Was doing some mild bowl work on World S/R's. At first blush the casting looked real good--no real big ridges, good cast surface finishes, parting lines not big at all in the ports. When I started I noticed the bowls varied somewhat from one port to another, so I decided to even it up as much as possible. Was almost done with the grinding when I hit water on one of the exhaust bowls.


KHAAAN!!!


Strange thing is on the wall on that side, very near to the break through, the parting line is still visible (not in the picture though, unfortunately), and running a finger along that wall from the flange to the valve seat, the wall is now very even and level with a very smooth transition along the long side (as they all are now). I am very surprised and am guessing that the casting was just thin there for some reason (I didn't hog the pi ss out of these or anything, just tried to make them even and smooth). Sad thing is I was basically ready to do the final smoothing/polish & take 'em in for a valve job, resurface, and get 'em flowed.

I have them in the trunk right now, I figure at lunch I will go to have a shop look at them and tell me if its even possible. Next, if its fixable, I'll have to compare costs of getting a sonic check to see if its tin foil thin anywhere else plus how much the repair would cost versus the cost of some bare Sportsmans or something. I see a lot of iron castings are about $575/pair bare, as compared to getting these worlds sonic checked, repair break thru, valvejob, resurface. This shop qouted me $225 before for a serdi 5 angle valvejob, don't know if this is on the high side or if this valvejob is overkill for a mild street build.

It will be a shame if I just created a big doorstop, as I've spent quite a few hours here--chambers and bowls are mostly done, only things completely untouched are exhaust floors, intake entries. I think I'd be too nervous to get one new S/R and start over, though this would only cost ~$260 and there's no guarantee that something about the castings haven't changed (I got these like 5 years ago).

If it is repairable, is there still a big chance the durability of a weld in cast iron will be dicey? I have no real experience here.

Here are the pics--sorry they suck. I took them late last night, plus Photoshop's image size indicated they were all ~97K, when I saved them on a disk, they're closer to ~26K. I'll have to look into that.

 

Hard to see in this one, in the exhaust bowl, its the black spec left of (or under, in the pic) the guide.

 

It can barely be seen in this pic, in the left exh bowl its the black spec to the left of the guide.

 

While I'm at it, a pretty shot of the chamber.

 

A couple of intake bowls.

 

And finally, down the intakes.

 

Well, I spoke to a guy at the shop and he basically said he wouldn't even try it. I may get a second opinion from some welding outfits from the phonebook since this shop probably doesn't mess around with this stuff. I'm just concerned that if it can be welded up, the weld would need a good bit of grinding again, and I still don't know how thin any other spots are.

 

if you have good access nickel tig if not nickel mig wouldn't be hard to fix, might be hard to get to and to see

 

to continue something i left out you wouldn't want steel filler since it'll draw all the carbon in the iron to the weld and you wouldn't be able to grind or work it

 

Thanks for the reply ede.

With the nickel MIG wire is special preperation & techique still required like slow preheat before and slow cool down after, fill small sections at a time, etc? What I'm getting at is what are the odds that a non-professional welder could do this repair (Should I leave this to a pro)? I have a MIG and am decent with mild steel but if special training is needed I'll look around to have it done. If I just read about this in a book I wouldn't even think to try it, but I get the impression this might be doable at home.

To summarize:

Is there still a large chance of a crack forming even if done properly?
can I do this at home? (if not, disregard the other questions)
any special method/chemicals to clean the area?
Can't really clean the other side. Problem?
special technique?
Can I start with the head @ ambient temp?
Use pure nickel wire?

Thank you.

 

i doubt if i'd pre or post heat it, just weld it, but it wouldn't hurt to pre heat

 

I guess first I'll see if I can get in there with the gun; if so, I'll give it a shot. I figure what the hey, I have nothing to loose at this point.

If I weld it up and it air cools without cracking, do I stand a good chance of the repair being durable? Obviously, the temps it will see will be much lower than welding but I don't know if the repeated cycling of temps will have any adverse effects.

 

Is this the hole?

You can repair it with FireSeal2000
Or simular product.

it works.....

 

Woops forget the pic.


While its drying/curing ya need to get serious on those
intake ports.

 

This is where we send any thing cast that needs to be "welded"... They're good.

Herculock

 

F-BIRD'88, thats the hole. The carbide chattered for a second and cracked through before I stopped the tool. I know the pictures are small and fuzzy--I took them late at night. I will get one or two better ones tonight.

Have you used that Fireseal stuff? I've never heard of any epoxy working in exhaust. I think I'd be more comfortable with the hole welded, but the trick appears to be to do it w/o cracking it--I don't know how thin the whole area is and I don't know if I have enough room to lay a single bead correctly, let alone several. One way to find out I guess. Of course, I need to add the cost of a roll of nickel wire to the deal.

As far as getting serious with the intake, I don't think I have the guts to do anything more to the intake, at least in the bowls. The max I would do at this point would be matching the intake flange to a 1205 and making sure the roof is a straight shot into the bowl, and widen the pinch a bit.

In any case I am concerned about the long term durability of any repair in this area, so I don't know if I will even use them at this point. Since the other ports are very similar, unless this port is a freak in the casting, the others can't be far behind. I think I'll go back to the shop to see if they can determine exhaust port thickness on the 'good' head with a sonic test to some resonable degree of accuracy in the areas they think are important for longevity on the street and such. Then, I *may* reconsider one new bare S/R and start over if the outcome is good. Otherwise, hello Sportsmans or Vortecs. Just trying to sort this all out and avoid throwing good money after bad.

 

i'd go with the epoxy if it'd work in the heat. there isn't any big trick to getting the head to weld without cracking. heads are a fairly good casting and easy to weld. the big trick is making it leak proof.

 

its not epoxy. epoxy is a 2 part thingy. This is a one part silica-ceramic / metal deal.
Its simular to muffler cement but a lot stronger and thicker. I repaired a hole in my cylinder head worse than that one. never leaked. The stuff loves the heat.

 

yeah that's what i mean silica-ceramic/metal deal, what ever it was you said. guess due to not knowing or understanding any better it's all epoxy to me

 

Sorry F-BIRD'88, I think I called it epoxy too.

Well, just found out nickel mig wire is not only typically a special order type thing, its even more expensive than I thought. They said the smallest they could obtain is 0.035" in a 10lb. roll for ~$22/lb. I was hoping for 2lbs of 0.023" or something. Rods are more common but I can't get to (not to mention don't know how to use) a TIG. Therefore, it would have to be done by a shop if welded. The silica-ceramic/metal repair is looking much more attractive now.

In either case, let me bounce one more idea off of you guys: Say the repair fails at some point, and coolant/exhaust are no longer separated. Due to the location of the hole, I can't imagine any damage resulting to the motor from this in any operating condition as pressure differential would always carry it out the exhaust (not even O2 sensor if I install on passenger side ); the only damage I can forsee would be if after a failure the engine was stopped and some coolant leaked past the valve into the cylinder and sat for a while.

I'm willing to take a chance if all I stand to loose from it failing is some gaskets and time (well, and a valvejob/resurface). Am I overlooking anything that could get damaged?

 

By the way thank you both for your input, I do consider it invaluable.

 

If the exhaust valve is open when the engine is shut off after the repair failed, you'd fill the cylinder with coolant. Hydralock isn't a good thing.

Either you trust the repair, or you do something else.

 

As bad as it sounds, you may have to call it a door stop.
Not knowing how thin the surrounding area is, it may just blow into a crater.

 

Hydrolock certainly is not a good thing. But if you were unfortunate enough to have the repair fail unbeknownst to you after shutting the engine off, and the motor stopped in a position with that particular exhaust valve open, and crank the motor to start it again, it should get forced out of the cylinder since the valve would remain open until ATDC. Of course, there could be a condition where the exhaust valve was just beginning to open and the piston is near BDC, the cylinder filled partially with water, and cranking could cause a similar (to hydolock, that is) shock to the rotating assy once the last bits of air escape and its the coolant's turn to exit because it can't get past the still open valve fast enough. So, since none of that is designed to pump liquid, I guess the outcome is a little too unpredictable to risk.

I'm sure you meant this in the best way, and presume not as a blanket statement. If the worst possible outcome of the repair failing was limited to my labor, some gaskets, and no risk of damage to other components, I wouldn't have to have absolute trust in the repair because I'd be willing to accept these consequences. If there would be risk of damaging the rest of the engine, this wouldn't be acceptable to me. Your post was the one that actually helped me think the possible consequences of a failure through more--and knowing the costs and possible outcomes of each avenue is the way to make an informed decision which is what I'm attempting.

In any case, it looks like its up to me to make a decision at this point, thanks to all for your input.

 

On a small block chevy the the exhaust port is offset from the center of the valve. thats why the area around the guide boss is wider on one side than the other.

Ya don't need to "straighten out" this built in offset.
You just went way too far with the porting.
If you look at the intake bowl you'll see it is offset too.
This is not core shift or a flaw. it called Port Bias ...
Its what causes the flow to swirl as it enters the chamber. On the intake side you actually want to incease this "port bias" by working on the common wall and the area between the common wall and the valve guide boss at the roof where it meets the bowl.
This is a high flow area. Other than the usual "pocket porting the bowl area, this area is where you can really gain some flow on the intake port. the only danger is breaking through the common wall right where the cylinder head bolt passes between the two ports.

 

I wasn't trying to straighten out the port bias or alter the overall 'run' or path of the ports, I was trying to equalize the repective shapes between the ports to the best "as cast" shape. Basically, I'd find the most 'open' feature among the 8 ports, and after cleaning up the surface a little I'd index off the valveguide and flange with a template and equalize as best I could that same feature in the other 7. Variations would still exist, but they'd be pretty close. I didn't try to make both sides of the guide the same. It worked well for me on the intake and seemed logical at the time. I suppose I could have improved on the accuracy with some telescoping gauges but didn't think it was necessary; I figured the templates would be good enough.

I wish I could either I could take a better picture (I haven't gotten back to it yet) or you could see the part 'in the flesh,' so far the people that have seen it are surprised I broke through that way, in that spot. I was pretty cautious about posting this since I wasn't just in there hogging random stuff trying to make giant shiny ports, there was a method behind my actions there though it may seem otherwise from the nice little hole in the bowl. Oh well.

In any case, I know all the options now, and they are:

1) repair by weld
2) repair with the silica-ceramic/metal stuff
3) replace

All I have to do now is decide between them. So far one place said they wouldn't be able to get in there to sonic test. If I choose to junk the head I'll see about getting it cut open to satisfy my curiousity as to what the backside of all the ports look like (might as well not let this learning experience go to waste).

Thanks guys