Macadoo

I dropped my block, crank, and pistons at the machinist today and he was concerned about the weight difference between the stock 455 pistons and the Sealed Pro L2323F 30 over pistons. He said a little balancing is no big deal but if they are a lot heavier, the plugs will get VERY expensive.
I've been looking for weight specs and can't find anything about either piston.
Anyone have experience making this swap?

Macadoo

Okay, so I found this over on Real Olds Power:

"stock early 400 piston and pin = 455 weight, about 865 g. iirc, pin weight is about 190g."

And:

"Speed Pro L2323F= 684g"

I would assume the 30 overs are a little heavier. And so far no listing for pin weight on the L2323F's.

wr1970

It isn't a problem on the balance of the rotating assembley. These have been around awhile. Never heard of anyone needing to add plugs for these.

cutlassefi

You won't need any heavy metal with those pistons. But you will need extra clearance, 004-.005 total piston to wall. Too bad you picked that piston though.........

seansolds

Hi Macadoo, been awhile.. Good to see the upgrades!
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You have me curious about this. Are you talking about the Compression Ratio or the quality of the piston itself?

cutlassefi

It's probably the worst forged aftermarket piston available for a 455 Olds. Heavy, short, and with an antique ring pack, the worst.

Macadoo

I haven't purchased the pistons yet (I dropped off my stock pistons and rods) but I did find a good deal on the L2323F's with Hastings molly rings.

If I go with a lighter piston then we'll need to remove material from the crank counterweights, yes?

Mark, I'm listening. What pistons would you recommend?

Macadoo

Hey Sean. Good to hear from you my friend!

wr1970

No you will not need to remove material with lighter pistons. Mark will tell you what pistons but you need to tell him your budget.

Troys Toy 70

My vote listen to Mark. Here was my philosophy build the best bottom end you can afford. I understand budgets and there are plenty of L2323's out there to say they are adequate. Price your options and make your decision. The machine work will cost basically the same no matter which piston you use. You can gain some extra power and have a more efficient motor with better pistons. L2323's put you around 9-9.5:1 with standard heads and gasket.

Macadoo

The budget went out the window already, lol. When I see what pistons Mark recommends, I'll adjust from there. The goal is to have the motor ready for next summer so I'm not in huge hurry, other than needing to tell the machinist what I'm getting.

The Rocket Racing .028 Cometics are on back order and not expected to be back in but I'll go as thin as I can, but that depends on the pistons. The chambers CC'd around 82 but I'm going to double check that. I'd like to get somewhere around 9.5 - 9.75:1 but that's a hard mark to hit, apparently, without decking and/or milling the heads. I don't want to get into intake fitment issues.

olds 307 and 403

I must have bought one of the last sets of .028" head gaskets from them. If you buy a better piston, 0 decking will require less milling, just use the regular .040" Felpro head gaskets with iron heads.

joesw31

Mac, its been a long time. Those speed-pro pistons have been around since the 455 has been around. And thanks to technology we much more choices out there for our engines. I have used these pistons, and I didn't have any issues. Most people/ machine shops make the error of not putting enough clearances on the piston pin, and piston to wall clearance. I think knowing your performance goal would help Mark in his recommendations.


I have steel shim head gaskets if you decide to go that way.

Macadoo

Well fellas, I double checked my CC measurement and I think I nailed it this time. I didn't see any leaking through the valves or spark plug and zero bubbles in the alcohol. Looks like I have a whopping 83.5 CC chambers. I suppose that's due to all the polishing that was done to the chambers.

Performance goals are difficult to articulate exactly. I won't be taking it to the track, I don't think. It needs to be street friendly but at the same time I want to be able to tear up said street when the mood strikes. Honestly, one of the reasons I picked up the 455 is, well..........with the wife, and sometimes her brother, in this heavy car, I feel like I'm driving a 1975 Mustang II. If that makes any sense.

So I'm looking for a piston that will yield around a 9.5 CR with minimal decking and an 83.5 CC compression chamber. Several trusted people have advised against shim gaskets. Rocket Racing does sell custom .028 gaskets but they're pricey. $105 each if memory serves. In any case, I want to stay under 10:1 CR. I'm used to using 93 octane Shell fuel (I push the advance on the small block pretty hard) but I don't want to get into boosters or constantly carrying acetone in the trunk.

cutlassefi

Either the Wiseco or KB Icon piston would be a much better choice.
With an 83cc chamber, .015 deck and regular head gasket you'd be around 9.6:1 or so. Very safe for premium pump gas.

joesw31

The 455 will give that torque you need! I have never had a shim head gasket fail on me in all the years that I have used them, I believe its personal preference. It sounds like you may need an engine built more for torque, maybe equivalent to towing. I'm sure Mark can get you the right camshaft for your needs.


Good luck with your build.

dalilama

Ha! I fully expect to be watching you and Copper smoke the tires at Joliet Raceway. 'Tis a no-brainer

Macadoo

https://www.go-parts.com/wiseco/wise.../i-589409.aspx

So, it looks like a CR point drop for every CC increase in chamber size (probably not that simple, but a starting point), I might be looking at a 9.6:1 CR with these pistons and no significant head milling? Am I on the right track?

Thanks Joe. Yeah, I used Smitty's shims on my current small block with a thin coat of copper spray on each side. No problems here either and they helped me keep my monstrous 8.3:1 compression ratio, lol.

Troys Toy 70

Keep in mind cam profile and overlap also have an influence here not just CR. It sounds like your are sorting it out to get all of your components to work together. Waiting to see where you end up.

tru-blue 442

Following along guys, carry on.

Macadoo

My cam is a donor from CopperCutlass and he's tossing in new lifters. Much appreciated, the deeper I go the more I need donations, lol.
The specs:

512/512 224/232 duration @ 050 0n a 110 lsa. Its a howards.

Lift I understand, duration too (a little) but lobe separation I don't quite understand yet.

Macadoo

I dunno' dude. After this build I won't be able to afford the helmet!

Macadoo

For anyone following this thread, Wiseco changed their part number for these pistons from PT053H3 to PTS537A3. I called and they said the dimensions are the same but they improved the forging process (?) and include a better ring pack. The rings are file-your-own so I guess I have some work to do. Or I may look for another ring pack. My machinist said they are good pistons "for the money". The weight varied by a couple of grams from piston to piston and he said there really wasn't a good place to grind to even out the weight but he wasn't too concerned.
Because of the part # change, I might have overpaid. I found these with the upgraded # on eBay for about $80 less than what I paid:

https://www.ebay.com/i/391593224610?chn=ps&dispItem=1

For more updates on this build, check out my other thread: "Mystery 455"

Macadoo

After taking another look at the eBay ad, I don't see where it mentions the ring-pack. Odd but may account for the cheaper price.

RandyS

Look again down in the description area ......... (Comes with Rings - Yes)

cutlassefi

Uhh I thought you were going to let him charge you whatever anyway?

Macadoo

True. But I might have mentioned the eBay price. I wasn't privy to his cost. I was just posting this info for anyone looking.

Macadoo

Oh, yeah, I get what you're saying. It was badly worded. I didn't buy my pistons outright, I got them through the machinist which is probably why I paid more than the eBay price. But the original part# was higher on-line than what he was charging me.