Payton

Anyone have the tune up specs for a 1991 454 Mag? I've got carbs, not sure if there even was an mpi then.

Mainly plug gap and timing. Everything but the flame arrester is stock.

Thanks
Mark

formula31

idle rpm (in forward gear) 650-700
plug gap .035
8 degrees BTDC

Payton

Thanks Formula.
Now I just have to get my body wrapped around thoses engines enought to get the plugs changed. The plugs I've pulled so far are sure dirty and the gap seems to be almost twice what you said. I guess it wasn't a fresh tune up when I bought it.
In a way, maybe that's good news. I might pickup a few rpms.

formula31

Those specs were for a Mark 4 Thunderbolt IV. I think thats what your 91 Mag still is but I might be wrong. Anybody else?

Griff

My 93 454 Mag had the same specs as those formula1 gave. It was a GenV with TB IV.