Another A15 build thread, piston selection and such.

[Stoffregen Motorsports]

You have a military tank?

[pdp8]

I wound up with a set of pistons made by ITM.  Never heard of them, but they were cheap, available, and came with rings which claimed to be made in Japan.

The wrist-pins all measured within .1G of each other, the rings did as well, but the pistons, well ouch.  2.6g from the heaviest to the lightest.  That's about 1% of the weight of the piston and represents quite a bit of aluminum to remove on such a small piston.  Still, after most of two hours now the pistons are also within .1g of each other.  I'll weigh them with rings and pins to make sure I don't stack any errors on assembly.

 

Next up, con rods.  Factory rods and STD bearings.  I have to build a little fixture so I can balance the big and small ends separately.

 

All my aftermarket valves and guides arrived and they do check out in terms of meeting factory spec for diameter and clearance, which is more than I can say for the used factory parts I had, but even at that they are on the loose side of what the manual calls for.  The guides might shrink very slightly once pressed into the head I suppose.

 

I also spent many hours cleaning up the block preparatory to boring, honing, and coating.  Hours with a die-grinder and detail disk sander removing casting roughness and flash, rounding holes, trimming down some lumpy bits.  It's a silly and time-consuming way to shave a few ounces of weight, but sometimes you just have to embrace it I guess.

[datzenmike]

I think the guides once installed are reamed to perfect correct sizes. Don't forget to properly check and set the ring end gap.

[Stoffregen Motorsports]

11 hours ago, pdp8 said:

I wound up with a set of pistons made by ITM.  Never heard of them, but they were cheap, available, and came with rings which claimed to be made in Japan.

The wrist-pins all measured within .1G of each other, the rings did as well, but the pistons, well ouch.  2.6g from the heaviest to the lightest.  That's about 1% of the weight of the piston and represents quite a bit of aluminum to remove on such a small piston.  Still, after most of two hours now the pistons are also within .1g of each other.  I'll weigh them with rings and pins to make sure I don't stack any errors on assembly.

 

Next up, con rods.  Factory rods and STD bearings.  I have to build a little fixture so I can balance the big and small ends separately.

 

All my aftermarket valves and guides arrived and they do check out in terms of meeting factory spec for diameter and clearance, which is more than I can say for the used factory parts I had, but even at that they are on the loose side of what the manual calls for.  The guides might shrink very slightly once pressed into the head I suppose.

 

I also spent many hours cleaning up the block preparatory to boring, honing, and coating.  Hours with a die-grinder and detail disk sander removing casting roughness and flash, rounding holes, trimming down some lumpy bits.  It's a silly and time-consuming way to shave a few ounces of weight, but sometimes you just have to embrace it I guess.

 

 

ITM is an aftermarket brand that has been around since I can remember. Pretty standard stuff.

 

While you're in there, make sure to chamfer the oiling galleys, like in the main bearing saddles on the block and in the crank journals. Do you know what an eye chamfer is? It is shaped like an eye.  You can do it with a cartridge roll on a porting tool or die grinder.

 

Here's a pic.

 

 

The holes in the block don't need an eye chamfer, but a gentle hit with a chamferring tool, and then be sure to deburr them too.

 

Also, make sure your cam bearing oiling holes all line up before you install them in the block. You could chamfer those holes too in the bearing and in the block.

[Hendrik]

What is the best way to build an NA A14/15 Race engine to make the most Hp possible 

[Stoffregen Motorsports]

Race engine for what? Road racing?

[Stoffregen Motorsports]

There are very few companies still making competition parts for A series Datsun motors. ARE still makes aluminum valve covers and dry sump systems for them.

https://drysump.com/index.php/oil-pans/nissan-datsun/81-datsun-a12-a13-a14-dry-sump-pan-1140