Ran Platinum plugs on a MSD ignition

[Bear76]

I switched to platinum tipped plugs on my 400M, that has a complete MSD ignition (6AL box, Blaster 2 coil, Billet Distributor part# 8580). 3 days later it started to run very poorly, but it was rainy and wet so I wrote it off to that. I then found out that you are not supposed to run platinums plugs with the MSD set-up. I thought all I needed to do then was switch the plugs back over to the recommended copper plugs. When I did that, it made very little difference. It seems to run like it is out of time, but I have checked it twice now with the same results, it is set correct. When I step back by the rear pipes, the exhaust sounds like there is huge pressure there (hard to explain). It does idle, but roughly, for the most part it has some power from the line, not like it did, but still respectable. It then seems to fall flat or pull flat like it is starving out of fuel or not advancing. This motor is only supposed to have around 12,000 on it when I bought it off a guy. Before this happened this thing ran like a scalded dog all summer long. It was great, seeing as it had been sitting for 4 years behind my garage, neglected. I would take it to a professional to figure it, but I can not get any one person to recommend the same place twice, if anybody on here knows a reliable shop into Fords and performance in the Central WI area, please let know too.

I beg of anybody that has ANY ideas, good bad or ugly, fire me a reply and I will give them a whirl. I am at my end as far as ideas go. I really want to put my toy back together.

Thanks for your time.

 

[poncho]

platinum plugs are for mileage not performance. sounds like it could be timing chain and gear if its idling erratic. those nylon gears tend to rot and get brittle if thats what you got. anyway we just put one in an 85F250 plow truck and it did the same thing. went through to carbs before it smoothed out. Had to retime it because we didn't cap the vacuum advance. advance it till you get knock then go a degree back if you got engine run on till it stops. I think around 12 is where we ended. If you don't have headers or duals you will get major back pressure. we had a week fuel pump to. popped the out line off and run a hose into a bottle. Let's see. Had one that just quit. timing good everything. 8 yrs after it was already out and i was selling it found out it broke the shear pin in the distributor good luck. spark, fuel, then go mechanical.

 

[Bear76]

I am going to pop the valve covers off this weekend and see if there is anything wrong in the valvetrain/heads. I got fuel, spark. MSD told me that having bad ground leads to the motor and frame causes issues. The reason I am pulling the covers is that my buddies all think I might have dropped a valve or even wiped a lobe off of the camshaft, I love how they think so positive.

Thanks for the reply. If the timing chain slipped, I will just have to install that gear drive I have been stalling on. Darn.