273 Exh Port MisMatch

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eekvonzipper

eekvonzipper

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How can this Ever Seal?
The 1st pic shows the clean port with Fresh Paint...
The 2nd Pic Shows the Mismatch on Cyl #7
Stock '65 Manifold on a Stock '65 Head... What Gives?
The Last Pic Shows How well the Right-Side Manifold fits the Same Head.
The Drivers side exh leak is noticeable to say the least, it looks like the inside of the port is totally outside the manifold. What can I do?
No, Gaskets when I took it apart the First time, but I put gaskets in there.
All Sealed but that one and it blew the gasket out

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port2.jpg


port1.jpg


rht sd head.jpg
 
That is a serious mismatch! What casting number manifold are you using? THose look 360 ish! Does your driver side manifold have a rear facing exhaust flange or a slightly forward facing flange? 273's had a rear firing exhaust flange, 340's had a slightly forward facing flange and much larger ports.
 
here are some 273 ports (red) and some 360 ports. some of the 360's are gasket matched.

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It almost looks like the ports weren't surfaced enough. Hard to believe they have been leaking for 50+ years.
 
pishta said:
That is a serious mismatch! What casting number manifold are you using? THose look 360 ish! Does your driver side manifold have a rear facing exhaust flange or a slightly forward facing flange? 273's had a rear firing exhaust flange, 340's had a slightly forward facing flange and much larger ports.
Click to expand...
They're "315" Heads, Small Valve with the Rear Firing Manifold.
 
Max1196 said:
It's just the tinfoil gasket that was put on backwards on that one port.
Click to expand...
Interesting That "One Way" fits the Manifold (How I Installed it)
and the "Other Way" fits the Port (This would be better)
Can I Chamfer the Manifold some to the inside to better accept the port?

mismatch.jpg


match.jpg
 
So, This (pic) is the "Actual" size of my #7 Exh Port...
It looks like I should Grind to the Outside of the Head Port
and take some off the Inside of the Manifold Port to open up the mismatch. Right???

port.jpg
 
toolmanmike said:
It almost looks like the ports weren't surfaced enough. Hard to believe they have been leaking for 50+ years.
Click to expand...
Can I Weld-Up this Lower Corner where the Manifold hangs over the surface?
Will a Mig or Flux-Core even Stick to the Cast Iron?

weld.jpg
 
Since the other 3 ports on that same head are in the proper position it looks like the one port had a misplaced or broken exhaust port core when that cylinder head was cast in the foundry.
I would look for a replacement head.
If you choose to repair the existing head, to properly weld gray iron the entire head should be preheated to around 1100 F prevent cracking. And then you can get into some warping when heating a fully machined casting.
If you really need to save that head building up the gasket area with some kind of high temp epoxy may work for a while.
Another option would be to see if Remflex has a gasket that fits a 273. The Remflex gaskets are thick and are much more robust against blowing out than a stock style gasket. Perhaps a combination of a Remflex gasket with a healthy glob of high temp epoxy as filler for the missing material around the outside would make a long lasting seal.
 
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eekvonzipper said:
Can I Weld-Up this Lower Corner where the Manifold hangs over the surface?
Will a Mig or Flux-Core even Stick to the Cast Iron?

View attachment 1715811268
Click to expand...
Now I see it. The mismatch looked different in the other photos. My guess is that you are using the wrong gaskets. Not 273/318 gaskets but 340/360 instead. Just guessing.
 
eekvonzipper said:
Can I Weld-Up this Lower Corner where the Manifold hangs over the surface?
Will a Mig or Flux-Core even Stick to the Cast Iron?
Click to expand...
You're about to go down a rabbit hole that doesn't even need to be considered.
You had the end gasket reversed, that is all.
Avoid all this, and just ditch the header gasket entirely. Manifolds were never intended to use gaskets anyway, and as you found out can cause more issues than they solve.
 
you have another option. Get a port flange like 1/8 thick and mill that portion down 1/8. Bolt that between the manifold and the head to give you another mounting surface. hit that area with a stone and get it flat so you can see where the low spots are. Ultra copper RTV works on exhaust flanges. I think you got enough to seal with only the manifold. dab some paint (zinc oxide) on a manifold and put it on and see where the paint hits.
 
Professor Fate said:
You're about to go down a rabbit hole that doesn't even need to be considered.
You had the end gasket reversed, that is all.
Avoid all this, and just ditch the header gasket entirely. Manifolds were never intended to use gaskets anyway, and as you found out can cause more issues than they solve.
Click to expand...
Lol, okay. What about some Chamfers to open it up some, I can at least do that right?
 
Not fat actually, just Very worn rings... I pulled it out last night to address the cylinders and noticed the Exh leak.
I just Freshened the Heads in the Early Spring to stop the Smoking but it persisted and Compressions are low.

out2.jpg
 
Am I the only one that realizes it the manifold hangs over the port that badly that you're running the wrong manifolds?
 
eekvonzipper said:
So, SmallBlock Mopar wont work then???
Click to expand...
Chit if I know man. Since you've not bothered to post a picture of the offending manifold, I don't even know why I'm trying to help. You think you might can do that? The WHOLE manifold? Then the offending port. A casting number and date code.
 
Well, I thought everyone here was familiar with a 273 rear firing manifold already but okay.
Its still in the car. I pulled the motor around it.
I'll go get my Sawz-All and my phone... brb
 
eekvonzipper said:
Well, I thought everyone here was familiar with a 273 rear firing manifold already but okay.
Its still in the car. I pulled the motor around it.
I'll go get my Sawz-All and my phone... brb
Click to expand...
A 273 rear firing manifold?
 
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