Isphius

I just picked up an 84 z28 HO, Couldnt get it to start cause of bad gas, but i got it to start up after putting about 5 gallons in it and putting a little in the carb. Anyways, The car wont run well, itll start, die right away. If i start it up i can get it to run by constantly playing with the gas, and it will backfire and stall. And if i floor it, it backfires 2 or 3 times out of the carb and then stalls. It runs this way while driving too, and has hardly enough power to move itself. Could this running issue (not the coolant) be the Q-Jet junking out, or a deeper issue like a headgasket or broken valve or something? or a combo of both? The coolant bubbles, so im guessing exhaust is getting in it. It doesnt look oily though so i think the block is ok. Tommorow im going to test the compression and change the plugs, just to be safe. That should reveal more, but i dont know what to do for now!! I have all spare parts, holley manifold and carb if i need it, another q-junk, another set of good 305 heads, etc. so if i need to change something let me know how to find out before i take it apart!

bigj350

iTrader: (1)

Did you check your timing.

Damon

If the gas was bad there's a good chance that the fuel filter and other things are gummed up inside the carb.

Agreed, check the timing too.

And last on the short list is to see if there are any vacuum hoses that are unplugged or otherwise deteriroated and leaking,

Isphius

I didnt check the base timing, but i spun it around by about 25 degrees both ways from where it was and it would only start at the position it was in. It seems to be missing in 2 or 3 cylinders, but what is the reason for the backfire while its running? i guess that would mean bad timing or one of the valves is hanging open or something

ljnowell

could be a clogged fuel filter, bad timing, bad plugs, wires, coil, cap, rotor, module, insufficient voltage, or a whole other host of things. You need to start at the beginning. Air, fuel, spark. You need all three to make a good bang. Ensure the integrity of the basic ignition components. Check for adequate fuel supply. Once you have the basics worked out, and known to be good, then you can dig in deeper. Dont be surprised to find out that your problems were basic. It happens.

bigj350

iTrader: (1)

Another thing to check is the timing chain, maybe too much slack. I think there is way to check it by taking off your dist. cap and turning the crank pulley. Do a search on how to do it.

Isphius

Yes, ive read on how to check the chain slack. Move the crank back and forth with a breaker bar and see if the rotor moves back and forth too. Im going to replace the plugs tommorow, check the wires resitance, and probably put my 99% new HEI distributor in. Will the check engine light come on without the electronic distributor? It didnt even come on when i took the alternator completly out to see where the coolant was leaking from and i started it, so i dont know if it even works. I have a lot of work ahead of me tommorow!

five7kid

iTrader: (14)

Don't replace the distributor. The carb won't work properly without the proper distributor.

I totally agree with the bad gas assessment above. Getting the ignition up to snuff isn't a bad idea, though.

Isphius

I ran it around a little today and it cleaned up but still runs like crap. but now at least it will idle. I cant run it long because its burning up coolant, which could even be why its running crappy. I have a feeling im gona have to pull the heads off and see whats leaking the coolant. It could even be the intake manifold or something, ill just check as i go.