Tune Changed Overnight

[Thumperbird]

Bingo Barry!  Here's the latest, solicitiing some more feedback for a couple new observations also.

Pulled the carbs, you can tell the plates are just stamped, they don't exactly stick in the bore but not smooth either.
Cleaned up all plates, smooth as butter seating perfectly now every time, set primary slots to just barely see them, made sure they are equal, they were off say 0.015" one to another.  There was a little flash at the edges of the bores for the throttle shafts, cleaned that up.  Used secondaries to set idle.  Idle screws at about 5/8 turn out

Test drive was fun as ever!  Lots of power, not near as rich at cruise, nice steady 12.5 a/f at idle, 14 to 15 a/f at cruise.
Huge improvement over the way they were even before thy changed.

Now here is where the fun begins:
Question 1 Bottom end is stronger if I leave the pcv disconnected and bleed air into the base of one of the carbs, thoughts on this?  No baffle in valve cover so I know I am pulling a little oil into the intake.

Question2  I noticed a few days back a light tick when cold, went away when warm.  Today after my 3rd or 4th launch and first succesful 6000rpm strong pull she was ticking like crazy, running a hair rough at idle.  By the time I got home it had cleared itself, I suspect this is a sticky lifter?  They are morels.  Thoughts on this.

[Thumperbird]

So, by the way, thank you Drew, Barry, Battlestar G. and all the rest for all of the input on how to run duals, very helpful, would not have gotten to where I am without you guys, much appreciated!  She scares me now up near 100, the front of the big bird likes to float around but sure is fun geting there!

[Drew Pojedinec]

Question 1 Bottom end is stronger if I leave the pcv disconnected and bleed air into the base of one of the carbs, thoughts on this? 

Since you are officially a carb tuner now    I'll toss it back to you.....
why do YOU think unmetered air is making your engine run strong down low?

[Drew Pojedinec]

and yeah, I've said it before, but I'll say it again....
on a 2x4 set of carbs, when everything is restored, I have it all laid out, and I go to assembling, I spend about 1.5 hours assembling the baseplates.  I only spend an hour assembling the rest.  It matters.

[427LX]

Tbird..glad you got it straightened out! I built up my Holley dual quad setup from scratch and run a much retuned 660 Center Squirter as the secondary carb and a 650 VS as the primary carb which handles cruising on the primary only.
The FUN begins past 40% travel!!! Works like a champ!


Those jet numbers are all 68

[Thumperbird]

Nice setup 427lx, I see you cut the horn off the main, I may go at mine this winter.
Drew still a hack of course but learning.  Not sure on the unmetered air, it did run a bit leaner of course so I had the idle screws out another 1/4 turn and cranked the secondaries closed a bit for idle rpm.  The thing has always liked a little bleed down low, are they all that way?  I wish I had a nice technical spot on answer but nope. 

[cammerfe]

I would check for a leaking power valve.. I had this happen the other week.. they were fairly new valves, but all of a sudden i was having all sorts of issues.. pulled the carbs, broke them down and found the secondary carb had a wet power valve chamber.. I tested the valve and it held on a vacuum test, but i replaced it and we were all set again.running great..

Plus one on the faulty power valve. I had an experience such as yours on my 'two-days-past new-delivery' '64 Custom/427. I'd had dual quads on my previous car, a '54 Customline/312 but those are completely different carbs. The '64 was my first experience with the 'new' Holleys.

I went back to the dealer and their resident carb expert, called 'Tiger', knew right away what was wrong. The rubber was all blown loose on one side of a power valve. Replaced within about 15 minutes and I was good to go.

At one time I'd accumulated a whole bunch of miscellaneous Holley parts, but when Holley came out with their 'bolt-on' EFI, I made the switch. Haven't owned a carburetor for more than 20 years now.

KS

[Drew Pojedinec]

Drew still a hack of course but learning.  Not sure on the unmetered air, it did run a bit leaner of course so I had the idle screws out another 1/4 turn and cranked the secondaries closed a bit for idle rpm.  The thing has always liked a little bleed down low, are they all that way? 

Still a hack here as well, I just put a lot of hours into it all
If nothing else changes and you add air, if it runs better it was too rich before.

If you are inducing an air leak and compensating by trying to richen it up, well.... don't.

You have an O2 sensor, and that is handy, but engines are gauges for these things too.  If you hang around engines often enough and listen, you can hear lean and rich.  Lean is super easy to notice at cruise and idle.  Richness less so, but the word "fat" sure does seem to sum up how it feels/sounds.  A lot of folks are used to how an overly fat carb runs on an engine, the first time you feel it right where it needs it to, it is liberating, the clean feeling the engine has at power, etc.

I have had so many people bring me carbs that didn't run right I've lost count.  That said, I've seen 1 blown power valve in my life.  Either way, it takes 5 seconds to check, just fill bowl with fuel and look at the bottom of the carb, is it leaking out of the PV signal hole?  yes/no?  In my limited experience I've seen plenty of power valve gaskets that leak, but yup....1 blown PV.  I often wonder why so many other people have blown pv's?  A mystery for sure

[wowens]

and yeah, I've said it before, but I'll say it again....
on a 2x4 set of carbs, when everything is restored, I have it all laid out, and I go to assembling, I spend about 1.5 hours assembling the baseplates.  I only spend an hour assembling the rest.  It matters.

I hope you are available when I get to the carb phase .

[Thumperbird]

Wowens all I can say is if you carbs have never been massaged by the likes of Drew or others don't bother installing them without going through them first and making sure they are smooth and repeatable mchanically and plates are positioned identically in the bores.

Still need to play to get to the sweet spot a/f wise but geteting closer now.
Any way I can deal with a stuck lifter without taking the top off if it happens again?

Tahnks again all.

[My427stang]

Is this a hyd roller motor?  They can be fussy on oil viscosity. 

Of course that is a comment on the noisy valvetrain not the carbs

[Drew Pojedinec]

I hope you are available when I get to the carb phase .

You live 100 miles due north of me.....  just stop in

[Barry_R]

That said, I've seen 1 blown power valve in my life.  Either way, it takes 5 seconds to check, just fill bowl with fuel and look at the bottom of the carb, is it leaking out of the PV signal hole?  yes/no?  In my limited experience I've seen plenty of power valve gaskets that leak, but yup....1 blown PV.  I often wonder why so many other people have blown pv's?  A mystery for sure

Lots of folks blame the power valve for their problems - but they do not fail very often at all.

The power valve resides in a cavity right below the accelerator pump transfer passage.  A good backfire can pressurize that cavity and compromise the gasket seal below the pump passage.  Especially in situations where the gasket surfaces are not flat as a result of bowl over tightening and heat cycles.  The gasket failure allows fuel from the pump to get sucked into the vacuum in the cavity, and it runs poorly followed by a dead hole from the now dry pump.  Replace the gasket when replacing the assumed "bad" power valve and everything is "fixed' until the next time.

Holley was aware of this issue decades ago, and some carbs had a pump transfer tube that was sealed by o-rings - - - bean counters eventually killed that good idea.

[Thumperbird]

Hydraulic roller, Harland Sharp rockers and Morel lifters.  Running 10w-30 VR1.
Just went for another drive and ticking again after 6000 rpm run, frustrating, did not clear by the time I got home today.
At least the tune has been stable for a couple days now.

[My427stang]

How much preload did you set it up with? What are you seeing for oil pressure?