ok here it is i just got my hands on a set of .030 pistons that are domed and the only distinguishing marks i can find on them are 7009p stamped on the top of them . i just need to find out 1. whos pistons are they, 2. what kind of compression they have. they are supposed to be for a 350 but im not a 100% on it. ive done a search on here and on the web but couldnt find anything on them .

any help would be greatly appreciated.

thomas

 

No need to go further than "domed." I don't suggest using domed. It hinders flame travel and can create VP issues.

Determining compression with just saying "domed" doesn't accomplish anything. To come up with even a half-assed guess we need to know the negative cc's of the domes. Knowing the heads and head gasket and deck height also help.

 

but i need some help on how to check what the cc's are of the piston's, but if i knew that i could figure out the compression with different head gasket combo's. if i could just figure out who made them that would help me out a whole lot.

 

If you took them to a machine shop they might be able to ID them.
I had a set that I needed a replacement for and the shop owner knew at a glance.

 

you need a CC checking fixture and a burrett, not rocket science, to find the CC displacement of the pistons.

 

Pistons dont cost that much, and to build an engine around a set of domed pistons is just plain foolish.

 

domed pistons have been in some of my motors, we ran about 12.5 to one compression. in a pre 1968 327, and a 300 cam. the motor had a nice sound to it, but it was a little hard on spark plugs , but we ran it very rich so the plugs didn't last long. 350 pistons are easy to spot. as they don't look at all like 327 or 400 pistons, 350 pistons have only a very thin space in between the oil wiper ring land and the wrist pin. don't you have any old speed shops near bye?it seems that any of the guys who have building hot rod chevys for 30 years could spot a 350 piston in a heart beat. how much crank HP are you looking for

 

im not going to build a motor around a set of pistons just like to know what i have so that way if i need them or say a buddy needs them for a specific reason ill know what i have and maybe use them for a specific purpose,im not a complete newby to engines (not the smartest by far) but not completely green just wanna know what i got my hands onto.

thomas

 

thanx i called a local machine shop that my father in law does a lot of dealing with and they were able to tell me exactly what pistons they were. they are speed-pro forged pistons l2252af .030 .200 dome,1.560 comp height,1/16 1/16 1/8 rings ,with 76 cc heads they will yield a 10.22:1 compression if you werent to deck the block.

 

lol, im having the same problem. im trying to figure out what type of pistons my mechanic put in my car (i have the heads off) because he can't seem to remember (i smell bullsh*t). anyway, all i can tell is that they're domed. like i said i have no idea what type of pistons they are, but i'll do anything to find out. without taking them out, is there anything i can measure that i can check against other brands of pistons to possibly find a match?

 

It's pretty hard to measure the dome on a piston. Or at least it would be hard to make an ID by any measurements that you could make with the engine in the car the way it is.
So what's the story behind this anyhow?
How did your mechanic end up putting domed pistons in your engine?
Has your engine been run with them yet?
If so, how does it run?

 

do they have any numbers cast into them on the top of the piston,like mine, they have 7009p on them thats how my machine shop was able to help me identify them if you can see any numbers lemme know and ill call my machine shop and see if they can tell me anything about them.
streetiron85 say i used these with set of 882 heads which i know i can get my hands onto ,newer 350 block bored .030 1.94,1.5 valves, xr282 roller cam,750 double pumper,set of 1 5/8 headers with 2 chamber flowmasters in my 89 firebird ,3.42 gears ,700R4 what kind of hp and tq numbers could i expect and what kinda of numbers do you think i would lay down? im just throwing an idea out there to see if they are worth using.

thomas

 

You would be a lot better off with some flattops, and real heads that actually flow.

 

TTYTT, I'm not too good at guestimating TQ/HP numbers (disclaimer) But mebbe 350hp, mid 13s.
If you're determined to use those pistons with 76cc factory heads... well, at least they'd be better than flattops with those same heads, cause you'd have some compression.
If I had those parts sitting around waiting to be used and my car needed an engine and I was low on money, I'd put em together.
I've tried those heads on a truck, in fact I have them on my truck engine now. It's a 327 with 8.8/1 CR, performer intake, 750 vac sec, 252 Comp cam. It's a lot more powerful than the 350 that came stock. Both in TQ and HP.
Guys that have a really top notch combo would consider it mediocre by comparison, but for you it might be a total kick in the pants.
When/if you get tired of it, you can upgrade it.

 

i blew my motor and had him do a rebuild on my car. completely new bottom end. thing is, i saw the pistons, rods, and crank before he put them in and i asked him for the info on the rebuild kit. he said ok, but when i got my car back, he didnt have it and couldn't find it. everytime i ask him for it he says he'll find it but he never does. pisses me off. the car ran fine, no problems with it except that the tip of the roller rockers where it meets the valve and the springs were chipping away metal off the rocker because the assh0le didn't lock in the locks on the rocker stud. the rocker came loose and pieces of metal chipped off the rocker and went through the system. f*cking sucks =\ but w/e, i took off the heads to have them flow benched since they're ported, and i wanted to find out what pistons i have in there since i know it's going to take him forever to get me that info.

firebird, ill check tomorrow on the top of the pistons for any numbers, but all the pistons have (after 1500 miles) some carbon deposit on them. ill see if i can see anything, but i doubt i will. where did you find the markings on your pistons? have a pic? thanks for all the help guys

 

For those locking nuts to stay put on the studs, the tops of the studs need to be ground/milled square. Is it possible that might be why your rockers came loose?

 

possibly. i took the heads off and send them to a machine shop to be flow benched and for them to put arp screw in studs. would i have to mill the studs for the locks to work right, or are they good to go out of the box?

 

ARP studs are good out of the box.
Keep your eye on those locking nuts too and if they still won't stay locked, get some quality ones like ARPs or Comp.
I'd hate having a set of rocker arms coming loose on me.

 

the numbers on mine were right on the flat part of the piston opposite of the dome.

 

no numbers i dont know what to do, my mechanic keeps stalling and it's pissin' me off

 

If I were you I would be looking for a better mechanic for next time. You wouldnt happen to have pictures of any of this stuff, would you?

 

i have a new mechanic... the one who rebuilt my engine was the only one i could find at the time. my new mechanic took me for a ride in his 69 camaro the other day... 427 sbc, forged bottom end... ati procharger pushing 22#'s i believe... f*cker made me drop a load in my pants when it took off.

ill try to take a picture of the pistons right now

 

here ya go... i put them on my site. iroc.djhaf.com/pistons

 

http://kb-silvolite.com/performance....tails&P_id=155

Look familiar?
You can tell they're KBs cause they have those notches alongside the valve reliefs.
They may not be the 12cc, take some measurements and compare them to the others shown to find out for sure.

edit: Some vortecs would work well with those

 

yeah i was looking on summit and noticed they look like KB hyp. pistons... now just to find out which ones they are would be really awesome. thanks for your help man

 

I'd bet money they're the 193s. It sez those are supposed to be stock replacement for 71-90.

They're a better piston than the factory dish cause they have the D shaped cup.

BTW they aren't domed

 

well... my (ex) mechanic told me when he was doing the rebuild.. "do you want stock compression, or 10:3 to 1?" ... i told him i wanted the higher compression. now here's my problem... now that i think about it, they look like the 12cc d-cupped pistons. ill measure them tomorrow to be sure... but if they are, i would only have 9:6 w/ 64cc heads, and 10:3 to 1 with 54cc heads. what im confused about is that i had a compression test done to my car when i had the comp cams 502 cam and 1.6 rr's, and i had 180 psi in each cylinder. i had a friend running a slightly larger cam, same psi, and pushing 10:8 cr. when i tried to figure out my cr with that formula on smokemup.com, it comes out with 11:6 to 1 cr with 64cc heads with the 12cc pistons. now im confused i also have to ask... what would cause all that carbon build up on an engine that's fairly new... only 1500 miles. could my compression indeed be too high causing the carbon to build up? i also noticed the car has a slight miss... never had a chance to run octane booster on it to see if it went away because i took off the heads before i had a chance to do that. im pretty stumped. what do you guys think my cr could be? since my heads are at the machine shop, ill ask them to see if the heads were milled and if the cc's were changed. thanks for all the help... sorry for jacking your thread dude lol

 

hey, is there any way to measure the cc's on the pistons i have? tia

 

You could fill the entire dome of the piston in with play doh or modeling clay, then take it out and drop it into a graduated cyl that has some fluid in it and look at the increase in vol as the fluid rises.