Hi all -
I'm filling in the floor of the exhaust ports of some motorcycle heads for vintage racing. I've had some success, but it's sure hard and I could use some help getting "over the hump" so to speak.
One issue is of course that the heads are 40 years old, and very contaminated. I've been bead blasting the ports, die grinding to clean and washing with carb cleaner or acetone (whichever I happen to have at the time). That seems to work ok, once I get going. Getting things clean enough to weld seems to take several iterations of weld/grind/weld/grind. They're of course way too small for a stainless brush, even a cut down one.
Another issue is that I'm more than maxing out my machine - a Synchrowave 180 (and the breaker it's on). I could use more power. I am pre-heating before welding and it helps but not enough.
The third issue is just a matter of size, the ports are very small and difficult to reach into far enough. I could use an arc bender... :-)
It's very hard to reach in the ports at all, even with a way too small cup on the torch, especially as far in as I need to reach in and fill for best flow. I would usually be using a gas lens, but there'd be no way to see or put in filler with a gas lens setup - the cup would pretty much fill up the port. Also, the port forms a nice venturi to drag air into the weld no matter what you do with gas flow. I've tried using alum. foil stuffed into the valve seat with moderate success there. I've thought of using a gas lens and rediculous tungsten stick-out but haven't tried it.
What I've been using so far that's worked as well as anything is a 1/8" pure tungsten, a #5 cup which is about as large as can fit in the port, and about 20-25 cfm of pure argon. To reach way in I have to stick the tungsten too far out and have a lot of problems with oxygen contamination and arc wander around to other parts of the port as it's almost impossible to get much of an angle at the floor of the port. The part of the port near the exit is a piece of cake by comparison.
The first pic I've attached is an unmodified port - It's hard to see but you should be able to get relative size by the torch - it's a WP20 size with a #5 cup.
The second and third pics show partially modified ports.
The fourth pic shows a partially modified port on a later model head, with much more shrouding around the exhaust port exit making it even harder to reach in the port.
I do have a weldcraft water cooled bendy torch that's straight, but it's no smaller around than the #20 with the gasket under the cup, so it won't help in this case. Would be the bomb probably in deeper slightly larger ports.
So far my best success for getting weld far enough in to reach the "short side turn" and make an effective change is to put a blob of filler partway into the port, and use arc blow to shove some of it in farther. I'm definitely maxing out my maching trying that, and it takes a lot of weld/grind/weld/grind cycles to do anything remotely effective.
I've been doing a lot of research both here and on weldingweb.com and it looks like some of you might really be able to help with some advice on gasses, etc. Also, if anyone has any ideas about arc redirection or how to weld in really tiny ports.
Now - these don't have to be quality welds, inclusions are even okay I suppose though I like to do quality work always. What I'm doing is reshaping the ports for better flow and proper size. We've learned a lot about proper port size and shape since these heads were made.
From what I've read, it looks like I want to experiment with helium mixes at least, possibly straight helium and DCSP. I do have an XMT300 with an HF-251 box in the shop as well (usually hooked up to a 22a wire feeder) - which would entirely solve the power problem if DCSP and helium is the answer.
It also sounds like a helium/argon mix with the Syncrowave might be worth trying, either buying a bottle of mix or trying to mix my own from a separate helium bottle and a y fitting. I've been watching ebay for a smiths mixer for several months, and I'm sure I will eventually fine one, but right now they're not coming up.
My inclination is to buy a bottle of helium and try both about a 50-60% mix of helium/argon with the syncrowave on AC and a y fitting, and straight helium and DCSP with either the syncrowave or the xmt.
Any advice appreciated. If I can make this significantly easier and quicker than it is right now I think there'll be a market for modified ports. As it stands I'm doing this for my own racer and a couple of my sponsored "development riders."
Thanks -
Michael
I'm filling in the floor of the exhaust ports of some motorcycle heads for vintage racing. I've had some success, but it's sure hard and I could use some help getting "over the hump" so to speak.
One issue is of course that the heads are 40 years old, and very contaminated. I've been bead blasting the ports, die grinding to clean and washing with carb cleaner or acetone (whichever I happen to have at the time). That seems to work ok, once I get going. Getting things clean enough to weld seems to take several iterations of weld/grind/weld/grind. They're of course way too small for a stainless brush, even a cut down one.
Another issue is that I'm more than maxing out my machine - a Synchrowave 180 (and the breaker it's on). I could use more power. I am pre-heating before welding and it helps but not enough.
The third issue is just a matter of size, the ports are very small and difficult to reach into far enough. I could use an arc bender... :-)
It's very hard to reach in the ports at all, even with a way too small cup on the torch, especially as far in as I need to reach in and fill for best flow. I would usually be using a gas lens, but there'd be no way to see or put in filler with a gas lens setup - the cup would pretty much fill up the port. Also, the port forms a nice venturi to drag air into the weld no matter what you do with gas flow. I've tried using alum. foil stuffed into the valve seat with moderate success there. I've thought of using a gas lens and rediculous tungsten stick-out but haven't tried it.
What I've been using so far that's worked as well as anything is a 1/8" pure tungsten, a #5 cup which is about as large as can fit in the port, and about 20-25 cfm of pure argon. To reach way in I have to stick the tungsten too far out and have a lot of problems with oxygen contamination and arc wander around to other parts of the port as it's almost impossible to get much of an angle at the floor of the port. The part of the port near the exit is a piece of cake by comparison.
The first pic I've attached is an unmodified port - It's hard to see but you should be able to get relative size by the torch - it's a WP20 size with a #5 cup.
The second and third pics show partially modified ports.
The fourth pic shows a partially modified port on a later model head, with much more shrouding around the exhaust port exit making it even harder to reach in the port.
I do have a weldcraft water cooled bendy torch that's straight, but it's no smaller around than the #20 with the gasket under the cup, so it won't help in this case. Would be the bomb probably in deeper slightly larger ports.
So far my best success for getting weld far enough in to reach the "short side turn" and make an effective change is to put a blob of filler partway into the port, and use arc blow to shove some of it in farther. I'm definitely maxing out my maching trying that, and it takes a lot of weld/grind/weld/grind cycles to do anything remotely effective.
I've been doing a lot of research both here and on weldingweb.com and it looks like some of you might really be able to help with some advice on gasses, etc. Also, if anyone has any ideas about arc redirection or how to weld in really tiny ports.
Now - these don't have to be quality welds, inclusions are even okay I suppose though I like to do quality work always. What I'm doing is reshaping the ports for better flow and proper size. We've learned a lot about proper port size and shape since these heads were made.
From what I've read, it looks like I want to experiment with helium mixes at least, possibly straight helium and DCSP. I do have an XMT300 with an HF-251 box in the shop as well (usually hooked up to a 22a wire feeder) - which would entirely solve the power problem if DCSP and helium is the answer.
It also sounds like a helium/argon mix with the Syncrowave might be worth trying, either buying a bottle of mix or trying to mix my own from a separate helium bottle and a y fitting. I've been watching ebay for a smiths mixer for several months, and I'm sure I will eventually fine one, but right now they're not coming up.
My inclination is to buy a bottle of helium and try both about a 50-60% mix of helium/argon with the syncrowave on AC and a y fitting, and straight helium and DCSP with either the syncrowave or the xmt.
Any advice appreciated. If I can make this significantly easier and quicker than it is right now I think there'll be a market for modified ports. As it stands I'm doing this for my own racer and a couple of my sponsored "development riders."
Thanks -
Michael
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