All Small Six Weber 32/36 rough idle

[beanmiester]

While I have you all here 1. Thank you for the help this has been a very tedious ride 2. If anyone has some tips for setting up a dui that would be appreciated. I'm going to leave the car alone until that gets here since I got the carb adjusted alright and the dui should be a better match up with the carb I'm using. Oh and is there a difference between the street/strip dui and a dui. I ordered it through vintage inlines and didn't notice a difference in the description

 

[DON]

No the vacuum shouldn’t change at idle with the DUI. It has been too long since I got mine, I don’t remember a choice. I don’t really remember any problems installing it. I used their plug wires, I powered it off a relay. It’s really not complicated. Do post if you have problems

 

[Frank]

While I have you all here 1. Thank you for the help this has been a very tedious ride 2. If anyone has some tips for setting up a dui that would be appreciated. I'm going to leave the car alone until that gets here since I got the carb adjusted alright and the dui should be a better match up with the carb I'm using. Oh and is there a difference between the street/strip dui and a dui. I ordered it through vintage inlines and didn't notice a difference in the description

One inch of vacuum will be ok at idle on the new distributor.

 

[DON]

If you want to be thorough, send your DUI to Bill ( on this forum). He will set the curve for your engine. He is in the Vendor section under Ambler Race

 

[awasson]

As @DON mentioned, use a relay to provide the ignition +12v to the DUI distributor. The existing ignition + voltage is likely supplied through resistor wire and won’t be adequate.

Also, regarding the Weber carb. Is it a Redline or Clifford Performance carb? Find out what the idle jets are. I wonder if they’re not correct. These carbs are supposed to be pretty much bolt on and go. Mine needed a little tweaking because of the cam I’m running but it was really good out of the box. Same with the one I had in another car.

 

[awasson]

I found another discussion on Weber Carbs and it has a chart of the OEM jets and some related info. The middle column on the linked post shows the OEM jetting for the 32/36 for reference and the right column shows the changes the person posting had made to theirs due to engine mods, porting, camshaft and exhaust.

All Small Six Post in thread 'Weber 38/38 progressive jetting'

Jul 18, 2024

Yes I hope so too. But I haven't found any info online on how to jet a progressive 38 for a six cylinder.

The standard jetting of the 38/38 is lower as what I have in my Weber 32/36 right now, so I'm struggeling what jetting I should start with.
Here is a little jetting overview:

	Standard jetting 38/38	Standard jetting 32/36	Weber 32/36 as on my engine
Main jet primary	145	140	155
Main jet secondary	145	135	160
Air...

• clochard68

• 

 

[beanmiester]

As @DON mentioned, use a relay to provide the ignition +12v to the DUI distributor. The existing ignition + voltage is likely supplied through resistor wire and won’t be adequate.

Also, regarding the Weber carb. Is it a Redline or Clifford Performance carb? Find out what the idle jets are. I wonder if they’re not correct. These carbs are supposed to be pretty much bolt on and go. Mine needed a little tweaking because of the cam I’m running but it was really good out of the box. Same with the one I had in another cacar.

I bought the kit through vintage inlines but it's a redline. As for the relay can I use the old coil wire as the on/off input? I know I have to take the voltage from the battery to get a solid 12. Oh also I am a completely stock engine besides the carb and soon the distributor so the standard jetting should be fine right?

 

[Kritas]

I think the VI kits are already jetted for a 200, so that may not be an issue. From their site:

Note: Now jetted for 6 cylinder engines. However, occasionally you'll need to rejet the carb to get the best performance.

 

[Frank]

I bought the kit through vintage inlines but it's a redline. As for the relay can I use the old coil wire as the on/off input? I know I have to take the voltage from the battery to get a solid 12.

Some relays don't come in/stay in with lower voltage, others do.

Looking ahead- when you install the new distributor I recommend a dedicated ground be fabricated. Distributors, points or otherwise, ground into the block at the mounting point. I have had them loose ground completely or partially, and it's hard to diagnose what the heck is going on. Might even be your issue now, the symptoms are right.

 

[awasson]

I bought the kit through vintage inlines but it's a redline. As for the relay can I use the old coil wire as the on/off input? I know I have to take the voltage from the battery to get a solid 12. Oh also I am a completely stock engine besides the carb and soon the distributor so the standard jetting should be fine right?

Excellent! Yep, the Vintage Inlines kit should be perfect. I have the Redline 38/38 kit. Redline seems to hit the right jetting and initial settings. Also, yes, you should be good to go if you power the distributor through a relay and use the existing ignition to trip the relay.

The way, I did mine was by adding the relay just below the starter solenoid that's usually located beside the battery and I picked up all of my connecting points from the solenoid. I took power from the battery junction on the solenoid, inserted a fuse and took that wire to the added relay. I grounded the other side of the relay coil to the chassis and took my relay output to the distributor. I use the same relay to power my electronic choke.

One terminal says S (for start) and one says I (for ignition). I think the one farthest from the battery is the one that says I for ignition.

 

[awasson]

Some relays don't come in/stay in with lower voltage, others do.

Looking ahead- when you install the new distributor I recommend a dedicated ground be fabricated. Distributors, points or otherwise, ground into the block at the mounting point. I have had them loose ground completely or partially, and it's hard to diagnose what the heck is going on. Might even be your issue now, the symptoms are right.

Good point. These old cars have decades to generate electrical gremlins. When I had the engine out last year, I installed a new ground strap from the back of the block to a threaded nut-sert that I put into the firewall and my battery ground strap goes to the engine block as well. I replaced all of the electrical leads from battery to starter and grounds and checked my alternator wiring and grounding. My starter solenoid is fine but ancient so I recently changed that as well. I also added relays for the headlamps and high beams which I use the headlamp switch to trigger. Better safe than sorry.

 

[beanmiester]

Should I get the mini vip for the D.U.I? I don't need the performance it would give but it says it helps with voltage drops. Is that a big issue if I'm not doing anything crazy with the car? Before I changed the carburetor out when stopping at lights the voltage would drop to around 11v with the fan on. Im thinking it was the old carburetor causing the issue because the idle would go below 500 when stopping after driving for a few minutes.

 

[awasson]

Should I get the mini vip for the D.U.I? I don't need the performance it would give but it says it helps with voltage drops. Is that a big issue if I'm not doing anything crazy with the car? Before I changed the carburetor out when stopping at lights the voltage would drop to around 11v with the fan on. Im thinking it was the old carburetor causing the issue because the idle would go below 500 when stopping after driving for a few minutes.

You shouldn't experience a voltage drop if you use your ignition source to trip a relay that will provide 12v to the DUI ignition. Here's a little diagram I made up the other day to show how that works with a standard bosch relay. Bosch relays are pretty common and there are a bunch of knock offs that make the same relay. Make sure that you source 12v from the battery side of the starter solenoid and that you have a fuse between the 12v source and the relay.

 

[beanmiester]

So now I'm wondering if the oem rally pac can be used with the dui since the pac is current sensing not voltage sensing. From the diagram i got online it seems like it might be able to use the tach output from the dui with a ballast resistor to mimic how the resistor wire would work. I looked at another forum and someone mentioned some msd converter box thing. The guy never tried it and just went back to a point ignition instead so idk if that would work

 

[DON]

MSD has an adapter for there ignition box. They have a list of tacs that will work without one. I don’t know what it is. Probably cheap if it’s a resistor. It is something you plug into the box.

 

[Frank]

So now I'm wondering if the oem rally pac can be used with the dui since the pac is current sensing not voltage sensing

I do not know the answer to your question. Only hopeful input I have is, the DUI tach-out ran the tach accurately on a previously points fired aftermarket tach, and on the factory tach in a later model truck that had been EFI.

 

[awasson]

MSD has an adapter for there ignition box. They have a list of tacs that will work without one. I don’t know what it is. Probably cheap if it’s a resistor. It is something you plug into the box.

MSD used a choke if I recall correctly. It looked like something you’d find in a tube amplifier. It may have been used as a resistor but I never analyzed the circuit. I had a MSD 6A on my hotrod BMW 2002 a lifetime ago.

The HEI ignition I used has a separate coil and a wire labeled tach. It doesn’t work with my old school tach I have in my Mustang but connecting to the negative side of the coil as one would in the olden days does. I realize the DUI is coil in cap but I wonder if the negative side can be tapped without any modifications. I wonder if the DUI guys can advise.

 

[DON]

I use a newer tac with my dui. I would call MSD tec and ask them about the oem tac. Or put a newer replacement tac in your pac, same the old one
Edit: call DUI not MSD

 

[Frank]

I wonder if the negative side can be tapped without any modifications. I wonder if the DUI guys can advise.

It seems to me that must be what the "tach-out" wire on all coil-in-cap HEI's are- the coil negative. That tach feed has worked on every aftermarket tach I've had dating back 50 years to when they expected coil negative only as input. But I don't know this for fact.

 

[beanmiester]

It seems to me that must be what the "tach-out" wire on all coil-in-cap HEI's are- the coil negative. That tach feed has worked on every aftermarket tach I've had dating back 50 years to when they expected coil negative only as input. But I don't know this for fact.

So since the tach out is most likely negative all I would have to do it run a wire with a ballast resistor to mimic the pink resistor wire the old ignition uses and it should read properly