383 Piston slap

[Done Swimmin]

Hey All

My 383 has 51900 Diamond forged pistons and the cold start slap is disturbing. Any one have similar experience?

Pete from Peterborough

 

[AJ/FormS]

What clearance did you put them in at?

 

[GTX JOHN]

Not unusual for my engines to have some noise
the first minute upon startup with the clearances I
run on the skirt. Now if it lasts longer than that or sound
like someone has a hammer inside = that is a significant concern.

How much piston to wall clearance on the skirt 90 degrees opposed to
pin hole (That is how I check it)?

 

[33IMP]

4032 shouldn't do that, unless they are installed too loose.
If those Diamonds are 2618, that's expected, and normal, and nothing to worry about.
A friend and i ran a 440 in a Duster with CAST pistons at .008 (supposed to be around .001-2) and the piston slap was noticeable, and didn't go away when warm.
It must have been a problem, the car would only run mid elevens at 115.

 

[RustyRatRod]

As long as it goes away or gets quieter when it warms up, I wouldn't worry about it.

 

[Done Swimmin]

Hey All
I didn't build it so not sure of the clearances at assembly. It does quiet right down when up to temp so i am guessing that it will one day be a problem but for now i will drive it while i look for a block for a stroker.

 

[MOPARMAGA]

I'm surprised that piston manufacturers haven't had an "in between" alloy developed yet, with the great qualities from both 2618 & 4032.
I had to have my 4032 pistons coated from line2line coatings and run .0015 p/w clearance with gas ported total seal top rings.
The previous machinist didn't pay attention, nor did the assembler. It had close to .0065 clearance.
(I have had no issues with this engine since)

 

[MOPARMAGA]

4032 shouldn't do that, unless they are installed too loose.
If those Diamonds are 2618, that's expected, and normal, and nothing to worry about.
A friend and i ran a 440 in a Duster with CAST pistons at .008 (supposed to be around .001-2) and the piston slap was noticeable, and didn't go away when warm.
It must have been a problem, the car would only run mid elevens at 115.

Wow .008 with a cast piston.
I just had to hone a block to .003 over recommended bore finish size for cast pistons.
Customer wanted it to stay with a .040 overbore but it had locked up at some point and there was aluminum transfered on the cylinders and a bunch of surface rust. ( Car 351 Windsor in a boat )

 

[RustyRatRod]

Hey All
I didn't build it so not sure of the clearances at assembly. It does quiet right down when up to temp so i am guessing that it will one day be a problem but for now i will drive it while i look for a block for a stroker.

I think it's fine. Some of these guys don't understand that there are many, MANY types of pistons. Most all modern pistons are what's called "cam ground" pistons. They are not round at room temperature. They are oval. Once up to operating temperature, they expand and "get round" and all the clearances fall into spec.

 

[Carnut68]

Loose is fast.

 

[RustyRatRod]

Loose is fast.

That's how it was with the gals in school.

 

[3forty]

That's how it was with the gals in school.

That's what you heard.

 

[Killer6]

Hey All
I didn't build it so not sure of the clearances at assembly. It does quiet right down when up to temp so i am guessing that it will one day be a problem but for now i will drive it while i look for a block for a stroker.

My (well,...ALL) 2.2 Turbo II's came with forged Mahle pistons, thay all rattle on a cold start ~45°F & down...no biggie..

 

[Scody21]

My (well,...ALL) 2.2 Turbo II's came with forged Mahle pistons, thay all rattle on a cold start ~45°F & down...no biggie..

So did BMW M12/13 turbo engines from the 80’s F1 and IMSA cars pushing about 1400 HP from 1600cc’s…

 

[DieWilde13]

"A loose Motor is a happy Motor"

 

[Brooks James]

Loose is fast.

Agree, I had a 62 SS Impala with a 327/350 HP that ran like a scalded dog just before it blew up