3.720 Piston Rings

schaferstephen

Well-known member
Looking to source some rings - getting custom pistons made (3.720" bore) and i need the size of my rings for RaceTek...Does anyone know the dimensions of Mike's rings? Or can you recommend another source for Moly rings for a .040 over 250? Thank y'alll.
 
Most all piston companies like JE, Wiseco, Venolia and others often have rings for the piston sizes they offer. Check with them first and confirm that size ring is available before you have pistons made, or you may end up being like a ship without a harbor so too speak.
 
Most aftermarket custom piston companies make their ring sizes different than what the stock sizes are, so you'll need to discuss that with Racetek when you order your piston set and make sure the bore size and width are available for they are making them.
 
schaferstephen":1k8hiqo8 said:
Looking to source some rings - getting custom pistons made (3.720" bore) and i need the size of my rings for RaceTek...Does anyone know the dimensions of Mike's rings? Or can you recommend another source for Moly rings for a .040 over 250? Thank y'alll.


Just curious on what custom pistons you're getting. Are they forged? Different compression heighth? Or something else.

What are they costing you?
 
I'm getting custom forged, they are identical to the ones that... 66bronco? I believe? Is using in his 250. I am building the 250 w/ longer 300 forged rods, and by using these shorter pistons I effectively get 0 deck. They're running me about 600.
 
Top marks, ticks and accolades for supporting your own industry, and thinking outside the square!

That is such a good option. I know 600 ping is a lot of bacon, but it eliminates lots of problems so long as they are clearanced properly, and you don't run the engine hard without a proper warm up. You've got the toughest rods, the toughest pistons, and the best small Ford six, the 250.

For those of us who have 200's, those same pistons can be used with the commonly avaliable (in the US, and everwhere overseas that they have 2.0 liter Capris and Cortinas and Escorts and Transit vans) ages old 1970-1974 Pinto 2.0 nominal 5" rod which can take eithet the 0.945 or the large Big Six large wrist pin, and have the crank ground down to the Pinto rod bearing sizes. Its a very strong rod, despite being a factory econo crap box conrod.

For others who cannot over bore there 250 block any longer due to cracks or score marks, in the Scatt cataglouge on page 44,
http://www.scatenterprises.com/docs/cra ... s-pdf.html
there is a common small wrist pin 6.059" Aussie EL2, BA-FG turbo conrod, incorrectly listed as 0.992 wrist pin size that is designed for the CP 0.866" wrist pin forged piston.

If you have a bearly salvageble 250 US block, adding some cheap Clevite list sleaves and taking down the bore to 3.652" will allow you to get the cheaper 1.1629" deck non forged ACL's with 0.912" pins, or the increadably strong factory Turbocharged CP 26 cc dish 20 thou over pistons. With the longer bomb proof 6.375" Scat Pontiac or Nissan 240SX rods, you'll improve the rod ratio upwards on even the 6.21" Big Six rod, and you'll then have something that will last a long time under any load you wanna throw at it. You might loose capacity (it will max out at around 246 cubic inches or 4027 cc exactly, a loss of 62 cc's or 3.78 cubic inches over the factory stock bore 250 capacity), but you will save the block, and something equally as strong as a Race Tek pistoned 200 or 250.

Manly and Scatt do US made Aussie conrods for about 300 US, and with a good 20, 30, 40 or 60 thou overbore, you can run the common normal Australian 250 3.70/3.71/3.72/3.74" ACL or Mahle non forged pistons with 23 cc dishes, which you can take down from there stock 1.531" compression height to 1.455, and still get a 12 cc dish. This takes up the nasty 103 thou piston short fall all 250's have, and you a better qaulity piston. The cost equation still works out in favour of the non forged piston, but you then might have problems getting the high silcon pistons from the Australian suppliers.

The CP's forged pistons are a little cheaper than Race Teks, but you get better US backup for the RaceTeks.

viewtopic.php?f=3&t=67134

There is little bit of head scratching with small sixes, but your solution is the very best option.

For 600 dollar US pistons and proper 4.9/300 cube Big Six conrods in the 250, it solves having to hunt around for sleaves and oddball rod and pistons combos.


Down here, we find that our conrods and pistons are able to take very high revs in high boost situations, where 500 hp is possible without going to forged pistons. I use factory non forged pistons and a special kid of Ford marketed forged conrod, and the EF 12 counterweight cranks with sleaves because its cheaper, and more reliable under the moderate 12 psi boost conditions I'm using in my planned engines. I've spent ages looking at how to keep engines in the 375 to 425 hp range together, and years of work by Ford and Holden gurus has shown that you don't have to go to forged pistons fi there is a really good hyperutectic.

In the US, all your cast alloy pistons for Ford small I6's look to result in failure in heavy use, but I'm not sure why. Aussies had the same problem untill 1964 when Ford Australia changed the piston design, and kept the forged conrods forever. It could be the subtle differences with HSC 2300/2500 piston offset, the oil relief holes, or a combination of factory low quality conrods, don't know, but using forged pistons and big six rods for the US 250 six is the only option since the stock rods were so badly downgraded from the ealier forged rods for so many years.
 
xctasy, thanks for the info. It is good to hear you approve!! For me, it's worth a bit of extra cash to have the reliability of the forged internals, and the ease of finding them... I definitely want an engine that I can run hard and not worry about. The 200 I have now is shot to hell... Starts to vibrate badly around 4000 RPM, burns oil like no tomorrow... But it still runs, it's a beast in its own right! The sleeves you mentioned are an interesting idea, but one I did not look into...Maybe in the distant future, but honestly, probably not for this engine.

Can't wait to get this 250 up and running. If you have any more advice, don't hesitate to let it fly! Always appreciated.
 
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