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Re: Jump timing (the discussion continues)



Hi Thomas:

I don't disagree with you, that a snapped timing belt doesn't necessarily result in complete disaster, because when the belt snaps, the engine stops as the cams have stopped. I never said otherwise. But if a timing chain is still intact, and at the same time displaced by enough to snap two valves, it will necessarily snap all the valves. This must happen because the engine is still turning, and the valves are still timed the same as they were, in relationship to one another, as determined by the cam lobes. And, as Alan (owner of the Spider in question) mentioned, he was driving his Spider at 100mph when the problem started, and continued to drive it, after the chain allegedly jumped. That's how I'm certain his timing chain didn't jump.

Considering that the Spider had just been messed with by one mechanic, before the incident, and then another after the incident, it may be hard to know who did what, but my money is still on a loose vacuum hose, cracked distributor cap, bad ignition wire, loose injector plug, etc, and unless mechanic #2 screwed with the timing chain tensioner, those valves are just as intact now as they were before the car started running badly.

Unfortunately, I'll bet our fellow Alfa owner is not being taken care of as best he might be, and that was my concern. He never replied to my direct email, or asked for assistance from the Digest to get another opinion about his Spider via personal inspection. I'm not implying Alan had any obligation to reply, either, but he asked for our help. Later, he did send a somewhat frantic request to the Digest for all kinds of specs regarding valve spring tension, valve clearances, etc., and that can't be a good sign. None of those specs in question were of any consequence, anyway, and any Alfa mechanic wouldn't be asking for them, even if they were necessary. He'd already know what to do, and wouldn't be looking for help from the car's owner.

Maybe I'm just a little over-protective of fellow Alfa owners that aren't experienced enough to take care of their own cars, as perhaps you and I are, but I think that's part of the deal in owning an Alfa, and I'm always more than willing to help any other Alfa owner. It's like our own Hippocratic oath, where we swear to first do no harm and to share our knowledge about Alfa's with other Alfa owners. Maybe the sequence of events didn't occur exactly as they were described by Alan, but in any case, something is wrong with the whole story.

I'm certainly glad to hear that your V6 engine survived its bout with a semi-toothless timing belt, and I'm not sure if/how you got the impression I'd feel otherwise. Anyway, comparing the Alfa V6 to the I4 is like apples to oranges, or pecorino romano to parmagiano reggiano, if you prefer.

Regards,

Dean
'74 & '87 Spider Veloce's

At 07:44 AM 4/19/2003, you wrote:

Date: Fri, 18 Apr 2003 21:11:23 EDT
From: [email protected]
Subject: Re: alfa-digest V9 #429

Dean and John,
I've got a news flash for you two... I'm not defending the mechanic who
claimed an Alfa spider jumped the timing chain but I can tell you from
personal experience that losing the timing belt in a 2.5 liter GTV-6 at 6250
RPM will NOT necessarily destroy the entire engine. At 53,000 miles I
stripped 50% of the cogs off of the timing belt while charging up an on ramp.
I had just hit the rev limiter when the failure took place... The engine died
immediately. I tore the heads down and sent them off to Sperry for an
upgrade. As a professional machinist I have access to any precision measuring
and testing equipment imaginable and I and a qualified NDT inspector. The
only damage to the engine was three bent intake valves and a minor nick in
the top of #4 piston. ALL other reciprocating and rotating parts were
undamaged! I reassembled the engine using the original pistons, liners,
pushrods, connecting rods and cam followers. Currently the engine has over
100,000 miles and you can ask anyone in the Mid-Atlantic Alfa Club's
Tidewater branch or Georgian Gaz and they will tell you my GTV-6 runs just
fine and will still turn to the limit any and every time I so desire. It does
now wear a mechanical belt tensioner and the belt gets swapped yearly...
Cheaper that way!
Thomas Gonnella
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