backfire and bb's on tin roof

[jimdrechsler]

are these signs of detonation? i hear the backfire mostly when cold and under hard acceleration. the bb's is under light load in lower rpm's i can hear it pretty good. i have used both super and regular gas with same results. any ideas how to fix or if running bad?

thanks,

jim

[Dark_5.0]

My car does that when I run too much timing. Whats your timing at?

[jimdrechsler]

timing is around 14-16 degrees. i changed it to 12. anyone give a quick recap how to do this again? this is what i did- i took off spout connector and then started car with thing around the wire closest to bumper on left side facing car (number 1), and then shoot with gun? when i adjusted it, i turned car off then put the spout back in and tightened bolt. is this right? thanks,

also, what should mny timing be at? it seems sluggish until it hits about 3 1/2 grand in each gear. i also run 75 shot of nitrous at times.

thanks

[KiltedBanshees93GT]

#1: DONT RUN THE N2O UNTIL YOU GET THIS CORRECTED. Just friendly advice
#2: I would say take the timing back to 10 degrees(stock), and see if its still happening. I would also re-check the timing after you tighten the bolt to make sure it doesent "wander" while tightening. (You can also try a higher grade with the timing at stock, and see if it make a difference)
What do the plugs look like? Lots of ash, or oil fouling?
Some other q's would be, when did this start/did it come on gradually? Last general tuneup?

Please tell me that you retard your timing when you use the nitrous?! 12 or 13 degrees btdc is fine, but if it's still pinging you need to back it off until there is no detonation. You should retard the timing down to 8 or 9 degrees btdc when using the nitrous. But check your plugs too, like KiltedBanshee said.

[jimdrechsler]

someone told me that i could spray with a little higher timing with the jacobs ignition sysytem i have (i think i remember correctly?) i havent sprayed this year yet though. timng is still at 12, and havent had a chance to check plugs. would retarding the timing that much make it feel more sluggish?

ALSO- after setting the timing. do i turn the car off first, THEN attach the plug? or, attach it, then turn off the car. i did the aforementioned!

[~The Jester~]

Yep, it sure would. Timing has alot to do with how well the car "feels". Sounds like time for a good tune-up as someone mentioned before. You might have some carbon deposits staying hot, and lighting off the mixture before it's ready as well. Leave the timing at 10, give her a good tune up (Plugs, wires, cap, rotor, etc etc.) Then see what happens. If all is well, kick the timing back up to 12, see what happens. Then try 14, see what happens.... With me?

Originally Posted by jimdrechsler

someone told me that i could spray with a little higher timing with the jacobs ignition sysytem i have (i think i remember correctly?) i havent sprayed this year yet though. timng is still at 12, and havent had a chance to check plugs. would retarding the timing that much make it feel more sluggish?

ALSO- after setting the timing. do i turn the car off first, THEN attach the plug? or, attach it, then turn off the car. i did the aforementioned!

When setting your timing, it doesn't matter when you put the plug thing back in. The car can be off...or you can leave it running the entire time. Doesn't make a difference. Do what Jester said with the timing thing...retard it down...then gradually advance from 10 to 12, & so on. But even with an aftermarket ignition system like your Jacobs...never run your timing over 10 degrees with the nitrous! Never. 8 or 9 degrees would be even safer. If you're only doing a 75 shot I'd say 10 degrees is fine. But with a 100 shot or higher definitely put it down to 8. Better to be safe than sorry.
Also, what are your plugs gapped at? Normally you can open up the gap some with an aftermarket ignition, such as your Jacobs. The stock gapping is .054...with an aftermarket ignition you can open it up to .060...some guys even go to .065. But since you're running nitrous you'll want to find a happy medium. I'd stick with somewhere around the stock plug gap, between .050 - .055. I run a 150 dry shot of nitrous and have my plugs gapped at .050 with a Crane HI-6 Fireball ignition. Using nitrous with the stock ignition...you'd have to close the gap up even more...down to around .035.

[jimdrechsler]

thanks for replies. i will lower timing to 10-12 and check the plugs.the distributor, plugs and wiresare new on this car. i would say about 10-12 thousand miles on it. they are accell wires i think (blue i n oclor if that matters). maybe i can take some pictures of the plugs and post them here to see what people think. it backfired again today in second gear under medium acceleration when cold. does not do it when warmed up nearly as much.

[jimdrechsler]

ok, here are 4 of the spark plugs. all are from the driver side (easily accessible). what can yo utell if anything? left to right plugs are from bumper to inside.
i looked at the plug wired and they are jacobs brand as well. im assuming he bought everything together, wires and distributor cap. i have autolite 24's in gapped stock. i am pretty sure i put these in last year.
thanks,

jim

It's kind of difficult to read the plugs from the pictures. But from what I can see the porcelain is very white...which might mean you're a little lean. You'd have to post a better picture of the plugs (or plug) that is up close, before I could say for sure. I'm assuming you have the 30lbers because of the nitrous. With that Hollye Systemax kit...24lbers would be plenty. Or does the Holley kit recommend the 30lbers? What do you have your fuel pressure set at? What, if any fuel system upgrades have you done besides the 30# injectors?? Is this a dry system you're running?

I know I said this before...but if you run your nitrous again, make sure the timing is set at 8-10 degrees btdc. 12 is too much.

When is the last time you've changed your fuel filter?

[jimdrechsler]

try clicking on the picture and it should get bigger for you. it is a pretty close shot. i think thats all i have done to the fuel system is the 30 # injectors. people say it is way too much for what i need. i could be fine with 19#. dont know if it makes a difference though. i believe the fp is at 38psi. sound right?thanksoh yeah, i also have the bbk FPR.

[Hethj7]

Is your mass air meter calibrated for your 30# injectors?

Also, is your car actually backfiring, or does it just make a popping noise that sounds like it may come from the exhaust? I ask because my car used to "pop" at times. Turns out it was a fuel injector going bad. That could also explain your slightly lean condition.

Not that I would normally recommend going to a dealership, but if you rule out other causes for the problem, Ford can flow test your injectors for an hour's worth of labor. I am not sure how they do it, but when I had it done, I am pretty sure everything stayed in the car. They charged me for an hour of labor and gave me a nice print out of what each injector was flowing. Just a thought.