rebuild kits
- Thread starter PhXStAnG
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Yep, there are some radical shallow deck pistons which can take the Aussie or even F150 300 I6 rod. Both these rods are 6.275 and 6.209 " respectively, with, in most cases, a 912 thou wrist pin which fits right on.
Possibly too much is made of the shorter than ideal 5.885" 250 rod in the Aussie and US sixes. But the short deck ACL pistons are super light, very strong, and cheap. Going to the 300 six cylinder rod is going to give you a huge improvement it upper rpm power, and result in no loss of torque at the bottom end. They are also very resistant to cracking. Some GM Holdens run them with turbo pressures of up to 18 psi. Here is some info, but hook on this link http://fordsix.com/forum/viewtopic.php?t=5269
4.1 x-flow 6.275" rod hi comp/performance acl auzzie pistons have 8.6cc bowl (6mkry9412)
4.1 x-flow super duper flat top i (think these are 6.275 " rod pistons too -xecute) (6mkry9413)
ACL is a piston maker who now have affiliations with BMW piston supplier Mahle, who did M3/M5 pistons, and has links to the Repco company who did production based race engines with considerable sucess in Formula One, Production Enduro and F5000 in the 60's and 70's. These days, ACL supply the Buick/GM 3800-based Formula Holden open wheelers (where cars have 320 hp+) with parts for these machines, along with 290 hp+ Holden 253 V8 control engines for the Commodore Challenge. The pistons, rings and bearings survive scorched earth tactics of some hard cahrging Aussie racers.
The rest of the engine, especially the US crank with its wider thrust and main bearings than the Aussie sixes, has huge appeal.
Possibly too much is made of the shorter than ideal 5.885" 250 rod in the Aussie and US sixes. But the short deck ACL pistons are super light, very strong, and cheap. Going to the 300 six cylinder rod is going to give you a huge improvement it upper rpm power, and result in no loss of torque at the bottom end. They are also very resistant to cracking. Some GM Holdens run them with turbo pressures of up to 18 psi. Here is some info, but hook on this link http://fordsix.com/forum/viewtopic.php?t=5269
4.1 x-flow 6.275" rod hi comp/performance acl auzzie pistons have 8.6cc bowl (6mkry9412)
4.1 x-flow super duper flat top i (think these are 6.275 " rod pistons too -xecute) (6mkry9413)
ACL is a piston maker who now have affiliations with BMW piston supplier Mahle, who did M3/M5 pistons, and has links to the Repco company who did production based race engines with considerable sucess in Formula One, Production Enduro and F5000 in the 60's and 70's. These days, ACL supply the Buick/GM 3800-based Formula Holden open wheelers (where cars have 320 hp+) with parts for these machines, along with 290 hp+ Holden 253 V8 control engines for the Commodore Challenge. The pistons, rings and bearings survive scorched earth tactics of some hard cahrging Aussie racers.
The rest of the engine, especially the US crank with its wider thrust and main bearings than the Aussie sixes, has huge appeal.
Howdy PhXStAnG:
You might try working with your machinist. Most machinists who do a lot of rebuilds have a kit source who give package pricing and machinist discounts. It is best to not order pistons until the cylinders have been assessed and repaired.
When you say "Performance" pistons, what level are you talking about. In the USA you have two choices; stock type cast pistons and custom forged.
In cast, you can get both the small and large dish type, a flat-topped and a taller 255 ci V8 piston with an increase of .085 deck height. Any of these pistons are cheaper than forged and good up to 10:1 CR and about 250 HP. Anything above that and you're better off with the extra expense and noise of Forged pistons.
With a 250, one of the biggest performance hinderances is the monstrous stock deck height. Mine measured a full .150" stock. You may be best off to deck the block .065" and use the 255 V8 pistons at .085 taller (less deck height) to get closer to zero deck height. If neccessary, to control compression, you may need to mill a "D" shaped dish in the piston top that mirrors the combustion chamber. Even with the extra custom milling these pistons would be cheaper than forged.
If you go this route, be sure to use hardened washer on the head bolts to prevent them from bottoming out in their holes.
Adios, David
You might try working with your machinist. Most machinists who do a lot of rebuilds have a kit source who give package pricing and machinist discounts. It is best to not order pistons until the cylinders have been assessed and repaired.
When you say "Performance" pistons, what level are you talking about. In the USA you have two choices; stock type cast pistons and custom forged.
In cast, you can get both the small and large dish type, a flat-topped and a taller 255 ci V8 piston with an increase of .085 deck height. Any of these pistons are cheaper than forged and good up to 10:1 CR and about 250 HP. Anything above that and you're better off with the extra expense and noise of Forged pistons.
With a 250, one of the biggest performance hinderances is the monstrous stock deck height. Mine measured a full .150" stock. You may be best off to deck the block .065" and use the 255 V8 pistons at .085 taller (less deck height) to get closer to zero deck height. If neccessary, to control compression, you may need to mill a "D" shaped dish in the piston top that mirrors the combustion chamber. Even with the extra custom milling these pistons would be cheaper than forged.
If you go this route, be sure to use hardened washer on the head bolts to prevent them from bottoming out in their holes.
Adios, David
I'm not sure there is adecent webiste. They had a downloadable catalogue, but you needed an understanding of the mnemonics... Like I said, alloydave is a good guy to look up. He's not able to sell direct (shame, 'cos he'd make a killing on this site), but will give good honest answers. Typical price for ACLs with file fit rings comes to about USD$300 plus postage.
As XECUTE noted, these pistons can take serious boost!
Regards, Adam.
As XECUTE noted, these pistons can take serious boost!
Regards, Adam.
