hey guys, i recently installed a msd 6al on my 68 camaro with 4 wire hei distributor. everything seems to be working, but after i installed it, i checked timing and it moved. it was way advanced. i then adjusted timing to about 12 due to the cam i have and it seemed to run better, but when i rev it up in neutral to about 1500rpm, it backfires once out the tail pipe every 10-15 sec. i checked all my connections and are all good. the car ran great before the msd....any ideas on what it is?

i had previously installed new cap, rotor, wires before the msd and vehicle was running good....thanks ahead....

btw, i was instructed to remove the ignition module in the hei distributor in place of the msd box....

 

did u have the hei in the car before the msd? ive never messed with the hei's we have a 6al box in out 33 ford but we run a stock distributor with points and have never had a problem with it.

 

I would run the stock distributor with the msd,is your timing still a bit off?

 

Only if your distributor had a 4 pin module. If you have a 5 or 7 pin module, it stays in.
Also, did you check your rotor phasing to make sure you're not getting any cross-firing under the cap?

 

yea, i had the hei in before the msd install already. it does have the 4 pin module. i triple checked it agianst msd installation guide.

i noticed that when i have the timing light on while the rpm is at a steady 1500 rpm or so, the timing advances, but every now and then, it will jump to way advance and then return thus causing the backfire at times....i dont know if i have a bad msd box or a bad vacuum advance?

i also forgot to mention that the msd box was used....it was said to have been in working condition when removed and looked in working condition also, but i have no way of proving it.

 

Gives instructions on how to test and be sure its working correctly.
6AL Test - MSD Tech Support Forums

 

You didn't answer the above. I ask because with the MSD setup, you have less leeway for things to be "out of whack".
Also, what vacuum source is the distributor advance hooked up to?

 

sorry camaro69....i did check the cap and rotor and did not see any obvious signs of any arch....i have ported vacuum as a vacuum source for the advance....

ill95.....the link you gave me only shows troubleshooting for a no spark. i have spark and runs, just not right.....i would think if it wasnt installed correctly, it wouldnt start due to the removal of the factory ignition module.

 

Here, I found a link to what I'm referring to. I wasn't talking about the condition of the cap, or carbon-tracking.
http://www.msdignition.com/uploadedF...or_phasing.pdf

 

hey thanks for the link camaro69...i'll check it and see whats wrong.....btw...if i was to drill the hole to see the rotor, that means i'll have to buy a new cap right? and if i was to buy another cap, it could possibly be off agian because rotor and cap has changed....or would i be ok with one hole at the top of the distributor?