351c motor frame mounts

rackerm said:

Unfortunately, Hemikiller is correct as always. When I spoke a few months ago with "thee" guy at Mustang etc. He said they were working on getting the rubber insulator for the 73 verts. He seem hopeful that it would happen but he offered no timetable as to when. If you can use a pair of 71-72 or 73 vert or hardtop frame mounts, I have a collection of them. I would be interested in your 73 Vert mounts.

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Hey rackerm, with whom did you speak to at Mustangs ETC? I used to work there many years ago, and at that time, the original owner of the place, Arnold Marks, had passed, and his son, Garrett was soldiering on with the place. Just wondering if Garrett was the guy you talked to.......

Good point. The motor frame bolts are subjected to both shear and tension. Grade 8 hardware is always a good idea here as well.

Hi all,
I had a 1971 mustang that I raced and had Lakewood muscle motor mounts. They failed because they had a bolt through motor mount which after many drag race launches the drivers side failed. You had to cut a hole in frame mount as well. What happened when the bolt failed was the mount then ripped apart and the engine torqued up, which then the engine twist, pushed against shift rods causing car not to shift to 3rd gear unless to you let off gas or kill the ignition. The 1973 mounts are the best design! They are like all modern ford designs (my 1998 mustang has same design) in which if rubber fails they still do not allow engine to lift away from frame. I remember an old buick with mechanical throttle linkage and drivers side motor mount failed. The car would accelerate and the only way to stop this 430 cubic inch monster was to turn the key off.

I'm also in this same dilemma with my 73 vert. I've started a new engine build and would like to upgrade the engine mounts, but can't seem to figure out what combination(s) I will need if I want to use the Prothane mounts. I did see these available on NPD, but would like to see if anyone has any feedback if they will work on the 73 vert. The listing shows it will work on 65-72 and are adjustable. In the vehicle information section, there is a note that says "73 is very different".

https://www.npdlink.com/product/mot...2Bmount&top_parent=200001&year=1972&year=1972

INPete said:

I'm also in this same dilemma with my 73 vert. I've started a new engine build and would like to upgrade the engine mounts, but can't seem to figure out what combination(s) I will need if I want to use the Prothane mounts. I did see these available on NPD, but would like to see if anyone has any feedback if they will work on the 73 vert. The listing shows it will work on 65-72 and are adjustable. In the vehicle information section, there is a note that says "73 is very different".

https://www.npdlink.com/product/mot...2Bmount&top_parent=200001&year=1972&year=1972

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Those absolutely will not work on a 71-73, they're for the 65-70 cars. Those cars have a bolt on frame bracket like below, and the RMP mount replaces that and the insulator.

The simplest remedy is a 71-72 coupe/sportsroof frame stand and either a set of Anchor 2257 insulators or the Prothane mounts you want to use.



@Rick@NPD might want to correct that listing. They're also not going to work with the 65-71 intermediates

Hemikiller said:

The simplest remedy is a 71-72 coupe/sportsroof frame stand and either a set of Anchor 2257 insulators or the Prothane mounts you want to use.

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Thanks for the heads up on the NPD adjustable mounts and the simple remedy. A quick question on the frame stands, would it also be ok to use the 71-72 vert/big block along with the Anchor 2257's? Looking at the pics of the two different frame stands, I notice there is a slight difference in angle. Didn't know if that would cause any vibration issues in my 73 vert.

INPete said:

Thanks for the heads up on the NPD adjustable mounts and the simple remedy. A quick question on the frame stands, would it also be ok to use the 71-72 vert/big block along with the Anchor 2257's? Looking at the pics of the two different frame stands, I notice there is a slight difference in angle. Didn't know if that would cause any vibration issues in my 73 vert.

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No, those won't match up properly.

INPete said:

I'm also in this same dilemma with my 73 vert. I've started a new engine build and would like to upgrade the engine mounts, but can't seem to figure out what combination(s) I will need if I want to use the Prothane mounts. I did see these available on NPD, but would like to see if anyone has any feedback if they will work on the 73 vert. The listing shows it will work on 65-72 and are adjustable. In the vehicle information section, there is a note that says "73 is very different".

https://www.npdlink.com/product/mot...2Bmount&top_parent=200001&year=1972&year=1972

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The prothane captive-style mounts are designed like the 73 captive motor mounts, but for a 71 or 72 frame mount. You can use them with your 73 vert if you also use the 71-72 vert/big block frame mounts. The prothane will not work with the 73 frame mounts hardtop or vert. The only motor mounts that work with the 1973 D3ZZ-6028-B or a D3ZZ-6029-A frame mount is 1973 captive-style motor mounts (D3ZZ-6038- X which went through 8 engineering revisions before the dust settled. The rubber insulator in side the captive motor mount also carried a part number, for example, D3A-6038-BD). What makes even more confusing is the active motor mount rubber insualtor is different between hardtop and convertible. This difference is enough that a company that rebuilds 73 motor mounts can only do Hardtop mounts, they cannot rebuild 73 convertible mounts.

Any Ford motor mount having a Ford interchange part number older than D3 is most likely not compatible with the 73 frame mounts.

I heard of folks shimming the 73 frame mounts up (I don't know how much), so they sit taller like the 71-72 frame mounts and then using a 71-72 style motor mount.



I have a set of 71-72 vert/big block frame mounts I could sell, if you decide to go that direction.

I'll keep those in mind. I have found a set of 71-72 hardtop brackets that I'm working a deal on at the moment.

INPete said:

I'll keep those in mind. I have found a set of 71-72 hardtop brackets that I'm working a deal on at the moment.

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They are slightly shorter and have a different angle than the convertible brackets, if you shim the bottom two bolts about a 1/8" to 1/4" you can raise them as tall as the convertible frame mounts and give them more angle like the vert mounts, that should work with the Protane active motor mounts. Good luck. Please let me know, iIf they do work for you. Also if your current deal falls thru, I have a set of 71-72 HD mounts as well.