Seem odd, sanity check :eek:
 

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 :eek: ! 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?

Re: Seem odd, sanity check :eek:
 

Anthony. The front ports are 7/16 top and bottom and the middle and rear ports are 3/8. The headers typically have holes in them that are big enough to go over the 7/16 bolts at the front but the rears are a loose fit on the 3/8 bolts.

That's how it should be.

If you have any non front exhaust port bolt holes that are not 3/8 thread they must have been modified by a previous owner.

Mart.

Re: Seem odd, sanity check :eek:
 

At least you caught that the front holes are 7/16".
Seem to recall a few posts here wanting to know where to get Helicoil inserts to fix the stripped front holes.
Would be interesting to find out why Ford did it this way.

Re: Seem odd, sanity check :eek:
 

It is much easier to use hex socket bolts. A guy can get a hex key (aka Allen Wrench) in there a lot easier than an open end wrench.

Re: Seem odd, sanity check :eek:
 

Merc, My guess is that they had bigger fixings at the front ports because the earlier ones had the exhaust system attached at the front port. If you think about it, the later manifolds have 7/16" studs where the exhaust system attaches.

Re: Seem odd, sanity check :eek:
 

Very interesting!! The education never stops ;)! Thx for the education!!!

Re: Seem odd, sanity check :eek:
 

Aren't these guys awesome! You never stop learning here.

Re: Seem odd, sanity check :eek:
 

:) :) :cool:

Re: Seem odd, sanity check :eek:
 

Several companies have 12 point screws with reduced wrench diameter but with shoulder washer. Absolutely the best solution for using a socket and ratchet.

Re: Seem odd, sanity check :eek:
 

Sounds like a good idea, also like Kube’s using socket bolts & Allen wrench, seems access would be much easier!