Previous Thread
Next Thread
Print Thread
Brazing an exhaust port on an iron head #1056744
08/19/11 01:09 PM
08/19/11 01:09 PM
Joined: Jan 2003
Posts: 9,670
Lima, Peru
domingo Offline OP
EL Master
domingo  Offline OP
EL Master

Joined: Jan 2003
Posts: 9,670
Lima, Peru
I know that its always said that you can braze intake ports to fix cracks, pinholes, etc because of the lower temps found in the intake port....

...but when you are taking about exhaust ports you CANT braze them due to the increased temperatures found there which would soften the bronze and it would do little to prevent cracks or pin holes from seeping water.

Now....

What if you had an exhaust port that had been opened up a tad bit too much and you would want to fill it up some by brazing and then reworking it. This is at the very end of the port opening where the gasket sits. Seems somebody port matched and went a bit overboard and enlarged the port opening a bit too much.

This port doesnt have cracks or pin holes, I just want to fill it up some at the very end of it and port match it again.

Will bronze hold up or will it melt????

Any other ideas?

Thanks!

Domingo

Last edited by domingo; 08/19/11 01:09 PM.
Re: Brazing an exhaust port on an iron head [Re: domingo] #1056745
08/19/11 01:17 PM
08/19/11 01:17 PM
Joined: Jul 2006
Posts: 4,595
On the south side of Nowhere
S
S/ST 3040 Offline
master
S/ST 3040  Offline
master
S

Joined: Jul 2006
Posts: 4,595
On the south side of Nowhere
Brazing is a very common practice for repairing exhaust ports.


Re: Brazing an exhaust port on an iron head [Re: S/ST 3040] #1056746
08/19/11 01:27 PM
08/19/11 01:27 PM
Joined: Jan 2003
Posts: 9,670
Lima, Peru
domingo Offline OP
EL Master
domingo  Offline OP
EL Master

Joined: Jan 2003
Posts: 9,670
Lima, Peru
Quote:

Brazing is a very common practice for repairing exhaust ports.






really?? I always thought it was OK on the intakes but a real NO NO on the exhausts!!!!

Is there a possibility that a bronze filling actually MELT off on an exhaust port?

Re: Brazing an exhaust port on an iron head [Re: domingo] #1056747
08/19/11 01:28 PM
08/19/11 01:28 PM
Joined: Aug 2003
Posts: 11,179
Atco NJ
DJVCuda Offline
I Live Here
DJVCuda  Offline
I Live Here

Joined: Aug 2003
Posts: 11,179
Atco NJ
I've seen exhaust manifolds that were brazed to fix a broken ear, or crack last years and years...

Re: Brazing an exhaust port on an iron head [Re: DJVCuda] #1056748
08/19/11 02:16 PM
08/19/11 02:16 PM
Joined: Jan 2003
Posts: 9,670
Lima, Peru
domingo Offline OP
EL Master
domingo  Offline OP
EL Master

Joined: Jan 2003
Posts: 9,670
Lima, Peru
Well, exhaust manifolds are farther away from the heat....and an ear is not in direct contact with the heat.

I am concerned about how will a bronze filling behave INSIDE the exh port walls!

Once again, it wont be sealing any cracks or pinholes or trying to prevent water from seeping. The exhaust port is just fine, and it passed the water pressure test just fine. I just want to fill it some to rework it.

Re: Brazing an exhaust port on an iron head [Re: domingo] #1056749
08/19/11 02:34 PM
08/19/11 02:34 PM
Joined: Mar 2006
Posts: 2,675
Mt. Eden Ky.
Hemi Allstate Offline
master
Hemi Allstate  Offline
master

Joined: Mar 2006
Posts: 2,675
Mt. Eden Ky.

I have seen exhaust ports brazed and filled on the bottom when raising them for SS etc.
The intake side could be epoxied, but exhaust is brazed.


http://marsh-racing.com/Mark%20Mahorney-Allstate.htm
1996 Ram 1500 Sport
1968 road runner
1952 Sears Allstate licensed, pump gas, Hemi 5.98 @ 115.73 1.33 60 ft. The best is yet to come. Painless Performance / Street RODDER magazine Top 100 for 2019
Re: Brazing an exhaust port on an iron head [Re: domingo] #1056750
08/19/11 03:54 PM
08/19/11 03:54 PM
Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY Offline
Master
MR_P_BODY  Offline
Master

Joined: Jun 2003
Posts: 52,972
Romeo MI
If your really worried about brasing it, weld it
with high content nickle rod

Re: Brazing an exhaust port on an iron head [Re: MR_P_BODY] #1056751
08/19/11 04:46 PM
08/19/11 04:46 PM
Joined: Jan 2003
Posts: 16,376
D
dogdays Offline
I Live Here
dogdays  Offline
I Live Here
D

Joined: Jan 2003
Posts: 16,376
The wall of the exhaust port has water on the other side so it probably is cooler than the exhaust header.
R.
You could drill a hole in an exhaust header or manifold and insert a brazing rod with a square tip. Run the engine up some hills and then take out the rod and see how it looks. This actually sounds like a fun experiment.

Re: Brazing an exhaust port on an iron head [Re: Hemi Allstate] #1056752
08/19/11 05:17 PM
08/19/11 05:17 PM
Joined: Jan 2003
Posts: 9,670
Lima, Peru
domingo Offline OP
EL Master
domingo  Offline OP
EL Master

Joined: Jan 2003
Posts: 9,670
Lima, Peru
Quote:


I have seen exhaust ports brazed and filled on the bottom when raising them for SS etc.
The intake side could be epoxied, but exhaust is brazed.




Thats exactly whay I am looking to do....kinda what SS racers do. I know they raise the exh ports on the heads and make em smaller....I wonder if they do that by brazing the exh ports. If that is the case, I know I will be 100% safe.

It'd be great if Jeff (modern cyl head) could chime in....I know he does heads for the SS guys.

Re: Brazing an exhaust port on an iron head [Re: domingo] #1056753
08/19/11 05:40 PM
08/19/11 05:40 PM
Joined: Dec 2009
Posts: 1,074
detroit, mi
POS Dakota Offline
super stock
POS Dakota  Offline
super stock

Joined: Dec 2009
Posts: 1,074
detroit, mi
I cant see the port reaching any critical melt temperature given the fact that the head is constantly being cooled by water. It might cool slower than aluminum, but I cant see the head itself reaching any temperature where the repair would melt.

If an exhaust manifold that is not cooled holds, the head will hold fine is my thought on it.

No????

Re: Brazing an exhaust port on an iron head [Re: POS Dakota] #1056754
08/19/11 06:06 PM
08/19/11 06:06 PM
Joined: Nov 2003
Posts: 5,160
Texas
dannysbee Offline
master
dannysbee  Offline
master

Joined: Nov 2003
Posts: 5,160
Texas
The melting point of brass is 1700 degrees, aluminum is 1200 degrees.


Getting old just means you were smarter than some and luckier than others.
Re: Brazing an exhaust port on an iron head [Re: domingo] #1056755
08/20/11 11:45 AM
08/20/11 11:45 AM
Joined: Mar 2006
Posts: 2,675
Mt. Eden Ky.
Hemi Allstate Offline
master
Hemi Allstate  Offline
master

Joined: Mar 2006
Posts: 2,675
Mt. Eden Ky.
Quote:

Quote:


I have seen exhaust ports brazed and filled on the bottom when raising them for SS etc.
The intake side could be epoxied, but exhaust is brazed.




Thats exactly whay I am looking to do....kinda what SS racers do. I know they raise the exh ports on the heads and make em smaller....I wonder if they do that by brazing the exh ports. If that is the case, I know I will be 100% safe.

It'd be great if Jeff (modern cyl head) could chime in....I know he does heads for the SS guys.




How's this look? It may be some of Jeff's work!


http://marsh-racing.com/Mark%20Mahorney-Allstate.htm
1996 Ram 1500 Sport
1968 road runner
1952 Sears Allstate licensed, pump gas, Hemi 5.98 @ 115.73 1.33 60 ft. The best is yet to come. Painless Performance / Street RODDER magazine Top 100 for 2019
Re: Brazing an exhaust port on an iron head [Re: Hemi Allstate] #1056756
08/20/11 12:11 PM
08/20/11 12:11 PM
Joined: Jan 2003
Posts: 9,670
Lima, Peru
domingo Offline OP
EL Master
domingo  Offline OP
EL Master

Joined: Jan 2003
Posts: 9,670
Lima, Peru
Thats all I needed to see!!! Thanks! I will go ahead and fix my heads that way....thanks!!!!

Re: Brazing an exhaust port on an iron head [Re: MR_P_BODY] #1056757
08/21/11 09:25 AM
08/21/11 09:25 AM
Joined: Nov 2003
Posts: 2,715
closer to Canadian beer!
torkrules Offline
I'm neurotic
torkrules  Offline
I'm neurotic

Joined: Nov 2003
Posts: 2,715
closer to Canadian beer!
Quote:

If your really worried about brasing it, weld it
with high content nickle rod





+1 on that. I had a pin hole in an iron head. we heated it with a torch and zapped it with a high nickle rod. I think the heads are still around to this day.

Re: Brazing an exhaust port on an iron head [Re: torkrules] #1056758
08/21/11 11:45 AM
08/21/11 11:45 AM
Joined: Oct 2003
Posts: 21,345
Marysville, O-H-I-O
70Cuda383 Offline
Too Many Posts
70Cuda383  Offline
Too Many Posts

Joined: Oct 2003
Posts: 21,345
Marysville, O-H-I-O
I don't know a lot about brazing yet, but I've watched my dad do it a few times, oxy/acetylene hot blue flame to heat the metal to cherry red and touching the rod to it to melt the brass into it...that's GOTTA be hotter than any exhaust is going to get.

unless you run stupid lean!

but, if you're really worried, maybe look for someone who can weld cast aluminum up with steel rod.


**Photobucket sucks**
Re: Brazing an exhaust port on an iron head [Re: 70Cuda383] #1056759
08/21/11 12:09 PM
08/21/11 12:09 PM
Joined: Oct 2003
Posts: 11,678
W. Kentucky
justinp61 Offline
I Live Here
justinp61  Offline
I Live Here

Joined: Oct 2003
Posts: 11,678
W. Kentucky
Quote:



but, if you're really worried, maybe look for someone who can weld cast aluminum up with steel rod.




I'd pay to see that trick

Re: Brazing an exhaust port on an iron head [Re: justinp61] #1056760
08/21/11 12:17 PM
08/21/11 12:17 PM
Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY Offline
Master
MR_P_BODY  Offline
Master

Joined: Jun 2003
Posts: 52,972
Romeo MI
Quote:

Quote:



but, if you're really worried, maybe look for someone who can weld cast aluminum up with steel rod.




I'd pay to see that trick




LOL.... same here

Re: Brazing an exhaust port on an iron head [Re: domingo] #1056761
08/21/11 12:30 PM
08/21/11 12:30 PM
Joined: Feb 2004
Posts: 1,093
Long Beach, CA
Mike Swann Offline
super stock
Mike Swann  Offline
super stock

Joined: Feb 2004
Posts: 1,093
Long Beach, CA
Back in the 70's, I was given a 70 Pinto with a 1.6 crossflow head that was wounded. After taking it apart, it had a burnt ex valve and cracked seat. After consulting with the wise shop owner that I worked for, I gound out the crack, we heated the head in the oven to 400F then brazed/filled the crack. Then, I had a seat put in it and ported the crap out of it. That motor got me though college and saw 7500rpm daily.


8.30's @3400 lbs
Re: Brazing an exhaust port on an iron head [Re: domingo] #1056762
08/21/11 12:52 PM
08/21/11 12:52 PM
Joined: Jul 2010
Posts: 3,502
SOUTH JERSEY
HEMIFRED Offline
master
HEMIFRED  Offline
master

Joined: Jul 2010
Posts: 3,502
SOUTH JERSEY
Quote:

Thats all I needed to see!!! Thanks! I will go ahead and fix my heads that way....thanks!!!!




you had better know how much pre heating and cool down time it needs. all I have seen done used a furnace to braze


home of the
Sox and Martin Hemi Duster








Powered by UBB.threads™ PHP Forum Software 7.7.1