Technical EVERYBODY is Stumped with no suggestions

'54 Chrysler 331 hemi, WCFB manual secondaries, 1 1/16" front and rear venturis.

Fully and thoroughly cleaned every single p***age and orifice in Chemtool, air blown and pipe cleaner brushed wherever accessible, spotless p***ages, no corrosion from Ethanol. 101148 original verified miles on engine and car, tight throttle shafts.

My current specs:
Front Jets where metering rods sit: .080"
Metering rods tip diameter: .059-.060"
Rear jets in base of fuel bowl: .055-.056"
Low Speed Jets front (long jets in top edge of bowl): Top of jet .061-.063", Bottom of jet tube .027"
Low speed jets above Rear bowl Identical specs:
Air bleed holes, All 4 br*** plugs: .020"
Float level set to 9/16" front and rear, then (after carb kept flatlining on any secondary throttle use) raised rear float a few thousandths to wet the threads on the fuel site screw holes on drivers side of Carb bowl.

Vacuum piston for metering rods works freely and correctly.

Car works flawlessly on primary venturi's and I can easily reach 65 mph, but no further when entering into any throttle amount of the secondaries. It simply flatlines at partial or full secondary use. No acceleration whatsoever regardless of driving speed or free spinning speed in neutral when secondaries are activated.

Timing initial at 14 degrees, all in at 3500 rpm with 50 degrees total timing.

Fuel pressure from (OEM Carter 737)fuel pump is 3 PSI even. There is an installed inline draw through electric pump that produces 5.5 psi maximum, which is simply used to fill the carburetor after sitting over the winter and the fuel evaporates, but even when engaged while driving or testing effects nothing. Even under ***ist 5.5psi there’s zero results.

Engine starts perfectly with ONE pedal depression even from cold start. Choke is properly adjusted, Factory suggested timing is 4 degrees, even at those specs with an all in of 44 degrees at 3500 rpm the carburetor still flatlines when opening the secondaries.

What suggestion would you make for this issue?

I can ONLY think of one possibility that would make this carburetor do that and that's the carb top gasket possibly blocking an important air p***age, causing the secondaries to starve for fuel, even though the video I took showed the br*** tubes flowing fuel when the secondaries opened, and the engine refused to gain ANY rpm...

Don’t say backed up exhaust- no car gets to 65 on primaries at 5000 plus lbs with plugged exhaust.

I just removed the carb AGAIN to check top gasket, I see zero red flags. I need a funking GENIUS suggestion.

the car is unmolested one owner all original.

 

Can you confirm that the secondaries are or aren’t opening at speed? I had a car do that once with a quadrajet and the vacuum pots were shot the secondaries weren’t opening at all.

Paging @carbking

 

Any way to try a different carburetor, so you can try to verify if it's a carb problem or something else.

 

I don’t know if anyone local to me with a running 450-500 cfm square bore carb, much less a known hood runner, but I’m definitely putting out feelers for one.

 

You had me lost about 5 lines into all the carb lingo
But I had a Qjet that did similar. The secondaries would stick closed.

 

This is manual secondaries they open with the throttle linkage when the choke is fully open.

if they weren’t opening, then moving the throttle past, the halfway point would have zero effect. Because the carburetor runs fantastic I’m just the primary venturis.

this carb is rated about 380 cfm according to the math offered here on the HAMB.

 

I had a buddy with a similar problem on his 1963 Ford Galaxie running a 390 with a 4 barrel. It ran fine until he wanted to put his foot into it. He took me for a ride and sure enough when he put the hammer to it it fell on it's face at about 40 MPH. Now I am not saying this is whats going on with you but offer this as info. When he opened the hood I saw he had no air cleaner on the carb. He also still had the original hood insulation in place and I could see where it was hanging loose on one corner. Yup you guessed it! When he put his foot into that 4 barrel it ****ed the hood liner down onto the top of the carb and killed the motor until he took his foot out of it. Then it would pop back up. Told him to put a damn air cleaner on it or remove the hood liner. Problem solved.

 

This does it from idle in neutral sitting in the driveway, any opening at all end of the secondary blades totally flatlines. Here is a video of the secondary showing that they pull fuel when they open.

never mind. Damn file is too large at 13 seconds.

 

Why did you rule out an exhaust restriction? That’s exactly what it would do. Some Hemis have an exhaust heat riser valve that are prone to sticking. Might take a closer look there.

And I’ll second the idea about secondaries not opening.

 

Are you kidding me? A 5000+ pound car going 65 mph on the two primary Venturi‘s and you think it’s an exhaust restriction? Or did I not add that in one of my explanations?
It cannot be an exhaust restriction if I’m holding the throttle to 3500 RPMs on the primary’s, but it flat lines into the secondary at any increment. Also, if I pull it just off of idle and slam the secondary and primary’s open at the same time it falls on its face then also so everything is saying not enough fuel….
But every single p***ageway is perfect and original on this carburetor I have thoroughly cleaned it.
Even the secondary Jets are supposedly spot on to this 54

 

Hard to tell exactly but in the picture (blown up) the right rear air bleed looks clogged.

I'm no Hemi guy but is it supposed to have 50 deg. total timing? Even 44 seems like a lot.

 

Had a 4jet that I’d run out of fuel in the bowl. Goofy me didn’t pay attention during ***embly and the floats were way off. Fell on its face. Idled great.
But I’ve also seen those exhaust heat baffles stuck partially open. Also bogged down yet ran at slow speeds just fine
The Qjet that would stick closed worked fine on the bench. Under a vacuum, not so much.
But ran as fast as I wanted in a 6500 pound ride. But the acceleration ****ed. Especially on a hill.

 

Are you kidding me? All I did was suggest you look. Your friends probably aren’t stumped, they just don’t want to help someone that’s too smart to figure out why his stock Chrysler won’t run. Good luck.

 

Since there's no secondary air valve like a Q-jet or AVS style carb uses, I'm thinking you might still need some accelerator pump shot not just for the primaries opening, but also when the secondaries open as well. Kind of like a manual secondary Holley carb with dual accelerator pumps. I would check to see if you still have any pump shot left when the secondaries begin to open. Maybe needs an adjustment to the accelerator pump stroke. Or maybe something missing (spring or check ball?) or not sealing properly with the pump inlet or outlet check valve.

Did the carb work OK prior to rebuilding it?

 

Wow, you took that all wrong. They are you kidding me part is that it was one of the first things I wanted to be sure it wasn’t. My apologies if I made you think I was the smartest guy on the internet. I definitely am not. But I try

 

Gary -

You are barking...up the wrong tree !! Actually, not even in the correct forest !!

Read that...weak valve springs. They are done, used up, or in any case, just too weak.
99% on this.

Mike

 

Well, 100k+ miles on an old ride probably =s 250-300k mikes for a newer ride

 

It certainly sounds like you aren't getting fuel delivery on the secondary's. Does it ever pop back through the intake when the secondary's are open?

I did have a Ford drive me nuts because it would run okay up to about 50, but if you opened the throttle all the way it would fall on it's face. Back off on the throttle and it would run fine. Sure acted like it was starving for fuel. After having everything in the fuel system apart multiple times, I finally found a weak coil. A guy I work with mentioned a coil and I thought that I had tried everything else, why not? A new coil was the fix. I have an old Sun coil tester with a small scope. The scale goes to 30K. The new coil would top it out, the old coil output between 10K and 15K.

 

I rebuilt a carb over a ballast resistor going bad.

 

I like the way you think about that accelerator pump needing a little more push after half throttle. I will have to take some measurements and find out if it will adjust to that.
My all in timing is 50° at 3500 right now.

this carb stumbles the very Netanyahu the secondaries open while in neutral fmrevving from a dead idle of 500 rpm at 14 degrees advance, and ANY other rpm.

the car was brought to me in very cruddy running conditions. my distributor recurve guy over in Tacoma said that the motor has likely never seen more than 3200 RPMs in its life because all the wear and tear in the distributor advance system basically wouldn’t go to full advance due to wear spots. He corrected that that, the mechanical timing curve is:
0 at 500-1000 rpm
6 at 1500
12 at 2000
16 at 2500
23 at 3000
All in at 26 mechanical at 3500

my 14 idle no vacuum initial timing brings all in at 50 @3500 and above.

if I can get 3500 on primaries only, but zero rpm advance at ANY time I go past half throttle into the secondary’s, then that possibly means that the jets need to be up sized, or as the other gentleman said that there should be an extra long shot of the acc pump to help the transition. But that wouldn’t factor in during an off idle slam to the floor of the pedal, because the acc pump continues to squirt past half throttle where the secondaries begin opening.

the only downfall to testing bigger jets in the secondaries is that every time the top of the carb comes off, the accelerator pump cup must be slid into a small round of cardboard and heated for over a half hour at 90 degrees in order to dry it out so the leather cup fits down into the pump shaft without the cup catching on the slot in the pump well.

 

Also tested with brand new coil. The ignition is pertronix and it works perfect, still no change.

 

I just recently got an old school coil tester, but I didn’t use it because it’s quicker going with a new coil, nothing changed. This is still 6v positive ground system.

 

Also on coil exhaustion or ballast resistance, there’s no condenser or ballast resistor in the 6v system.

 

Didn’t even know they had a 6v pertronix

Well I be

 

Well, what you need to know about pertronix is that it is a simple magnetic switch. It will work to open and close the circuit as low as 4 1/2 V from what I’ve tested them at. And they work absolutely perfectly on 6 V. They are delicate enough that the switch opens and closes The same way as it does with 12volts

 

So, 14 deg. BTDC vacuum disconnected + 26 deg. mechanical in the distributor is 40 deg. Not 50 deg.
The more advance you have the leaner it gets. I think you said you had a video showing fuel flowing from the boosters. Try fattening up the secondary jets or rolling the timing back. Factory timing is only something like 4 or 6 deg. BTDC. High speed lean out is not good.

 

I did not say vacuum disconnected I said with zero vacuum going to the distributor. Once I did that I verified it by removing the steel vacuum line going to distributor from the carburetor and verified yet again. I am not afraid to leave my vacuum advance hooked up when I know there is no vacuum draw on the distributor. It’s a very small access point underneath the fuel filter in order to get that thing off and I wanted everything set before I took it off, but the settings did not change. It was still at 14° at idle at 500 RPMs. My apologies for being confusing.

 

After rebuilding the carb, the factory setting was 4° when I had the distributor rebuilt it took me two weeks to find a proper 11.5° vacuum advance, diaphragm that is identical to what came out.

the original flat line shows up at 4°. And it is there at 14 degrees also.

 

Ok no problem. I guess I'm still confused. Your engine is idling, your engine has manifold vacuum, the vacuum line/hose is connected and you have zero vacuum? I guess you were checking the integrity of the vacuum advance diaphragm? At any rate, another thing to think about is that Pertronix. Do you have the correct module for a 6v positive ground system and is there a ballast resistor or possibly resistor wire in the system? You may have to remove any resistors and have the correct coil resistance for that set up. Just throwing that out there. Hope you figure it out.

 

This is not a Chevrolet that likes to runoff of manifold vacuum this is like a Ford. It is a Chrysler, and the vacuum operates off a Venturi, the port for the vacuum is above the throttle blade and only gets vacuum as the blades open.

does that make more sense?