Hello guys,

Ive been stumped for a few weeks on which type of piston I would like to get for my 425. Forged or cast? Ive heard positives and negatives about both.

I hear forged need more bore clearance because they expand which in turn you get piston slap during start up and while it warms up. I'd like to keep this engine going for a very long time and I don't want to hurt the bores. This motor will not be getting any power adders either which is what forged are good for.

Cast I dont see a problem with but when I ask the car buddies they all say go with forged. I just don't want to have to run into any problems and regret my decision on pistons. They are kinda a big deal. And what do you guys think of the Egge or Kanter brand cast pistons??

The motor has to be bored at LEAST .030 over due to the bore sizes being .010 difference between bores and it's not getting bored till I get the pistons.

Any advice would be greatly appreciated! Thanks! By the way just snagged a 69 cutlass!

 

I'm definetely not an expert, but this is what I went with for my strictly street 1967 425ci engine... Kanter.com.... http://www.kanter.com///cart.aspx?Tg...Cat=32&Prc=362
I choose the 0.30 low compression pistons, they call them 2 barrel pistons. BTW... these were the only pistons that I could find for my engine at the time. Egge and Badger said they are not currently making them because the demand is not there.

Good luck with your rebuild!

Jaybird

 

Thank you!

 

Go with the cast, unless your going to build a high hp build. I have cast pitons in my 468. Its got alot of miles with no problems.

 

I've been going nuts trying to decide what I want to do! Hah, I just don't want to get something that I regret down the line. And no it's not going to be a high rpm motor, its gonna be a street torque monster. You should see how clean that block is! You wouldn't recognize it!

 

 

 

wow!!! that looks like a virgin casting! how'd ya do it? i've got a couple spare blocks that i'd love to be able to get that clean before i preserve them for storage...

 

i have a complete set of pistons wiith rods that are supposed to be balanced i believe there from a early olds 455.PM me if anyone is interested.

 

That looks good. But keep it covered and in climate control. You dont want it to start rusting. Good luck with it.

 

dick miller has pistons for the 425 but they are spendy... the name brand escapes me at the moment but i believe that they are diamond. at any rate good stuff and lightweight which is always good.

oldsy, do you mean 425?

 

no..from a 455.

 

For a stock build, cast is OK. CP and others can make you custom forged pistons.

 

They won't work in his build unless you use them with a 455 crank.

 

he's going .030 over so I dont think they will work.

 

I brought the block in to get pressure checked and magnafluxed and they cleaned it for me! I keep it oiled. I ended up going with a set of cast pistons, sorry such a late response. But I'm not going to be using any power adders and it's not going to be a race motor so cast should be perfect!

 

I have a set of bone stock factory Hi comp 425 pistons on the rods. came from a low mile engine. pm me for more info.
Also be sure to note when you buy the cam to spec it is a 45* block. Everything else you can think 455 (rod brgs, mains, cam brg, freeze plugs, timing chain) be sure to get the split rubber rear main seal. You may have to specify it as a Ford 460 rear main seal.
Be sure to align hone the mains with the bolts or studs you are going to use. Also deck block for straightness. You can install crank and one piston and check for deck height and decide how much to take off for compression.
Gene

 

FYI Olds 92 I do 45 degree cams as well.

 

Hey Olds92: Where did you end up getting your pistons from? It looks like Mondelleo might have some 425 pistons.

http://www.mondellotwister.com/PisPinRingBrng.htm

 

Stock build go with cast like GM put in there.... EGGE has pistons for the 425.

 

Good choice. Thats all you will need.


On a side note. Im going to be getting a small shop. Signing the lease this week. Its out in Big Rock,Il you should stop out sometime.

 

Be sure the pistons from Mondello in Paso Robles Ca are 425 pistons. I bought a set a few years back from him and all they did was mill off the tops of 455 pistons which left the top ring land to close to the top. They didn't last but a few trips down the road. The tops all warp and eat up the rings. They were only good for the trash bin. You need .200 or more from the top of the piston to the first ring.
Sounds from what you have said, cast will do just fine.

Gene

 

I ended up getting my pistons through EGGE along with a set of rings. They had them in stock and I got them in about a week. Felt longer. So just a cast piston. I'm happy with what I got and glad I didnt go with a forged. Those wouldn't be necessary for my application.

 

Hey congrats! You starting a buisness or just for your own stuff?

 

Alittle of both. Need more room for my junk, and my buying/selling junk. Now maybe i can get my 65 done this winter!

 

Never Mind