Here is a clip (thanks to Mike aka talonguy2005) of my motor. I wanted to post this before I start driving the car just to make sure this is piston slap and im ready to start breaking in the motor. My oil pressure seems good and my FP is around 20-22psi at idle. I still have a vac leak, that im going to try to get fixed tomorrow after work. Other than that, my idle is okay, when it seems to get warmer for some reason, it idles shitter, lol. i think because my plugs. I have the BKR-7E11 plugs but im going to get the regular BKR-7E's i guess and try those, yes im gapped correctly too, lol. well anyway, how does this sound, piston slap or what? it gets quiter when it gets warmer in opertaing temp, but you can still hear it, will this ever go away, and is this safe to actually boost on? sorry for the annoying questions, but im not used to driving yet with slap yet, lol.
holla, here is the clip:

http://hhclan.aowc.net/user/22858/files/pistonslap2.zip

I've built a couple v-8's with a loose bottom end and it sounded similar, and also had parts rub that sounded the same(flywheel mistaken for a knock by quite a few and also a pully with a bad bearing rubbing on the alt housing) personally I would pull the pan and check it out before you started to break it in. You won't have to worry about boost for a little while anyways till its broke in so if its a bad bearing it will probablly go before then anyways specially if it started now and theres no miles on it yet.

Yeah that is piston slap. I always tell people it sounds like a diesel engine. I don't know if you were doing something next to the mic though, like around the 2:10 mark and on, there is some strange noises going on there hehe.. As for boosting, try and stay off of it until a few hundred miles or so, then start lightly boosting it. I had VT machine my block, adn I did my assembly, and just as info, I was boosting around 12 psi at about 250 miles :) After my motor is fully warmed up, I cant really hear the slap anymore though..

Originally posted by XtremeRS
Yeah that is piston slap. I always tell people it sounds like a disel engine. I don't know if you were doing something next to the mic though, like around the 2:10 mark and on, there is some strange noises going on there hehe.. As for boosting, try and stay off of it until a few hundred miles or so, then start lightly boosting it. I had VT machine my block, adn I did my assembly, and just as info, I was boosting around 12 psi at about 250 miles :) After my motor is fully warmed up, I cant really hear the slap anymore though..

Lol I think he was breathing hard and getting all excited it sounded like, I guess I would be also.

Who did the machine work? What tolerences was it bored to?

best time so far 14.3 @ 101.1mph(no traction)
www.cnnmotorsports.com

Hehe, well if you have never heard a 420A with JE's in them before, then anyone may freak out a bit :) I was lucky, because I had already heard what it sounded like before I built my motor.

If your slap doesn't go away when its fully warm, then your machine shop may have used a bit more piston to wall clearance than suggested. This isn't an entirly a bad thing, because now your motor is capable of handling a ton of boost, since more boost means more heat, which expand your pistons even more. I've known some 4g63 guys who purposely give a ton of wall clearance just for this. I don't know for sure, but excessive wall clearance *may* have a slight effect on how quicly the cylinder walls wear, but i'm not sure on that.

And for the breakin, you dont have to be super anal about it, just drive the thing normal. Dont baby it, but dont exactly redline the thing right away either. I lightly boosted several PSI right after I got my motor running and driving. Did a compression test at 150 miles, and got 195 psi accross the board. I've been beating on my motor since about 300 mile mark, and still runs like the day it first started up, and still has great compression(approx 30,000+ miles on it now)

Originally posted by XtremeRS
And for the breakin, you dont have to be super anal about it, just drive the thing normal. Dont baby it, but dont exactly redline the thing right away either. I lightly boosted several PSI right after I got my motor running and driving. Did a compression test at 150 miles, and got 195 psi accross the board. I've been beating on my motor since about 300 mile mark, and still runs like the day it first started up, and still has great compression(approx 30,000+ miles on it now)

lol you know what this sounds like?, a new section of 2gnt. Finally a success section devoted to the good a 420a can do instead of a ton a sections all on how to fix them. ;-)

Just curious as to whether mine sounds the same as yours "eclipse982nrRST"... here is a short vid of the chatter, as mentioned previously the chatter quiets down as the car warms up and becomes nearly non-existent while driving.


http://www.teampocketrocket.com/movies/PistonSlap.wmv

Afew Questions:
Would some better tuning eliminate the slap further?
How long after rebuilding an engine is a good time to introduce boost?
When boosting is synthetic oil recommended w/ 92 Octane?


Any help is greatly appreciated..

okay cool, no more worrying over it then!
so will this sound ever go away or what though?
im not boosting on it until i get about 1000-1500 miles on the new motor.

Originally posted by eclipse982nrRST
so will this sound ever go away or what though?

No.

Originally posted by DarkOne

Originally posted by eclipse982nrRST so will this sound ever go away or what though?

No.

oh well, i guess im rocking the diesel sound for life then :)

that sound makes me horny.

Well, I guess this is new to me so don't get pissed. I'm guessing piston slap is caused because of a cylinder wall is bigger than it should be compared to the piston??? I'm in the middle of a rebuild and am going with JE 8.8:1 pistons, is my motor gonna sound like that?? It's just something new to me that I have never come accross before so help me out.
~Jeffo


Hey, have you seen my new tail lights? Yeah, cool huh, get used to looking at them.

from what i understand, some ppl get the slap and some dont. i heard its super common with JE's with the 420a tho.

I had slap with my Je's but that sounds pretty excessive. Maybe i just got lucky but it was never that fuckin bad.


Nick
97RS


THX KAPTAIN MYKE FOR HOSTING! www.kaptainmyke.com

If your motor was machined properly for the forged JE's, then they SHOULD make noise when they are cold. I would actually be more worried about a motor that doesnt slap when cold, then one that does it excessivly. The JE's expand considerably when they get warm, which is why they slap when cold. I would be kind of worried to run too much boost on a motor that didnt slap when cold..siezing a piston in a cylinder doesnt sound like fun :)

at idle, when it gets to operating temp, yuo can still hear the sound, but its not as loud as it is when they are cold. you can still notice the slap there, but its not loud at all. its there, but kinda quite.

Originally posted by Collente
I had slap with my Je's but that sounds pretty excessive. Maybe i just got lucky but it was never that fuckin bad. Nick 97RS THX KAPTAIN MYKE FOR HOSTING! www.kaptainmyke.com

I had Howell build my bottom end with JE piston and I don't really hear the pistons making any noise. If I listen real close when it is cold I can hear them very faintly. But again, it is not a noticeable sound.