1965 MOPAR, 273 Exhaust Maifolds
This came to me because the guy couldn't get rid of a bad exhaust leak, no matter how hard he tightened it down. Hmmm...
To illustrate the point, here is a head with air injection bosses.
I put on the ('64-'66) early A manifold and snugged it down.
The red circle shows the point of interference. The green circle shows the remaining gap between the manifold and the head. That's just shy of 1/4 inch! Even with a gasket, that ain't gonna seal. You could try grinding the boss, but there is a water jacket just under the surface, you don't want to hit it. I have- junk head.
The answer? As I stated above, use a header flange as a spacer (and appropriately longer studs).
Now. the manifold fits like a glove.
Lotsa clearance now. The header flange may need it's edge beveled in some cases, but here it just clears.
Now, someone mentioned bolting these up to Magnum heads. So, just for sh*ts and grins, I test fitted the early A manifolds to a Magnum I have on the stand. Guess what?
The interference isn't as bad, but it's still there, leaving about a 3/16 gap at #7. It seems to be caused mostly by casting flash and a very minor bit of head interference. How you would want to deal with it is up to you, but be aware that it's there.
And this is what happens when you try to tighten it down.
This came to me because the guy couldn't get rid of a bad exhaust leak, no matter how hard he tightened it down. Hmmm...
To illustrate the point, here is a head with air injection bosses.
I put on the ('64-'66) early A manifold and snugged it down.
The red circle shows the point of interference. The green circle shows the remaining gap between the manifold and the head. That's just shy of 1/4 inch! Even with a gasket, that ain't gonna seal. You could try grinding the boss, but there is a water jacket just under the surface, you don't want to hit it. I have- junk head.
The answer? As I stated above, use a header flange as a spacer (and appropriately longer studs).
Now. the manifold fits like a glove.
Lotsa clearance now. The header flange may need it's edge beveled in some cases, but here it just clears.
Now, someone mentioned bolting these up to Magnum heads. So, just for sh*ts and grins, I test fitted the early A manifolds to a Magnum I have on the stand. Guess what?
The interference isn't as bad, but it's still there, leaving about a 3/16 gap at #7. It seems to be caused mostly by casting flash and a very minor bit of head interference. How you would want to deal with it is up to you, but be aware that it's there.