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Bolt size for engine mounts

Wietse

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Hey guys,

I am going to replace my engine mounts, the old mounting bolts on K-member side are changed out by some metric bolts with lock nuts, thread inside the nut is drilled out so i don't know the size.
As far as i came these bolts are 7/16"-14 x 3-1/2" long, correct?

I don't want to modify my new mounts so i need to get a set of proper grade 8 bolts.

'69 Coronet with 440 engine if it makes a difference.

Thx!
 
all my stuff uses the factory type 7/16"-20 bolts with a locking nut.
 
Thx lewtot, was quite sure it was 7/16" by rough measure.
The nut comes welded on the mount, i could add a lock/double nut for extra peace of mind.
Locally i can get some 7/16" x 4" bolts, i need to shorten them a bit so i can leave some on for another nut.

I am going to use the mity mounts from Dynatech.
 
my mounts/brackets don't have nuts welded to them and they are factory pieces. i'd confirm your thread pitch before buying bolts. somebody may have added something to the brackets.
 
The rubber mounts (biscuits) do have a nut welded to them.....is that what you are talking about? The 'brackets' that land on the mounts do not have nuts welded to them.
 
re-thinking my comments; the isolator does have a nut welded to one end and it uses a 716-14 bolt that passes thru the k-member. the brackets that bolt to the block used 7/16-20 bolts and don't have nuts welded to the brackets.
 
It's the long bolt that connects the mount with the K-member, bolt B in below picture.
The nut for that bolt is welded on the metal plate of the mount.

On the old mount they probably stripped the threads in the past and drilled it out to fit a metric bolt through the hole and secure it with a separate lock nut.
I want to fit it like it should be but have to get some UNC bolts, the threads on this nut is course thread for sure.

The brackets that are connected on the engine are still as from factory and do not have nuts or so welded.

Screen Shot 2019-07-08 at 22.48.15.png
 
Yup, like Lew said, 7/16'ths 14 iirc....and about 3 1/2" long....maybe a tad longer. Nothing much was standard length on cars lol.
 
I did find some replacement bolts, OEM style from R/T specialties on moparshop.de.
But unfortunately they do not have any stock and have a 2-6 weeks delivery time so i'll opt for something more easy to get.
Ordered some 7/16"-14 x 4" bolts, will have to shorten them a bit, they are not fully threaded and the treaded part is just long enough after measuring the engine mount bracket, still needs a washer as well to get some more clearance.
Will be as close as it can get!

Thx for the help guys!
 
I probably have some here in my bolt buckets.....but no gaarenteeee...lol
 
Thx Cranky, i've ordered them and should be coming soon.
Shipping is always the biggest problem on this side of the pond :mad:
 
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