4.3 giving problems-- greatly retadring timing

update:
89 S-10 Blazer, TBI 4.3, 700R4
Timing set as per man, at 4DBTDC. After setting, computer advances to 10ish DBTDC and shows knock sensor trigerring. The is an auditory knocking sound
that goes away when in neutral or with transmission in gear but TC in neutral.
Did some snooping-- found some movement in left side motor mount <installed new les than 20K miles ago>. used my prybar to put an upward load on the part of the shell attached to the motor-- audible knocking went away.
In short-- problem is a bad motor mount allowing the steel shell of the mount to knock against each other, fooling the knock sensor.
Ideas? Replace motor mount with poly parts, perhaps? I've also seen a solid steel motor mount for SBC that'll fit the 4.3.
No telling how long this has been going on-- I think it's a bit ridiculous for a mount to go south within 20 big clicks....
Got to snooping this evenng and think I have it figured out.
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10ish
<installed
solid
Just one thing to say..................ATTA BOY! Try this, with the load on the engine mount to stop the banging, does the KS signal cut out like it should?
Doc

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sound
on
Haven't tried that yet with my lappie attached. I noticed that the audible knocking went away wheneve I powerbrake over the last couple months. Obviously the motor is torquing away from the mount and therefore, no knockage.
Damn thing had me worried, though- sounded EXACTLY like a main going bad. Garrr... that woulda SUCKED. I'd have been supremely pissed if the motor died so soon- and would have been SOL as warranty ended last August.
So-- whattaya think-- time to go poly? I'll replace it when I do the SFA <speakin' of--gotta get me arse back out there and get to putting stuff away>
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I'd go with solid mounts. Anything non-solid is just for asthetic/smooth-ride benefits which absorbs power from your engine which can be better used at the wheels.
I went through 2 regular mounts and a urethane one (within 18 months) with a buick 3.8L I rebuilt several years ago and it was suggested I go to the solid mount....I've never looked back and with the couple of vehicles I've owned since, changing to a solid mount is one of the first things I do :)

--
Dennis
DJKdesigns
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the
load
Unless these models have a problem with the mounts I would stay with a standard mount or you could go polyurethane. Solid mounts can cause you to feel motor harmonics while driving and as well a solid mount has the potential to fracture faster than a standard mount. Solid mounts benefit rac ing vehicles that want the motors torque all going out the crankshaft. But they don't drive these cars 25,000 miles a year.
Brian
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Doc-- whattaya think of this?
Since the steel parts of the motor mount on the left are cose enough to be knocking- I thnk I'll sick my MIG on it, stitch them together, reset the computer, and see what happens?
It won't be a permanent solution by any means-- but will tell me if I'm correct in my thinking.
'Bout time for a Jeg's order anyway-- I need another 2 1/16" gauge cup, probably the poly tranny and motor mounts, a set of crimping dies for plug wires, and some 8.8mm plug wire terminals...

10ish
<installed
solid
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sound
ridiculous
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there ya go.. man after my own heart... if it's trash, screw with it and see what you can make it do...
to quote that guy on the comedy tour <much as I hate to>:
"Get 'er dun!"

the
the
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Inline....................

see
Kinda my theory with the ol' Elky, he he he he.

Atta Boy!
Doc
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