compression

54-4x4

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I built a small fly cutter from an old bolt and brazed a carbide on the end.The carbides I use are from a sawmill and when the mill went to narrow curf on their saws the old carbide teeth were given to me.They are perfect for making a lathe or milling cutters.After grinding the carbide cutter to the shape that matches the dish in the old pistonDSCF4279.JPG I did a trial cut for the dish on the piston.I started with a .100" dish then measured the CCs.Too deep as I got 15 CCs and was hoping for 12.Good thing I have 2 extra pistons.I'll try about a .070" deep cut on the next piston and see what the CCs are.I was a little wide on my cut as well so that will make for more volume.Next try I will leave about .050" from my line then on my last cut go to the line.Live and learn I guess.
 

THE FRENCHTOWN FLYER

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I really like your methods. Did you use a rotary table to spot in the OD of the dish?

What do you use to profile a carbide cutter? I've tried to use a green stellite grinding wheel with limited success.
 

Mdixon300f100

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THE FRENCHTOWN FLYER":1678s038 said:
I really like your methods. Did you use a rotary table to spot in the OD of the dish?

What do you use to profile a carbide cutter? I've tried to use a green stellite grinding wheel with limited success.

We use diamond wheels in our machine shop for cemented carbide.
 

54-4x4

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This afternoon I played around trying to get the correct shape and depth of cut to obtain a 12 CC dish.Lots of foolin' around,cutting 10 thou at a time then trying to get the CCs with no bubbles.DSCF4280.JPGThis is my setup.I was fortunate a friend had this rotary table that he said he never used for 14 years so take it home with you if you think you can use it.That was cool.I never used one before so it was fun getting the hang of it.DSCF4285.JPGI used some solvent with a little ATF for colouring.No bubbles this time.DSCF4286.JPGProbably hard to tell in this picture but the bottom piston is a keeper.12 CC dish,.090 deep and cut just to the line.Now if I can do the rest the same I'll be smiling.
 

54-4x4

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THE FRENCHTOWN FLYER":19k8ojrp said:
I really like your methods. Did you use a rotary table to spot in the OD of the dish?

What do you use to profile a carbide cutter? I've tried to use a green stellite grinding wheel with limited success.

I did use a rotary table with a 4 jaw chuck and a dial indicator to center the piston and get it leveled.
To grind the carbide saw tooth I use for the cutting ,I profile it with a green stone in the grinder and use a small square against the tool shank to check for a flat cutting edge on the bottom.The angled part I just eyeball it and do a trial fit on the old piston with the bottom cutting edge resting on the flat of the dish.When I get the angle correct I can't see light where the carbide meets the dish.
The saw filer that gave me a handful of carbides said to use silver solder to attach them but I just braze them on.
 

54-4x4

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After milling a 12CC dish .090 deep in the rest of the pistons and juggling the heaviest wrist pin with the lightest piston I found a weight difference from the heaviest to the lightest of 2.3 grams.
 

THE FRENCHTOWN FLYER

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2.3 grams will be OK. Its less than three standard paper clips or three raisins. The carbon build-up on the pistons will probably vary more than that.
 

pmuller9

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Radius all of the edges from the piston top going into the dish and any other sharp edge you see on the piston top.

If you want the pistons closer in weight add larger radiuses in the underside of the heavier pistons or blend in the casting area which has the crosshatch where it extends on to the inner side of the piston.
Removing casting lines helps.

Very Nice work!
 

54-4x4

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I'll try and get a picture of the pistons tomorrow.They came out pretty close.I will make them weigh the same.Should the edge of the piston top have a slight chamfer on it where it meets the cylinder wall?
 

pmuller9

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Yes on the slight chamfer to the piston top outside edge.

I want to revise what I said about weight reduction after looking more closely at the piston bottom view.
The bottom of the skirts are rough looking and you can smooth them out and also remove a small amount all way around the bottom of the skirt to get equal weight.
 

54-4x4

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Thanks for the kind words yesterday you guys.
I evened the weights of the pistons and chamfered the top edges and took care of the sharp edges in the valve relief areas too.Polished the piston heads a bit as well.DSCF4287.JPGDSCF4292.JPGhere's the tops,they all weigh the same 827.4 grams.I have 7 to choose from.DSCF4293.JPGyou can see the difference from the stock piston and the modified 352 piston.Stock weighs 825 grams,modified 827.4 grams.The stock pin is 149.5 grams compared to the 352 pin 185.1 grams.The pins are the same length and diameter so you could use the the stock pins in the 352 pistons and get a lighter combination.This is the heaviest piston that required the most modification inside the skirts to balance the same as the lightest one.
I am quite pleased the way they came out.
 

pmuller9

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It's a shame that you are going to hide those pistons in the engine!
It been fun watching you work.

Where did you leave off with the cylinder head?
What size valve are you going to use?
 

bubba22349

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54-4x4":10p5v6ao said:
I would like to use the stock lighter pin but I realized I turned two of them down to a light fit like a floating pin so I could mock up the pistons in the block to do my clearance check for deck height.I should have turned down 2 of the 352 pins because I have 8 of them.The 352 pistons will be a little lighter than the stock pistons so that would make a better combination.
Maybe I should look at boring out the 352 pins or even taper boring if that is feasable?

Very nice job on machining and matching the weights of the 352 Pistons! Curious did you decide to taper or bore out the 352 pins to make them a little lighter too? :nod:
 

54-4x4

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pmuller9":yjrpgujr said:
It's a shame that you are going to hide those pistons in the engine!
It been fun watching you work.

Where did you leave off with the cylinder head?
What size valve are you going to use?
I left the cylinder head for the time being.I wanted to do the pistons.I will revisit the head after I get these pistons in the block.
 

54-4x4

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Bubba22349,I tried boring a pin but it was pretty slow.It surprised me how hard they are compared to the stock pins.I need to make up a small carbide boring bar.I think I will leave them alone but still want to try boring a pin just to see if I can do it.
 

54-4x4

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This afternoon I built a little jig to hold a piston while installing a wrist pin in a heated rod.DSCF4295.JPG
Is there some kind of formula to figure ring end gaps for 4.030 pistons?
 

pmuller9

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The following is from Speed Pro.

SPEED-PRO PISTON RINGS - INSTALLATION GUIDELINES
RING END GAP RECOMMENDATION GUIDE (FOR 4.000 INCH BORE)

Speed Pro Top Rings (ductile iron, 4" bore) 4.000" Example Minimum Gap Factor
Moderate Performance .016 - .018 (.004 per inch of bore diameter)
Drag Racing, Oval Track .018 - .020 (.0045 per inch of bore diameter)
Nitrous Oxide - Street .020 - .022 (.005 per inch of bore diameter)
Nitrous Oxide - Drag .028 - .030 (.007 per inch of bore diameter)
Supercharged .024 - .026 (.006 per inch of bore diameter)

Speed Pro 2nd Rings (cast Iron, 4" bore) 4.000" Example Minimum Gap Factor
Moderate Performance .020 - .022 (.005 per inch of bore diameter)
Drag Racing, Oval Track .022 - .024 (.0055 per inch of bore diameter)
Nitrous Oxide - Street .024 - .026 (.006 per inch of bore diameter)
Nitrous Oxide - Drag .028 - .030 (.007 per inch of bore diameter)
Supercharged .024 - .026 (.006 per inch of bore diameter)

Use .018" for the top ring and .022" for the second ring.
The two oil ring bands aren't critical but should have at least .016" end gap. They will probably come in just over .020"
 

54-4x4

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It seemed like a long time getting my rods installed on the wrist pins in the pistons.Things went fairly smooth.I was glad I took the time to build the little jig to hold the piston and get the wrist pins in the correct location on the rods.Whoeey.Gapping the rings was easy using a
fine file clamped in a vise with some painters tape to protect the file.The vise has a nice smooth flat surface to keep the ring gaps square.I touched up the burred edges with a very fine jewlers file.I'm happy with that procedure.DSCF4302.JPGDSCF4303.JPGThe pistons are now in their home.
 

pmuller9

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It's a lot of work to plan and detail an engine build but you gotta feel great when each major step is complete and looks that good!

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