Manifold machining

[larrys40]

Jack,
Put along straight edge across them. I have a bonified old style cylinder/head flat straight edge for checking. If you have access they are best, if not use a long carpenters square on edge and use a feeler gauge. If it's out more than .005 surface it. Almost all need some cleanup....It helps insure that you get a good seal for intake and exhaust and helps to keep from cracking any ears on the manifolds. If the edges are pitted it may be a problem. Use a straight edge across the ports and make sure they line up well. If sagging too much on #4 It may be best to buy a new Exhaust manifold. The new Snyders ones are very good. We are lucky to have them available. Even with the new manifold I would mate properly to the block for alignment, tighten two 5/16 bolts holding the two together.. and check for straightness on the bench as described above. I would surface them no matter what.... but then I do my own so I'm use to having the equipment at my disposal. $40 to surface one very reasonable...

Happy Model A Motoring...
Larry