Originally Posted by GammaBoy
Okay, Currently chasing a missfire. Basically, she runs fine up to about 1/3 throttle, tip more in and it missfires badly... can feel the fuel lighting off in the extractors under my feet... It still pulls very strongly when you get up it, just feels like its dropping a cylinder or two.
Ignition is a Motorcraft Points dizzy thats been converted to Electronic with a GM-Delco type ignition module.
Now, things I've changed that might have an impact:
1. Fresh Plug leads. Good 10.5mm leads From Queensland Ignition Leads (nice custom set cut to order while I waited) Put these on cos I assumed that the breakup might have been part of the batter acid issue I had (Boiled the battery, acid ate the plug leads) I'm severly doubting these to be the problem
2. Fresh Plugs - NGK BCPR5ES was having trouble finding straight BCP5ES's, resorted to these after making a couple of quick calls as to wether they'd cause problems with my ignition setup. Now, My guess is these plugs may be the prob?
Coil was located in a spot where the battery acid didn't have had an effect.
Dizzy cap perhaps?
Any thoughts?? Its really sh1tting me off
Change the leads back to your old ones, this will eliminate the leads as a cause of the problem or maybe even fix it. I have seen brand new leads cause a misfire. Try and get some V groove NGK plugs in the heat range that suits your engine.Check the gap as well.
I wouldnt think dizzy cap unless there is signs of cracks or spark tracking.
Ignition timing check, comp check, valve clearances, fuel filter, partially blocked carby jets.
Rev that engine and place your hand over the carb, let it suck till it nearly stalls and remove your hand. Be carefull the carb can backfire, shoot out flames etc. Do this a few times. This may help clear any Shit in the carb.
If acid ate the plug leads check the wiring to the coil it may have been affected. Check coil + voltage. Check the coil look closely at the + and - terminals. Wash the engine to get rid of the acid residue if you havent allready.
Good Luck, dont assume anything, check everything twice.