Hi guys, ( keep in mind while an experience mechanic on newer overhead valve engines it is my 1st & only Flathead)! So, the left header (Reds Headers) is throwing me curves @ every turn
! 1st had to loosen engine mounts, drag the engine hoist out lifting left side of engine to get enough clearance past the steering box to get header in place, no biggie just a PIA in a tight garage maneuvering the hoist after I thought I was done with it & put it away. So I got all the hardware installed on the right side & guess I didn’t relize or don’t remember when taking them off but I’m realizing the mounting hardware is two sizes (I started project over a year ago & health issues prevented finishing til now) The left side has all the top bolts & hole sizes on the headers is for 7/16-14 & all the lowers on that side are 3/8-16 then the right side only the 1st upper is also 7/16-14 then all the rest on that side are 3/8-16. This can’t be standard? Or is it? The finish inside all the header mounting holes is same as in headers (aluminized ceramic I think). So headers made this way. On a side note the heads on the 7/16 hardware doesn’t allow using a socket wrench as it’s almost against the header tubes so a open end is required. Seems maybe at some point internal threads striped & retapped to 7/16? Maybe Reds worked with engine builder to make mounting holes custom?