cylinder head modification

admin

This one is difficult to photograph, so here's a combination of photograph and drawing of the changes being made to the intake and exhaust ports.  The engine is a 1972-1994 Alfa Romeo 2 liter.  It's history is similar to the Chevy small block . . . original design in the early 50's, bored and stroked a couple times, but retaining the same basic architecture with many parts being interchangeable between the earliest and latest engines.  Unfortunately, the port design was never really improved.  The biggest problem is the short side radius.  The sharp corner causes the flow in the exhaust port to detach from the bottom of the port and form an eddy.  On the intake side, the mixture just doesn't want to go around the sharp corner.  The drawing shows the desired finished shape and the photograph the welding required to get there.The real project was finding a way to shield the arc while still being able to see it.  I first welded around the lower edge of the valve seat.  Because of the angle, that extended into the port only about 1/4 inch.  The rest had to be done from the manifold side.  I tried a WT-24W torch first.  It physically fit in the port . . . about 1-1/2 diameter . . . but it was almost impossible to feed the filler.  I swithed to a WT-20 with a gas lens and stuck the tungsten out about 1-1/2 inches, but couldn't get good gas coverage regardless of argon flow rate.  Plugging the port at the valve seat and adding argon through the valve guide made some improvement, but still didn't really solve the problem.  Then I made a plug to replace the valve seat that incorporated a gas lens and purged the port opposite the torch.  90% of the time it worked well, other times, I had to play with flow rates between the torch and the purge.  Sometimes it worked with 5 CFH purge and 25 CFH at the torch, other times just the opposite.  Obviously, I'm getting comtamination from the open end of the port, but just haven't been able to figure out the exact flow pattern.  For setup . . . I used 2% Lanthanated tungsten, a gas lens with #8 cup on the torch, up to 250 amps with the balance at 70%.  Running a higher frequency (150 Hz) helped arc stability.At this point, all 8 ports have been welded and rough machined.  I'll take more photos when the porting is finished and seats installed.-jimDynasty 300DXSmith He/Ar gas mixerMM350PHobart Handler 120Smith LW7, MW5, AW1A
Reply:How were you able to make sure that when machining you kept enough wall thickness to the water jacket?  It looks like the right side (from your sketch) port modifications come pretty close to the jacket.
Reply:I have look jn geting one of torches would this work ?   http://www.ckworldwide.com/micro_torch.htm Attached ImagesLast edited by T E B; 04-06-2011 at 10:36 AM.
Reply:Originally Posted by FegenbushHow were you able to make sure that when machining you kept enough wall thickness to the water jacket?  It looks like the right side (from your sketch) port modifications come pretty close to the jacket.
Reply:Originally Posted by T E BI have look jn geting one of torches would this work ?   http://www.ckworldwide.com/micro_torch.htm
Reply:Great project!You have any success with welding up behind the valve seats?  I know of a few 2 liter heads that like to mimic blown head gaskets when hot but have leaks under the valve seats.
Reply:Originally Posted by david_rGreat project!You have any success with welding up behind the valve seats?  I know of a few 2 liter heads that like to mimic blown head gaskets when hot but have leaks under the valve seats.
Reply:I have one of those CK torches, bought for same reason. Will not handle amps needed for welding in port. I have arced through a few of the heads (torch) trying. I plugged seat side and welded in port without gas cup. This gave best visibility. Your efforts to purge seem good, why do you think you are loosing coverage? A lot of castings are full of crap and will not weld nice no matter what you try. Your efforts look good from my experiences.PeterEquipment:2  old paws2  eyes (that don't look so good)1  bad back
Reply:Originally Posted by castweldI have one of those CK torches, bought for same reason. Will not handle amps needed for welding in port. I have arced through a few of the heads (torch) trying.
Reply:If contamination was on a fairly clean weld that will rule out "casting crap"! Keep trying, oh and post what does work. To get into some tough ports I have milled a window through water jacket and one side of port, welded and replaced windows. Fun. I get a kick out of customers asking "can you?" Some freak about price though.PeterEquipment:2  old paws2  eyes (that don't look so good)1  bad back
Reply:Originally Posted by castweld To get into some tough ports I have milled a window through water jacket and one side of port, welded and replaced windows. Peter
Reply:I did a similar build up operation on the short side radius of an aluminum intake port.  I was having all kinds of problems getting good gas coverage, until I came up with the following solution.  I just cut off one side/edge of a standard collet body gas cup, which allowed me to fit the open end of the cup right up close to the heated area, and get the gas in there.  To grind the cup I used a diamond burr, kept wet with water.I remember doing some of the welding on that project, with the torch stuck in one end of the port, while looking into and feeding filler rod through the other open end of it.  Some of it (being located on the short side radius) I couldn't even see, so I had to stick a tiny little "mirror on a stick" I had into the port to check progress, in between weld deposit attempts.  Pretty much a "guess what you think the puddle is doing, and then stop and check" method.  Maybe think of it as "using the force" while TIG welding.  That was definitely a challenge.  I dipped (and had to regrind) my tungsten quite a few times on that one. Attached ImagesLast edited by jakeru; 04-07-2011 at 03:00 AM.
Reply:Any chance you could build a glove box with enough visibility and with the ability to maneuver both the part and the torch, plus afford the argon to clear all the oxygen/nitrogen well too? Maybe go really fancy and have remote sensing and a screen to see what you're doing, like with some fancy medical operations done today?
Reply:Originally Posted by Oldiron2Any chance you could build a glove box with enough visibility and with the ability to maneuver both the part and the torch, plus afford the argon to clear all the oxygen/nitrogen well too? Maybe go really fancy and have remote sensing and a screen to see what you're doing, like with some fancy medical operations done today?
Reply:Looks like you jumped in the deep end of the pool 4sfed, and seem to be doing well.Is this something for your own hot rod, or does it have customer potential?Matt
Reply:Originally Posted by Matt_MaguireLooks like you jumped in the deep end of the pool 4sfed, and seem to be doing well.Is this something for your own hot rod, or does it have customer potential?Matt
Reply:Tough shielding gas flow kind of suggests "glove box" to me as well.Interesting project, to say the least.  Like many things, the 'idea' is simple.  It's turning the idea into reality that is a bit more dificult.     The best laid schemes ... Gang oft agley ...
Reply:Just wondering if ultrasonic cleaning of the cylinder head has been tried before welding?AWS certified welding inspectorAWS certified welder
Reply:I agree the chamber/glove box would solve the shielding gas problem, but access is difficult enough without having to work inside inside a box.  For the purge setup, I used one of the large champagne nozzles inside an aluminum plug, but it quickly melted the screens because it was too close to the arc . . . probably losing some effectiveness.  Next time I plan to add a couple inches of tubing to move it farther back.I did not use an ultrasonic tank . . . sshhhh! . . . after bead blasting, I used the wife's dishwasher . . . when she wasn't home.  Plus, I believe Castweld was right Originally Posted by castweldIf contamination was on a fairly clean weld that will rule out "casting crap"!
Reply:Originally Posted by castweldI have one of those CK torches, bought for same reason. Will not handle amps needed for welding in port. I have arced through a few of the heads (torch) trying. I plugged seat side and welded in port without gas cup. This gave best visibility. Your efforts to purge seem good, why do you think you are loosing coverage? A lot of castings are full of crap and will not weld nice no matter what you try. Your efforts look good from my experiences.Peter
Reply:Originally Posted by brandon75173 What you have going there doesnt look bad, really.  Run it!
Reply:Originally Posted by jakeru . . . I just cut off one side/edge of a standard collet body gas cup, which allowed me to fit the open end of the cup right up close to the heated area, and get the gas in there.  To grind the cup I used a diamond burr, kept wet with water.I dipped (and had to regrind) my tungsten quite a few times on that one.
Reply:I have an aluminum head I am planning to do some modifications on and it will need a good bit of tig welding. Do you have to (or should you) heat treat the head after welding is complete? If so- where do you get that kind of thing done? Nice work btw.