my fresh BB won't idle

I'm looking for some ideas with my 451, trick flow240 heads, 11:1, m1 intake, comp solid flat tappet XTQ294S-8, quickfuel 1050an carb. I bought the carb off a member here don't remember his name. Was supposed to be used very little. I tried a 750 I have and it wasn't much different. I do have another carb I could try.

Right now with the 1050 it's idling at 1650. If I lower either idle speed screw 1/4 turn it dies. With 4 corner mixture screws I have to have them only like 1/2 turn out. Timing is around 25. It don't want to start, or restart. I have to give it a lot of gas and open the throttle to get it to fire and stay running.
Vac is 11"

I want to go through the valves, but I haven't yet.

I would look for vacuum leak to start with, you've already tested two different carbs that had the same problem on your motor
is the PCV port,tube, on the carb blocked off?

i would go 1.5 turns out on the idle MIX screws, try to get it running and the idle close enough that you can lean our the idle mix after the motor is warm.

yes, def check that the PCV hose is hooked up to the carb.

are both accelerator pumps working?

X2

Sounds like a vacuum leak so look for that before you tune the carb.

If there isn't a vacuum leak then you'll need to sort out the idle circuit since it is way off. If you don't have a wide band then you'll have to do it the old way. Get it running at a fast idle and then start to turn the idle mixture screws. If it dies when you screw them out then you are too rich. If you are too rich at 1/2 turn out then the IFR in the metering blocks are too big. Reduce the size by a couple of numbers and try again.

A 1050AN is a very tunable carb. Do you have the right jets for that carb. The idle jets are a small size. Getting the idle circuit correct is the key to having the carb run right.

I did go through the old school way with the mixture screws. It runs smoothest and highest vac with them 1/2 turn out. The 750 liked them farther out, like 1-1/2. I figured the 1050 idle circuit needed some work after that. I pulled the intake off looking for any sign of a vac leak. I have the bathtub with gasket on each side. The gaskets had a good imprint from the bathtub, BUT on the bottom rear ports the gaskets were wet. I couldn't tell if it was from gas or it was sucking oil up from the valley pan. I don't like the imprint on the carb gasket vs the spread ore pattern on the m1. I did spray carb cleaner around the carb base, and the top of the intake to head, but maybe it's leaking on the bottom side?

You should be able to squirt some in the valley. As bad as it sounds like it is if it's leaking under there it'll probably flutter

If you take air away from the top of the carb and the engine gets happy, it's sucking air from somewhere else.

I had an m1 leaking thru the stud. I epoxied it in and it worked out.
Do a squirt test see if that works.my .02$

Not sure on that carb, but on my Holley HP, the hole for the air filter stud goes through the carb and will have a vacuum leak if no stud (or bolt) is installed.

Being a used carb, check the sizes of the air bleeds, idle restrictions, power valve restriction, jets, and emulsion holes and see if they have been changed from the stock specs.

Air bleeds are stock, jet is a couple sizes smaller than stock, I didn't check the restrictions.

Where do you have the initial and total timing set at?

Do you have vacuum leaks?

Are you running a PCV valve?

Initial is around 25. I'm not sure where the total is at. Don't know if I recurved this distributor already or not.

Open up the carb and post what all of the jet sizes are. Mains, idle, emulsion, air bleeds, etc. Post pictures if you can.

You might have a gasket problem or a vacuum leak or just a carb that is way off. Hard for us to help you though if you don't give us the details.

Are the feed restrictions marked? I can do that.
I don't think this carb has the air bleed air cleaner stud deal.
I have pcv valve in the valve cover and a breather in the other.
I went and picked up
Some carb cleaner and used it to try to find vac leak. Put air cleaner on and did some spraying
I get a change in 2 areas, seemed like between carb body and baseplate, and under the intake.

Your on the correct path, fix those area next and then think hard about fixing the oil seeping into the intake manifold from the valley pan

I removed the intake and the paper gaskets. There was signs of oil getting between the gaskets and valley pan. i want to try just the tin, is it a bad idea with aluminum intake and head? I sat the intake on with no gasket or tin and it is nice and tight. I never used the paper gaskets. I had a rpm and stealths on the last one with just the tin, but didn't run that setup very long.

Remove the valley pan and clean both the heads and intake mating surfaces very thoroughly and then take a set of feeler gauges with a .0010 to .0025 gauge and set the intake on the heads and rock it around to locate it and then see if you can get your thinnest feeler gauge to go between the heads and intake surfaces at the bottom and top of each manifold corner Write down what you find on each corner, top and bottom
Let us know what you find

Is it fixd yet

Yeah I tried that, With the intake sitting on dry and can't get my thinnest feeler gauge in anywhere around the intake.

I rarely use the paper gaskets with the valley pan.

Curious what sealant if any you use, Dwayne.

Years ago I used “high tack”.

More recently I’ve used a very thin smear of black “the right stuff”.

I’ve run them dry as well....... usually when I know there will be manifold swaps involved.

Until I had things more sorted out, I’d remove the pcv valve and use 2 breathers, and lock out the distributor...... start out at like 32deg.

I'll try again tomorrow. I put the intake back on.

No gaskets and two beads of Right Stuff on both sides valley pan hopefully...

That's what I did, I had right stuff. I never used the gaskets in the past, Spray copper or smeared a thin layer of the ultra copper or something like that.
This engine i dropped the parts off to the machinist I've known for 20 years. I just wanted machine work, I wanted to assemble it. I never had an issue with his work, great guy. He talked me into him assembling it and run it on the stand, break in the cam.

Right on! Hopefully it will help the issues.

Any update?

Possible.... have you tried giving it more timing anyways until it breaks up? Ive had an MSD box play with my timing light and give a way off timing indication. also are you using a factory balancer and timing indicator??

I was thinking about the msd giving a false reading the other day. It's an old
6al. Maybe I'm way off on the timing. I hooked up the lm2 wideband yesterday and ran it. Light throttle it's 12.2-12.8. When i drop the idle down there is a point where's 1/4 turn on the idle speed
Screw just kills it, is that when it's switching over to the idle circut? It's
not killing it because It's closing too far, I Checked the transfer slot.
At that point when it starts to stumble and die it jumped up to like 15.2.

I did take the carb apart last week and write it all down, I just don't have that in front of
Me right now.

It's an aftermarket balancer professional products or something. It's not a
Big money piece.

sounds like the transition slot is keeping it running and as you drop the idle speed down once you get close to idle speed (and less of the transition slot is below the butterfly feeding fuel) it goes lean and dies.

i would turn the idle MIX screws out to richen it up (a good initial setting here is 1.5 turns out), start it and then drop the idle speed down to where it needs to be. then slowly turn the idle mix screws back in to find your leanest idle tolerance.