I just got my new motor all in and ready to roll. it is a 383 Stroker all forged with 8.5:1 Compression. I have a Powerdyne 6 PSI SC on there. At idle the car idles good except it has a LOUD back fire I would say every 15-30 seconds. I tried to drive it to the gas station (1/2 mile away) and I didnt even make it out of the neighborhood. The car was backfiring so bad Then it would just shut off. The car hasnt been tuned yet it is running a a PCMFORLESS tune for my old 383 solid roller motor. Could it not being tuned cause this or is it something else? Someone PLEASE help me as I am totaly Stumped If it is the tune I saw here somewhere there is a list of basic tunes you can download to build a tune off of but cant remember the site. if anyone has a link to that I would also appericate that as well.

Thanks
Matt

 

Hey that's got to be a fast car. Probably the PCM is detecting boost and the engine is way too Rich. Once you Tune the car it should all be fine.

 

Im guessing the sc has nothing to do with it. since it pops at idle and sounds like light throttle while normal driving. the SC isnt making any boost till way off idle, so it cant have anything to do with it. and for the tuning, prolly not either. that would make a diff. in power, and even driveability, but not cause poping. is it poping into the exh. or the intake? my money is on either the timing chain isnt lined up properly (usually wont even run when this happens) or the valves are too tight. first thing Id try is readj. the valves. how did you set them to begin with? I always set them with the eng. running after the initial startup. do a search on here and you'll see the proper method of setting the lash w/the eng. running. if its popping into the exh., the exh. valve has to be open when the combustion is happening. or very close to being open when the spark happens.
cjros

 

Recheck your plug wiring....could have a couple of wires crossed.

Emil Dusek:93Z,383,Vortech

 

Thats what it sounds like to me too. Dont ask me how I know.

 

EXCELLENT idea. only takes a few mins. and I remember now someone here haveing that same thing happen!

 

Check plug wires.
Check MAF and Opti connections.
Check injector wires.

Awnser me this... Did you install a cloyes timing chain set or other true roller ? I had one on mine and set it to what I thought was the proper notch. Timing was off and it backfired horribley.

-Shannon

 

the plus wires are on right...I checked them like 50 times. As far as timing chain yess it is the Cloyes double roller timing chain and yes the 2 dots are PERFECT checked a number of times.

Matt

 

Ill put my money on the tune being too far off.

 

Well Everyone I found the problem. The oil fill cap had white crap on it so I decided to drain the oil and a 7qt oil pan filled my 14 Qt bucket and then some of nothing but water! SO I have a BLOWN HEAD GASKET

Matt

Thanks for all the help I bet no one saw this 1 comming

 

No way it can be that much water already from a blown head gasket. This is a brand new motor right? Did you put sealant on the head bolts?

 

and, if its act. a blow head gasket, Id look at two poss.s. one the head/deck surface needs to be milled, or two the head gaskets werent torqued properly. or like josh said you left off the thread sealer.
chris

 

did you take the intake or anything off after you had the engine installed and forget to change the oil? water might have gotten into the lifter valley & oil pan.

 

Who clearanced the block? That would explain the water but not the miss. Unless you have "rattled" the s*** out of it you don't have a blown gasket. I would recheck the valve adjustment after you cure the water problem.

 

Yep brand new. No the builder didnt put thread sealer on the head bolts. also when the heads were off yesterday 2 ports looked new and all the others were black. SO I would say it was blown. I redid it all yesterday new gaskets and thread sealer and made sure they were torqued right. I guess what they say is true "If you want something done right, You have to do it yourself"

Matt