Hey guys I have a question. I just recently put a new motor in my 1970 cutlass. it is a 455 out of a 69 Hurst olds. I put the motor together with brand new everything, including a full msd ignition with a 6al2 box and pro billet aluminum distributor, and the car is misfiring and I cant figure out why.

 

if you guys have any ideas or know why this is happening I could use all the help I could get.
Thanks

 

did u degree the cam make sure the wires are on right and u have the motor grounded to the frame

 

There's a lot of things that could cause this, and there could be more than one thing happening at once, in my case a vacuum leak and a dying fuel pump. Best thing you can do is go down the list and just test stuff, eventually you'll land on something not working right.

http://repairpal.com/misfires-and-their-causes

 

We need a better description. Does it miss at idle like one cylinder is dead? Does it idle ok and miss on acceleration? What do plugs look like? Is one plug colored different then the others?

 

Spark plug wires miswired, bad spark plug or wire, wires not securely fastened, etc...

 

Lots of things can cause a misfire. Do all the free stuff first like checking fuel pressure. Look for vacuum leaks, spray carb cleaner around the intake, if the idle changes you have a leak. Look under the hood in the dark to see if you have ignition leak(s). You will see the sparking in the dark. Check the dist cap for cracks or lines or even a greasy finger smudge on the inside that can misguide the spark. Put in the BEST spark plugs you can afford! I spent months and hundreds of dollars trying to cure a misfire because I put in junk plugs! They ran like crap even when new on a stock motor! Did you degree the cam? Timing sets and cams can be off enough to cause problems with valve timing

Does it misfire all the time? Only when idling? Cruising? WOT? Inquiring minds want to know!

 

Just a thought about an old-school diagnostic tool. Put your radio on AM and tune it off station. If you hear ignition static, you may have a leaking ignition.

 

plug wires in reverse order due to Chevy Voodoo?
Olds dist'r goes CCW- follow the vacuum can in and around the shaft- which works for any motor ever.