Technical EVERYBODY is Stumped with no suggestions

You have had a hundred or so suggestions already.

 

ummm yep, my ***le was slightly off. What I meant was nobody local to me had any suggestions that I had not already thought of and disregarded…

I am not the old dog who doesn’t learn new tricks.

 

Yeppers, and I’ve been through all of them, or technically will have been by the end of today.

I may learn slow, but I still learn.

 

On most carbs you only have an accelerator pump on the primary side of the carb...The only one that is different is Holly double pumpers...and there are variants on that with center squirters...Then getting back to the early days with carbs that have no accelerator circuits...

 

Yessir I’m aware of that. I’m replacing this new pump because it’s been removed and dried and put back in so many times that I don’t have confidence in it anymore. That’s basically it.

 

I recall years ago before pcv systems and better oils a similar case of your symptoms which turned out after many days of searching to be intake valves which were badly coked with carbon and restricted flow and vacuum/fuel. Ran ok to 35-40 mph. Felt very similar to todays plugged cat converter but no overheating symptoms. You might see in there with a bore scope or just lift off the manifold. I feel your pain and do let us know what the fix turns out to be.

 

I can sneak down and over the borescope through the manifold and see what’s up, I know what you’re talking about. So thanks for another good idea.

 

Okay, report 1: it’s not exhaust restriction through heat risers, it don’t have any, was removed centuries ago by the looks of it. Car was raised in Texas heat…

 

Bore scope through intake, is a no go. Corners too tight for the neck length on my Depstech bore scope.

 

22.5” vacuum at fast idle choke working.

warming up, more tuning and numbers soon.

 

I 'corn-fess'.....I dinnut read ALL the posts.
BUT.......did you try another carb to verify it WAS indeed your carb ?!
6sally6
PS......and checked the linkage ?

 

There are exactly 0- square bore carbs in my area that are on known running rigs I could borrow. So the only verification I can get is by making this carb work better, starting with proper jet sizes and proper gaskets….

idle advance is now 13.5-14 degrees at 545 rpm.

39 degrees at 1300 rpm with 21” vacuum

44 degrees at 2000 with 21” vacuum

all in at 50-51 degrees at 2500 up to 3500 rpm with 21 “ of vacuum.

now for the final test…. Will the engine rev up when the secondaries are opened today???? Up next are the results!

 

Big fat nope……. Far smoother than before new gasket and rear jets, visually plenty of flow into the secondary circuit, but it bogs at primary WOT also when I lock out the secondaries…

okay Jon, I’m emailing you the video I just took. I’ll await some ideas from you, whike I put out the notice once again for a known working square bore to use in troubleshooting this engine.

 

OK, so I went so far as to, use a squirt bottle in Square the **** ton of fuel in there as it was flat lines, and that did not change anything. So…..

I’m going to unfold the exhaust at the flanges and give her a flying go just to see what happens

 

Unless somebody else has another idea of what’s causing this and yes, I did it with a full 5 1/2 psi pressure going into the carburetor

 

What is the vacuum at 3500 or 4000 rpm (hold RPM for 15 or 20 seconds), engine at operating temp. trans in neutral?

 

The vacuum never dipped below 20”. Except when cracking throttle momentarily.

 

The exhaust sounds amazing. I just did a little video of that but I’m gonna send to John also but it doesn’t sound like there’s any restrictions at all. Sounds like it’s got a nice pair of gl*** packs on it and the flow seems decent little bit of blue smoke out of the left Bank.

 

Going into carb one more time to up the primaries to .094, I know it’s only two sizes, but it’s what I have available.

Just as Jon and several others have suggested too much carbon, plugged exhaust and possibly weak valve springs, I can feel that possibility, but I’m not hearing a floating valve with my old bad ears, it’s kind of a distinct sound, but that don’t mean it isn’t happening…

2500 rom to full open primaries it falls flat, it will eventually reach 3840 rom and nothing higher…

so one last outing to install the .094 primaries, then test. Then I’m just going to disqualify myself from further work on this rig. It’s running ten times better than when it arrived, and I guess sometimes that’s gotta be enough without a rebuild.

you guys are great, thank you.

 

Here’s one more thought, if the valves were floating wouldn’t I lose a lot of vacuum at that particular time because it stays just above 20 inches when I have it wide open

 

Unbolt the exhaust at the manifolds and cruise it with the vacuum gauge
Is the vacuum dropping as you throttle it?

 

The vacuum is a very steady 20-22” at idle and at wot.
What kind of vacuum signal does one experience during valve float?

 

I read some of the posts
Did anyone suggest ? Or have you considered
Trying a Carter AFB in place of the WCFB
The afb is a much better carb than any wcfb in pretty much every way. Reliability, performance, tuning,
And parts availability is waaaay better. not to mention the choke design from a modern afb edelbrock carb
Can be kitted on most of the older carter carbs
Electric choke swap in a snap.
I’m pretty sure all the afb have dual bolt mount design to be accepted on a small pattern intake.

 

I have considered many options, including that one but none of them are viable without a very large adapter plate. Here’s a reference to the base gasket for this Carter WCFB and the base plate on a carter AFB.

 

Hopefully I didn't mislead the OP with my earlier comment about possibly still needing some accelerator pump shot as the secondaries begin to open. I've got limited experience with the workings of WCFBs. But probably too many years ago I recall some other Carter 4 barrel models having a pump shot from idle to wide open throttle. Maybe it was on an AFB or possibly some version of an AVS. Or maybe someone else "modified" it before I laid eyes on it. Perhaps @carbking can shed some light on the matter in case I've completely run off the tracks here.

 

20"-22" at wide open throttle? With or without a load on the engine? ?

 

Shouldn’t the vacuum drop significantly at WOT then climb back up?

 

Clay and Anthony, you never truly lose vacuum at wot, but the signal definitely weakens for an instant. I can show the effect in a video but they are too big to post and the site won’t upload them.

and I understand about the pump travel in different carbs.

I literally squirted fuel in at WOT from a squirt bottle to zero effect on the motor which is making me lean towards valve float but my carburetor guy says that valve float will send the vacuum gauge fluctuating like crazy, which it does not doing this case

 

WOT vs. WOT under load are two entirely different beasts

 

Indeed, that is correct. But if I cannot get a good burn on wide-open throttle without a load, then there’s no way in hell I’ll get a good burn on WOT under a load.

Right?