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Author Topic: Team Go Dog, Go! Modified Partial Streamliners  (Read 520268 times)
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wobblywalrus
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« Reply #2775 on: May 01, 2017, 01:10:37 AM »

Both of my pipe welds looked good.  The welds were ground flush with the surrounding metal.  An expert, in a PM, suggested I check for porosity.  He saw some in the picture of one pipe.  Some rubber stoppers were put on both ends of the pipes.  A hose and spigot were attached to one stopper so I could blow air into the pipe when it was underwater.  Little bubble trails indicated pinholes on both pipes at the outsides of the bends.  These little holes proved to be impossible for me to fix.  The metal around the welds was ground a little bit when I made the welds flush.   Now it was far to thin and perforated.

Some work with a center punch showed where the thin places were.  I tried to build up the metal thickness using little pulse welds.  It worked.  Tomorrow I will put on another layer to fill in the gaps and holes.

Yesterday I welded my skoolwork project to the metal table.  The prof brought over an electric angle grinder to remove it.  He asked "Do you know about these?"  I said "Yes, I am very familiar with this tool."


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wobblywalrus
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« Reply #2776 on: May 02, 2017, 08:41:49 AM »

Last Sunday Gretchen was trying to learn some sort of French etude on the piano.  She kept banging away on the same line of music till she got it right.  Then she moved on to the next one.  That is what I need to do and it is to repeat the same thing till I get it right.  So, a bunch of lobster back practice rings are cut from a 16 gage straight section.  The gap between the two sections was set at .030 and it was tacked up.  Then, I went around the periphery with small tack welds one next to the other.  No penetration.  Tonight I will do the same thing with tacks except I will make a small circular movement to put more heat into the weld pool.


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Peter Jack
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« Reply #2777 on: May 02, 2017, 08:56:44 AM »

You're now learning why tig is so much nicer for this type of work Bo. With the control pedal you can vary the heat as you work and it's almost impossible not to get the proper penetration. I have no doubt you'll succeed with the mig. Your determination to master whatever you attempt sometimes amazes me.  cheers cheers cheers  grin grin grin

Pete
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wobblywalrus
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« Reply #2778 on: May 02, 2017, 10:26:21 PM »

Some stuff about MIG welding stainless is on Lincoln's website.  They say to follow the seam with a back and forth method.  Sorta like walking in a straight line and taking two steps forward and one back.  The weld in the first photo shows a 3/4 inch long pass made that way.  The second photo shows penetration on the other side before I remembered to turn on the back purge argon.  The third photo shows penetration with argon.  Note how it is much better with than without it.  The hole in the pipe happened when I was working with the torch too far away.  It is vital to keep that 10mm tip to part distance.


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wobblywalrus
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« Reply #2779 on: May 05, 2017, 08:14:51 PM »

The cylinder head flow data arrived from Kibblewhite.  This last intake tract test they made was on a head with 2mm larger intake valves, porting, a hogged out Triumph manifold, 39mm Keihin flat slide carbs, and oiled foam pod filters.  The setup flowed around 212 cfm at 28 inches.  Bigger carbs and a pleated oil gauze filter was recommended by Kibblewhite.

The bigger carb and filter idea sounded good.  How to do it was confusing.  A conversation in Sacramento with the tuner for the factory Triumph mile bikes gave me the answer.  He had a set of 45mm Mikuni's with big K and N filters.  I bought a pair and they were installed with a hogged out Triumph Performance manifolds. This does the job.  Flow with the same valves and ports goes up to 230 cfm, an 8.5 % increase.  The basic horsepower formula says:  0.26 x 230 x 2 x 0.9 x .86 = = 92  hp at the rear wheel at B'ville.  This is not enough to get me a record.  It will be good for over 150 mph with a streetable motor running on unleaded with a muffler, which is a long term goal.

The valves in a Cosworth design are at the corners of the combustion chamber.  Larger valves and seats require metal removal from the periphery of the chamber and this dramatically drops compression.  A tuner needs to be aware of this and increase valve sizes just enough to do the job and no more.  The intakes had larger seats installed and a 2mm increase in diameter.  The exhausts were enlarged 1mm and the stock seats reworked to give better flow.  This increased flow between 2 and 16 percent depending on valve lift.  The desired exhaust flow is between 80 and 90 percent of intake flow.  That target was hit.  The intakes and exhausts flow the same at low lifts near 1/8 inches.  This is not uncommon and no need to worry according to the expert at Kibblewhite.  This cylinder head is the best it can be.

The K and N sock was used over the filter during the flow tests.  It was on the filter when I sent it to him and I asked him if it is a good idea.  He said yes.  The sock is a good thing when considering the racing environment.

   

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wobblywalrus
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« Reply #2780 on: May 10, 2017, 12:18:08 AM »

Progress is being made in weldingville.  My welds are ugly but better than before and functional.  A mount is cobbled up for the back end of the collector and a lobster back piece is attached.


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Peter Jack
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« Reply #2781 on: May 10, 2017, 12:32:11 AM »

Keep up the welding with as many projects as you can and then build another set of pipes in a year or two after you've had a reasonable amount of practice. The results will be totally different from what you're getting now. Hand skills take a while to build up and actually seeing what's happening in the puddle takes a while too.

Pete
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wobblywalrus
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« Reply #2782 on: May 10, 2017, 07:05:52 PM »

I was told to use .025 or .023 wire to keep the welding a bit slower and easier.  That helped a lot.  The teacher showed me how to lay the pipe on its side and to weld vertically in the downhill direction on the side of the pipe.  That helps to get penetration.  Also, he said to set the pipes up with a small .030 to .050 gap.  This helps.  Also, chamfering the pipe ends helps, too.

This place is backwoods.  A week and a half ago I ordered the .023 308L-SI wire through a local welding supply.  Four stores do not carry it.  It was due to come in today.  The wire was never shipped 'cause it was less than some exorbitant minimum order.  No one told me.  So, I cancelled the order.  it was ordered from Grainger and will come in on Tues or Wed next week.  Now, everything the welding stores do not have on their shelves for instant purchase will be ordered through Grainger or McMaster Carr.

The next set of pipes will be made from 18 gage.  These 16-gaage pipes weigh as much as a baby elephant.  There is no need for ballast. 
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wobblywalrus
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« Reply #2783 on: May 14, 2017, 01:24:37 AM »

The collector is finished an mounted.  It is 2.5 inches ID which seems awfully big for a 1,000 cc engine.  The virtual modeling tells this big diameter is needed to get correct wave action.  In fact, the program would go nuts and give me goofy results if I used a smaller diameter collector like 1.750 inches.


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wobblywalrus
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« Reply #2784 on: May 14, 2017, 10:58:20 PM »

Argon is used as a purge gas inside the pipe.  Lots of folks tape the pipe ends or use corks to keep the gas inside.  These will not work for lobster back construction.  Short tubing rings are welded onto the pipe and the welding is near the end.  A cork or tape would be burned.  This is another method to keep the gas in the pipe.

Washers that are leftovers from hole sawing are used with some metal plates.   One washer that is just small enough to fit in the pipe is attached to a square plate with an eyebolt.  A spring is attached to the eyebolt and a chain is attached to the spring.  A round disk is also made up with a washer and eyebolt for the other end of the pipe.


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wobblywalrus
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« Reply #2785 on: May 14, 2017, 11:03:40 PM »

This is the gas fitting on the other side of the round plate.  The chain is threaded into the pipe and the square plate is held up against the end.  The chain is threaded through the pipe and the piece to be attached to the pipe.   The spring is stretched and a link of chain is attached to the hook on the round plate.  The remaining chain is inside the pipe.


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wobblywalrus
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« Reply #2786 on: May 14, 2017, 11:06:41 PM »

The spring tension holds everything together for welding.  The purge gas is retained in the pipe, too.


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wobblywalrus
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« Reply #2787 on: May 16, 2017, 11:08:52 PM »

Equivalent gasolines so I can tune for MUL-C are not available here for a reasonable price.  The MUL or its Sunoco equivalent need to be shipped.  The freight is very expensive.  Two drums of Sunoco's highest octane unleaded are ordered.  It is GT260 Plus.  One drum will be for tuning and the other for B'ville.  There is no shipping charge for this blend.

Cam lobe and lifter failure have been a problem when cams taller than the all-purpose #813 grind are used.  The situation was reexamined by the expert at Kibblewhite.  The lobes are too close to the edges of the lifters.  The the head is being bored for 30mm tappet buckets to replace the standard 28mm ones.  That will put the bucket edges 1mm further out and it will be just enough for the higher lift #408 cams.

The valve springs were ordered for a set of cams much more radical than the 408's using a 10,000 rpm redline.  Careful tuning using salt flats density altitude says these milder cams with a 9,000 rpm redline will work just as good, or better.  Kibblewhite examined the spring rates for this milder setup and reduced the pressure over the nose by 30#.  That should help valve train life.

The 308L-Si wire arrived today.  It lays down and penetrates better than the 308L wire.  It is better for pipe building.  The megga is done.  This short bugger gives the best wave dynamics according to the virtual model.  Progress is being made.   


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wobblywalrus
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« Reply #2788 on: May 17, 2017, 11:14:18 PM »

It is no problem to make a decent MIG weld now.  The only issue I have is seeing where I am going.  Do the top end welding helmets give any advantages for this?  The one I have now is a Miller Digital Infinity.
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« Reply #2789 on: May 17, 2017, 11:20:36 PM »

Better helmets do definitely help IMO.
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