Big tube header vs small tube header on a stroker

I have never, ever seen a 340 lose power with an 1.75 header. Ever. If you are over an honest 10.75:1 compression and have a cam that isn’t totally wrong for the application, a 1.875 header on a 340 will NOT lose power or low end.

I’m going to dyno at least 1.750 and 1.875 headers on the dyno next late spring. May do 1.625 too if I can find a set, but I’ve done that enough to know on a 340 it’s a power loser.

I can’t think of any 400 plus CID engine that can’t benefit from a 1.875 header.

BTW, when using a split pattern cam with an *** load of exhaust duration and a wider than it should have LSA the small header will be damn near equal to any other header because the cam timing is wrong.

And changing the header won’t fix that. But, if you fix the cam timing and then try the small header it will kill power everywhere. But put the big headers on it and it will gain everywhere.

When I hear a big tube header lost power the first thing I look at is cam timing.

The only exception to this rule is building headers like Calvin Elston does it, and that requires rethinking everything from the induction side to the end of the collector.

And, when a bigger collector doesn’t do anything or slows down the car, it’s most likely too short. In fact, most collectors are significantly too short.