10049Views18Replies
What would cause every other cylinder not to fire on a big block chevy?
In my truck I have a 366 big block chevy motor and cylinders 2, 3, 5 and 8 are not getting spark and the firing order is 1,8,4,3,6,5,7,2. So I am not getting spark to every other cylinder I have an H.E.I distributor. I am thinking it could be the ignition module but am not sure any help is appreciated.
Comments
6 years ago
Sounds like the ignition module is set on 4cylinder firing instead of 8cyl, take a closer look at the module and how its being triggered.
Answer 6 years ago
The truck had been running fine and ignition is not my strong spot. The ignition module has been replaced but like I said the truck was running fine up until now. Do you think that the ignition module has gone bad again?
Answer 6 years ago
Thats where I'd be looking, it doesnt really sound like a mechanical problem, more like electronic related.
Answer 6 years ago
So I had the ignition module tested and it passed so still not sure what it is now. Is there a chance it could be the coil?
Answer 6 years ago
There is only 3 or four things to check, compression, fuel, spark and timing. It not likely to be compression, if you have a timing light you can check spark at each lead, or pull off a dead lead and put a spark plug in the end of it to check. which leaves fuel, its possible that one side of the carb is blocked, check the runners on the manifold do 2, 3, 5 and 8 all go to one side of the carb?
Answer 6 years ago
You are 100% correct on the carb. I have a dual plane intake and left side of the carb feeds 2,3,5,and 8 I am not sure what caused it but the left float was not lowering all the way and not getting fuel to that side I fixed that and it works fine. not going to lie I feel kinda dumb that I didn't notice that I thank you for the answer very much.
Answer 6 years ago
good to know it helped you out
Answer 6 years ago
Most cars have a single coil feeding the distributor, in the unlikely event you have dual coils, its possible one of them isnt firing.
Another thing I seem to recollect is dual points in the distributor of some V8's, so you could check to see if you have such a beast, it might need new points of have a condenser shorting out one set.
It should be a simple matter to trace out one of the offending cylinders spark plug leads to see which set of points is triggering it, and then sand/clean points or whatever is necessary.
Answer 6 years ago
So I feel a little dumb I figured out what was wrong and it had nothing to do with the distributor. I have a dual plane intake on my truck so the right side of the carb feeds cylinders 1,7,4 and 6 and the right side feeds cylinders 2, 3, 5 and 8. the left side float was messed up I fixed it and it works perfectly now. So what I thought was no spark was actually no fuel. I thank you for all of your advice
Answer 6 years ago
Ok thank you I will pull it off and have it tested. That is kind of what I was thinking it was.
6 years ago
Pull the plug on the #1 cylinder and crank the engine until the piston is at TDC on the compression stroke. Pop the distributor cap and see if it is pointed directly (or nearly directly) at the number 1 contact on the distributor cap. If it isn't pull the rotor off and move to the correct position.
I'm a Ford man but if I recall correctly, I believe there are 13 positions the rotor can be set on a Chevy and only one of them is the right one.
Answer 6 years ago
On my distributor the cap and rotor only go on in one position and the distributor is turned to set timing. That may be true about diffrent position on some distributors but thank you for the answer.
6 years ago
If this system uses contacts to trip the spark then the rotary switch cam could be worth looking into.
If it uses flux switching i don't know.
Answer 6 years ago
Ignition is not my strong spot. all I can tell you is that it is an MSD HEI distributor.
6 years ago
It sounds to like you have the distributor cap rotated 180 degrees. Or, you've put the plug wires in the wrong holes.
Answer 6 years ago
Well the truck had been running fine all week and out of nowhere this happened so I am sure the cap and wires are right. Thanks for the answer tho
6 years ago
Sure sounds like a distributor problem. If it was the ignition module then the misfire would not be so uniform. Check the contacts in the distributor
Answer 6 years ago
I'm sorry I forgot to say that there is a new cap on it, that was the first thing I replaced when I got the misfire.