Had a pretty decent size nitrous backfire while making a test hit on my 5.3 swap camaro. It sounded fine after it happened until about 1 more block and it started knocking pretty loud. Its not down on power and there is no metal in the oil, all the rockers checked out and so did the springs. Just looking for advice on where to look next. Any help will be great. It was on a 175 shot.

 

You already pull all the plugs out and check them? If not start there

 

Yes it melted #3 plug, just the strap. Replaced with a new one and still no change. No blow by or anything. Would it be possible for a lifter to have collapsed?

 

Check compression on that cylinder, better yet maybe all of them.

Also check pushrod, valves, or springs.

 

Planning on checking the compression this weekend. Pushrods where good. Springs appeared to be fine. Thank you for the pointers!

 

What made it backfire?

 

Honestly I have no clue. Running a good tune and I was on race gas just to be safe. I bought the kit through nitrous outlet so I know its a good kit. Was a good solid run and right after it shifted into 3rd all hell broke loose lol. Car doesn't smoke, doesn't run bad its just knocking pretty loud. Doesn't seem to be any blow by. I didn't get a decent log that run so I have no clue what it could be

 

Not a good tune if you melted a plug. I bet too much timing.

 

Any idea of how much timing you had in it? Air/Fuel ratio? What plugs were you running? How big of a shot?

 

I said the same thing and ended up with 4 spun bearings and a bent crank.

 

What I was thinking, Probably wrong plugs also.

Once you melt the plug it can lite off random like a glow plug, cause random backfire.

 

what plugs?

 

I believe the plug was br7? I'll have to look. Sorry about the delay. I got the motor tore down and only thing that was hurt was a few lifters. I guess you can think a unknown mileage junk yard motor for that. Lol. It got me into the low 11s so it hasn't been too bad. I think it'll be up and running next month with a better tune for sure. Thanks guys