I need some ITA opinion: Flames are coming out of my headers at idle!!

The engine: 388" SBC, PSI screw "A", 10.5:1, brand new Rage Fuel System just flowed and built for this combo. This engine ran for three years going 5.80's and had an old style square barrel valve and a 110 pump.

Whats changed: Im running a MSD AL-3 with a crank trigger.

Fuel system: 20 psi idle check, 17 check on the 8 port nozzles, 3 hat nozzles, started at 70% leak down. I have the same nozzles and poppet checks it always had.

The story: Dynoed on an Inertia Dyno saturday with closed exhaust system and started up with the inertia weight. Made 1750 hp @ 7500 and was climbing, and made 1500 ft/lbs at 5900rpm. Ran on a AL-2 Box with an old "bottle" style coil. Everything worked great.
Put the engine in the car, still warm from the dyno. Started it up on a AL-3 and a Big MSD Coil. It would run for 7 to 9 seconds, and start throwing FLAMES!.
Checked the timing, and it was at 28 degrees. Stopped for the day.
Last night we restarted it after checking the barrel valve and knowing my setting was at 70% and looking to turn it down to 50% and knowing how many flats it took to do it.
Its still throws flames!! So I turned the barrel valve down to 50% while it was running, and no differance.

So we then changed: spark plugs, Exhaust lash (from .022" to .032") to see if the valve was open to early, moved the cam back to 114 c/l from the 109 c/l we had moved it to, moved the timing to 30 degrees, and I removed all the plugs from the injector idle settings and the rpm went up, but still flames.

The engine has been checked for: top dead center on the degree wheel, crank trigger phasing, distributor phasing, valve lash, plug heat is the same.

Ill be checking the leak down, my two poppets to make sure nothing got into them.

When I get back from indy, im putting the Mallery 3 mag in it and it will be back to the way it was when it ran in its day..

So throw out some stories or "ive had this happen" as Im not done with everything, but its strange that I change alot of stuff, and its like a top fuel car!. I cannot get raw fuel out of the pipes.

Im hoping that when I put the Mag in it on Monday it will work. Im wondering if a an AL-3doesnt like a screw blower and the higher fuel pressure they run versus a roots.

 

The only times I have had flames out the headers was when my plugs were going away, it was igniting the fuel outside the head and in the header. The one other time was when I had an exhaust rocker hang up and it wasn't letting the valve close fully, but that was only one pipe (it was pretty obvious).

Corey

 

What was your EGT's on your dyno pulls ?

 

I tried a set of solid core plug wires one time with a points mag and got flames....actually burned a few holes in our carpet that we used as a pit mat back then....was spitting flames and a little raw alcohol....so I found out solid wires are a no-no....

 

It seems to me that your idle and port checks are backwards; 20 psi idle and 17 psi port checks? Joe

 

Ive had a few phone calls...and Its looking like its still to rich. A screw blower car on a 388" engine needs way less fuel at idle than most anything else that exists.

So im going to make some changes monday and see what we can make happen..thanks for the info, and thanks to those close to this deal!! Lots of minds make a big differance!!

BTW...

I had no EGT's on the dyno....

And I know my idle check is 20.....

Scott

 

Your distributor is probably one tooth off................

 

we run a 400 cid roots deal, and have found out are cam grind was making it pop and flame at idle, freaks everyone out but runs 4.0s 1/8 in a altered. changed cams and it stopped but also could only get the car to run 4.40s.

 

Check the timing, 28 degrees go 30 or 32

 

None of your poppets are backwards are they ?
RAGE may have modified your spool in your barrel valve like mine was.
I had to put a stock spool back in mine to clean things up.

 

fire

our screw chevy blew flames high enough to scare crew at the starting line before. never knew why. Just did it occasionally. Bubba Stantons wedge did it too starting rumors of nitro.
Retarded mag will make the flames really big.

 

Idle check should be about 6 to 8 psi to allow fuel back to the tank at idle.

 

The 7-AL3 will lose 4 degrees of timing within the box from the AL2. It`s in the instructions. Also, the 3 needs good wires. MSD 8.5 mm wires worked for me. Tom.

 

Solved!!!

Lowered my port check from 20 psi to 16 psi with 40% leak...runs like a champ!!!

 

Good news -- so is it safe to say Critical Mass post was correct and maybe you mixed up your poppet location when you got your system back from Rage ?

 

40% leak? Is that because its a screw?




Corey

 

In this case yes. Typically screws on Hemis still have 70%.

Im not sure how many 388" with screw blowers still exist. I know of 5 that ever existed....

 

If I understand correctly, you richened it (because you allowed the port nozzles to come on) and the flames went away?

 

Nope....I lowered the fuel pressure at idle, and it wasnt cracking open my port check and causing it to go as rich..

So now I will open up my barrel valve leakage and drop my idle check and port check pressure more.