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Which of these 2 mounts is correct for a 67 L79, manual with air?
The first on sits correctly on the frame with the 3 and 3/4 bolt and has 2 and 5/8 between the internal lugs that mount on the frame.
The second has 2 and 7/8 between the mounting lugs, so it has a fair bit of slop on the frame mount.
Any help appreciated.
First mount
Both should fit.
The first mount is the original style that fails after a few thousand miles. The rubber bonds the two metal pieces together and eventually rips apart - generally on the driver's side first. A GM recall added a cable and bracket to tie the exhaust manifold to the upper A-frame on some cars (e.g., 1st generation Camaros) as the engine rocks up and could lock the throttle open, etc.
The second is GM's answer to the failing rubber problem. The two plates are tied together mechanically to prevent the engine from rocking due to torque when the rubber fails, as it will.
Some say the superior materials in the Corvette mounts did not fail and thus the recall was not needed - just a rumor I don't know if it is true.
I generally run the second design on the driver's side and the original design on the passenger's side. However, you may have trouble running the plug wires in the original routing.
The correct mount shouldn't have any fore/aft play between the mount point.
The top one looks correct but I can't tell from the picture.
Corvette's weren't affected by the recall. Their throttles didn't hang wide open in the event of a mount failure. OEM Corvette mounts were much more robust than regular passenger car mounts. My dim memory says they were the same part as pass car 409 but I wouldn't bet on it.
What did you use to take up the extra clearance on the second version as it is 1/8" larger between the mounting faces.
Assuming you are talking about between the bolting ears on the second mount - I never noticed an additional 1/8" and thus did nothing. I haven't changed motor mounts in any of my cars for years. I wouldn't think 1/8" is going to be a problem, but I am not an automotive engineer, just a redneck.
Please note that the original style mount will last for years before it fails under normal driving conditions, but then again few of us drive these cars normally (as grocery getters).
The first on sits correctly on the frame with the 3 and 3/4 bolt and has 2 and 5/8 between the internal lugs that mount on the frame.
The second has 2 and 7/8 between the mounting lugs, so it has a fair bit of slop on the frame mount.
First mount
Second mount.
The slop is being reported as 1/4" not 1/8"
Chevrolet used a variety of mounts that looked very close but wouldn't fit or interchange. I'm thinking the one with the large gap, when installed to the block will also not allow the fore.aft bolt to align with the frame mounts.
It's been a long time since I played with this problem.
I am thinking the bottom one may not be for a small block as it appears to have washers tack welded to the inside of the bolting ears.
I have a set of new (2001 from AZ) in a box and they measure 2-5/8" =/- a hair. I also have a GM take off from the 70s (old style) that measures 2-5/8" also.
emdollar - that's what I was talking about. Missing the bracket on one of my 68s.
I am thinking the bottom one may not be for a small block as it appears to have washers tack welded to the inside of the bolting ears.
I have a set of new (2001 from AZ) in a box and they measure 2-5/8" =/- a hair. I also have a GM take off from the 70s (old style) that measures 2-5/8" also.
emdollar - that's what I was talking about. Missing the bracket on one of my 68s.
I believe the difference in all those block side mount dimensions has nothing to do with SB vs BB but rather with the chassis mounts and the location and configuration of the chassis mounts.
Here's one of the Camaro/Chevelle/Impala recall cable setups; Corvette wasn't affected by the problem, as it didn't go to WOT when the mount separated.
Engine Mount question
