[HO LEMANS]

I am getting closer to ordering parts to rebuild my 428 and I am apparently not knowledgeable to understand all of the info to make a great choice on the pistons.... I have looked at Butlers site and wow there are alot of choices, so if I could once again beg your help in deciding that would be much appreciated.
the engine will be topped with large valve #16 heads the factory intake with a RA4 cam and Crane high intensity lifters, I intend on having it balanced as well, I have read many different things stating how deep the dish needs to be in the pistons to stay just under 10.1 ranging from .007" up to .20" a ton of different opinions ..... this is going to be a street engine hopefully a spirited one but a street engine
so if you all could hit me with recommendations on which set would head me down the right path it would be super helpful

[johnta1]

Would need more data.
Stock rod size or longer?
Piston to Deck height?
Bore size?
Chamber cc's?
Also head gasket thickness"

With stock type data for .030" over bore and 72 cc head chamber you would need around 20 cc piston relief/dish.

[HO LEMANS]

Originally Posted by johnta1

Would need more data.
Stock rod size or longer?
Piston to Deck height?
Bore size?
Chamber cc's?
Also head gasket thickness"

With stock type data for .030" over bore and 72 cc head chamber you would need around 20 cc piston relief/dish.

Thank you for the reply
the rods will be stock
piston to deck height I honestly do not know at this time
bore is going to be .030" over
chambers if I remember correctly (it was a while ago they were checked) they were right at 72cc
head gaskets I have not purchased anything yet ....
but at the end you pretty much answered my question and I thank you

[hgiv]

The recipes are many. If you have a builder get their recommendations. Plus you need to know what has been done, or not done, previously. Or call butler and talk to them in person. They get paid to do this!
I think it’s best to start with a goal and a budget and work backwards. Street strip v casual cruiser.
A 428 already has a ton of torque. Doesn’t take much to build a monster. If you want one. But be careful of compression.

[HO LEMANS]

Originally Posted by hgiv

The recipes are many. If you have a builder get their recommendations. Plus you need to know what has been done, or not done, previously. Or call butler and talk to them in person. They get paid to do this!
I think it’s best to start with a goal and a budget and work backwards. Street strip v casual cruiser.
A 428 already has a ton of torque. Doesn’t take much to build a monster. If you want one. But be careful of compression.

the one thing I do know for sure is nothing has been done to the engine except oil changes and tune-ups since it was born and is still in the car (the car almost seems too nice to part out until you open the doors and see your feet where the floor boards are supposed to be.
the short block is what I need to focus on as the heads are ready to bolt on so I was just trying to get some info to proceed with.
it will not be a strip monster or anything like that I just want a strong street cruiser to enjoy.
Thanks for the input it is helpful

[steve25]

What rear gears and transmission does your vehicle have?

Here’s what come up with for needed CC volume assuming you want a 9.5 to 1 compression.

Your total cylinder CC volume at .030” over is 886.55 .

Your total CC volume at TDC that you need for that 9.5 compression is 104.3.

Knock 72 out of that leaves you with 32.3 CCs

Knock 9.4 CCs out of that for the average head gasket leaves you with 22.9 CCs.

Knock 5.079 CCs out of that for a .018” deck height leaves you with 17.82 CCs

17.82 is the dish size you will in your piston to have a 9.5 compression.

[hurryinhoosier62]

Originally Posted by HO LEMANS

Thank you for the reply
the rods will be stock
piston to deck height I honestly do not know at this time
bore is going to be .030" over
chambers if I remember correctly (it was a while ago they were checked) they were right at 72cc
head gaskets I have not purchased anything yet ....
but at the end you pretty much answered my question and I thank you

With you going to this expense ditch the stock rods for a set of aftermarket forged rods. Go with Molnar; IMO, they are the best AFFORDABLE aftermarket connecting rods. All the ones I have seen do NOT have to be tweaked because of taper and being too tight or too big on both ends. Pistons? All the custom piston makers are quoting some outlandish lead times. Contact DSS Pistons in St. Charles. IL. They normally have 428 pistons for use with the stock length rods on the shelf; the best part with their pistons is you will get a modern ring package( 1.5/1.5/3.0 mm) with Napier second rings being available. You have a competent local machine shop, yes? They CAN ensure your crank is on stroke and has no taper on the rods or the mains? How about having a set of Pontiac torque plates? Own a profilometer? ALL modern ring packs have specific finish specs for the cylinder walls.

[b-man]

Zero deck.

Have your pistons made with the correct compression height (piston pin to piston crown) to achieve that or something very close to it.

I had my 421 built with a custom Ross piston with the correct dish and compression height to achieve as close to a .040” quench as possible. My pistons actually ended up .007”- .008” above the deck even though we tried to get them at zero.

I used a .045” thick Butler composite gasket for a very nice .037”- 038” quench distance.

421 build thread: https://forums.maxperformanceinc.com...d.php?t=771742

Always shoot for zero deck, however .018” below the deck would require a .020” or .025” Cometic MLS head gasket which would be okay too.

Recently had a powerful air-cooled 2276cc VW engine (140 hp / 151 torque) built and my smart engine builder always insists (as do I) on a .040” deck height / quench distance, these engines have no head gasket. He trimmed the bottom of the cylinders to set the deck height and checked every one of the Icon forged pistons at TDC. All ended up between .037” and .041”.

The tight deck makes the engine more octane tolerant and it runs cooler as well. Don’t hesitate to get the pistons made correctly for a nice .040” quench distance, you’re already paying a bunch for a custom piston so do it right.

[Goatracer1]

I assume you will not be doing your own machine work. Give the shop the information on what you want the engine to be then let them supply the pistons. They will order the size you need and then bore and hone the block to fit them.

[steve25]

You’re assuming a competent machine shop is within his area!

I would not leave a piston order up to a shop that is not a dedicated race shop and does this kind of thing on a daily basis.

I would sooner ring up a piston manufacturer and speak to one of there tech’s.

[Half-Inch Stud]

Reco buying the pistons AFTER the Block is bored, and all 8 CYLs inspect as cleaned-up. Then you know the overbore sized piston to get.

See, i got caught flat-footed when my STD 421 needed 060 to clean-up. That would be 428+030

[HO LEMANS]

Originally Posted by steve25

What rear gears and transmission does your vehicle have?

Here’s what come up with for needed CC volume assuming you want a 9.5 to 1 compression.

Your total cylinder CC volume at .030” over is 886.55 .

Your total CC volume at TDC that you need for that 9.5 compression is 104.3.

Knock 72 out of that leaves you with 32.3 CCs

Knock 9.4 CCs out of that for the average head gasket leaves you with 22.9 CCs.

Knock 5.079 CCs out of that for a .018” deck height leaves you with 17.82 CCs

17.82 is the dish size you will in your piston to have a 9.5 compression.

Steve25
it has an M20 with 3.55 gears (67 Tempest)

Thank You for that breakdown I am not up on this stuff well enough to know that (which is why I keep bothering you guys)

[chiphead]

You order pistons AFTER the block has been checked out.

1: You need the shop to tell you the rough overbore you'll need, The final hone to size is done AFTER pistons are in-hand and measured.

2: You need the shop to tell you the deck height from center of crank tunnel to top of uncut deck. Measure lowest valve chamfer in cylinder edges. Top ring must be approx .075-.100" below the valve chamfers. Then proceed to 3

3: Select crankshaft and rod type/length. Measure those parts, and the dimension from Step 2 to determine piston pin Compression Height required. Piston CH should be .010-.020" below deck stack-up to allow final square decking on BHJ Square Deck machine or equivalent.

4: Have shop complete ALL machine work to cylinder heads. Then CC chamber size to confirm final chamber size DO NOT ASSUME. DO NOT ASSUME CHAMBER SIZE. DO NOT ASSUME THE CHAMBER SIZE

5: Select approximate camshaft grind. This will help determine compression, fuel requirements and any special valve pockets on piston.

6: Calculate compression based on 3, 4, 5. If you're not a super tuner, keep compression to 9.5 with iron heads. If you ain't skeered of blowing it up, bump compression to 10:1.

7: Select ring pack and piston material type. Old school 1/16" is good. LS style metric ring pack is great. 4032 alloy is great for hot street NA or mild nitrous/boost. Any serious power adder, use 2618 alloy.

8: Order pistons. Now that you know bore size, compression height, dish required, ring pack type/location, pin type (pressed vs floating) and aluminum alloy, order the pistons.

[HO LEMANS]

Thank You to all that responded it's all great info and some stuff I had not thought of or didn't know or both.... I will take the advice given and have a discussion with the machine shop and move on from there.

once again as always I do appreciate the knowledge here and find it fascinating reading some of the threads on here, the stuff you guys know and have done the data and info about the cars and engines which plant did this and which plant did it like this etc.... it's just awesome

Thank you