Help with ignition problem

[bigbear90]

I have a 1984 Blazer with a presistant ignition problem. ive gone through all of the normal routes ( Plugs, Wires, Coil, Cap, Rotor, and the ignition module) The timing is set correctly and the timing chain is brand new, Also the whole top end of the motor has been redone < 1 month ago.

now theres the back story. the problem im having is when under load starting from 2200 rpm and up i am getting a misfrie. it idles fine, and when i push the petal to the floor in neutral it doesnt do it.

the only thing that i can think of is the computer is failing, or i overlooked something

thanks

 

[diesel4me]

hmmm...

Well,you replaced everything but the pick up coil in the distributor..so if your SURE its ignition thats at fault..maybe its that..or the ignition switch itself??

I don't think a stock '84 would have a computer either..maybe an "ESC" spark box..if the module has more than 4 prings on it,then it has the "ESC" (Extended Spark Control" box..which could also be faulty I suppose..but not likely..

Make sure the big pink or red wire to the HEI is not cut,corroded,or getting low voltage due to a bad connection somewhere..the HEI needs 12V,if its not getting full amps,it will show up under loads the worst..like pulling up a hill,etc..also make sure the coil has its ground strap under it where it mounts,and its clean..good luck..

 

[Leper]

What he said. Also make sure the plug wires arent touching anything. On some motors, ERG problems can cause that also.

 

[73k5blazer]

I'd try the pickup coil first.
If that's not it, if you have ESC disconnect the harness from the distributor and jump pins A & C, this will bypass ESC and allow the vehicle to run.
You could have a carb icing problem in New Jersey there, if you'v disconnected the heat riser tube and valve, try connecting it back up.
Or lastly, a valve is not seating correctly. Perform compression and leakdown on all cylinders. If you just did the heads, there is a potential somethings not sealing up right.

I'd say, pickup coil, or valve not sealing are my bets.

 

[bigbear90]

thanks for the help

today i cleaned all of the connections on the distrubator made sure i was getting voltage, and ran a new ground back to the battery. sadly these didnt help, tomorrow im going to try to see if the pick up coil is faulty ( the part i overlooked) and try to jump out the ESC.

if this fails to do anything im just going to change out the old distrubator ( please forgive the spelling errors) with a new one, with that said can anyone suggest a good replacement distributor?

thanks

 

[diesel4me]

not much choice..

If you have the "ESC" distributor,your better off keeping it..just put a new pick up coil in,or have someone do it if your unfamiliar as to how too..its not that easy,but not impossible either..I'd say buy a complete rebuilt distributor instead,but you already replaced all the other parts,so it makes sense not to in a way..and many of those have cheap tiwan modules and pickup coils in them too!..

I kind of wish I'd have left the ESC distributor in the 305 I put in my 79 C10..it was from an 86 G10 van,but I forgot to rob the ESC spark control box from the van before I junked it! --so I had to use an "old style" HEI with a vacuum advance I had instead..I think the "spark advance curve" is different enough so I can feel the difference in performance,but i still runs pretty decent..bet it would be better stock though..

I don't reccomend any of the "hot rod" distributors in general..many guys I know have Accell,MSD,etc,and have nothing but grief..they made the mistake of buying a "race only" version without a vacuum advance on trucks and street cars that needed one..even the "right" ones with a vacuum advance have special caps and rotors , modules, and pick up coils most of the time---and try and buy one on sunday if your out in the sticks..

 

[hack500]

ok, not to be smart-ass but how do you know it's an ignition problem and not something with the carb? also what plug gap?

jsyk changing the pickup coil is less than a 45-minute job. just do the following 3 things
1. distributor housing to block
2. rotor to housing as installed
3 rotor to housing at the spot where it moves to when taking it out.

imo, knocking out/re-installing the roll pin for the distributor gear is the hardest part.
when you re-install line up 3 then lines 1 and 2 should line up when you drop it back in and you'll be good to go. but what do I know I'm just some hick that can't afford to pay others to work on my buggies.