View Full Version : Ignition Installation
09-14-2003, 01:23 PM
i have installed a new 6a msd system on my small blk chevy. i have not been able to get my car to run properly. fortunately i have two old chevies so i have been able to interchange some parts to eliminate certain possibilities.i have a new dist,new box,new intake,new wires and new plugs all being msd except the intake and plugs. i sent the 6a box back to msd and it checked fine according to the techs i reinstalled all the parts and i continue to have a backfiring problem thru the carb. i have double chked and triple checked all the wiring. so looking at other things that could be the problem, i pulled the carb off the other vehicle which runs fine and the backfiring still continues..i have looked for vacuum leaks and none are to be found. i know this sounds stupid but on the rotor button there is an msd logo which is 180 degrees from what i think is the #1 plug site, could that logo possibly be the #1 plug designation. i'm an old hotrodder with many years of experience, i feel like i know what i'm doing but nothing has seemed to work. the car will crank on ocassion but backfires and spits then when i try to restart it its a no go. i'm so frustrated i hope u can help! thank u
09-14-2003, 07:45 PM
First, you need to make sure the rotor is pointing to number one cylinder position on the distributor cap when the ignition fires. You will need to rotate the engine over until number one cylinder is at top dead center (TDC) on the compression stroke. Then lift up the distributor cap slightly and look to see which terminal on the cap the rotor is pointing to. Which ever terminal the rotor is pointing too is now where your number one spark plug wire should be attached too. Then follow the firing order to put the rest of the wires on the cap. If you want to get even more precise than that, rotate the crank back to where you want to set your idle timing at (lets say 12 degrees BTDC). Remove the distributor cap and line up one of the reluctors paddles with the center of the magnetic pickup. Tighten the distributor clamp and then put the cap back on and secure it. Usually you will be within 1-2 degrees of your selected timing when you do it that way.
09-15-2003, 05:10 PM
i have a degreed fluid dampr and have rotated the crank to the zero setting. i have also removed the #1 plug and got the compression to blow out the plug hole that way too.
my question was, on top of the msd rotor there is molded msd letters with a molded line thru it...which is exactly 180 degrees opposite from where the rotor lines up. in my frustration i am asking i guess lol if the msd letters with the line thru it could be the # 1 plug location,
the car will cold start but spit and backfire thru the carb, i doubt it would crank if it were 180 degrees off, so i assume the rotor and plug wires are in the correct location..over the years i have did this many many times, i'm just grabbing at straws trying to figure my problem.
assuming the rotor is set at #1 and the firing order correct.......spitting and backfiring thru the carb....timing?, vacuum leak? thank u so much for your help i feel like a big dummy.
09-15-2003, 08:40 PM
I guess you were trying to use the MSD Letters with the molded line trough it to discribe a location. Sorry I miss understood that. If you brought the crank around until the piston was a TDC and you had air coming out of the cylinder then the position where the rotor is pointing to in the cap is going to be the correct position for the number one spark plug wire. After the engine starts, what are you setting the initial timing at (how many degrees)? What color advance springs are you running in the distributor?
09-16-2003, 06:40 AM
the carb and motor are running so rough that it will not stay cranked for me to set the timing...it won't idle...i did change the advance springs in accordance with the directions that came with the distributor, i will have to pull the cap and get back to you on that one..i thought that it backfired so much thru the carb that i had blowed a power valve or had a big vacuum leak but when i placed the carb on my other car it ran fine.....i'm at a loss tks
09-16-2003, 09:40 AM
Make sure to double check the firing order, and that you are following the correct rotation of the distributor. Also check that the rotor tip is pointing to the #1 cylinder and in compression stroke.
09-16-2003, 11:35 AM
all of this has been done many times over..it is a standard chevy sm block 18436572 in clockwise rotation
09-17-2003, 09:02 AM
If everything has been checked and gone through as far the setting up the distributor, then I would recommend checking mechanical parts are far as compression, valves adjustment. Let me know if you find the problem.
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