Piston options for Buick 430

I’m currently looking for new pistons and needed help with a selection. The engine is going into my 67 wildcat built for street ( cruising with a extra kick). I have iron heads not ported, TA 212 cam with a stock intake with most oil mods done. I know I want forged pistons which are hard to find ( it’s already 30 over but want to go to 40). I’m hoping to get more horsepower with upgrades. Maybe some one could tell me what they think it’ll gain.

My first question is what’s the benefit of going forged instead of cast and is it really worth it.

Second, can I just take a 455 piston ( smallest one they have).

And lastly, my rods are in really good shape do I have get new ones.

Any help would be greatly appreciated

 

Somewhere i read a fellow used a set of forged 454 Chevy pistons (4.250 bore) in a 430 with minimal work. There are so many cheap options i think it was cost effective..

I've had cast pistons in my 430 for 17 yrs now with out issue..

 

If the cylinder walls are thick enough, you could bore to 455 standard size, and use 455 pistons. Question is, are the cylinder walls thick enough.

Cast pistons are perfectly adequate for mild performance use, forged are better if detonation is expected. NO piston will survive heavy-throttle detonation, but forged will last longer than cast under moderate detonation. Light-throttle detonation can largely be ignored, GM called light-throttle detonation "The Sound Of Economy".

I wouldn't sweat forged pistons for your use. GM is putting hypereutectic cast pistons into most of it's "performance" crate engines, and virtually all of the as-sold-new-in-the-car engines.

The big advantage to the pistons sold by Tri-Shield Performance (Jim Weise) is that the compression height is correct for the Buick block and available head gaskets. The OEM piston compression height is way low, which was bad enough with embossed-steel-shim (THIN) head gaskets, but even worse now that those gaskets are extinct and the common replacements are twice as thick.

 

A big plus for Forged Pistons with today's fuel that few seem to mention is that they run atleast 100 degrees cooler which helps big time with quelling potential ping and knock issues!
If your not time or money wise too pressed I would go the Forged route!

 

The Buick 400 and 430 have an unusual issue that makes most common aftermarket cast pistons worthless.

The compression distance is incorrect.

The Sealed power 368 is, for example, 1.947.

That will leave your new pistons around .080 in the hole... I Have had several recently rebuilt 430's with cast pistons sent to me, to re-do, because they detonated so bad, they were unusable.

This is because when the 400/430 were introduced at the SAE Conference in Jan of '67, the information given pegged the deck height at 10.540, but no production BBB was less than 10.570. So either that information, or incorrect early piston blueprints were used by the aftermarket to build the pistons with the wrong CD, and they never bothered to correct the CD,,, not for 50 years anyway..

There maybe some obscure cast piston manufacturer that corrected this, but I have yet to see it. I rarely build cast piston motors, my experience is mainly limited to fixing them, with correct spec forged pistons.

ON the 430, I like to go to 4.250, better ring availability.

I have the done both 400 and 430 pistons with Auto Tec, these 4032 forged pistons carry the correct specs to be used with the stock rods, and have some wiggle room with dish volume, to get the compression ratios correct for both Iron and Alum head builds.

JW

 

Oh my, I just stumbled on this thread. I'm currently rebuilding my engine (1969 430) and I just set on reusing the pistons I put in 15 years ago. Only drove 10k miles, and they're looking fine. The invoice states I have Silvolite 1728. So I assume they're wrong too? I didn't experience detonating issues, engine ran fine. Is there something I can do or check? Or leave them in? I did just order new piston rings from TA.
(@OP sorry for hijacking this thread a little bit)

 

Silvolite is typical "rebuilder" pistons. Cheap, and almost certainly short on compression height.

Put one in the block, connect to crankshaft, see how high it comes up in the bore. I bet you'll be horrified.

 

Hm. How much should it be? .050, since there apparently is a .030 deck difference?

 

You will have to check

 

These older GM engines were usually designed to use an embossed (stamped) steel shim head gasket, typically .020 thick or thereabouts.

With a .020 piston-below-deck, you get .040 quench distance total. Works good.

At rebuild time, you cut .020 off the decks to straighten and smooth them, and use a .040 composition gasket. Quench is still .040, and it still works good.

'Course, some guys think they can put an embossed steel shim gasket on the decks after they've been cut. Carnage ensues when the piston hits the head at higher RPM. The aftermarket responds by building "destroked" pistons, the compression height is deliberately lowered by .010 or .020, so that even an idiot can rebuild an engine without measuring quench distance.

Now you have the problem where Buick has a taller deck-height than expected. (Chevy* also had this problem, as did Ford**, and--probably--everyone else) The original pistons were way the hell too far down, and the aftermarket puts 'em even lower. And to add injury upon injury, GM has long ago discontinued the embossed steel shim gaskets leaving us with no good (inexpensive) choices to close-up the quench distance.

You can:
Mill the hell out of the decks
Stroke the crankshaft
Buy pistons with proper compression height
Buy (custom) rods with added length
or some combination.







*GM was having problems meeting advertised horsepower specs for a certain range of SBC engines. The engineers discovered that the compression ratio was too low. They go to the engine factory, and discover that the deck height was uniformly too high on a bunch of bare blocks that they measured. The factory manager was getting BONUSES for telling his production crew to go to the extreme high end of the tolerance range--it saved both time on the machining line, and it reduced wear on the cutting tools "saving GM money". The guy was being paid EXTRA to sabotage the engine block machining.

**Ford did essentially the same thing on some of the Big Block engines, except this was intentional--they raised the "official" deck-height spec in order to drop compression ratio for emissions reasons.

 

Hey,

What costs the custom pistons for the 430?

 

Chevy use a .990 pin so anything save in those pistons would be ate up by having to get new rods to accept .990 pins.......which might be a mute point if buying rods anyways