[Paisan]

Hi guys - my son and I are finally at the point to purchase our Forged Pistons. I am looking for recommendations from the experts. To summarize where things stand at this point:
481988 block standard bore
061 Heads, Ported, new valves, new seats, screw-in studs & upgraded springs
We still need to finalize our cam selection and rockers, but see no reason not to pick up the Pistons now.

Thanks for your input

[yahooskidoo]

Autotec from Paul at Muscle Motors.

[Paisan]

Sorry guys , I suppose I should actually ask a question. Do you have any preferences regarding a good set of Forged Pistons? What about pressed versus floating pins? Is a there a an upside to one versus the other?

Thanks

[Will]

I can't comment on brands, last set I bought was Ross and they seemed like very nice pieces, but that was a long time ago and there are more options now, such as the autotecs yahooskidoo is recommending.

As for the pins, I would always go floating if I had the choice. Several advantages - no heating of the rod end to install the pins and no chance the pins can work out and destroy a cylinder wall being the main ones.

[steve25]

JE has a great alloy for there Pistons that allow for a tight near cast piston bore clearance !

[blykins]

I use Racetec pistons in about 99% of my engine builds. Very pleased with them.

A floating wrist pin is the "modern" thing. As others have pointed out, it's easier to set up and assemble.

I also use modern ring packs on my stuff....most of the time going with a 1.5/1.5/3mm ring pack.

For the price of an SRP/JE/Diamond off-the-shelf piston, you can have a fully custom Racetec piston, which would allow you to adjust the compression height to your specific build, adjust the volume, etc, etc.

[snake charmer]

Look into DSS, they make a very good set of Pontiac pistons and are priced reasonable.

[Paisan]

Once again guys, I appreciate all of the input. One additional question. When I initially took the short block to the engine builder and when he disassembled it, he noted what good condition all of the components were in - including the Pistons. He said that even though Pistons were in fantastic shape, I should upgrade to forged as well as upgrade to ARP rod hardware. He said that boring the block was absolutely not necessary.. What are your thoughts? Before I spend money on Pistons, should I have the cylinders border? I see that most Pistons are oversized and the selection of standard bore designs is limited.. I spent the money on the ARP hardware, but still may upgrade to forged rods. The builder says that as long as I don't plan to beat on it regularly above 5500 rpm, it is not necessary.
I do not want to waste money, but don't want to skimp and regret it later..
Thanks again for all of your input.

[ponyakr]

Originally Posted by yahooskidoo

Autotec from Paul at Muscle Motors.

X2 on the Auto-Tec pistons. You can get extra pin height, at no charge, so less will need to come off the block to achieve near zero deck height. Probably cost less than $500, total.

But, if your heads have 72cc chambers, you might have just a hair too much compression for pump gas. The Auto-Tec pistons have only 3.8cc valve reliefs.

I ran these #'s thru the Wallace CR calculator:

400 + .030, 72cc heads, 3.8cc valve reliefs, .039 x 4.3 head gaskets, .010 deck height

http://www.wallaceracing.com/cr_test2.php

Calculator says: CR = 10.52

Some say you can get by with this IF you bleed off some of the compression with the correct cam and have exactly the correct carb and timing tune. I say: Why take a chance ?

Might be better to go with a Race-Tec custom, or something else with a small dish, to lower CR below 10.0. Some say 9.5 is safe. Others say that's ridiculous and is just being repeated from reading it online somewhere. But it's your money, therefore your decision.

I-con makes a 14cc dish 400 piston, with a 1.720 pin height.

http://www.rpmmachine.com/shop/index..._detail&p=6218

http://www.cnc-motorsports.com/icon-...-150-bore.html

Low budget guys still use the heavy SP L2262F forged press-pin pistons. A set of these with moly rings are about $375 on Ebay. They have 6.7cc valve reliefs and a 1.714 pin height. They come in std bore, as well as .020, .030, .040, & .060 oversize. They are plenty strong, but are heavy and use wider rings. So, most of today's engine builders badmouth 'em. There have been thousands of Pontiac engines built with these pistons. I built and raced several myself. Never had a single problem with 'em. They were TRW brand back then.

http://www.ebay.com/itm/Speed-Pro-TR...RWvhp2&vxp=mtr

"...I spent the money on the ARP hardware, but still may upgrade to forged rods..."

I'd go with the RPM 5140 forged rods, minimum.($288)

http://www.racingpartsmaximum.com/sa...tockrod-2.html

If you decide you want floating pins, you can upgrade to RPM bushed H-beam rods.($400)

http://www.racingpartsmaximum.com/sa...elhbeam-2.html

"...I see that most Pistons are oversized and the selection of standard bore designs is limited..."

The SP pistons and the 8-eyebrow I-cons come in std bore.

http://www.summitracing.com/parts/ue...-std/overview/

[berniearlta]

Contact Paul Kippens (PAUL K) of this forum. He can direct you to exactly the right piston for your build. Super nice guy.

[blykins]

Originally Posted by berniearlta

Contact Paul Kippens (PAUL K) of this forum. He can direct you to exactly the right piston for your build. Super nice guy.

Where exactly are you located? I'm about 30 minutes east of Louisville....

[berniearlta]

Originally Posted by blykins

Where exactly are you located? I'm about 30 minutes east of Louisville....

New Albany.

[blykins]

Wow, you're close....

[Will]

If the bores are in such good shape that an overbore isn't needed, then I'm curious how to ensure proper clearance if buying standard size pistons.

What if the bore ends up just a tad on the big side after re-honing (which will absolutely be necessary) and you end up with excessive clearance?

[blykins]

Any piston made for a standard bore should have the proper clearance built into it.

However, if you had to hone the block several thou to make sure the bores and straight and round, then the custom Racetecs can be made to any bore size, in .001" increments.

[berniearlta]

I'm assuming that he is looking for pistons after cylinder clean up. Weather it a bore or a hone. No matter which clean up, the tolerance must be right for the alloy used. That is why he needs to consult with Paul K and his machinists.

[Will]

Originally Posted by blykins

Any piston made for a standard bore should have the proper clearance built into it.

Well yeah, but there can be variances in the factory bore sizes and the assembly workers had different size pistons available to account for this. As you know, just a couple thousandths can make a big difference, so it just seems to me the possibility of error is higher if going this route.

Of course, if you know your bore size after the cleanup then you would know whether a particular piston would work so I'm probably over thinking this.

Originally Posted by blykins

However, if you had to hone the block several thou to make sure the bores and straight and round, then the custom Racetecs can be made to any bore size, in .001" increments.

That is good to know.

[72blackbird]

You guys are suggesting $500- 600 pistons to the OP? It doesn't sound to me like he's trying to build an all-out race engine. Sealed Power forged pistons are fine for his application- pressed pins are also fine as long as the machinist knows what he's doing.

A forged 5140 rod is a good upgrade too - cheap insurance. Both of these will live forever in a 400 that will never see more than 5500 rpm.

It's typical to overbore and hone to the next size up as well- this keeps all of the tolerances within spec and assures the cylinder bores have the right finish and roundness to allow the rings to seat properly. It goes without saying that the new rotating assembly should be balanced as well to assure long bearing life. Oil clearances should also be blueprinted to assure good oil pressure- these are all engine building fundamentals that should not be skipped to save costs, provided you want your rebuild to last a long time.

Geno

[tom s]

I put Racetecs in my last 2 builds.They are about 5 miles from my house.Tom

[Cliff R]

I have JE pistons in my engine, have used quite a few Ross and more recently Icon pistons. Never had any issues with any of them. You couldn't give me a set of the Speed Pro/TRW forgings, I'd toss them on CL quicker than it took me to type this!......Cliff