Super Six Idle Issues... Bit 'O' Help Please!

So I just finished the "Super Six" conversion on the wagon... factory 2-barrel manifold, Holley 2280 from my Scamp parts stash (ran great 10 years ago on the 318, I rebuilt it, of course), Lokar throttle and kickdown cables...

I've got timing set at 8° advanced at idle, mixture screws set to give highest idle/highest vacuum, the engine idles at 700-725 RPM in gear with the idle speed screw backed all the way off. With the 1-barrel, it idled 100-150 RPM lower...

If I place my hand over the top of the carb, it takes a good 30 second for the engine start running crappy, which tells me its already too rich...

The car runs fine, except that it gets hot in traffic now. Used to be dead steady 195° all the time, now after 5 minutes or so, in stop-n-go, (hehe, i'm a poet and I didn't know it!) the temp starts creeping up. My theory is that the trans is loading a bunch of heat into the cooling system because at that RPM, it wants to move...

I remember the old trick of drilling holes in Holley primary blades to bring adjustability back to the carb, and I seem to remember reading that Carter BBD 2-barrels had their throttle blades drilled for Slant 6 applications.

So, any suggestions??? I'm considering drilling the blades a last resort, for obvious reasons, I'm hoping someone out there has the magic fix, or suggests something that I've overlooked.

If you hold your hand over the carb that long before it runs bad, it's lean, not rich. It has a vacuum leak somewhere. That will also cause it to run hotter.

150 rpm isn't that big a difference for the trans. Running lean tends to build heat. Like Rusty said, it sounds like a vacuum leak.

More than likely it’s a carburetor base gasket leak or other intake leak, or if your using a PCV, it’s pulling too much air though the crankcase.

The super six intakes are known for vacuum leaks mostly the aluminum and sometimes the cast iron ones. Try running some water over the intake before it heats up and see if a vacuum leak is there. If the carb is running rich, wants the exhaust look like?

First, RRR, what were you doing awake and on FABO at 4am???

Second, DUH!!! Of course its lean... You ever get so fixated on something you ignore the obvious? I was so hung up on the fact that I backed the idle screw all the way off, that I didn't pay attention to the clues the car was giving me...

1) Its getting hot (lean condition)

2) Part-throttle cruise surge (lean condition)

3) Diesels occasionally (lean or timing)

4) The carb is making that "lean whistle"

Thanks all for setting me straight! It better not be a bad manifold... this one is cast iron, so hopefully I'm good there. I'll let you all know what I find!

Find and fix the intake leak, probably at the head .
Verify your fuel level is correct.
Set your transfer slot exposure to a little shorter than wide.
Set the idle trimmers to 2/2.25 turns out. Forget setting the mixture screws to obtain the highest idle. That has never been right.
Set the idle speed with timing; don't move the curb-idle screw at this time. Do not retard the timing to afterTDC.
Reindex your accelerator pump per the instructions.
Roadtest it, at various Part-Throttle settings; do not floor it.
If it seems to take throttle ok, with no hesitations or backfires on the roadtest, then;
Put the linkage up on the fast idle cam to obtain about 1800rpm or a bit more; exact number not important. Now adjust the trimmers to highest idle speed. Then richen them up 1/4 turn and flip out the fast idle cam; don't touch those screws again.Your mixture is set right for cruising; or at least as right as it can be with the current parts.
Now for the idle;
first reduce the timing to get about 550 rpm. Next, adjust the Speed screw, (NOT the trimmers) for best quality idle, and not targeting the highest speed.It should not take more than 1/2 turn in either direction. By adjusting the transfer slots, you will not screw up the cruise mixture at 1800plus.
Finally, crank the idle speed to whatever you want it to be, using timing. I like 450 to 500 in gear, but slanties can idle a bit higher. I just like them ticking over sweetly at 450/500. Sometimes I idle them right down until every shot shakes the car, and the exhaust is thoop-thoop-thooping along.You can do this with a slanty because they fire 3 shots per revolution at 120 degrees apart every one of them.
Revisit the accelerator pump linkage adjustment.
Then roadtest it.
Get the idle and low-speed circuits worked out, solving tip-in sags or flat-spots as they may appear.
If it pings, that will be another post or thread.
Working out the timing rate of advance is another post or thread.
Wot is another.....

This has worked very well for me; your results may vary.

flingdingo said:

First, RRR, what were you doing awake and on FABO at 4am???

Second, DUH!!! Of course its lean... You ever get so fixated on something you ignore the obvious?



I was so hung up on the fact that I backed the idle screw all the way off, that I didn't pay attention to the clues the car was giving me...

1) Its getting hot (lean condition)

2) Part-throttle cruise surge (lean condition)

3) Diesels occasionally (lean or timing)

4) The carb is making that "lean whistle"

Thanks all for setting me straight! It better not be a bad manifold... this one is cast iron, so hopefully I'm good there. I'll let you all know what I find!

Click to expand...

I ignore the obvious all the time. Sometimes intentionally. LMAO

But yes, 99 times out of 100 when you have a whistling noise it's almost always always always the carburetor base plate gasket.

I had the same problem on my Super Six set-up one fine day. After it had performed well when I got it together. I have two carbs that I can go back and forth with. I noticed also that the damned thing felt like it had a vacuum leak. Traced it down to a loose throttle bushings, after rebushing with some brass inserts, this tightened up the carb throttle shaft, no more vacuum leak. After spraying different spots on carb with WD-40 I noticed it ran better spraying base of carb, replaced base gasket, no luck, then the shaft bushings. bingo

probably a vacuum leak.........
but also on the butterflies on the 2280 if its a 318 carb sometimes it will have holes in the butterflies which will cause it to idle a bit higher no matter if the idle is backed all the way off , i usually put some screws in it self taping drill screws. Holley 2280 is the better two barrel, Better economy Carb, and it doesnt get throttle shaft wear like the BBD.

When the throttle shaft bushings get worn, usually or often the throttle-arm side is worse. This allows the transfer slot exposures to park differently between them, and may or may not close one throttle more or less than the other, which screws up the trimmer flow. The intake has an open plenum so it don't care about this.
This usually only makes a difference when you crank a lot of idle timing in and the butterflies are too far closed, and/or somebody is trying to run the Vcan on manifold vacuum. When you do this , you are bound to create a tip-in hesitation, as the transfers cannot respond fast enough. So then your solution is to fatten up the pump-shot..... and then maybe you can't figure out why your slanty gets such rotten mpgs around town.
If your slanty is stock, you will be hard pressed to improve anything by advancing the idle-timing.

My solution is to put the T-slot exposure back where it belongs, which requires an idle-timing reduction back closer to "normal". Then I fix the distributor and change the rate of advance.
Doing it this way, those bushings can be really sloppy and the engine runs just fine. Because in the grand scheme of things, the air entering there is miniscule compared to what the PCV is drawing.

AJ/FormS said:

When the throttle shaft bushings get worn, usually or often the throttle-arm side is worse. This allows the transfer slot exposures to park differently between them, and may or may not close one throttle more or less than the other, which screws up the trimmer flow. The intake has an open plenum so it don't care about this.
This usually only makes a difference when you crank a lot of idle timing in and the butterflies are too far closed, and/or somebody is trying to run the Vcan on manifold vacuum. When you do this , you are bound to create a tip-in hesitation, as the transfers cannot respond fast enough. So then your solution is to fatten up the pump-shot..... and then maybe you can't figure out why your slanty gets such rotten mpgs around town.
If your slanty is stock, you will be hard pressed to improve anything by advancing the idle-timing.

My solution is to put the T-slot exposure back where it belongs, which requires an idle-timing reduction back closer to "normal". Then I fix the distributor and change the rate of advance.
Doing it this way, those bushings can be really sloppy and the engine runs just fine. Because in the grand scheme of things, the air entering there is miniscule compared to what the PCV is drawing.

Click to expand...

AJ the Holley 2280 carb he has doesn't get throttle shaft issues only the carter BBD does.

My description is generic and applies to all carbs from roto-tillers to 4-bbls.
Well on tillers you don't find T-slots nor pairs, but the result is the same; The worn-out business leads to a throttle-valve parking problem relative to the low-speed circuit discharge holes or slots. This parking problem is particularly troublesome on small engines with single barrels or old 2-stroke snowmobiles when someone tries to idle them down......... because they might be running too fast.... for whatever reason....lol. A 2bbl is just two singles ,side by side, sharing a common fuelbowl. and usually but not always,also sharing a throttle shaft.
A lot of base-plate wear stems from the angle the cable is pulling from, in combination with where the return spring is anchored to, as well as the power in that return spring. I mitigate this with a two-stage/two spring system,and whenever possible, having the spring anchor, the pivot arm, and the pull-cable in as direct a line as possible. I set my first stage to my cruising speed, and hardly ever use the second stage spring. I get away with that cuz I live on a prairie with about the same elevation for several hundred miles in any direction,lol.

Well I finally had a chance to look at the wagon today, and it didn't take too long to find the vacuum leak... Bad EGR gasket. Changed that out, and everything seems to be good.

flingdingo said:

Well I finally had a chance to look at the wagon today, and it didn't take too long to find the vacuum leak... Bad EGR gasket. Changed that out, and everything seems to be good.

Click to expand...

Well, how bout dat, yo?

RustyRatRod said:

Well, how bout dat, yo?

Click to expand...

I felt so good about accomplishing something, that I lubed the front end, and took the car for a drive.

That's when I found out my dash pad has been held in place by nothing more than positive friction! Scared the hell out of my son when it fell in his lap!