5130digger

Guys I have a modified LS to a 408 running on methanol, with mechanical fuel injection through a single plane GM performer manifold. Throttle body is a DSR with 4 by 2.25inch butterflies, heads are standard cast number 5346 heads with stainless steel valves & new valve springs to handle a cam lift up to 0.675. Camshaft is a 3 bolt with .660 lift & 108 lobe centers, has high compression pistons to give a compression ratio of 13.8:1, and also has a gear driven timing arrangement on the front of the engine, using an MSD 6010 ignition system with the timing to 36’ from 4000rpm to 7500rpm. Spark plugs being used are auto lite AR3910 with a gap of .020’ with 10mm leads. The problem I have is that the engine was running fine & then next time it started it was misfiring out the exhaust on both banks, so checked the battery & has good voltage. When driving the car it would back fire until about ½ throttles & then it clears & fine until you back off & then start misfiring again.
So any help would be great…

s57_s2k

May be you fouled the spark plug, take them out and check .

5130digger

gents,
found that the crank gear on the rear of the crank had moved 1 inch causing the timing to be out of wack. Got corrected & found to be all ok after this...