Backfire trying to start

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Staging Lane

Joined: Jun 2005

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From: New Orleans

Backfire trying to start

I recently swapped from fuel injection to a carb set up. Pulled ls1 intake, and factory ecu and installed a Holley single plane manifold, Holley 750 Dp, and MSD 6014 box. The long block is a fresh SBE ls1 with tsp torquer v4 112+4.

car ran decent on EFI. Now with carb it turns over and backfires through carb. The MSD is set to ls1 ho at the moment. Should I put more or less timing at the start to help?

Dec 12, 2019 | 07:36 PM

G Atsma

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From: Central Cal.

Why did you switch to carb? You said it ran decent on EFI. A carb can't improve on it

Dec 12, 2019 | 08:30 PM

Thread Starter

Staging Lane

Joined: Jun 2005

Posts: 77

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From: New Orleans

I switched BC it ran but had lots of drivability issues. And I’m not familiar with tuning EFI and don’t want to have to pay a tuner to change something.

Dec 13, 2019 | 07:22 AM

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Try putting the 6014 in auto detect. We have ours at 15 degrees to start and straight to 28 after it fires. Get rid of the rest of the dots the tend to make the timing wander. Your right. It is much easier with a carb. When you get it dialed in you will never want to mess with EFI and it will run better too. I agree with you on who wants to be at someone else's mercy to get the correct tune. Seen many times people chasing their tail with the tune. We have a dominator on ours and the way it runs you would swear it's fuel injected.

Dec 13, 2019 | 10:25 AM

G Atsma

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From: Central Cal.

You'll be messing with the carb a lot more than you ever would with EFI. Once tuned, EFI IS set and forget. Carbs need tuning for every different circumstance.

Dec 13, 2019 | 12:22 PM

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From: Iowa

Quote:

Originally Posted by camaross82

Backfiring through the carb means it's firing with a valve open so timing would have to be off by quite a bit.

Quote:

Originally Posted by camaross82

I switched BC it ran but had lots of drivability issues. And I’m not familiar with tuning EFI and don’t want to have to pay a tuner to change something.

You should have went with Holley EFI, The hand held tune would get you running well just by answering a few questions and fine tuning can be done with a computer if wanted/needed and you don't have to pay a tuner.

Quote:

Originally Posted by TTur1996

Your right. It is much easier with a carb. When you get it dialed in you will never want to mess with EFI and it will run better too. I agree with you on who wants to be at someone else's mercy to get the correct tune. Seen many times people chasing their tail with the tune. We have a dominator on ours and the way it runs you would swear it's fuel injected.

I run both carb and EFI, No doubt you can get a carb to work very well but in the end you still have to know how to tune, The only difference is you don't get your hands dirty tuning with a computer. EFI will always have the edge because it's ability to keep up with changing conditions. I would much rather hit some keys on a computer than smell like fuel. If you're buying a carb doing the slap it on and go thing and not making jetting /boosters/PV/linkage changes then you still are not tuning anything. If you know the how and why to tune with a carb then a tuning with a computer should come easy because in the end you're still doing the same thing just getting there a different way.

Dec 13, 2019 | 12:35 PM

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From: Iowa

Quote:

Originally Posted by G Atsma

You'll be messing with the carb a lot more than you ever would with EFI. Once tuned, EFI IS set and forget. Carbs need tuning for every different circumstance.

Unless you plan on driving from sea level to the mountains you normally don't have to make tuning changes with a carb, Temperature/weather changes will effect the tune but not usually enough to cause any issues. I run the same settings when it 100* or -10, On a race engine you might give up a little power if you don't adjust to weather but most people at the track run them without changes once they get it dialed in the first time. The only real downside to a carb is the getting the choke set so you can jump in it cold and drive away and without having to sit and wait for it to warm up a little first.

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Dec 13, 2019 | 06:59 PM

Thread Starter

Staging Lane

Joined: Jun 2005

Posts: 77

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From: New Orleans

Thanks for the replies. After some more investigating, it appears that I had the coil harnesses flipped. Ran out of time before work so I haven't had the chance to try it just yet. But hopefully that will get me in a better place.

Dec 14, 2019 | 04:40 AM

#10

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Quote:

Originally Posted by camaross82

Sounds like you only have one backwards if its poping thru the carb. The ones I have seen that have them both flipped usually actually run where you can't tell until you get up in rpm. Red wire to number 2 and lay out and the purple wire to number 1 and lay out. Hopefully that will take care of it for you.

Dec 14, 2019 | 05:08 AM

#11

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The way it sounds by the replys as respect to EFI. What do you guys do, put it on self tune and leave it there? How is that tuning? Getting the tune correct is not as easy as everyone makes it out to be. Then throw a 4l80E in the mix and its a total pain trying to get everything to work together. Watch to many pulling their hair out at the track trying to get it right. Then still get smoked by a carbed car with a TH400. I guess we can just agree to disagree. To each is own.

Dec 14, 2019 | 03:46 PM

#12

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Quote:

Originally Posted by TTur1996

With the Holley system it is actually that easy, Self tune is just for the fuel tables and you set everything else yourself. Once fuel tables are set you can choose to turn learn off or reduce it to around 10% incase you have a fuel flow issue or something else that will allow the system to save you from a blown engine. You set the timing/idle/desired AFR and a few other perimeters. Setting up the trans is simple also, They have preconfigured it for you so all you have to do is make basic adjustments to suit yourself or leave it as is and run it. Basically it allows you to set it and forget it. You can do a simple setup and it will run great but it also allows you to change every aspect of the tune if you want to. Then you throw in Logging/Built in Wideband/Monitoring anything you want/Tune swaps in seconds/Fail safes/Boost control/Multistage nitrous/2-step/Boost Builder/Multiple rev limiters/Traction control and a host of other things you can do with it since it's a computer.
It beats the stock ecu or carb by miles when it comes to usability.
The tune in my truck is 3yrs old and drives like stock but makes around 580hp, I don't have to do anything other than fire it up and drive it. My son in-law has a 6.0 4l80e in a Nova. Tune was untouched for a couple years and then I put a different cam in it. Other than letting the fuel adjust and putting the idle higher for the bigger cam it was good to go in minutes tune wise.

This quote is your own, Sounds kind of funny coming from someone ******* EFI in this post.

"Wish we would have gotten the Holley Dominator box. Wouldn't have needed our AFR meter, Progressive controller, Tach, or Gauges. Can't justify changing after buying all that stuff.

Last edited by LLLosingit; Dec 14, 2019 at 04:12 PM.

Dec 15, 2019 | 01:33 AM

#13

Thread Starter

Staging Lane

Joined: Jun 2005

Posts: 77

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From: New Orleans

Got the wires straight and it fired right up. Working nights this weekend, so I haven't had a chance to let it warm up and get the idle adjustment just yet.

A far as aftermarket EFI, I would have gone that route if money wasn't an issue. But I'm happy where I am at the moment. Paired with a 6 speed in a 69 Camaro should make for a fun cruiser for a while. Not trying to start a pissing match between efi and carbs.

Dec 15, 2019 | 04:58 AM

#14

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I do wish we would have gotten the Dominator set up for the exact reasons I posted. That has nothing to do with running a carb. You do not have to run EFI to run the dominator box. So how is that funny? Relax, Like I said before. To each is own. We can at least agree to disagree. I'm Out.

Dec 15, 2019 | 05:24 AM

#15

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[QUOTE=camaross82;20184162]Got the wires straight and it fired right up. Working nights this weekend, so I haven't had a chance to let it warm up and get the idle adjustment just yet.

Glad to hear you got it. Have fun!!!!!

Dec 15, 2019 | 07:56 AM

#16

Pop N Wood

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It is usually something basic like that. Glad there are a few helpful people still left on the board.

Ever wonder if we should have a separate forum for the trolls to rant about EFI?
Yeah, no chance of accidentally swapping a wire with that solution.

Dec 15, 2019 | 01:31 PM

#17