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Carburetor junk
#734575 April 02nd 2018 9:55 am
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pockets Offline OP
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So I am at a loss here. Bought a holley 1945 reman carb for my 82 slant six. This is the stock style carb that came with the van new, has the vac line that connects to the top of the carb for the diaphragm assembly. I know, they are all junk, but what do you want me to buy when they don't make new ones. I also bought a rebuild kit to rebuild it, and i did. Converted it to hei over a year ago. So here is what I did. Rebuilt the carb, put everything to spec, checked for leaks and all the usual troubleshooting stuff. Problem number 1: carb will idle fine then wont. Its a sporadic problem. Sometimes it idles fine and sometimes it barely can stay running. no rime or reason. Problem 2: again a sporadic problem with no rime or reason. At times it chugs/stumbles while accelerating, flat road, up a hill, doesn't matter. I have been trying to figure this out for a while and am at a loss. I have played with the carb settings, timing, disconnected and reconnected, you name it I've probably done it. And yes my timing mark is spot on. I could use some suggestions here. Any suggestions no matter how odd I will try. I'll even try a carb dance if anybody knows one. In the mean time I will look for a nos carb to rebuild but I would rather try to get this one to work first. If I don't have to spend the money I'd rather not. So anyone have any ideas.


edit note: If anyone perhaps has a carb that will make my van happy I may be willing to buy it if the price is right.

Last edited by pockets; April 02nd 2018 10:06 am.
Re: Carburetor junk
pockets #734581 April 02nd 2018 11:22 am
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You say you "put everything to spec", but have you adjusted the idle mixture screw to try and smooth out the idle? Carburetor manuals and instructional videos for your carb can be found here: http://www.slantsix.org/forum/viewtopic.php?t=55801

Another thing to check is the jet size in the carb. Chrysler jetted slant carbs very lean. It is not uncommon to have to increase the main jet size 1-4 sizes to get the Holley one barrels to run smoothly. What size main jet do you have in your Holley?

Other ideas: Have you checked your fuel pressure? Clogged fuel filter? Clogged fuel pickup in tank? intermittent vacuum leak (do you have a vacuum gauge mounted in the van to watch while you drive?)?

If you are in the market for a new carb, or looking for someplace to send a carb to to get rebuilt, I recommend tyring these guys:

http://www.nationalcarburetors.com/lookup.aspx?partnum=nd1411

Looks like $160 plus shipping will get you a new carb for your van that should be bolt-on and go.


Windows- they're what make a van worth owning!
Re: Carburetor junk
Reed #734584 April 02nd 2018 12:11 pm
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pockets Offline OP
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Played with the idle mixture screw-yes, able to get it to idle fine when it isn't throwing a tantrum

Changed out the jet to a 62

Fuel pressure and related components are good

I do have a vac gauge. I can go for a quick drive, what would you like me to tell you?

To be honest the last carb I got from national carburetors was trash. Threads were stripped and and was not rebuild able so I'm not sure if I want to give them a second chance or not.

When it isn't having a temper tantrum it runs perfect.

Last edited by pockets; April 02nd 2018 12:16 pm.
Re: Carburetor junk
pockets #734589 April 02nd 2018 1:36 pm
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Interesting. Maybe bump the jet up to a 64 and see if that helps? I have never personally bought a carb from National, but the process they describe on their website sounded more thorough and careful than the cardone crap you get from Autozone or eBay. If you have bad luck with them, don't use them.

RE: vacuum. What is your vacuum at idle? When the engine begins acting up what does the idle do?

Have you tried a different HEI module? Coil? When you upgraded to HEI what coil did you use? Did you bypass the ballast resistor? Did your van originally have a lean burn system? Did you verify tha tthe carb you got has the correct port for ported distributor vacuum advance and not manifold? The Holley 1945 carbs from the 80s could have a fitting for the distributor that provided either manifold or ported vacuum and you have to be sure ot get ghe right one for your application. I wouldn't trust a parts store to get into that level of detail.

I can check and see if I have a 1945 stashed in my garage.


Windows- they're what make a van worth owning!
Re: Carburetor junk
pockets #734600 April 02nd 2018 5:18 pm
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My van had a lean burn system originally. Non feed back carb. I replaced the carb and stupidly got rid of it. Should have kept it to rebuild. Replaced the distributor with one that had a vac advance on it, which is hooked up properly to a ported line. The ignition module is a gm 4 pin and the coil is a Blue Streak FD478 Ignition coil. And my van didn't come with a ballast resistor.

So I went back out to play with it more. I pulled the carb off and opened it up to spray all the holes and what not with carb cleaner just as a why not it's not gonna hurt. I also double checked the float level. Everything looks good. Put it back on and start it up. Idles real low and lumpy. Idle was jumping between 420 to 490 and vac gauge was jumping between 15 and 18 real quick, not a steady needle. I adjusted the idle mixture screw, idle went up to 700ish and vac gauge needle fluctuates between 20 and 22 real quick. Idles good there, little high but I'm not gonna complain at the moment. Give it a day and I'll bet you things will change. I'm still gonna be in the market for a carb because I know this won't hold. It runs good for a bit then has a fit. It's very sporadic. Didn't have this problem with the other carb, I only got rid of it because the threads were all stripped out and it leaked fuel because of it.

Re: Carburetor junk
pockets #734602 April 02nd 2018 6:22 pm
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Had to run out to the food store. 4 mile round trip. Ran there and back with no problems. What gives.

Re: Carburetor junk
pockets #734614 April 03rd 2018 12:07 am
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Interesting. If richening the mixture increased your idle 250-300 RPM, then I bet the idle mixture is still too lean. As you are probably aware, getting the curb idle and curb mixture settings corect is a dance between idle mixture screw opeining and curb idle speed screw setting.

20-22 inches of vacuum is great for idle. However, the fluctuating vacuum at idle is worrying. The vacuum, especially at idle, should be solid and steady. Where are you tapping into to get your vacuum reading? Are you drawing directly off the vacum tree on the #6 intake running? That signal can cause a vacuum gauge to jump at idle since it will ready the pulses in the #6 runner. A better place to tap for an accurate reaing is the hose that operates the vacuum choke pulloff. Install a T fitting in the middle of the hose.

Most of your issues sound like a lean running condition. I bet cleaning the pasages out and richening the idle mix got you much closer to solving the problem. Spend some time adjusting the idle mix and curb idle speed screw setting to achieve maximum vacuum at about 700-750 RPM in park.


Windows- they're what make a van worth owning!
Re: Carburetor junk
pockets #734616 April 03rd 2018 7:29 am
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I'll play around with it more and see how it goes. My idle screw is turned out about 1 1/4--1 1/2 turnes. I go any more in or out and it startes to stumble. It seems to like it there for some reason. Pretty lean compared to other engines/carbs I've had. But this is the first slant I've dealt with.

On the needle movement note. I have no idea. It jumps only 2 marks. I know a moving needle can indicate an internal problem like rings,springs or valves. It dosent burn oil, exhaust is not black or smokey, just normal exhaust. I do have a sticky lifter that acts up at times, but mmo with the oil changes have been helping clean things up. Once the weather warms up more I will be pulling the valve cover off to see how much it cleaned up before I take the rockers off and manually clean it all. I'm just trying to avoid pulling the head if necessary

Re: Carburetor junk
pockets #734620 April 03rd 2018 9:24 am
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Ok. So I went out and started the van. Same thing, can barely hold an idle at about 480. Decide to drive it around the block to get hot before I do anything. Drives fine when going down the road. Being a stick is probably the only reason it doesn't stall when stopping. Get back hook up the timing light and idle is the same. Let it sit and run for a little to get good and hot. As it does the idle starts to increase. The choke is working as it should. I did hook up the vac to the choke pull off and same movement in the needle. So what could cause it to run better after 15-20 minutes?

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