New Stroker Running Rough Daul Quad Quick Fuels on RPM Air Gap Final Answer

[Thumperbird]

My newly built 445 is running rough on anything but mild accleration, looking for ideas?

445, modest cam from Lykins, edelbrock air gap dual quad, custom adaptors for bk/bj carbs.
Aluminum heads, good headers, target was 10.2:1 compression.
Torque converter might be a little too loose but hard to tell without much torque.
Broader trans. will not easily drop down in to 3rd for some reason.

Here is how it behaves:
Starts well, idles ok but a bit rough, not familiar with a build like this so hard to judge
Temp. is good, oil pressure is good, no reason to believe there is a bad cylinder or ? but not sure yet, have not done cylinder by cylinder compression check yet
Very poor low end torque, will accelerate more or less smooth if I am easy on the throttle but if I try and get on it it just starts to shake a shutter quite a bit, not a bog, but gets rough and not much power, will not wind out at all
I feel like it is rich but no Air/fuel sensor yet, plugs look clean, almost too clean but only have a few miles on it.
No smoke out the pipes, does not smell overly gassy at idle at least.
Revs in park just fine.

Confident initial timing is close, around -15, seemed to idle slower and rougher at 15 but was not sure 20 initial was a good idea.  All in at around -30 right now, probably at around 3000rpm's black bushing in MSD pro billet
Dual quad but adjusted slip linkage to take second carb out of the picture for now, this helped a bit
No changes to carbs yet, idle vac is -14 so I think the power valves are staying closed
A little but not much response from idle mixture screw adjustment, not as much control as an old 390 I had way back in the day

Before I start down the power valve and jet routine was looking for any and all ideas as to likely condition of tune from this description.

Thanks.

[blykins]

Give it some fuel.  A stumble is generally a lean condition and everything that you described (very clean plugs, no smoke, etc.) point to that as well. 

[Stangman]

As far as cam is it solid , hydraulic ?. If solid are valves adjusted properly. Was piston to valve clearance performed. If you put your hands over the carbs does the idle change? Just a couple of quick things to check. Is adapter definetly not a vacuum leak

[machoneman]

How's the squirt from the pump shot(s)?

[Thumperbird]

Hydraulic roller, comp cams, morel lifters, Harland Sharp Rockers, all alignment items in valve train looked great, set rod length so adjusters are as high as possible, sweep across valve tip is centered and nice.
Piston to valve clearance good.
Degreed cam, it was dead on.
I believe I did a proper job of preloading the lifters, I do maybe hear a mild tick but not sure, they are very close at least.
I think all adaptors and carb flange joints are nice and tight, engine is dry all the way around so far.
Squirt looks strong at least when in park.
I believe bowl fuel level is good and mechanical pressure never sways from about 5 psi.

Vacuum is stronger than i expected, maybe power valves are coming on too late?  Stock BJ/BK's are 6.5 I think.
When I stab the throttle in park vac. drops to 5.
Thanks.

[My427stang]

Which heads are you running?  Almost any will like a little more total than 30.  If Edelbrock, get it to 36, if BBM and tight quench, add 2-3 degrees.  Readjust idle speed, then a/f again to best idle and see what it does

Don't let the PV get in your head yet, it'll get you going down a path that won't help.  This sounds like timing or carb adjustment to me.

[scott foxwell]

Did you check for pushrod binding on the rockers? With the adjuster at the highest position, the p/r cups may be hitting the rockers. You won't necessarily hear it, but it will wreak havoc on everything.

 

[Drew Pojedinec]

Shudder is normally lean.
Stock bj/bk came with .025 shooters, I find after 50+ years of sitting around the actual holes are more like .020 due to shellac.
I typically drill them anywhere from .025-.035 depending on usage, most normal engines end up at .028, of course you have a pretty cavernous intake which will require a large pump shot.  Also be aware that there should be NO gap between the accelerator pump screw and pump arm.  For some reason folks still set these with a .015 gap which makes no sense.

This will cause the exact scenario you are describing (as will a dozen other things, but this is an easy check)

[Thumperbird]

Edelbrock heads, stock valve size with good valve job.
Port matched to intake and exhaust, cleaned up runners and bowls a bit.

Yes, made sure I had clearance rod cup to rocker, adjusters are out about 1 thread max I would say.
No gap on accelerator pump, looks like it starts coming in immediately.
These are noew carbs from Carls.

Things are getting more fun now, in a good way...
Found that one of the floats was stuck on the second carb.
A quick tap with a wrench fixed that, this made me want to bring the second carb back into play so I adjusted slip linkage so it starts to come in at about 1/4 main carb throttle.  This woke it up a lot, of course there was no second carb shot happening, big problem.  I also added some timing, around 36 all in.

I think it wants even more fuel the more I play with it, very thirsty it seems to me.
Idle vac. is a little under 10 now so will have to review power valve setup I suppose among all other carb and timing stuff of course.  Low end is still not great but not nearly as poor.
Slight hesitation still at low rpm launch but at part throttle it gets up and goes.
I disconnected the trans modulator for now, this stiffened up shifting a bit.

I will measure the shooters and see where they are at, one side on the second carb does seem a little more weak than the others.

Thoughts on jetting, accelerator pump cam or pump shot?
Thanks much everyone.

[Drew Pojedinec]

Thoughts on jetting, accelerator pump cam or pump shot?
Thanks much everyone.

White cam #1 position, 66jets, I'd start with a .035 nozzle and go lower until a stumble is found.  You have a really large open intake and I think you'll find .035 is going to be far closer to happy than where you currently are.
Also BJ/BK's are really lean in the secondaries, like .059 main feed and .029 idle feed.
On my custom 2x4's I run .076 main feed and .035-.040 idle feed

Remember, the "magic" of bj/bk's is that they worked well with a stock 427, change the engine, cam, intake, cubic inches, etc, all of a sudden the magic vanishes and they are just high priced 600cfm carbs, with a cool list number.  My honest advice to anyone that doesn't need bj/bk's for a number matching build is to either sell them or put them on the shelf and make your own 2x4 carbs that you don't mind drilling on (or buy Qf's from Barry/Brent/Blair that have adjustable restrictions).  I'm not aware of the reproduction calibrations, so i can't comment further on that, but I assume it's close to the original.

(anyone have some repro bj/bk's I can borrow for a couple days?)

[Tobbemek]

edelbrock air gap dual quad, custom adaptors for bk/bj carbs.
The adaptors to make the Holleys fit  that air gap intake can screw up fuel distribution as well. Making calibration even harder to understand and far from normal procedure. 

[Joe-JDC]

The .015" on the accelerator arm clearance is at WOT, so that the arm doesn't close the little pin holding the ball in place and shutting off the fuel supply hole.  No fuel will come in, or not enough if that happens.  Joe-JDC

[Drew Pojedinec]

Of course Joe.... yet I still see people suggesting .015 clearance between the arm and adjusting screw, it's a pretty common bit of misinformation.

[FElony]

Additional info, may be of no help. This carb talk reminded of a thread starring Chipmechanic. Dug it up.  https://www.fordfe.com/bj-bk-carb-specifications-t49374.html 

[Drew Pojedinec]

Felony, his measurements are way off. The ifr and emulsion specifically. I don’t think he realized the ifr is inside the idle well.

He wrote:

BJ carb...List 2805

Primary main air bleed .030"
Primary idle air bleed .062"
Secondary main air bleed .025"
Secondary idle air bleed .028"
Squirter .025"
Primary Jets 66
Transition slot width .025" all 4 corners
emulsion jets .029" ...both sides both jets
kill bleeds .028"
idle feed restrictors .042"
Power valve channel restriction .043"
secondary metering plate same as 600 holley
PV not marked but seems to be same as 85. Pretty stiff.
straight leg boosters, standard 600 holley sized plates and venturi
yellow squirter cam position 1

Several errors like assuming the metering plate is the same... it is NOT even close.

I Measured with Starrett Pin gauges, not with pin drills, which are very inaccurate.

List number         C3AF-9510-BK List 2804 and C3AF-9510-BJ List 2805
Type            2x4 4160's
Primary            
Float            Large brass, side hung
Booster            .140 Straight leg
Pump nozzle          .025
Pump type and cam      White #1
Idle air bleed         .063
High speed bleed      .031
Metering block#         4033
Main Jet         66
Power valve         6.5
PVCR            .042
Emulsion         2 @ .028 in each airwell
2 @ .026 in upper dogleg feeding emulsion tubes
Kill Bleed         none
Idle Feed restriction      .026 in idle well
Needle and seat         .097
Venturi size         1 5/16
Throttle plate size      1 9/16

Secondary
Mechanical or Vacuum?      VS
Spring color         Yellow
Diapghram length      2.050
Float            large brass, sid hung
Booster            .140 Straight leg
Pump Nozzle         na
Pump type and cam      white #1
Idle air bleed         .028
High speed bleed      .025
Metering block/plate#      #13
Idle Feed Restriction      .029
Jet size or Main restriction   .059 (often quoted as 63 jet equivalent, not certain on that)
Needle and seat         .097