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Kabooom... back fire thru carb

Posted By: Jeepmon

Kabooom... back fire thru carb - 08/18/09 02:56 AM

I thought I would share this with you since its something I have never seen, heard about or ever experienced..

Being a skool boy learning this nitrous stuff.. I made a silly little error that could have been quite costly.. Luckily, the motor seems to be ok..

In the pits this last weekend, we hooked up the bottle, put the warmer on it and got it up to temp.. For some dumb reason, I decided to purge it by using the micro-switch on the gas pedal.. I know.. I know.. what was I thinking

An hour or so later, they called my number for first round time trials and I hopped in the car and was all excited to break new ET's and MPH...

I crank over the motor and KABOOOOM !!! people 6 rows away ducked for cover.. The ol nitrous back fire..

Well.... we needed to put all the rubber vacuum lines back on the carb and then decided to fire it up to see if there was any damage.. the motor fired right up, but shot up to 3500 rpm.. Turned off the motor and looked everything over once again.. turned on the fuel pump, no fuel running down the carb.. so we fired it back up... right up to 3500 rpm and fuel was gushin into the secondaries..


Decided to miss the 1st round and pull off the carb and to my surprise, the backfire bent both butterflies on the secondary almost a good 70 degrees pointing upward... which explains why the motor raced to 3500 rpm...

We flattened them back out and the motor seems to have survived without any issues.. However this was sooooo freak, I thought I would share it with you guys...
Posted By: WILD BILL

Re: Kabooom... back fire thru carb - 08/18/09 03:00 AM

Wow, that could have been much worse. Glad to hear no one was hurt and your motor appears to be unharmed.
Posted By: S/ST 3040

Re: Kabooom... back fire thru carb - 08/18/09 03:04 AM

That ought to teach you...........now get that crap off of
there and do it the right way.
Posted By: 70dusterjohn

Re: Kabooom... back fire thru carb - 08/18/09 03:06 AM

Thats crazy force behind those NOS booms...
Posted By: BobR

Re: Kabooom... back fire thru carb - 08/18/09 03:11 AM

Quote:

I thought I would share this with you since its something I have never seen, heard about or ever experienced..

Being a skool boy learning this nitrous stuff.. I made a silly little error that could have been quite costly.. Luckily, the motor seems to be ok..

In the pits this last weekend, we hooked up the bottle, put the warmer on it and got it up to temp.. For some dumb reason, I decided to purge it by using the micro-switch on the gas pedal.. I know.. I know.. what was I thinking

An hour or so later, they called my number for first round time trials and I hopped in the car and was all excited to break new ET's and MPH...

I crank over the motor and KABOOOOM !!! people 6 rows away ducked for cover.. The ol nitrous back fire..

Well.... we needed to put all the rubber vacuum lines back on the carb and then decided to fire it up to see if there was any damage.. the motor fired right up, but shot up to 3500 rpm.. Turned off the motor and looked everything over once again.. turned on the fuel pump, no fuel running down the carb.. so we fired it back up... right up to 3500 rpm and fuel was gushin into the secondaries..


Decided to miss the 1st round and pull off the carb and to my surprise, the backfire bent both butterflies on the secondary almost a good 70 degrees pointing upward... which explains why the motor raced to 3500 rpm...

We flattened them back out and the motor seems to have survived without any issues.. However this was sooooo freak, I thought I would share it with you guys...



You guys need to know this stuff is NASTY and to treat it with a lot of respect. You could have hurt yourself or somebody else. It will lay in a manifold for a long time and this is exactly what happens.
Posted By: 452RT

Re: Kabooom... back fire thru carb - 08/18/09 03:19 AM

I was inside my car and it sounded like a M80. I was glad you figured it out.
Hope you enjoyed your time up north here in the Great NW.
I would like to make it down south next year and race some of you guys, maybe even Bill or Al.

Posted By: 8secDart

Re: Kabooom... back fire thru carb - 08/18/09 03:26 AM

Quote:

That ought to teach you...........now get that crap off of
there and do it the right way.




What is the right way,go slow.Give me a break.Not everyone is 90 years old on here.
Posted By: S/ST 3040

Re: Kabooom... back fire thru carb - 08/18/09 03:38 AM

Quote:

Not everyone is 90 years old on here.



Then, hopefully most of us still have a sense of humor.
Posted By: sunroofgtx

Re: Kabooom... back fire thru carb - 08/18/09 07:37 AM

Wow Don. Glad that was it for the problem. That laughing gas is some dangerous stuff. Good luck , bud..
Posted By: Bad340fish

Re: Kabooom... back fire thru carb - 08/18/09 11:58 AM

A friend of mine had a pretty severe backfire in his stang years ago and it did lots of damage. A solenoid hung open in the shutdown area and it died, so he went to fire it up on the return road and BOOM. Hood, intake, throttle body, ring lands on the pistons were all done for.

I have done the same thing as you have, but mine bent the primary blades and I never could get it to idle right again so I had to get a new baseplate.
Posted By: Bob_Coomer

Re: Kabooom... back fire thru carb - 08/18/09 12:30 PM

Quote:

I thought I would share this with you since its something I have never seen, heard about or ever experienced..

Being a skool boy learning this nitrous stuff.. I made a silly little error that could have been quite costly.. Luckily, the motor seems to be ok..

In the pits this last weekend, we hooked up the bottle, put the warmer on it and got it up to temp.. For some dumb reason, I decided to purge it by using the micro-switch on the gas pedal.. I know.. I know.. what was I thinking

An hour or so later, they called my number for first round time trials and I hopped in the car and was all excited to break new ET's and MPH...

I crank over the motor and KABOOOOM !!! people 6 rows away ducked for cover.. The ol nitrous back fire..

Well.... we needed to put all the rubber vacuum lines back on the carb and then decided to fire it up to see if there was any damage.. the motor fired right up, but shot up to 3500 rpm.. Turned off the motor and looked everything over once again.. turned on the fuel pump, no fuel running down the carb.. so we fired it back up... right up to 3500 rpm and fuel was gushin into the secondaries..




Decided to miss the 1st round and pull off the carb and to my surprise, the backfire bent both butterflies on the secondary almost a good 70 degrees pointing upward... which explains why the motor raced to 3500 rpm...

We flattened them back out and the motor seems to have survived without any issues.. However this was sooooo freak, I thought I would share it with you guys...


Wow
Dont feel bad, you know 100% more than me about NOS, but someday I plan to run it..So its safe to say not to purge the line through the engine at all correct?
Posted By: BobR

Re: Kabooom... back fire thru carb - 08/18/09 02:13 PM

Wow
Dont feel bad, you know 100% more than me about NOS, but someday I plan to run it..So its safe to say not to purge the line through the engine at all correct?


Never put nitrous in the motor unless its running and WOT.
Posted By: maximum entropy

Re: Kabooom... back fire thru carb - 08/18/09 03:57 PM

Quote:

Quote:

Not everyone is 90 years old on here.



Then, hopefully most of us still have a sense of humor.

yeah. slow like the cuda in your sig pic. what a turd.
Posted By: S/ST 3040

Re: Kabooom... back fire thru carb - 08/18/09 04:15 PM

Quote:

Quote:

Quote:

Not everyone is 90 years old on here.



Then, hopefully most of us still have a sense of humor.

yeah. slow like the cuda in your sig pic. what a turd.



It is a pile.

10.74 @ 124.73

OEM heads, stock stroke 340, flat tappet, 727.........
Posted By: Bill_G

Re: Kabooom... back fire thru carb - 08/18/09 04:27 PM

Just went through this with a friend we put the spring loaded pressure relief valve on his SM tunnel ram, get one of these it will save you money in the long run!
Bill

Attached picture 5425080-wilsondetail_57_burst-panel-replacement-parts.jpg
Posted By: Jeepmon

Re: Kabooom... back fire thru carb - 08/18/09 04:46 PM

Quote:

Just went through this with a friend we put the spring loaded pressure relief valve on his SM tunnel ram, get one of these it will save you money in the long run!
Bill



What the heck is that and how does it work?
Posted By: BobR

Re: Kabooom... back fire thru carb - 08/18/09 04:49 PM

The round things are rupture discs that vent the explosion.
Posted By: moper

Re: Kabooom... back fire thru carb - 08/18/09 09:17 PM

Don... shame shame....

If you want a new engine or people to look at the car there are less dramatic ways to do it.

Posted By: emarine01

Re: Kabooom... back fire thru carb - 08/18/09 09:31 PM

When we sprayed, we never had a purge set up , I just purged thru the micro switch and cranked with the Ign power off to bleed off the gas, worked every time, not as many cool points as the guys blasting out the purge valve but very stealth
Posted By: 602heavy

Re: Kabooom... back fire thru carb - 08/18/09 11:01 PM

Guess you got lucky , i sprayed a 300 shot pulling too much timing for the distributor , blew the throttle bades & boosters right off the carb mid track , set fire to the bulk head wiring & fried the hood , have since fitted a 'cap adapt'.

Posted By: Lil Demon

Re: Kabooom... back fire thru carb - 08/18/09 11:14 PM

Quote:

I was inside my car and it sounded like a M80. I was glad you figured it out.
Hope you enjoyed your time up north here in the Great NW.
I would like to make it down south next year and race some of you guys, maybe even Bill or Al.





Jim - you had better stick with me - Al's car is way out of our league.
Posted By: Dodgem

Re: Kabooom... back fire thru carb - 08/19/09 02:02 PM

NOS is for kids and girls!
Posted By: blownzoom440

Re: Kabooom... back fire thru carb - 08/19/09 02:05 PM

Quote:

NOS is for kids and girls!



Posted By: BobR

Re: Kabooom... back fire thru carb - 08/19/09 02:09 PM

Quote:

Guess you got lucky , i sprayed a 300 shot pulling too much timing for the distributor , blew the throttle bades & boosters right off the carb mid track , set fire to the bulk head wiring & fried the hood , have since fitted a 'cap adapt'.





When spraying you should phase your rotor to what the timing will be on the spray or this is what can happen.
Posted By: blownzoom440

Re: Kabooom... back fire thru carb - 08/19/09 02:20 PM

Quote:

Quote:

Guess you got lucky , i sprayed a 300 shot pulling too much timing for the distributor , blew the throttle bades & boosters right off the carb mid track , set fire to the bulk head wiring & fried the hood , have since fitted a 'cap adapt'.





When spraying you should phase your rotor to what the timing will be on the spray or this is what can happen.

too pull too much timing wouldn't it have to be extream?a friend ran 50 NOS jet and ran 8* timing.[on a motorcycle]
Posted By: BobR

Re: Kabooom... back fire thru carb - 08/19/09 04:44 PM

Quote:

Quote:

Quote:

Guess you got lucky , i sprayed a 300 shot pulling too much timing for the distributor , blew the throttle bades & boosters right off the carb mid track , set fire to the bulk head wiring & fried the hood , have since fitted a 'cap adapt'.





When spraying you should phase your rotor to what the timing will be on the spray or this is what can happen.

too pull too much timing wouldn't it have to be extream?a friend ran 50 NOS jet and ran 8* timing.[on a motorcycle]



If the rotor is phased improperly when the timing changes it can be close to another cylinder's cap lug. The coil fires into the wrong cylinder and kaboom!
Posted By: blownzoom440

Re: Kabooom... back fire thru carb - 08/19/09 05:33 PM

[If the rotor is phased improperly when the timing changes it can be close to another cylinder's cap lug. The coil fires into the wrong cylinder and kaboom! ]

Posted By: sc301v

Re: Kabooom... back fire thru carb - 08/19/09 06:23 PM

We like to call that TACOING a carb...Leaky solenoids will do the same thing..

Have seen several carbs that were totally destroyed due to leaky solenoids.
Posted By: blownzoom440

Re: Kabooom... back fire thru carb - 08/19/09 07:16 PM

dont you feel that it is just a matter of time before something malfunctions no matter what NOS kit you have?a pressure reliefe i would think should come with every kit/system to limit the dannage.
Posted By: 602heavy

Re: Kabooom... back fire thru carb - 08/20/09 12:05 AM

Quote:

Quote:

Guess you got lucky , i sprayed a 300 shot pulling too much timing for the distributor , blew the throttle bades & boosters right off the carb mid track , set fire to the bulk head wiring & fried the hood , have since fitted a 'cap adapt'.





When spraying you should phase your rotor to what the timing will be on the spray or this is what can happen.



Yea i know , was only pulling 13* on a stock cap which should be good for around 20* of retard (MSD), since then have gone for a larger cap with two piece rotar , no problems since , cylinder pressure can be a killer.

It's difficult to phase a stock cap pulling 13* of retard to fire right where the rotor meets the cap terminal , with high cylinder pressures the rotor will prefer the easiest route , hence the next cylinder whilst the intake valve is still open , either a crank trigger or adapt a cap is the easiest way to avoid this happening , had to modify the valve cover to fit the 'adapt a cap'.



Posted By: S/ST 3040

Re: Kabooom... back fire thru carb - 08/20/09 12:22 AM

I don't see how a crank trigger alone would solve an out of phase rotor. It
signals the MSD box, MSD delays spark but, rotor still has to be oriented
correctly for the retarded spark.

Posted By: 602heavy

Re: Kabooom... back fire thru carb - 08/20/09 12:39 AM

Quote:

I don't see how a crank trigger alone would solve an out of phase rotor. It
signals the MSD box, MSD delays spark but, rotor still has to be oriented
correctly for the retarded spark.





It won't , if using a crank trigger a normal cap will suffice , just need to phase rotor/cap terminal with trigger.

Did'nt think i needed a long winded post to explain it , sorry.

Posted By: S/ST 3040

Re: Kabooom... back fire thru carb - 08/20/09 12:55 AM

I'm no electrical or nitrous whiz but, if the problem with intake
explosions were directly related to the nitrous, which I assume is
when you retard the timing, I'd think you'd want to phase the rotor
whereever the ignition was most retarded.
Posted By: 602heavy

Re: Kabooom... back fire thru carb - 08/20/09 01:02 AM

Quote:

I'm no electrical or nitrous whiz but, if the problem with intake
explosions were directly related to the nitrous, which I assume is
when you retard the timing, I'd think you'd want to phase the rotor
whereever the ignition was most retarded.



Correct , the rotor needs to be phased @ the point of highest cylinder pressure , which would be full retard , the adapt a cap allows the rotor to be phased up to around 20* of retard , more can be pulled but then the rotor is starting to get away from the cap terminal , although a lot more than 20* can be pulled & still be safe.
Posted By: S/ST 3040

Re: Kabooom... back fire thru carb - 08/20/09 01:06 AM

That wasn't all that long winded.
Posted By: Monte_Smith

Re: Kabooom... back fire thru carb - 08/20/09 05:17 PM

Quote:

Just went through this with a friend we put the spring loaded pressure relief valve on his SM tunnel ram, get one of these it will save you money in the long run!
Bill

This is a waste of money. A serious nitrous backfire will blow the carbs off and take the top off a tunnel ram. What good is a few quarter sized holes going to do to prevent that.

The fact that he sprayed the nitrous into a non running engine is not an issue. Simple fix, pull the coil wire, open the carb and spin it over a few times, problem gone. Nitrous is not the problem, nor is it dangerous. Improper use and lack of knowledge is the problem or danger. Nitrous gets a bad rap for most of the problems that are self inflicted. A leaky solenoid is not a problem either, unless the bottle is left on, which it should NEVER be, if the car is not running, or you don't have a ball valve. If you don't know much about nitrous, get some help from someone who does.

Monte
Posted By: an8sec70cuda

Re: Kabooom... back fire thru carb - 08/20/09 06:01 PM

Destroyed a set of split dominators, the hood scoop, windshield, and cracked a sheetmetal tunnelram a couple years ago due to a nitrous backfire. NOT pretty. It was noone's fault but the driver. He's been racing nitrous cars for nearly 30 years, but after a long day of frustrating testing, he wasn't thinking clearly. The hood scoop must have been 60 feet up in the air and landed 50 feet behind the car.
700+ miles from home, we leak tested the motor, borrowed another set of splits, JB welded the intake back together (after beating it back into shape w/ a hammer and 2x4 ), patched the scoop and windshield, and we were ready to race the next day.

That intake had burst panels, but like Monte said, they don't do much if it's gonna sneeze. CHIP
Posted By: Bad340fish

Re: Kabooom... back fire thru carb - 08/20/09 06:13 PM

I saw an Impalla with a Tunnel Ram pop both carbs off on the starting line, the only thing that kept them on was the fuel lines. Intake manifold went all over the place(cast)
Posted By: emarine01

Re: Kabooom... back fire thru carb - 08/20/09 07:10 PM

Last year we pitted next a injected rail that did some thing called dry firing a nos system it blew the hat off 100ft in the air and mangled a sheet metal mani Scared the pizz out me , the blast plate that was in the hat blew out and flew outa sight, It was pure luck that no one got cut up or killed, any body ever heard to dry firing? it was done with the engine running and was the 1st stage outa 3 that failed
Posted By: Voluster

Re: Kabooom... back fire thru carb - 08/20/09 07:12 PM

Like Monte said it was not the nitrous that cause the problem it was user error.

Seen it happen a few times and some nice carbs ruined. but again it was user error

if you ever inject nitrous in a none running engine. you have to pull the coil wire and spin it over and it will be fine

Rookie mistake just go play the lottery cause you got very lucky it didn't do any other damage


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