400 is out, question before machinist

[gk666]

OK... now as I said after waiting for the perfect saturday the 400sb came out on saturday, roughly 4 hours without cutting too much of anything besides the sh*t that i felt to be completely useless like power steering lines.... today at work it was relatively slow and so i got the block down to just crank and pistons and everything was pretty clean, no coolant leaks, little bit of sludge built up in the corners but its to be expected anyways... the important question... i can pretty much make up my own mind on everything else but this has way to many variables.... pistons, now iv asked a little about this before I think and unlike my audi where theres really only 1set I can buy, were talking small blocks so there's billions and the only way to narrow them down is by how much over I want to buy and the top style... even though questions still linger about the efficiency of different styles of pistons in different conditions, I would prefer to go with flat tops for the soul purpose that its in the lead for most of the discussion, but anyways... I don't really want to make the cylinder walls any tighter but I figured maybe I should go with a piston that's like 4.130 or 4.145 or something in between but also I should mention that I do not want to spend much more than 300-400 bucks... I also read why the kbs have a bad rep and I'm not really concerned with that so all I want to know is in your own wisdom great forum, for under 400 bucks what set of pistons would you recommend that are forged, flat top, and closer to 4.125 bore

now if anything I said is nonsensical correct me but thanks for any input

 

[DRIVEN]

As far as overbore is concerned - Less is more. You'll typically hear people say that either .030 or .040 is max on a 400. Maybe that's smart but I have one that's .060 over. I wouldn't have done it on purpose, I just got it that way. It's fine and only heats up when towing up a long hill. That may not be the bore as much as just not enough radiator. You didn't mention what your intended purpose for the engine is. Forged may be unnecessary in your case. You'll need to know what the head cc is along with head gasket thickness. Then you need to decide what compression ratio you want to run -- that will depend on your cam, head design, intake, carb, converter, gearing, etc. It's all about the package and it all needs to match. To paraphrase your paragraph-long question: "I have an engine. What pistons should I use?"

We need more info :lol:

 

[chevy2480]

As far as overbore is concerned - Less is more. You'll typically hear people say that either .030 or .040 is max on a 400. Maybe that's smart but I have one that's .060 over. I wouldn't have done it on purpose, I just got it that way. It's fine and only heats up when towing up a long hill. That may not be the bore as much as just not enough radiator. You didn't mention what your intended purpose for the engine is. Forged may be unnecessary in your case. You'll need to know what the head cc is along with head gasket thickness. Then you need to decide what compression ratio you want to run -- that will depend on your cam, head design, intake, carb, converter, gearing, etc. It's all about the package and it all needs to match. To paraphrase your paragraph-long question: "I have an engine. What pistons should I use?"

We need more info :lol:

+1 Just remember with flat tops in a 400 its easy to bump the compression up without trying it. I run a 4.155 bore with no over heating problems. If you plan on running pump gas go with a dish.

 

[Buford T. JuSStice]

You should have your machinist do a 0.027" over with a 0.003" hone for 0.030" over total. 0.030" over is way more than enough, and 0.060" over is about the absolute most you ever want to do. Any more and you risk permanent damage to the block, which is why it's better to stay away from going that far unless you absolutely have to (in order to correct damage inside the cylinders for example) or unless you need to squeeze every last ounce of power out of the motor as possible (drag racing, or dyno shoot outs for example)

 

[RITTER]

Is there a specific reason you are going with forged pistons :?:

 

[gk666]

ok to answer the question, I'm leaning towards machined stock heads one pump gas and its a normal street car but if im at a red light with my buddies or some of the 300hp range cars in my town I am gonna jam it and rev it and I was thinking forged pistons because I want quality internals (even though when I say quality, I sort of negate that by not wanting to spend 500-1000 bucks but regardless)

id be willing to jump the gun for 1200 dollar heads and 1000 dollar pistons if I wasn't planning on buying a muncie and the trz manual rack as well as some other suspension stuff and I also would like to be done by the end of summer

i could lean towards other heads and if you have a suggestion by all means but a lot of people say if you clean up the stock heads you will still have a lot of *ss.... but I could change my mind since the heads are a really important part of the build...

I also wont know if I need another crank until the machinist checks it out which can run a pretty penny... but I doubt I will since there's only like 100k on the motor but thanks again people keep em coming :lol:

oh and i forgot to answer the head gasket question, I dont know... at the moment I'm at work and I don't know off the top of my head how thick the headgasket on the 400 came but lets just assume I go back with a quality hg that the manufacturer encourages I use (unless you have a better one), and also given using the stock heads and normal thickness hg, what would a close guess to the comp ratios be between dish and flat top... If I remember correctly stock 400s with dish were like 7.8 or something, which I really dont care, it's just my daily with *ss, I go to meet and race people in my lincoln but I dont care how fast I'm going as long as its quick and fun and there are people in the same bracket of "slow"

 

[RITTER]

Forged pistons are just over priced, over weight and unneccessary for a street car. If this is going to be an "all motor" car, you are robbing horsepower if you put forged pistons in it :idea:

 

[gk666]

like i said i dont really care about the horsepower, but I do ask my cars to do a lot for street cars so I like to have strong parts made by people who knew what they were doing, I dont mosy around at 45 mph, I always drive like I mean it (and I definitely have a record to prove it :[... )which is why I dont like all this foo foo blow me sh*t they put in cars today BUT dont make me go off on a tangent like usual lol... like the lincoln, It's just a street daily, not so daily since i got a monte but it was a daily and i did power slides night and day at like 5 grand which in my eyes is asking a lot for a street luxury car lol even though it had a lot more *ss than people knew about... if you have an idea of a piston that can hold its weight for an ******* driver than suggest it because god knows when it comes to thermo dynamics and flame and volumetric efficiency... i have no ****ing idea lol

 

[kornball426]

I'd get 5.7 rods and hypereutectic pistons, they're much cheaper than forged and good enough to take whatever your stock crank can take. :lol:

That's just me.

 

[gk666]

iv heard the hyper pistons are good until something gets inside the chamber even if its just dirt is can muck up that coating on the pistons and become a problem later on, has anyone else heard that