[Shotimes] Engine noise identified

[Leigh Smith]

My point was that the tensioner on my motor was at the absolute limit of its
travel due to chain stretch. Therefore it couldn't keep the chain tight at
all and no wonder it made some noise.

A new chain should solve my noise problem, where a new tensioner would not.

I agree noise complaints are extremely difficult to diagnose properly. And
chains in general are a very high wear item.  I would go so far as to
suggest that people measure their chains for stretch at their 120k service.
The spec for brand new parts is a 1/4 inch rise above the sprocket. The
completely worn out measurement is a 3/4 inch rise.

Since I had access to both a brand new motor and a 100k motor (or engine) I
was able to come up with both specs.

Regards;
Lee


----- Original Message ----- 
From: "Donald Mallinson" <dmall@mwonline.net>
To: "Leigh Smith" <leighsm@comcast.net>
Cc: "SHOTIMES" <shotimes@autox.team.net>
Sent: Thursday, August 26, 2004 2:46 PM
Subject: Re: [Shotimes] Engine noise identified


> Re-read, you meant the small chains at the back of the
> motor, on the front and back heads....I thought you were
> talking about the front and back of the engine (passenger
> and drivers ends!).
>
> The slight noise from the tensioners is usually associated
> with low pressure at that point, since the tensioners are
> oil fed (with a spring back up).  Quite often, a new chain
> and tensioner will NOT solve the noise.
>
> Still, curious where you found a brand new engine.
>
> Don
>
> Leigh Smith wrote:
>
> > As some of you know I installing a brand new Factory fresh SHO crate
motor in
> > my 100k mile '94 MTX
> > due to engine noises.
> >
> > In comparing the brand new Ford motor to my old one, I have found 2
things so
> > far:
> >
> > I had a soft knocking noise which sounded like rod knock.
> > It did seem to be in the front valve cover near the coil pack.
> > It turned out the front cam chain was stretched, overpowering the
tensioner.
> > It had 3/4 inch slop (+ or -) between the sprockets
> > That is the absolute limit of travel on the chain tensioner, which
looked
> > almost new.
> > The rear chain had less slop, + / - 1/2 in slop,  so the adjuster could
still
> > function.
> > but the chains in the factory fresh engine only have 1/4 inch slop, and
have
> > 13mm of adjuster movement available to tighten chains in the future.
> > Note that the trensioners are not available anymore, but the chain seems
to be
> > the part that wears, and they are still available.
> >
> > Second issue was bearing clearances.
> > My old motor had 4.0 thousanths clearance on the rods, out of spec, and
was
> > not trusted to drive daily.
> > The bearings were very worn (much copper) but new rod bearings did not
help
> > the clearance.
> > The new Ford motor spec'd out at 2.0 exactly on the mains and the rods.
> > I am assuming the old crank is worn, but will know more shortly.
> >
> > Lee
> > (Inquiring minds want to know...)
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