I'm porting and polishing a set of old iron heads for my 350 buildup. They are coming out really great, but I have one problem. There is a large cavity in each intake port. It looks to go back abut an inch, below each intake valve stud. Needless to say that must create alot of turbulence and suck hard for flow.

Is there anything I can fill it with that will hold up? Will regular JB weld do it? I have the studs pulled, so I could even mask of the hole on the inside of the port, and fill it through the rocker stud hole, then polish it smooth with the port wall when it's dry. But what will work?

------------------
"American made baby. 100% American iron. The muscle among the masses. My hero. Yep, you can take your ergonomically designed, space age, computer controlled, 4 door, cup holding map lighted split double wishbone split fold down retractable cargo covered moon roof piece of transportation and keep it. For I have felt the thunder. And I know the difference!"
Jesters's Page of Sick Pleasure
Florida Thirdgenners Message Board
ICON Motorsports

 

one job i was on we had something called belzona, sort of a high dollar jb weld. not sure i'd want to trust anything inside the head like that though that wasn't welding in place.

------------------
-=ICON MOTORSPORTS=-
1st & 3rd

 

Jester,

Been there. Many later iron heads have the same design. The stud holes are drilled right down through the casting into the upper corners of the intake ports. Even the factory pressed studs don't fill the recesses completely, and allow a nice little diversion for intake air.

When I've pulled my studs and tapped the holes, I've filled the bottom of the recesses with modelling clay, then screwed in the studs loosely. Since clay is a mineral, it hardens when heated. I trimmed the clay back in the recesses, then nickel welded the recesses closed from the port side. Removing the studs and cleaning out the hardened clay from the bottom of the stud hole was all that was left. The clay didn't contaminate the weld since the water was allowed to steam off past the loose rocker stud threads. Porting the passages cleaned up the extra weld filler, and I'll never worry about a chunk of "plastic steel" getting sucked into the chamber.

I don't have a lot of faith in JB or other types of liquid metal products for engine repairs. I've had some less-than-stellar experiences in using these products to "repair" machinery. The thermal expansion rate differences of the base material and repair material always seem to cause problems for me, even when the temperature ranges of the equipment don't vary much. I've had bearings hammer the stuff flat, slides that pick up and grind the material into the rest of the "good" base metal, and various other failures. On something like a manual transmission housing, differential, alternator housing, or something less demanding, it might be acceptable. Maybe I just don't know how to use the material, nor do any of thirty-some repair techs in my area. What's the secret?

------------------
Later,
Vader
------------------
"Make Me Bad"
Adobe Acrobat Reader 4.0

 

Vader..I think you misunderstand. it's not just a stud hole, it's a whole little cave back up in there off a corner of the port. the opening is about an inch round, and it goes back into the head at least an inch.

 

Ive heard about belzona too, Shane Buss used it on his vortec heads and didnt have a problem with it at all

 

Welding cast is something of a mystic art (like picking cams). The only time I’ve ever had much success doing it is TIG with a cast filler rod. Watch the preheat and keep the temp around 350. When finished, cover the work up and make sure it cools sslloowwllyy. For tight spots, a straight torch helps.

I’ve used Belzona many times for process piping system repairs (concrete lined pipe mostly). It’s a high tech two part epoxy based filler. I’m not so sure that it will work on heads though I doubt that it will have the same expansion/contraction rates that the cast will. If not, it will probably fracture and come apart.

I’ll do some checking on this and get back to you. How far in the port is the anomaly? Can you get to it with a torch? Are you thinking it’s beg enough to cause an eddy current? The air flow through ports is usually around 1/8” off the port surface. Small defects wont affect flow, but a one incher’ might.

Mike

 

Hm..whats up with this Belzona? where can you get it?

 

Jester,

Check this out. Looks like it'll work for you.
http://www.dbrassociates.com/engine.htm


Mike

 

I checked it out..it does look very promising. thier page is pretty incomplete though . I was unable to find any info on pricing or where to get it. I wrote them..see if they reply.