435 Utiline.

The most obvious sign that a carb is a lean burn carb is wires going into the float bowl to control the stepper motor.

Do you have a vacuum gauge? What is your vacuum at idle? Is it steady or does it fluctuate? If it fluctuates, by how much does it fluctuate?

If the carb was the original carb off of a 77 or 78 van, it will be a BBD. However, who knows what carb was put on the van in the last 30+ years. It is fairly simple to identify a BBD vs. a Holley 2280. See THIS article.

The symptom of a rough idle can be caused by many many problems. Have you replaced your plugs? What are your plugs gapped to? Have you replaced the cap and rotor recently? Have you adjusted your valves properly recently? If not, see HERE. Have you replaced the fuel filter recently (hopefully with a metal one)? For general advice on a slant six tune-up, see HERE.

When you rebuilt the carb, did you set all the carb settings properly? On a BBD the metering rod setting is critical. Curb idle mixture is fairly simple to set, but you must do it right. Search this site for numerous posts on how to do it.

Don't just adjust your timing for best idle vacuum. There is a specific setting for your motor and distributor combination on the underhood sticker. Despite all having the same camshaft, 71+ slant six motors had base timing settings ranging form TDC to 12 BTDC. Until you are willing to put the time in to learn how and why the base timing specification was changed, you would be better off sticking to stock. Make what you have work best in stock form before you go changing things. Messing with too many variables at once can cause headaches diagnosing problems later.

I suppose you never got a chance to go back and look for that air cleaner? I would also be interested in the kickdown linkage (including the lever on the transmission), if the van was an automatic.

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Casually looking for a Clifford hyperpak intake for cheap.

Try 'Carter carb manuals with jet and metering rod sizes,' Found it on another post on this site, lots of info.

OK so, I do not have a lean burn carb. There are no wires leading to the carb at all.
I do in fact have a Carter BBD 2bbl that came with the intake. When I rebuilt it I meticulously read the instructions and set the metering rods and everything else perfectly plus I just rechecked it to make sure.
I did adjust the valves and it made a world of difference. I did this before I did the carb/intake swap and I just checked the torque of the bolts and they are all just fine.
Before I did this swap it was idling a little rough just like it is now and my original carb (the 1bbl) had a BADLY worn throttle shaft. It whistled like crazy at part throttle. When I squirt carb cleaner at the throttle shaft on the BBD on it now I defiantly get a change in idle. But everywhere else I get no response which leads me to believe that I have the same problem with this carb I found. But Would the idle become so rough from that alone?
I just checked my engine vacuum and it basically hangs around 19lbs of vacuum. It does jump around a bit up to 20 and down as low as 17.5. When it hits the "rough" part of the idling is when it jumps down to 17.5.
My plugs are not new but are decent looking and the gap is set at .40.
When I put my hand over the top of the carb and cover most of the opening the idle smooths out and the vacuum climbs to 22-23 and holds steady.
From what I can tell my 225 is stock as far as cam and everything else goes. But I could not say for sure.
I did get a chance to go back to the junk yard and that van that I found this set-up in was gone. I found a 318 air cleaner that I threw on my carb for the time being so that I had some air cleaning going on. I am going back today and will be looking for more stuffs.

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1965 D100 225 slant 6, NP435 Utiline.

mc_ryan,

When was the last time you checked the lash on the valves?
If they are too tight you can will see erratic vacuum fluctuations.
Settings are .010 for the intake and .020 for exhaust.
Doc always had me error on more seat time with .012 and .022.
and the vacuum readings read higher.

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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

Have you tried checking your distributor? 17.5 on the vac gauge shouldn't normally cause a rough idle unless you were super picky about it.

Do you have points or an electronic ignition?

Sometimes (well usually for me) you can have two problems happen at once. I put a 2bbl setup on and went through the same leaky throttle shaft stuff you have. After gettting it rebushed my car idled better but still not even close to the way it should. I could only get 15 on the gauge and 16 at it's height. So I went and bought a NOS BBD and it ran perfect right off the bat.

A couple days later it started idling bad again. Vacuum was at 20 and I couldn't figure out what the deal was. Turns out my distributor shaft was worn and I ended up buying a NOS electronic distributor. Ran perfect after that and haven't had to touch either since.

The problem is that a lot of these symptoms can look and sound the exact same but be totally different things. The bad thing is that if you don't have spares laying around, you can only troubleshoot so much before you have to just pull out your wallet and gamble on what it might be.

One more thing, how many turns out are your mixture screws on the BBD? You should start at 2 1/2 turns out and then work from there. The more you screw them out, the more your vacuum should rise. I think mine are turned out 3 1/2 or so and thats where I get my maximum vacuum reading.

OK well, I did some adjusting of the valves and it seems to have helped. I guess I had them set a little tight. When I adjusted them about 3 weeks ago it was my first time ever adjusting valves on a slant six and on a running vehicle for that matter. It seems that I have already gotten better. lol
I had seen .10 intake and .20 exhaust as a setting and even in a post from Dan I saw that some truck slant six 225's (which is what I have) had a setting of .14 / .24 so I decided to meet in the middle and set them at .12 / .22.
Right off the bat I noticed an increase of vacuum to 22 lbs and it was running steady and only fluctuating/dropping .5lbs instead of jumping all over the place. I also noticed that my #6 cylinder's exhaust valve got mighty clacky when I set it at .22. I would set it back to .20 and it would get a little quieter but it would run a little worse... So I left it clacky at .22 I might have to do some head work in the future but at least it is running smoother.
I also probed around with a hose in my ear for further vacuum issues and really hear sucking at the throttle shaft ends on my carb. That is the only place I hear noise... oh... and when I set my idle down to 600-650 RPM, my carb throttle plates (or something coming from INSIDE the carb throat) whistles like F'ing nuts... so I set the RPM at about 800 so it would not make me insane.
Last time I pulled my Distributor the gear and everything looked pretty good. I only cleaned and adjusted my points... I might just get new ones to say that I did it and keep my other ones as spares.
As is, it is fine for now. I think that I am looking forward to a carb upgrade and head-work in the future but as of now... screw it... It runs fine I guess. lol
Guys, thank you so much for the tips and support. And if anyone has a NOS BBD they wanna sell for a decent price... let me know.

-Marc

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1965 D100 225 slant 6, NP435 Utiline.

There are two different base gaskets for the BBD, using the incorrect one may upset your adjustments. You can see them on page 26 or thereabout in the Carter BBD manual link in the FAQ, in the section describing the new BBD for '77 Super Six and the differences between 225 and 318 carburetors.

Olaf

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Aspenized

Pardon me for asking if you have already answered this, but what is your base timing set for now? If it is too far davanced, this could make it hard to idle where is supposed to without closing the throttle blades too much. The lower initial setting on the later slants was to allow the throttle to be open further and still get idle down at lower RPMs. The wider open throttle blades produce better combustion and thus reduce tail pipe emissions at idle.

It sounds like you are getting this worked out. The BBD is an excellent carb when it is in good shape. It is worth the time it takes to fix it if it comes to that. I got between 22 and 29 MPG on my slant with that same set up and an OD trans.

Sam

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