Hello, looking for a little help here on jetting my 455+40 cast wz manifolds,i have the jm 18-20 cam in it, iron Ka heads, 331 cogs, turbo 400 2600-2800 coan stahl converter, i know from the factory for the 400 l69 the center jets are 63 and the ends are 68 right now i have 65 in the center and 72 on the ends, it runs out real good it will idle at 600 and rev to 5500 seems a little soggy on the mid to top end in the 1/4 mile iam thinking of putting in some 373 cogs next year, the car does have cut outs, iam just trying to get it to run its best before i uncork the thing, so far my best is 13.64 at 99 you would thing i would have at least hit 100 mph? this is in our 1967 442 car, thanks for any info !!!

 

My recommendation would be to get a Wideband O2 and tune it right. It'll save you a lot of hassle in the long run.