CarburetorsCarb discussion and questions. Upgrading your Third Gen's carburetor, swapping TBI to carburetor, or TPI to carburetor? Need LG4 or H.O. info? Post it here.
Welcome to ThirdGen.org!
Welcome to ThirdGen.org.
You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, at no cost, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, join the ThirdGen.org community today!
i swapped out my faulty running tbi that gave me nothing but problems over the years for an excellent running carbed 1970 350 from my 84 camaro. got it in got the mech. fuel pump, wired the distributor, got spark, but it back fires out the exhaust like the plug wires are out of order or somthing. i checked to see the sprk and it does but the boot i was holding onto shocked the hell outta me and im pretty sure its not supposed to do that right? so im guessing spark is getting out somewhere and ive already put on a new cap and wires so its not there, but that old tbi harness is in with the computer disconnected. could spark be comming from the old harness somewhere. idk can someone please help. thanks
That is your problem. If your going to run the stock distributor, you need to keep the ECM connected, otherwise your timing will be thrown out of the window. However, even with the ECM connected, your timing, which will hold at idle, will not be maximized because you removed corresponding sensors in favor for the carburetor. Your best bet would be to switch to a vacuum advance distributor, or get a chip burned to have the ECM control spark only....
Quote:
Originally Posted by robbyho21
i swapped out my faulty running tbi that gave me nothing but problems over the years for an excellent running carbed 1970 350 from my 84 camaro. got it in got the mech. fuel pump, wired the distributor, got spark, but it back fires out the exhaust like the plug wires are out of order or somthing. i checked to see the sprk and it does but the boot i was holding onto shocked the hell outta me and im pretty sure its not supposed to do that right? so im guessing spark is getting out somewhere and ive already put on a new cap and wires so its not there, but that old tbi harness is in with the computer disconnected. could spark be comming from the old harness somewhere. idk can someone please help. thanks
Seeing as it was a bit unclear from your post, are you running the stock EFI dizzy or are you using a vacuum distributor? If you swapped over, might sound like a dumb question, did you by chance install it 180 degrees off? I know that oil pump rod screwed me up the first time I swapped distributors. Went back, got the motor to TDC, and installed fresh. Fixed my problems real quick
Backfiring out of the exhaust usually points to; bad timing, bad mixture, arcing wires, weak coil. If he set the timing on the wrong stroke (off 180 degrees), it would backfire out of the carburetor, not the exhaust. It sounds like he's trying to run the stock electronic distributor w/out the ECM's signal....
i am running a non computer controlled engine so i have a vacuum distributor. i said that i pulled the engine out of my other car so i used that dist, i must have a spark arcing from somewhere but cannot figure out where. it is installed correctly cuz i did swap it 180deg and it back fired out the carb. it acts like only half the egine is trying to fire up. i followed the swap from this site completly and i cant believe no one else has done this swap with out similar issues, since its been done alot . i dont know where i went wrong. does anyone have any idea of where the spark could be getting out??? keep in mind the stock tbi harness is still in the engine bay but the computer is disconnected.
somebody please help me! spark is getting out somewhere, i changed the cap coil and plugs and nothing, it seems that only the left side of the engine is firing, cuz i pulled plugs out both sides and the right side are just wet with gas and left are dry. i have just the headers on the engine and flames will shoot out the left side when cranking it over. the ditributor is in right the wires are correct, spark is getting out somewhere because i help onto one of the spark plug boots with a plug in it to see if its getting spark and it shocked me. please i need your help. im trying to sell this car and have to turn everyone away cuz i cant get this this figured out. thanks
Was the boot still connected to the spark plug when you grabbed it and got shocked?
Sounds like you've got some wires crossed. 1-8-4-3-6-5-7-2 going clockwise on the cap. Cylinders are 1-3-5-7 on the driver's side front to rear, and 2-4-6-8 on the passenger side.
yea the spark plug was in the boot i was checking for spark and it zapped me while i was touching just the boot. ive checked several times and everything is in the right order. thanks for the reply
Remember, the plug must be grounded to get a spark across the gap. Electricity takes the shortest path to ground. If the base of the plug wasn't grounded, YOU were that path.
How did you ground the engine? Is the battery neg attached to the engine, or the frame? Either way, there should be multiple ground straps from the engine to the chassis.
If you think spark is jumping off the wires, try looking at the engine compartment in the dark. Any arcs will show up.
