Butterfiles are closed. No transfer slot is exposed. I've gone up to 40 degrees of idle timing with no change. 4 header primaries are barely warm to the touch while the other 4 are hot as expected (1, 2, 4 and 7 are dead and this is an LS-based engine for what that's worth). No fuel coming out of the boosters. I've gone down to 120 jets with no change.

This has to be an ignition box issue as I've also triple checked point to point wiring from the box to the all of the coils and power/ground circuits.

quote:

Originally posted by CSRacing:
Butterfiles are closed. No transfer slot is exposed. I've gone up to 40 degrees of idle timing with no change. 4 header primaries are barely warm to the touch while the other 4 are hot as expected (1, 2, 4 and 7 are dead and this is an LS-based engine for what that's worth). No fuel coming out of the boosters. I've gone down to 120 jets with no change.

This has to be an ignition box issue as I've also triple checked point to point wiring from the box to the all of the coils and power/ground circuits.

Being an LS engine the timing makes sense now. Id definitly be looking at pick up, or ignition box.

how could it keep idleing with 4 corner screws turned in if not pulling fuel from other source

quote:

Originally posted by rusty:
how could it keep idleing with 4 corner screws turned in if not pulling fuel from other source

Not sure. My dominator does the same thing. Originally a Pro Systems carb that was completely redone by Rupert. Same behavior, will run with idle mixture screws all the way in. Patrick had told me that was normal. I don't have much experience with alcohol carbs but all the gas stuff I've ever worked with would die with the screws in.

I did have the metering blocks off this carb and you can in fact blow air from one side of the idle circuit to the other. Took the metering block off my dominator and it does the same thing.

quote:

Originally posted by 329L:

quote:

Originally posted by CSRacing:
Butterfiles are closed. No transfer slot is exposed. I've gone up to 40 degrees of idle timing with no change. 4 header primaries are barely warm to the touch while the other 4 are hot as expected (1, 2, 4 and 7 are dead and this is an LS-based engine for what that's worth). No fuel coming out of the boosters. I've gone down to 120 jets with no change.

This has to be an ignition box issue as I've also triple checked point to point wiring from the box to the all of the coils and power/ground circuits.

Being an LS engine the timing makes sense now. Id definitly be looking at pick up, or ignition box.

No faults on the ignition box so I don't think there's a pickup problem. Just got off the phone with MSD and per their standard response, they say the box has to come back for evaluation. I hate to say it, but MSD sure has left a bad taste in my mouth over the last few years. Used to be the best stuff you could buy but I've had 2 bad 7AL2 boxes and now this brand new LS box that seems to be dead out of the box.

What is the correct LS firing order?

Same as a standard SBC with a 4/7 swap?

Is there a variety of camshaft firing order swaps for LS engines too?

goob- just throwing that out there....

Looks like you're in line for a FuelTech ECU.

Spongebob just did a dyno testing deal on a carbureted LS on his Youtube channel.

were the screws in all the way when power valve was plugged.if not i would try that test ,power vlves can pass fuel and be hard to detect

i have never had a carb that would idle with screws turned in,that would mean you dont have metered contol imo

you need another known good carb to try

quote:

Originally posted by rusty:
were the screws in all the way when power valve was plugged.if not i would try that test ,power vlves can pass fuel and be hard to detect

I was going to ask if you had blocked both PV's, or replaced them as well.

One other thing....I've seen metering blocks that were warped from years of being over tightened or whatever.

quote:

Originally posted by rusty:
you need another known good GASOLINE carb to try

If for nothing else, just to get some good heat in the engine and not kill the rings and cylinders.

BINGO now you tell us its a new MSD box on an LS engine -old rule when ya have a new problem and a new part they are almost allways the same problem-I would change put the box before going any ****her

quote:

Originally posted by Goob:
How does a person know if their alky is water contaminated?

Seek and I shall find...
hydrometer, duh.

You have to either be pulling raw fuel, firing order is wrong or the MSD simply isn't working correctly. I would lean towards the MSD.

We just got the new 6AL Pro Plus, hope they have it figured out.

quote:

Originally posted by CSRacing:
Butterfiles are closed. No transfer slot is exposed. I've gone up to 40 degrees of idle timing with no change. 4 header primaries are barely warm to the touch while the other 4 are hot as expected (1, 2, 4 and 7 are dead and this is an LS-based engine for what that's worth). No fuel coming out of the boosters. I've gone down to 120 jets with no change.

This has to be an ignition box issue as I've also triple checked point to point wiring from the box to the all of the coils and power/ground circuits.

I haven't read this entire tread but first understand main jets have nothing to do with ilde!! You could block them off and it would make no difference!

Ilde fuel comes from the idle circuit only. There are two paths, once from the transfer slots and one from a hole just under the slots. I believe the slots are controlled by the ilde screws and the holes are not, they are controlled by the idle fuel jet or hole in the metering block. That's why if you have too much slot exposed to manifold vacuum you can turn the idle screws all the way in without stalling the motor.

So you either have a carb issue, or a firing order issue or what's controlling the firing order is a mess! Since you have 4 holes that are firing/hot I'd say the carb is not your main problem.

Here’s a Tip from Mark Whitener on setup for the MSD 6014 ignition box that can be found at the very bottom of the page… might be worth your time reviewing.


https://drr.infopop.cc/eve/for...21504&s=3476075&p=11


If you’re unsure if a cnp is firing, clip your timing light to that plug wire and crank engine.

Check for additional holes drilled from the bottom of the well in the baseplate that the t-slot pulls from. I have seen bases where someone has drilled small holes through. The holes exit under the butterflies. This will obviously create a very rich idle and will idle fine with the screws all bottomed out.

Ditch the secondary PV. Never run secondary PV in drag engine. A leaking PV or PV gasket will also pull fuel and run rich.

quote:

Originally posted by rusty:
i have never had a carb that would idle with screws turned in,that would mean you dont have metered contol imo

I agree with Rusty here and also think you should try a known good carb.

I think Matt said that could be power valve leaking. I would block both power valves and see if it changes idle.

Bottom line is the fuel is coming from somewhere. It is leaking through the boosters, idle circuit or possibly power valve circuit.

As for the LS firing order that may be a 7/4 - 3/2 Swap from traditional Chevy firing order. Not sure as I do not do the LS motors.

quote:

Originally posted by 329L:
Why only 28 degrees? That thing should want 34 minumum, and 36-38 would not suprise me at all.

edit*

If your timing isnt locked, you need to lock the timing out, and get it set to 34-38 all the time.

I believe (?) the OP is using a MSD 6014 that controls the CNP firing sequence for LS engines. For a locked ignition value it would need to be programmed in the curve selection being used.

One thing to be aware of using a carb with CNP. When the engine is initially cranking and fuel is going in on the intake stroke, the spark does not begin firing until the sync orientation of the engine has been established.