[Diy_efi] vortec engine piston noise?

[mike katz]

--- Shannen Durphey <shannen at grolen.com> wrote:
> "Slap" occurs at idle also.

Only in no offset race motors.....
They used to do it in my low buck AMC motor due to
installing the piston in backwards. I like to go fast
for free.

> For 50 years GM made engines that didn't make piston
> noise until
> something went wrong.  Now, suddenly, the
> explanation is that they
> need more clearance around the pistons?  Nope,
> sorry.

Sorry again, Shannen. Gm has lots of TSB's for motor
noise due to loose clearances. Just about every 454
truck motor made had this problem. Every marine motor
did.

> 
> 300 hp out of a 350 ci+ engine is childs play with
> today's parts, not
> a "delicate balance."   GM is trying something
> different (again) and
> this time they made a "boo-boo." 

Sorry Shannen. For a car motor,no problem. For a truck
motor that can see continuous full throttle loading
with most of the work done in the head, serious
problems can occur.

 
> 
> 366 truck engines see more heat than any pickup
> engine.  I worked for
> the phone company when they'd get so hot at high
> idle as to melt
> plastic parts in the engine compartment.  Lotsa
> fires then, too. 
> Funny those pistons haven't "slapped" in, ohh...,
> forever. 

C'mon dude. Dont' try and compare a low CR motor to a
high CR motor. Peak pressures contribute a lot to
piston slap. Hot exhaust manifolds don't count.



 
> Know when piston slap started becoming super
> prevalent in the
> smallblocks?  When the zz series of motors came out.
>  It wasn't just
> the lifters that did the tapdance in those engines. 
> The short skirt
> hypereutectic slugs gm used made a ton of noise.

That's normal dude. I own a 93 ZZ3 motor, and it is
all valvetrain noise. A bunch of weenies complained
about the noise on a HP off road crate engine (give me
a break). Go talk to Keith Black about piston noise.
He will set you straight. Once again, loose is fast.



> If you spend 20 to 30 thousand and up for a truck,
> ain't no way you
> should accept anything like the kind of noise these
> engines are
> making.

You win on that one. They should cost 18 to 20 grand.
    

> Think for a minute what happens at trade in time
> when you have a noisy
> engine.  There's no dealer in the country that's
> going to give you
> reasonable money for your truck if it's making a
> noise like the
> engine's coming apart.  

If it can work for them, it will work for you. Just
hand them a copy of the TSB. That becomes a legal
issue.



I have been around racing motors for a long time. I
know what works and what doesn't. When it comes to
engine noises, I have heard them all.  My suggestion
would be that the everyday joe stop buying a truck as
his family wagon if noise is going to be a problem.

Mike :)



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