[shaker455]

Those are idle feed holes
Checking that the timing is not moving in and out of gear should be done before any mods.
Your car an auto trans?

[Formula jg]

700R4 with off the shelf 2400 lockup.

I have to add that timing check in gear to the process (it makes sense now that you mention it).

My next qesstion is not related to this issue, has anyone used this BLP progressive secondary link?

[shaker455]

I've used them on 4500 Dominators to make them behave as a 4150.

[Tom Vaught]

Originally Posted by shaker455

I've used them on 4500 Dominators to make them behave as a 4150.

X2 on that. Really helps the Large CFM Dominators drive a lot nicer and the "Baby" Dominators #80186 (750 cfm) really like that deal when installed on a Dual Dominator "Street Supercharger System".
The "normal" Internal Linkage Dominator Cam Secondary set-up could be a lot better.

Tom V.

[Formula jg]

Currently my secondaries open at approx. 40% and I want to experiment delaying that to maybe 50-60%, can I accomplish that with this link?

Shaker, just curious what are some of the causes that would move timing when going in and out of gear?

[shaker455]

Stumble, high idle causing improper throttle blade positioning.
Erratic idle, list goes on.
You want it nailed down..
Vacuum advance.. you got it on ported?

[Formula jg]

I tried endless combinations of weights/cam/ported/manifold etc. and this engines idles, cruises and just performs best with vac. adv. on full manifold.

Sounds like I need to have that secondary T-slot exposed, how much exposure would you recommend?

[Tom Vaught]

You want 1/2 of the width of the Secondary Transfer Slots exposed below the throttle plate.

One a primary side you want a "square window" 9mentioned many times in articles.

Tom V.

[shaker455]

John, looking @ your combo which is not that far off from mine I would not run a cam that size on full vacuum. Especially @ idle....more than likely the reason it idles too high with blades in proper position.
I understand you spent the past 10 plus years tweaking your combo since I first help you & I respect you and your effort.
If your car was here I would have a different approach.

[Formula jg]

Shaker, you've helped many people over the years including me and I've learned a lot but no where near the expertise you and several others on this board have.

This stumble issue has forced me to rethink some of my settings, so I'm open to any suggestions and advice you and others have. I haven't given up on this carb and it's come a long way from the POS it was brand new, so whether I'm being stubborn or just plain old stupid I'm not stopping now.

Now I'm curious how it would idle on ported and the secondaries opened enough to reveal the T-slot (before I go ahead and elongate them) as Tom described, I have to test it next weekend weather permitting.

[shaker455]

Give it a try

[Formula jg]

Quick question I’m replacing the original float with a notched one and need to know if I can bend upwards the curved tab in the pic in order to get the top of N&S (threaded area) a little higher? The threaded area sits to low and there isn’t enough exposed for the adjusting nut to grab onto.

[shaker455]

Compare it to one you took out to see what the difference is.

[Tom Vaught]

Originally Posted by shaker455

Compare it to one you took out to see what the difference is.

Some of the float levels can be off when you do a dry setting because the Combination of Manufactured Parts put the float in a different spot.

The "Sight Port"/"Sight Glass" helps with that issue if you have the correct bowls for the carb. Typically on the older carbs the position of the "Sight Port" was different for the Front (primary) Bowl vs the Rear Bowl.

The newer bowls with the larger "Sight Port" (once calibrated) make for consistent readings and settings. Many years ago Holley had a Tool that installed on the bowl and acted like a "U-Tube" manometer. You could read the actual fuel level vs a scale on the tool. Later they eliminated the Fuel Level tool and added the "Sight Port" to both of the fuel bowls. Much easier to work with but a bit less accurate. Some of the Black Floats from the aftermarket are all over the place.

Tom V.

[shaker455]

Yes Tom & Demon bowls have a large sight glass on side.

[Tom Vaught]

Today some of the higher end Holley carbs have the larger "sight glass" bowls as well as Marvin's Quick Fuel Bowls did years before they merged companies.
For sure an improvement over the old stuff.

Tom V.

[Formula jg]

I went ahead and bent the curved tab as suggested and that raised the N&S just enough to bring the threads up into the adjusting nut, that you guys.

Also, I didn't have the same success with the adjustable threaded secondary opening link (see my post #62). My goal was to delay sec. opening from current 42% to 50-60% but after messing with this for 1/2 a day including lengthening the slot that the link rides in on the sec. side it was obvious that the sec. plates would not fully open.

Is there a way to delay when the mechanical sec. open?

[Tom Vaught]

There is but you would have to install a #4224 style Cam and Roller type linkage and shaft system.

You would then file or machine the slot until you got the 50%/60% opening on the Primary Throttles.

Many used Tunnel Ram Carbs have this old linkage set-up. Look on E8ay.

Tom V.

[shaker455]

Tom,
How many degrees does the primary blade actuate before starting the pull the rears on a 4150?

[Tom Vaught]

With no modifications to the cam profile (as received) it opens the secondaries about 15 degrees of travel above idle rpm. A very quick secondary opening.

Holley also offered at one time a "Double Hump" cam profile for some carbs.
The double hump had a delayed secondary opening.
BLP offered at one time a Double Hump throttle assy. See link here.

http://blp.com/pdf/pg10.pdf

Picture at the top right of the page in the link. Easy to see why it was called a Double Hump linkage.

Tom V.