Don Terrill’s Speed-Talk

I have a set of heads that are cnc ported but for some reason a small hole has developed between the intake port and the ex port. Has anyone ever had this and is there any kind of epoxy that could repair this?

Hole as in the intake port is open to the exhaust or its into coolant in between the 2 ports? Aluminum or iron? I used some Blue Magic steel epoxy on my heads to epoxy the pushrod pinch area that was paper thin...I epoxied the outside so its exposed to engine oil...it seems to be holding well. Not sure on a hole through to coolant, that has to hold pressure. If its through to an exhaust port I see no epoxy that will last there very long.

Ya it's through from the intake port to exhaust port. small hole about the 1/2 size of pencil eraser. Kind of like a mini EGR.

It's not going to work. You will have a tough time plugging the hole. That will be a continuous problem with that set of heads. The other ports without holes, are paper thin, and will crack.

Can you each it with a tap? put in a repair pin?

Even without the hole your heating up the Intake charge a huge amount when runners are that thin and touch one another!
I question if the added Intake flow from the cnc work gets canceled out by heat?

Ciramic epoxy from Coltronics is the only thing I can think of other then welding to cure the issue, and if you go with the epoxy you will need to leave a small button size head of it on each side of the hole and just live with whatever flow reduction that may take place!

Epoxy is out of the question for anything that comes in contact with the exhaust. It will burn through in very short order.

Is the hole in the bowl area? I'm having a hard time imagining intake and exhaust ports on the same side as one another other than straight six.

Just weld the hole and be done with it. Sonic the area around the port and check all other cylinders the same way. If they're real thin then weld and blend those areas to.

fordified wrote: ↑Fri Aug 17, 2018 9:26 am Is the hole in the bowl area? I'm having a hard time imagining intake and exhaust ports on the same side as one another other than straight six.

Just weld the hole and be done with it. Sonic the area around the port and check all other cylinders the same way. If they're real thin then weld and blend those areas to.

Pretty much every domestic V-8 has the exhaust ports and intake port adjacent to each other. I have seen this happen numerous times though the years, where someone was a little over zealous in that area, and have seen numerous sets of heads cracked in that area. Sometimes it never causes an issue, other times it's a giant headache. Fixing it can be hit or miss, depending on how much material is left to work with. Welding paper thin aluminum usually just blows out and makes​the problem area worse. The crack can migrate under the seats and cause a bad leak, eventually, the exhaust gasses will get up under the seat, and erode away the material and poof, the seat is ingested by the engine. You would have to cut out both seats, grind the aluminum all the way down, and build the weld up towards the seat and re cut counter bores and install new seats.

The way he wrote it lead me to believe that he was talking about the port walls being next to one another like a straight 6 where the intake entry and exhaust exit are on the same side of the head next to one another. Every domestic V8 that I've ever seen has the intake entry and exhaust exit on opposite sides. The only place where they share a common area is in the bowl.

I think you and I are talking about the same thing. The hole is in the bowl.

No matter what he needs to have the bowls sonic tested. Depending on how much material he has to work with will determine what's next for the repair.

If he's got good material depth near the seat then he should be okay. No matter what I'd pull the seats before welding the bowl and have the hole remachined and new seats installed. I'd weld both the intake and exhaust bowls so the new material is solid. Hell. Even if he doesn't have a lot of material near the seat I'd still weld the hell out of that area and recut the head for the seat.

I mean I've had the misfortune of dropping a valve or 3 in my time and the repairs always held even with a valve stem going through the bowl.

The one thing the guy hasn't done is tell us what heads he dealing with. If their cheapo chinese heads then he may be pissing up a rope.

These are a set of GM lsx 454 heads that have been cnc ported by a reputable porter in the US.

I was thinking the same thing that there is no way any epoxy is going to stand up unless it is some kind of ceramic stuff. I am probably going to have to weld it. Very thin so I will basically have to use a backing plate and build up the weld then hand grind it down after.

This is some of the products I have used in the past.

http://www.cotronics.com/vo/cotr/rm_putties.htm

nhrastocker wrote: ↑Tue Aug 21, 2018 10:29 am This is some of the products I have used in the past.

http://www.cotronics.com/vo/cotr/rm_putties.htm

Wow ! now that is interesting, thanks I will contact them a see what will work.

I chased this problem on a set of max ported victor heads. I ended up welding all 8 intake- exhaust port blowthroughs. Accessed under intake valve bowl area. Then grinding it to smooth . Tried epoxy of all sorts. Did not last. Funny thing is it never affected performance. Go figure. You would think the intake charge would have been contaminated.

grant6395 wrote: ↑Wed Aug 22, 2018 4:24 pm I chased this problem on a set of max ported victor heads. I ended up welding all 8 intake- exhaust port blowthroughs. Accessed under intake valve bowl area. Then grinding it to smooth . Tried epoxy of all sorts. Did not last. Funny thing is it never affected performance. Go figure. You would think the intake charge would have been contaminated.

That is very good to know. I am thinking that it is going to get welded. I have three small holes on different ports and it never effected performance also. Thanks