1,2,3-4,5,6 is good for turbo manifolds and that is what I'll make for my Twin Scroll ERF 8474. 1,3,6-2,4,5 is "suppose to scavenge better. It would have been way easier to build if I built it 1,2,3-4,5,6. The header isn't perfect by any means, I have 1 tube 4" shorter than my planned 36" primary tube length, and my calc's showed it needed a tube size bigger than 1.5" but smaller than 1 5/8" Figured with the thought of adding my Vortec V1 I would error on the bigger side. I have to say, I was pretty darned excited when I test fit the header and it fit and cleared everything. the header goes in and out with the intake and passenger motor mount removed very easy. If I would have thought about it, I should have changed the layout of #6 tube so the header could have been used on high mount starter 200's as well. For those that don't know this is a 1981-83 low mount starter 200/3.3L block not a 250. I'll post pictures of the bell housing mod needed to use a SBF bell on this engine.
sharkhidestore.com
I had the machine shop mill the pushrod holes 60 thousands at the close area in every hole. 3/8” push rods make it pretty close as you know. Have you checked to see if you have had any rubbing? Do not Machine the push rods hole openings as the water jacket was hit and I had to repair the head. see the other thread for details.The clearance on the push rods looks familiar.
