73 Motor Mounts

[73QCodeMach1F]

This seems to be a popular topic here, I looked through some of the old forums and still a little confused as to the changes from the 71-72 mounts to the 73 mounts. Many of the replacements I’m looking at, they look close but the majority claim to fit 68-73 all. I have a 73 Mach 1 351 Cleveland. Pics of current mounts and pics of Power Torque Mount pn# B2257 carried by oreilly auto parts which claims to fit 73s. If these are a no go, what is my best source to get them? Would prefer not having to change frame mounts if at all possible.

 

[Hemikiller]

Anchor 2257 is the mount most commonly used 68-72, but only on fixed roof cars. Convertibles had a unique mount to deal with vibrations specific to the platform.

73 were a new "captured" style mount that prevented separation of the engine from the chassis. Again, fixed roof and convertibles had different mounts. They are not available in the aftermarket and no other mount fits properly - regardless of what the application guides say.

It appears that you probably have 2257 mounts that were forced into position and are now separating at the brackets. IMO, your best option is to get a set of 71-72 coupe/sportsroof frame brackets and carry on. Finding a good set of 73 mounts will often be an expensive procedure.


Forum member @rackerm created a nice comparison of the various components.




... and the 73 style mount

 

[73QCodeMach1F]

Anchor 2257 is the mount most commonly used 68-72, but only on fixed roof cars. Convertibles had a unique mount to deal with vibrations specific to the platform.

73 were a new "captured" style mount that prevented separation of the engine from the chassis. Again, fixed roof and convertibles had different mounts. They are not available in the aftermarket and no other mount fits properly - regardless of what the application guides say.

It appears that you probably have 2257 mounts that were forced into position and are now separating at the brackets. IMO, your best option is to get a set of 71-72 coupe/sportsroof frame brackets and carry on. Finding a good set of 73 mounts will often be an expensive procedure.


Forum member @rackerm created a nice comparison of the various components.

View attachment 81331


... and the 73 style mount


View attachment 81332

Wow… this just keeps getting better and better. I’d love to know who wedged the wrong style mount in there rather than doing the conversion. It made me wonder if the existing mounts weren’t rated for the added power in this engine setup and cracked for that reason. Clearly not the case. Makes absolute sense now. I hadn’t seen what the original 73 mounts looked like until you posted this. 71-72 mounts it is then. Thanks for your help.

 

[delawarebill]

yrs ago i also used rackerm's info. but my other '73 was a 302 engine. i found what i needed and replaced the upper/lower mounts with '71-72. perfect fit

 

[73QCodeMach1F]

Another question, bolt torque specs? I found the mount to engine bolt torque is 85 ft/lbs, what is the spec for frame bracket to frame bolts?

 

[Hemikiller]

2 or 3 uggah-duggahs...

Torque specs are at the end of the specific engine sections in the shop manual.

 

[73QCodeMach1F]

Thanks a bunch, shop manuals are on my never ending list of things to get.

 

[73QCodeMach1F]

Yet another question.. is there a reason why the bracket to frame bolts are reversed like this? Or is this something that someone did along the line? I would think they should all go the same way?

 

[Hemikiller]

Thanks a bunch, shop manuals are on my never ending list of things to get.

If a PDF works for you, the Detroit Iron manual is pretty nice and comes with a full set of wiring diagrams. Rock Auto has them in CD and USB flash drive formats. They also carry the paper versions.

Stay way from the David Graham manuals, as they plaster huge watermarks on everything.

https://www.rockauto.com/en/catalog...cid+v8,1132995,literature,repair+manual,10335

 

[73QCodeMach1F]

I want to thoroughly thank the members of this forum who helped me out with this. If not for you guys I’d still be sitting here stumped as to why things didn’t fit. Hope you guys aren’t sick to death of all my questions by now! Lol
Decided on the Prothane mounts, the cheap oreillys mounts were even thinner than what came out of there, so took the trip to NPD (very lucky to have one locally) to buy the Prothane mounts. The drivers side was a nightmare and a half to get in. One corner of the bracket did need to be ground down a small amount to clear my headers (Hooker comps) but it’s in there now. Passenger side was a breeze in comparison. Less than an hour for passenger, a good 8 hours on drivers side including time for trimming the tabs off the 71/72 brackets. I’d cringe to know what a shop would have charged to do this, IF they would even attempt it.
Pics of everything included for future reference for others.

 

[rackerm]

I want to thoroughly thank the members of this forum who helped me out with this. If not for you guys I’d still be sitting here stumped as to why things didn’t fit. Hope you guys aren’t sick to death of all my questions by now! Lol
Decided on the Prothane mounts, the cheap oreillys mounts were even thinner than what came out of there, so took the trip to NPD (very lucky to have one locally) to buy the Prothane mounts. The drivers side was a nightmare and a half to get in. One corner of the bracket did need to be ground down a small amount to clear my headers (Hooker comps) but it’s in there now. Passenger side was a breeze in comparison. Less than an hour for passenger, a good 8 hours on drivers side including time for trimming the tabs off the 71/72 brackets. I’d cringe to know what a shop would have charged to do this, IF they would even attempt it.
Pics of everything included for future reference for others.

Nice job! I want to try the Prothane mounts on my 70 Mach 351C which uses the same mounts as the 71-72s. Good luck with your build!

 

[73pony]

I'm running the Prothane mounts on my 73 with the 71-72 perches. They are very nice and I had no fitment issues with my headers.

 

[351c1971]

I have Prothane mounts on mine with the 71-72 frame mounts. No problems with 351C stock 2v exhaust manifolds (4V might be a problem, as they are bigger).

 

[AcesArneson]

Anchor 2257 is the mount most commonly used 68-72, but only on fixed roof cars. Convertibles had a unique mount to deal with vibrations specific to the platform.

73 were a new "captured" style mount that prevented separation of the engine from the chassis. Again, fixed roof and convertibles had different mounts. They are not available in the aftermarket and no other mount fits properly - regardless of what the application guides say.

It appears that you probably have 2257 mounts that were forced into position and are now separating at the brackets. IMO, your best option is to get a set of 71-72 coupe/sportsroof frame brackets and carry on. Finding a good set of 73 mounts will often be an expensive procedure.


Forum member @rackerm created a nice comparison of the various components.

View attachment 81331


... and the 73 style mount


View attachment 81332

Hey killer did you check out QSVT1's post about how to make a new '73 mount?

... you use the top part [see picture] from the Torino 'horse shoe' part that bolts to engine block.
the bottom/ clam shell you use from your 73 OEM mounts.

Sometimes the rubber of the Torino mount is hard to get it to form around the 73 OEM clam shell... just use the 73 bottom plate [only], with Torino horse shoe & clam top piece and bolt back together.


View attachment 89029


edited: here is a picture from a different post. the 73 OEM on left... TR on right.
the bottom plate from TR is wider than the 73 OEM. the rest is the same [aftermarket today ?]


View attachment 89030

I wonder if anyone that has done this has tried to use a mounting pad from another year to raise up the engine a bit so that headers will fit around the steering box? I might try it out when my new motor mount tops get here. The 1-3/4" long tube Headman 2V pattern headers touched the steering box when I test fit them. Instead of hammering away at my newly ceramic coated headers I might try some mounting pad magic. Either spacers between the old and new half of the motor mount or spacers under the mounting pad. I don't have much room left to play with on the NACA air seal so hopefully it all fits nice when bolted up tight. They are a bit too pretty to take a hammer to them. The local shop in Edmonton did a nice job on these. (JACK from Ceramic Coatings (780)886-4661 if you need some coating done.)

 

[Q1SVT]

LOL, m

Hey killer did you check out QSVT1's post about how to make a new '73 mount?


I wonder if anyone that has done this has tried to use a mounting pad from another year to raise up the engine a bit so that headers will fit around the steering box? I might try it out when my new motor mount tops get here. The 1-3/4" long tube Headman 2V pattern headers touched the steering box when I test fit them. Instead of hammering away at my newly ceramic coated headers I might try some mounting pad magic. Either spacers between the old and new half of the motor mount or spacers under the mounting pad. I don't have much room left to play with on the NACA air seal so hopefully it all fits nice when bolted up tight. They are a bit too pretty to take a hammer to them. The local shop in Edmonton did a nice job on these. (JACK from Ceramic Coatings (780)886-4661 if you need some coating done.)

most people want to use the converts pads to lower the motor for better handling [lower center of gravity]...

Depending how much more height for the headers look at making spacers for the motor mount and the engine block... Because of all the difference in header pipe routing it's not always do able Then there is that ram-air clearances lol

edited: the 73 OEM mounts are the same, the pads 73 convert lower the engine 1" [iirc'] so you can swap to a 73 non-convert... but 1" spacers and grade 8 bolds would be a lot cheeper.

 

[AcesArneson]

LOL, m

most people want to use the converts pads to lower the motor for better handling [lower center of gravity]...

Depending how much more height for the headers look at making spacers for the motor mount and the engine block... Because of all the difference in header pipe routing it's not always do able Then there is that ram-air clearances lol

edited: the 73 OEM mounts are the same, the pads 73 convert lower the engine 1" [iirc'] so you can swap to a 73 non-convert... but 1" spacers and grade 8 bolds would be a lot cheeper.

Thanks. I picked up some 71/72 pads I’ll fiddle around to see what works best.
Weren’t the 73 verts raised up to eliminate vibration?

 

[Q1SVT]

AcesArneson​

... I'm open to learn new info, The 429 M&C site for 1971 cars [I believe that their reference to 351C is for non-convert frame mount...] If the non-convert is higher ... then the convert is lower. I do not know about vibrations, I have always understood that ford lowered the mount for converts to help reduce unibody twisting, with lower center of gravity.... like all of the other convert sheet metal changes applied to their unibody. Where I never personally checked, I heard/learned that the 1971 Boss 351c used the Convertible frame mount to improve it's handling by lowering it's center of gravity...


"429 Frame Mount http://429mustangcougarinfo.50megs. com/components_4.htm
The left and right Frame Mounts are shown. Various installed views are shown below."

"A word about the 351 C Mustang Frame Mount
We often get asked if the 351 C Mustang frame mount is the same as the 429 Mustang frame mount. The answer is NO. The top surface of the 351 frame mount is just a little bit taller than the 429 frame mount. This taller height will prevent the 429 insulator from dropping down far enough to properly line up with the thru-bolt holes as shown in the photo below."


Here below the picture shows that the mount is installed at an ANGLE... so the thickness/depth is not important, you need to analyze the bolt hole location that the engine mount and pedestal are connected through as they sit attached.

You have your 73 OEM pedestals /frame mounts... I would install them and measure the distance between the holes left side to right side... I would measure the height from the holes to the garage floor...

So when you bolt in the "71-72" pads you will see what changed and if that's a good change.

jm2c good luck

 

[AcesArneson]

AcesArneson​

... I'm open to learn new info, The 429 M&C site for 1971 cars [I believe that their reference to 351C is for non-convert frame mount...] If the non-convert is higher ... then the convert is lower. I do not know about vibrations, I have always understood that ford lowered the mount for converts to help reduce unibody twisting, with lower center of gravity.... like all of the other convert sheet metal changes applied to their unibody. Where I never personally checked, I heard/learned that the 1971 Boss 351c used the Convertible frame mount to improve it's handling by lowering it's center of gravity...


"429 Frame Mount http://429mustangcougarinfo.50megs. com/components_4.htm
The left and right Frame Mounts are shown. Various installed views are shown below."

"A word about the 351 C Mustang Frame Mount
We often get asked if the 351 C Mustang frame mount is the same as the 429 Mustang frame mount. The answer is NO. The top surface of the 351 frame mount is just a little bit taller than the 429 frame mount. This taller height will prevent the 429 insulator from dropping down far enough to properly line up with the thru-bolt holes as shown in the photo below."


Here below the picture shows that the mount is installed at an ANGLE... so the thickness/depth is not important, you need to analyze the bolt hole location that the engine mount and pedestal are connected through as they sit attached.

You have your 73 OEM pedestals /frame mounts... I would install them and measure the distance between the holes left side to right side... I would measure the height from the holes to the garage floor...

So when you bolt in the "71-72" pads you will see what changed and if that's a good change.

jm2c good luck

View attachment 89149View attachment 89150

Thanks for the thorough response.