L2313 Piston-To-Wall clearance???

fasterdaddyfaster

A while back I picked up some 30 over NOS TRW L2313 forged aluminum pistons from Ebay for use in a 69 390. They came in what looks like the original box with pins and pin retaining clips. However they did not come complete with the original machining spec sheet. Could anybody let me know what the correct piston-to-wall clearance should be for these pistons? Also is there anything else that I should inform the machine shop about? Thanks, Norm.

fuzz401

I would think they would be the same spec as factory pistons to cly. wall

fasterdaddyfaster

Well from what I do know is that stock 69 390 pistons are of a cast aluminum construction and these TRWs (as well as many other high performance pistons) are of a forged aluminum construction. Even though stock and aftermarket are both made of aluminum, the forgings are much denser and thus stronger and more durable and all that affects thermal expansion. So piston-to-wall clearance is usually particular to the piston being used. So I am hoping that somebody else has an NOS set and also has the original machining instructions that would have come with these pistons. I‚Äôve also been told (but again no actual numbers were known) that there is enough material above the top ring land so that up to an xx amount of material can be milled off to lower the compression ratio some, but alas, again when you then go and say ‚ÄúOh that‚Äôs nice, so up to how much can be milled and roughly how does that relate to the compression ratio?‚Äù All I get is ‚ÄúI dun know!‚Äù

radamx

I don't know the exact clerances but I do have a old trw book at home and it might have them . anyway the stock clerance will not work forged pistons like these meed between 4 to11 thousands clearance. so you need to wait untill someone finds the specs. I will look tonight..

bobhalverson

from a speed pro book, the L2313f clearance is .005", and they say you can remove .055" from the top if you want to run them in a 401- these are high compression race pistons (11.0-1 to 13.0-1) and need serious octane!!!!!!!! RU ready to smoke some big blocks!!!!

jeepsr4ever

:t: I stay to the looose side .007 for heat purposes

1970amx

Hello, I have used those pistons before in a hot street/strip motor in my 70 AMX. They are NOT stock replacement pistons. They are forged pistons designed for hot pro street/strip engines. I would not run them with less than a minimum of .007 clearance. Personally I would shoot for .008-.009 If you clearance them tight you will scuff your cylinder walls and piston skirts ! It won't last long ! Also....be prepared to run race gas with them. If you run a large duration cam with lots of overlap you might possibly get by with a mixture of 93 octane super unleaded and race gas. Hope this helps Rob

jeepsr4ever

Good words Welcome aboard!

fasterdaddyfaster

Hey everybody thanks for the responses, (I've been away for a while). I feel much better now. It looks like my pic-a-part piece-meal approach hasn't stung me yet! My rough measurements are showing that the already machined bores range from .004 to .007 wider than the NOS pistons I found and it looks like you guys are recommending .005 to .009 (more to to wider side). So it looks like I'll just have the machine shop hone-to-fit in the .007 to .008 range. Thanks again, Norm.

Mudrat

fasterdaddyfaster wrote
My rough measurements are showing that the already machined bores range from .004 to .007 wider than the NOS pistons I found and it looks like you guys are recommending .005 to .009 (more to to wider side). So it looks like I'll just have the machine shop hone-to-fit in the .007 to .008 range. Thanks again, Norm.

Mudrat :mrgreen:

tufcj

The instructions that came with my Ross forged pistons are: Normally aspirated: Bore 3.475 and under .003 Bore 3.476 - 4.499 .004 bore 4.500 and up .006 Marine +.002 Nitrous applications over 250 HP +.002 It also says filled blocks and blocks honed without plates may require more clearance. My .030 over 390 was done at .006" Bob tufcj

Dusty

Mudrat wrote
fasterdaddyfaster wrote
My rough measurements are showing that the already machined bores range from .004 to .007 wider than the NOS pistons I found and it looks like you guys are recommending .005 to .009 (more to to wider side). So it looks like I'll just have the machine shop hone-to-fit in the .007 to .008 range. Thanks again, Norm.

Mudrat :mrgreen:

8)
http://community.webshots.com/photo/197187802/200793181hEVvkM
http://community.webshots.com/photo/197187802/281709745XKVdZS
http://community.webshots.com/photo/281709792/281709792veYOzQ
http://community.webshots.com/photo/210999610/200854050WKVRhJ
http://community.webshots.com/photo/210999610/211007949jWESgJ
and of course we all should voice our opinion at the end of the night http://community.webshots.com/photo/234714467/234715456ZABYHt

8) :roll: Maybe i should ask what you wanted pictures of :razz: .006" on my 401 .30 over older Speedpro's close to yours:wink:

Mudrat

fasterdaddyfaster wrote
Maybe i should ask what you wanted pictures of :razz: .006" on my 401 .30 over older Speedpro's close to yours:wink:

The block and process ... not the process of the block (heads) 8)
And you BLOCKED the babe (is this her? or HERE? :roll: ) in http://community.webshots.com/photo/210999610/200854050WKVRhJ what's up with that??? She has a right (I guess) to be there??? :oops:
And I hope you're not the slow one on the left here http://community.webshots.com/photo/234714467/234715456ZABYHt. He have a hard time spinning up, or was he soooooo spun-up (or, spooled down?) he couldn't react fast enough? :idea:

Mudrat the curious ... :mrgreen:

Dusty

LOL. you forgot to mention the end result after a little too much abuse.

Logjam is in other pictures she choose to abstain that night from anymore festivities including drunken photos how about the same group 4 bottles of Tequila earlier http://community.webshots.com/photo/210999610/200854042UqjsAh

Im the :razz: in the Montana sweatshirt not the short balding Gorilla, He's the one who put my 401 together. :lo1l:

I thought this was a better view of that night all together
http://community.webshots.com/photo/234714467/234715441byvjLj :idea:
:wink:

Then again sometimes an angel comes into play :t:
http://community.webshots.com/photo/210999610/281758455UeOfkm :idea:

#-o yes i try to always bring the digital camera, but i abstain from posting the topless shots :?:

Mudrat

Dusty wrote
LOL. you forgot to mention the end result after a little too much abuse.
yes i try to always bring the digital camera, but i abstain from posting the topless shots :?:

Only got thru the birthday pics - didn't open the other albums. But I think I'm going to!!!
Either one is ... wellllll ... you make the call
http://community.webshots.com/photo/281756480/281756480aDyetB
'Course is the devil child (2nd left) available??
http://community.webshots.com/photo/281756461/281756461dnHkgh

Muztabeendarat

Lifted79CJ7

Pardon my french, but this is Freak'n HILARIOUS!! OK, enough being sick, off to the bar with me!!!! :lo1l: :razz:

Dusty

Were you talking about this Devil http://community.webshots.com/photo/210999610/281758090TCIjdc if so you are more than welcome to her, Cause i'll take the angel :razz: Next Holloween i'll try and stay a little more sober so i can get you a few of thier names, numbers and email address' :shock: NOT :wink:

:razz: Dusty

Mudrat

Dusty wrote
Were you talking about this Devil http://community.webshots.com/photo/210999610/281758090TCIjdc if so you are more than welcome to her, Cause i'll take the angel :razz: Next Holloween i'll try and stay a little more sober so i can get you a few of thier names, numbers and email address' :shock: NOT :wink:

:razz: Dusty

HAHAHAha ... ahhhh ... no. But I agree with your taste in Angels. But maybe you need to sober up BEFORE the next party :-| :?
One of these should (or could) work though ... http://community.webshots.com/photo/281756480/281756480aDyetB :t:
But then again what does this have to do with 'piston to sidewall clearance' #-o

Mudrat

Dusty

Is this the old Train and tunnel annalogy? My piston has what kind of cleance to her sidewalls. :shock: Alright i dirtied and twisted things enough for you now :?

Lifted79CJ7

Don't forget to "skirt" your pistons for protection and hopefully it will be a self lubicating system.....