[Healeys] Lightened Flywheels

[Harold Manifold]

Bob,

I lightened the flywheel on my BT7 with no ill effects. The engine is
responsive and revs smoothly. The Healey's with the spring type clutch like
mine have a heavier flywheel than the later flywheel used with the
diaphragm clutch. To some degree BJ8's already have a lightened flywheel
compared to the earlier 6 cylinder Healey's. Picture of the flywheel is
attached.

I use the technique described by Hank when shutting off the engine and
there is no run on.

Harold

On Tue, Jun 18, 2024 at 1:13 PM Michael Salter <michaelsalter at gmail.com>
wrote:

> When it comes to flywheel weight the 6 cylinder and 4 cylinder have hugely
> different requirements.  The natural balance of the 6 means that there is
> much less change in rotational speed during each revolution and with the
> crankshaft itself being much heavier the gearbox requires much less
> protection.
> The type of driving that I do these days does not require "snappy" gear
> changes so I would tend to leave the flywheel as designed as I really
> appreciate the smoothness of the 6 cylinder engines however, each to his
> own.
> I  would definitely not lighten a 100 flywheel, particularly a BN1, for
> fear of eventually damaging the gearbox for the reasons described in this
> article.
> https://precisionsportscar.com/austin-healey-100-crank-failures/
>
> M
>
> On Tue., Jun. 18, 2024, 2:48 p.m. Hank Leach via Healeys, <
> healeys at autox.team.net> wrote:
>
>> The best way to stop run on is foot on brake, car in gear-It's not
>> hurting anything and is recommended by the likes of Geoff Healey and
>> others. Denotation has a worse effect on the engine.
>> The downside of the lightened flywheel is a heavier clutch engagement.
>> That said the heaviest part I ever picked up is a 100 flywheel.  Egad, what
>> a hunk of metal!
>> -However the issues with the flywheel/cracked crankshaft can be traced to
>> a lack of a front pulley dampener and that might be the better solution to
>> the issue.  It may in fact make dumping the clutch easier on the
>> drivetrain, but not proven. Since your problem is with the front of the
>> engine, I would address the seal replacement -felt if you are a purest -or
>> yes, the modern solution fancy cover to stop drips on the floor. I collect
>> my Healey oil in a small swimming pool I constructed to hold leaks, while
>> in storage. Then some kerosene quickly cleans up the mess when the car is
>> moved. Since they no longer oil the roadways, think of the benifit you are
>> supplying to the asphalt in longer life. Hank-------------------
>>
>> From: "Bob Spidell" <bspidell at comcast.net>
>> To: "Healeys" <healeys at autox.team.net>
>> Sent: June 18, 2024 at 10:03 AM PDT
>> Subject: [Healeys] Lightened Flywheels
>> Listers,
>> I know this one has been discussed--well, beat to death--but it looks
>> like I'll have to pull my BJ8's gearbox/OD to replace a leaky front seal,
>> so I'm thinking of installing a lightened flywheel while I'm at it. My main
>> reason for considering it is to stop some pretty significant run-on
>> ('dieseling,' which I get on my BN2 as well). I'm not totally comfortable
>> with dropping the clutch in gear to stop it, and any performance
>> improvements would be a plus. It just so happens I just caught an episode
>> of 'Engine Masters' on MotorTrend TV, where they seriously reduced the
>> rotating mass of an engine--an SBC, which is what they mostly do--and got
>> some interesting results: more HP and torque, as measured on a topnotch
>> dyno. The gains were shown primarily on acceleration which, intuitively I
>> suppose, were greater when RPM was raised at 300RPM/minute vs. 600. Any
>> constant speed increases weren't addressed as far as I could tell. The
>> late, great Gary Andersen, who raced, said the main benefit was faster
>> spin-up for rev-matching downshifts; anyone noted any other significant
>> benefits? The 'Dyno Master' on EM said he'd seen timing chain failures with
>> lightened flywheels; my main concern for both my Healeys has been
>> reliability, with minimal maintenance required, but if it stops/minimizes
>> the run-on I'd be happy. Anyone know how far you can go lightening without
>> adverse effects? TIA, Bob _______________________________________________
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