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head porting gone bad

big83chevy4x4

big83chevy4x4

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while porting my heads i went a little far on 1 intake port and got into the stud boss for the rocker stud. id like to seal it up to get a smoother flow. i was thinking JB weld and clean it up a little bit. my question is will the JB weld hold up to the heat of the heads. i don't want it flaking off and going threw my motor.

i think i could leave it like it is, but i just want extra security knowing that it won't have an air leak there.

should it use JB weld, something else or just leave it as is.

EDIT: BTW, these are 1973 049 BBC heads
 
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I wouldn't use it. I ended up with some epoxy looking stuff in my oil filter, I believe it was the JB weld I used to seal up some mis-drilled accessory holes. (yes, GM did this)

I don't know a whole lot about JB welds composition, but something tells me it won't stay adhered well to cast iron that goes through hot/cold cycles, because it doesn't expand and contract at the same rate.
 
if anything i'd weld it with nickel rod.
 
there is no way to weld it from the intake port. id have to fill in the hole for the stud, then drill and retap it. i don't feel that i can get the hole the right angle either.

i have used jb weld on the out side of the block before and it stayed there, but thats on the outside. acording to the jb weld site, its good to 500*. it also says one use is on cylinder heads, just not on exhaust manifolds or combustion chambers.

ill see if i can get a pic of it today.
 
here are the pics.

what i was thinking of doing if i go with jb weld, is screw the stud down all the way without the guideplate, fill the hole with jb weld and have a small bit inside of the port. then take the stud out and let it cure. the jb weld would be "mushroomed" on both sides and won't be able to fall out in a solid state. but im still up in the air about it.

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i have a local welder guy that does some crazy quality welding for over 25 years. he hates jb weld. and he told me it dosnt expand and contract with the heat to good.

my self i would not build and spend that much cash on a motor to chance it to a plug of jb weld poping threw the motor and trashing all of it. :doah:
 
Screw in studs, I'd throw some sealant on them and call it good. Maybe you can find a stud with a bit more length and simply grind the exposed portion flat.

If you could cut the underside of the stud wrench flat level, you'd probably get a bit more "length" out of it before the unthreaded portion bottomed out. You'd need to figure that all out before doing so, there may simply not be enough stud threaded length to even attempt that. Probably cheaper/easier/more practical to have it welded.

Yeah, flow will be less than optimal, but did you put these on a flow bench to finish them up? :)

I've had something try to fit between the valve and the seat while the engine was running, I wouldn't want a piece of JB Weld to try the same thing.
 
sweetk30 said:
i have a local welder guy that does some crazy quality welding for over 25 years. he hates jb weld. and he told me it dosnt expand and contract with the heat to good.

my self i would not build and spend that much cash on a motor to chance it to a plug of jb weld poping threw the motor and trashing all of it. :doah:
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agreed if possible get some threads and cut the end of an old bolt and grind a slot for a flat head screw driver and screw it in till it pokes into the chamber and grind it smooth
 
I have used JB weld on an Aluinmium intake manifold. Where I was straightening out the runners and went a little to far and put a little hole in a bend. It worked good but it was never subjected to the temp that heads are subject to. it was sealed from the outside so nothing could be sucked in to the compression chamber.
As said above i would seal the threads with lock tite or similar the best I could and call it good.
If you aren't flow benching the heads I dont think your little mistake will make a lot of diference.
 
Most of the time your better off not porting them. It's easy to make them flow worse. Just smooth out the sharper edges and try not to take too much off.
 
agreed if possible get some threads and cut the end of an old bolt and grind a slot for a flat head screw driver and screw it in till it pokes into the chamber and grind it smooth
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i never thought about that. i may just try that, sounds like it would work. if i can't get that to work, im just gonna stick some type of sealant in there and put the stud in. im not having them flow benched, i don't know of anyone around here that has one.

Most of the time your better off not porting them. It's easy to make them flow worse. Just smooth out the sharper edges and try not to take too much off.
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i wasn't exactly "porting" them, just a gasket match and blend that in and port the bowl a little to comensate for the bigger than stock valve. with this, there was a big lump sticking out for the stud. i tried to smooth it out like i did with the other 3 ports that have this lump and went just a bit further than the others i guess.
 
I've used JB weld before without a problem. BUT I welded up the hole first and basically just used the JB weld like bondo. Don't think I'd trust it if filling up a hole. If you put the stud in first, smoothed it out a bit with the grinder, cleaned the surface VERY WELL - use brake clean btw, or soap and water, most other solvents leave a residue that the JB doesn't stick to very well - and then used JB as a surface coat, I don't think you'd see a problem. I've got a set of heads that have 50k miles of hard driving and some strip time that are done that way.
 
Local hardware stores have set screws. :wink1: Screw it in with an allen wrench and grind it smooth, and use red loctite to make sure it cant move. This trick brought you courtesy of Brodix Aluminum Cylinder heads, who seem to drill into the intake port on many of their heads.....
George
 
I'd try the set screw idea as well. I would try to find out if losing the threads would have any adverse effect on the rocker stud. I'm sure you can loose some of the space/threads but how much?:dunno::dunno:
 
ill have to dig out the calipers and measure the depth, subtract it from the length of threads on the stud and get something that short for it. the thickness of the guideplate will be a buffer area. the set screw sounds easier than cutting a bolt.
 
well i measured the depth of the hole and the threads of the stud, the only threads that are left in the hole are the few at the bottom that are not fully cut. there is just over 1/8" of usable threads left. i don't think i can use a set screw or cut off bolt to thread in before the stud the way it is. im thinking about drilling and tapping it deeper, but it would make the hole bigger. i could always grind the stud shorter, but too much and i sacrifice strength.

also the local hardware store doesn't have 7/16" set screws, all they had were 3/8" or 1/2".
 
www.mcmaster.com part number 91375A662 7/16x14 three eighths of an inch long $7.58 for a pack of 25 plus freight.....
George
Now try finding a 7/8-18nf left hand tap that is an oddball size. I found a right but not a left
 
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