Technical Why are some Corvette motor mounts called "locking" motor mounts?

Its all in the title... I don't see what "locks" on these mounts. So what does the terminology signify?

 

They keep the engine from breaking completely loose from motor stand where non locking don't

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69 up have locking mounts

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So you are saying that the motor mount doesn't come apart if the rubber fails? I thought maybe it had something to do with the bolts.

 

IIRC (it's been a while since I installed a SBC in anything) there are fingers on the sides of the mount that interlock, but don't really touch during normal operation. That way if the hipo Vette motor revs up so much it would rip the rubber apart, the fingers would hold the engine in the car. Otherwise that SBC may go rolling down the street.......

 

Yes alchemy has a much better description

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There were incidents of broken mounts resulting in stuck, as in wide open, throttle so GM took appropriate action.

 

If anyone is interested, the stock ignition shielding won't fit on early cars with the locking mounts although the mounts themselves will fit. I had a bit of trouble finding non-locking mounts when I restored my '67. I ended up with a pair made in Israel. The seem to be of high quality though. Bottom line is that it should only matter to restorers.

 

Not only Corvettes!

 

I seem to remember seeing a version of this with small bits of chain attached between frame and engine.

 

I'd think more than one of us over 60 guys has had the throttle stick on a 58/mid 60's Chevy when the left mount broke and the engine lifted up and hung up the mechanical linkage. Not a fun ride and you learn to think fast and about all you can do is turn the key off or kick it out of gear.
Top should be non locking the other should be locking.

 

Somewhere out in the shed I have some of the strap setups that they had as a "recall fix" that bolted to the engine and had a cable loop around the Arm shaft to keep the engine from lifting too far. It was the norm for guys to bolt a short length of chain on them to prevent them from lifting back then and I think required at the drags.

 

I thank that was impalas with hippo 327 and 409

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The factory fix was a cable that connected the cylinder head to the upper A frame pivot.

 

^^^Had these on a 69 Camaro pace car, 396 engine. Factory recall item.

 

You also will need to change your shorts the first time that happens!
Found that out one time when driving my older brothers 327 equipped 66 BelAir wagon.
To those who scoff, that car could really go and it was stock.
Those replacement safety motor mounts can be tricky to put in some cars too.

Another thing, can you buy OEM motor mounts anymore that aren't Made in Korea?

Found an NOS set like this one years ago for my 67 Nova, back when it was planned as a restoration type car, still have it somewhere.

 

The ones I have out in the shed are similar to that but the mice have probably destroyed the boxes and paperwork in the past 25 years. A friend gave me boxes of "obsolete" parts from his Chevy dealership when the factory rep pulled them from the shelves.

 

I have some of both styles. I guess that only the drivers side is really needed isn't it?
I used to do a similar thing to an old big block Fairlane I had. I put a turnbuckle with some chain links on the drivers side of the engine and mounted it to the front frame rail.

 

Don
When I built my first drag car in the early 70's (65 Malibu) a chain/turnbuckle was one of the things I put on the engine after I got it going, also a fan belt guide and a Dayco outside mass fan belt.

 

Yes, unless you get really crazy driving in reverse.

 

Spent lots of my early Chevrolet dealer apprentice mechanic days doing the safety recall to install the brackets and steel cables to the drivers side of the smallblock engines in lots of different models.

 

My dad had a scorcher of a '68 Chevy wagon, 327, double hump heads, Q-Jet, TH400. It moved well. I was out beating on it one night and the mount lets go... WOT... jammed the gas linkage and pulled the vacuum hose out of the brake booster. I had to shut the key off... let a couple of turds roll down my pants leg and went home. I got a set of the locking mounts for it and put them on. Odd that this car was not fitted with the strap. I had a '66 and '67 Chevy that did. I guess the PO ignored the recall if there was one.

 

It’s an anti theft device to keep hoodlum hot rodders from stealing your Corvette SBC.
Allows you to lock your engine mounts

They’re really important to have because we know how popular Corvette SBC’s are

 

Hey now!
Don't make me pull out the "and all Y-block engines were from T-birds"

 

I had a 67 Impala with a 283 back in 72. It had a factory fix with cables on both sides of the engine. I believe they were there to back up the stock mounts and to keep the engine from twisting on it's side if a motor mount broke.

 

Left engine mount broke then the engine torque lefts the left side of the engine causing the throttle linkage rod to pull the carburetor wide open (it happens fast)

Most likely the reason for later changing to throttle cable.

 

I had a new '65 Impala SS with the 425 HP/396c.i. L78 option and it had the restraint cable added by the dealer.

Bob

 

Pontiacs did the same. Speaking from experience , a left turn with a shitty motor mount, fries tires right into traffic.
What a driving lesson...
It was my old 65 Catalina 389 4bbl.

 

There’s a lot of good answers here, most of them technically correct.

I still like my answer the best