Poll: ’70 2.2E: What P&C’s to use??

[19-911-65]

Hi Everyone!

I have a rebuild coming up this summer and would like to know the “brain trust” consensus on what would be the better of the two choices for P&C’s. As of right now the engine will go back together relatively bone stock. Our main concern is overall longevity of the rebuild.

I thank you in advance and any positive comments are welcome!

Glenn

[Steve@Rennsport]

Glenn,

For maximum longevity and durability, Mahle is the best choice.

[HawgRyder]

Or...if the wallet is a little fat...try Nickies....LOL
Bob

[tom1394racing]

I recently purchased a set of AA 84 mm Biral cylinders. I was was impressed with the overall quality. I did a dimensional inspection and found them to be spot on.

I also have heard that they perform well for street application and at $400/set are a bargain.

[19-911-65]

Thanks to everyone for their input and thoughts!!

Glenn

[Henry Schmidt]

I agree with Tom that the AA cylinders are a very nice alternative to used Mahles.

During our evaluation of these (we test all new products) we found the AA cylinders tested a few points low on the Rockwell scale.
In response to this issue (perhaps non-issue) we decided to Cryo treat the cylinders.
After a gradual descent, continuous chill for 40 hrs and a gradual ascent to ambient temp, the cylinders are heat cycled to xxx (trade secret) degrees three times to establish a stable molecular alignment in the cast iron.

Although this maybe overkill, we find the results compelling and reasonable insurance.

[chris_seven]

Henry,

I assume that you are measuring with Rockwell C - can you let us know the values?

I also assume that you are suggesting that Cryo treatment followed by some thermal cycling increases the hardness? and if this is the case what increase have you measured.

If you have a measurable increase in the hardness then this is a very significant result and worthy of a much deeper analysis.

[Henry Schmidt]

Originally Posted by chris_seven

Henry,

I assume that you are measuring with Rockwell C - can you let us know the values?

I also assume that you are suggesting that Cryo treatment followed by some thermal cycling increases the hardness? and if this is the case what increase have you measured.

If you have a measurable increase in the hardness then this is a very significant result and worthy of a much deeper analysis.

We tested them on the "B" scale.
The factory cylinders were 92 +or- 2 and the AA cylinders were 86 +or - 2.

We also measured the Mahle and AA cylinders after 40 or so hours of racing with Mahle cylinders showing about a 4 point drop in hardness and the AA showing no change.

The Cryo and subsequent heat cycle does not change the hardness of the cast iron.
It changes the cast iron at a molecular level making the iron more stable reducing wear and improving the cooling characteristics of the cast iron and the aluminum fins as a bonus.

[chris_seven]

Henry, Thanks, interesting numbers.

Both seem a little bit soft and I would have expected modern centrifugally cast iron liners to be somewhere between 99 and 106 Rockwell B.

The Rockell B scale is a little non-linear at high hardness levels so the differences are perhaps a bit greater than it seems to a brief examination. (Rockwell C is very non-linear in comparison)

There are still a number of liners being produced at around the 85 Rockwell B level but I think these are mainly used in industrial diesel engines.

It will be good to see how they last.

I have to say that I am a non-believer in terms of cryo treating grey cast irons but I am sure that this won't surprise you

[Henry Schmidt]

Originally Posted by chris_seven

Henry, Thanks, interesting numbers.

Both seem a little bit soft and I would have expected modern centrifugally cast iron liners to be somewhere between 99 and 106 Rockwell B.

The Rockell B scale is a little non-linear at high hardness levels so the differences are perhaps a bit greater than it seems to a brief examination. (Rockwell C is very non-linear in comparison)

There are still a number of liners being produced at around the 85 Rockwell B level but I think these are mainly used in industrial diesel engines.

It will be good to see how they last.

I have to say that I am a non-believer in terms of cryo treating grey cast irons but I am sure that this won't surprise you

The science is becoming very clear on cryo.
Every NASCAR team that builds there own components have in-house cryo. facilities.
I would be surprised to hear that any F1 team functions without cryo technology.
The US Postal service demands brake rotors that are cryoed from all of their suppliers.
The post office has documented up to 500% increase in rotor life on their stop and go delivery vehicles.
Off road truck are seeing 150 -300% life increases on axles and differential gears.
Drag racing engine builders are reporting 600%+ life extension on the valve springs.

The science is difficult to explain to layman like myself so I couldn't be expected to explain it to an engineer like yourself but I've seen the evidence in my own engines and ancillary components.
We use cryo in many of our rebuild processes.
Our reconditioned rockers are all cryoed as are cranks, rods and valve springs.
I am inches away from buying my own cryo system so I can control the cost and quality of the service. We also see improved clutch (including flywheel) life and grip from cryoed components.

[chris_seven]

Henry,

I don't think I should hijack this thread to discuss Cryo treatments as it could become quite involved but I can't resist making some comment.

Metallurgically there is some very good science with regard to the benefits of DCT particularly for tool steels and other heat treatable alloys and I started using this process to improve the dimensional stabilty of load cell blanks more than 25 years ago.

We have also recently made some 915 Gears and these were Cryo treated after case hardening but before shot-peening and grinding.

For the 'right' materials I would be happy to accept cryo treatments as good practice and would buy in to the process.

It is just the subject of Cryo treating Grey and SG Irons that I don't buy into.

Unhappily there is just as much BS flying around as there is good science and some of the claims being made show a very confused grasp of Physical Metallurgy to the point that it becomes unbelievable.

For example to claim that a typical cast iron brake rotor contains retained austenite which is transformed by the Cryo treatment is just plain wrong.

Most Rotors are still sand cast and hence are slow cooled, this process just doesn't cause retained Austenite.

The comment is made that the 'molcules' re-arrange themselves to fill up voids is another concept that I find bewildering.

Atomic migration in metals is certainly something that does occur but mechanisms of this type are always thermally activated - reducing the temperature stops diffusion from occuring. (Fick's laws)

I would also say that in over 40 years working in Metallurgy I have never seen voids in metals 'fill up' due to any process other than forging or rolling. I do understand why this statement is made and it is due to a concept concerning 'mobile vacancy dislocations'. These defects do exist in all metals and the number present is simply a function of temperature, Reduce the temperature the number reduces, increase the temperature the number increases again. It is simply a reversible process. To suggest otherwise shows a lack of fundamental understanding with regard to the nature of metals.

Many of the Cryo discussions also liken the Carbon in steels to Diamond - again complete and utter BS. In many Cast Irons there is free Graphite - soft and used in pencils and in steels the carbon forms carbides - either Iron of Chrome, Moly, Vanadium etc, etc. Nothing like diamonds.

Without a good background in Physical Metallurgy it is difficult to seperate the good from the BS and in general Cryo treatment does no harm so even if it doesn't meet the claims you only lose a few dollars.

[Henry Schmidt]

Chris, once again I am neither an engineer, scientist or even a smart guy like you but I have seen the benefits of cryo treating cast iron rotors, gear sets, R&P and other item like rockers first hand.
I own a first generation 4 wheel drive Tundra with totally inadequate brakes.
Given that I tend to drive pretty deep into corners (left over from my Porsche days) the brake rotors tend to over heat and warp with 2 or three weeks of install.

I use factory brake rotors because in the 280k I have on my truck, my experience is that they are the best.

After simply cryoing a new set of rotors, amusing that overnight I didn't change driving habits, not only is the brake warping issue completely gone, it seems that the rotor life was extended about 250 %.

I am now on my second set of cryo rotors and I am seeing the exact same results.
Antidote ? of course but personal experience is how I learn.

[Flieger]

Anecdote, not antidote. Darn autocorrect.

I find this all very interesting. Thanks for having the discussion.

[Henry Schmidt]

Originally Posted by Flieger

Anecdote, not antidote. Darn autocorrect.

I find this all very interesting. Thanks for having the discussion.

"I am neither an engineer, scientist or even a smart guy"
I think this statement covers spelling errors

[Hcarraro]

Subscribed

[19-911-65]

Thanks again everyone...we bought a new set of stock Mahle 2.2E P&C's

Glenn