11 replies to this topic

[PACINO]

I am going to rectify the block at 0'40 and I want to install some good pistons, and they take much longer to wear out than the ones I currently have. Only 20k miles have lasted.

I have to choose between Omega or Swiftune pistons.
What do you recommend?

Cheers in advance!

[nicklouse]

Omega most likely make the Swifttune ones.

 

there are different grades of Omega pistons.

[PoolGuy]

As it's a road car I'd be happy using either Omega cast pistons or the Swiftune (Mahle) cast pistons, you won't have any issues with either. I used Omega because the Swiftune weren't available in std size, I would happily have used Swiftune ones if they were available in the size I wanted. Get whatever ones are available at the best price in the size that you want.

[Cooperman]

For road engines I have always used the 21253 pistons which are available in up to +0.060" (1330 cc).

They are good for a sustained 5500 rpm to 6000 rpm with running up to 7000 rpm at times and at a CR of up to 10.5:1.

I have never had any issues with them except when an excessive CR has been used with incorrect distributor advance.

[PACINO]

As it's a road car I'd be happy using either Omega cast pistons or the Swiftune (Mahle) cast pistons, you won't have any issues with either. I used Omega because the Swiftune weren't available in std size, I would happily have used Swiftune ones if they were available in the size I wanted. Get whatever ones are available at the best price in the size that you want.

Thanks a lot for your opinion Poolguy. A salute!

[PACINO]

For road engines I have always used the 21253 pistons which are available in up to +0.060" (1330 cc).
They are good for a sustained 5500 rpm to 6000 rpm with running up to 7000 rpm at times and at a CR of up to 10.5:1.
I have never had any issues with them except when an excessive CR has been used with incorrect distributor advance.

Master Cooperman, this is what Minispares LTD says: "AE Hepolite is now owned by Federal Mogul and trademarked Nural".
These pistons are what I fit a few years ago. After 20K miles, I've lost compression in the cylinders as I showed with pictures last week. By the way, you didn't say anything about it.
I don't know the cause, but the compression engine is minor. Maybe the ignition was too early. Don't know. So now I'm looking for something of better quality. I'm even thinking of fitting forged pistons.

Thank you very much.

[mini13]

reading though your other post, you say the bores are not worn,

 

how worn are the pistons? I am wondering if re ringing the existing pistons with something like total real rings would be an option.

 

Also, as it is only 2 cylinders down on compression this suggest to be that there may be an underlying cause, for example not enough ring gap in those cylinders, or bore wash.

[PACINO]

reading though your other post, you say the bores are not worn,
 
how worn are the pistons? I am wondering if re ringing the existing pistons with something like total real rings would be an option.
 
Also, as it is only 2 cylinders down on compression this suggest to be that there may be an underlying cause, for example not enough ring gap in those cylinders, or bore wash.

Well, I dont know Mini13. I'm looking for the photos I took three years ago when I lifted the stock. The heads of the pistons did not move at all when given by hand. I saw them well. The inside of the cylinders do not show wear. But, the compression gives 130PSI/9bar and five years ago it gave 180PSI/12.5bar. In these last years I do less than 1000 miles a year. Oil and filter change every year. Millers or Valvoline oil.

[nicklouse]

 

reading though your other post, you say the bores are not worn,
 
how worn are the pistons? I am wondering if re ringing the existing pistons with something like total real rings would be an option.
 
Also, as it is only 2 cylinders down on compression this suggest to be that there may be an underlying cause, for example not enough ring gap in those cylinders, or bore wash.

Well, I dont know Mini13. I'm looking for the photos I took three years ago when I lifted the stock. The heads of the pistons did not move at all when given by hand. I saw them well. The inside of the cylinders do not show wear. But, the compression gives 130PSI/9bar and five years ago it gave 180PSI/12.5bar. In these last years I do less than 1000 miles a year. Oil and filter change every year. Millers or Valvoline oil.

 

That is not piston wear.  It’s valve seats and/or piston rings.

[OzOAP]

Cast Omega and Swift pistons use the same ring packs. I use both, no problems. Swift have a 6.5cc dish, Omegas the same and 10cc. Have also redished Swift brand to 8cc.
Minispares sell the Swift ones at a good price.

[PACINO]

Cheers Nicklouse and OzOAP.

[Cooperman]

I am quite sure Nick is right.

My advice is to check the bores for wear, hone and fit 'Total Seal' piston rings. These have a 'gapless' second ring.

Whilst it is down check and re-lap the valves, check the valve guides for wear and fit new top-hat seals, Check out the bottom end. I virtually always fit new main and big-end bearing shells, new crank thrusts, a new oil pump and new timing chain. The 21253 pistons should be fine unless you have run with excessive advance and broken the ring land(s).