New motor misfiring
#1
New motor misfiring
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.
#4
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.
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
#5
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?
#7
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!
Does it misfire all the time? Only when idling? Cruising? WOT? Inquiring minds want to know!
Last edited by cjsdad; October 5th, 2014 at 10:12 AM.
Thread
Thread Starter
Forum
Replies
Last Post
BLACKCADDY
Parts Wanted
12
June 2nd, 2015 09:38 AM