motor mounts

[164runner]

changed motor mounts and frame brackets to the 71-72 ones in my 73 mach1, 351c because of headers. went threw 3 set of headers, none fit very good on pass side, because it has a c-6 trans. so I put on 4v manifolds on it. engine sits lower now, but did not have clearance issue with fan shroud, but did not drive car, only started it, new engine. Trailered car to exhaust shop, had new exhaust installed from h-pipe back, after starting car, now fan is rubbing shroud. engine had to settle when I trailered it. how to fix ? 1. put back on 73 style motor mount and frame brackets. 2. shim between block and motor mount or between frame and frame bracket. 3. modify shroud. I loosened shroud its as low as it gets. ideas?

 

[73pony]

I made this same switch and did not have any problem at all. The 73 frame perches are shorter and the motor mounts taller than the 71-72. IE the 71/72 frame perches are taller than the 73. Are you 100% positive you got frame perches for a 71/72 sportsroof/coupe? I believe the verts are different. That might be backwards on the taller shorter thing. It has been a while. Regardless if matched up 73 perch with 73 mount the motor sits at same height as it would with 71/72 perch and 71/72 mount.

 

[164runner]

got frame brackets for the 71-72 of ebay, by looking at different pics, they look like they are for a fastback/coupe. does anyone have the height of the brackets? the gap at top of shroud was a lot less with the clamshell mounts versus what is in car now

 

[73pony]

See Post #9 in this thread. There are not measurements on there but it shows the different perches lined up next to one another. As you can see the 71/72 perch is considerably taller than the 73 perch to make up for the shorter motor mount.

https://www.7173mustangs.com/thread-motor-mounts-identification?highlight=motor+mounts

 

[TommyK]

Where is the fan rubbing the shroud? Top? Bottom? Sides?

There is some adjustment in the shroud and you can shim the trans mount up or down.

 

[6DUB606]

Where is the fan rubbing the shroud? Top? Bottom? Sides?

There is some adjustment in the shroud and you can shim the trans mount up or down.

I had similar problem from fitting after - market mounts.  Used a white marker to note where the fan blades were hitting and trimmed the shroud to suit.  Was only approx 1/2" in from the edge and maybe 5" - 6" total length at the very bottom as the engine sat slightly lower.   Cutting plastic is easy and beats the hell out of modifying or shimming motor mounts.  Doesn't seem to have effected cooling in any way.

Maybe worth a look ?

PKJ

 

[rackerm]

changed motor mounts and frame brackets to the 71-72 ones in my 73 mach1, 351c because of headers. went threw 3 set of headers, none fit very good on pass side, because it has a c-6 trans. so I put on 4v manifolds on it. engine sits lower now, but did not have clearance issue with fan shroud, but did not drive car, only started it, new engine. Trailered car to exhaust shop, had new exhaust installed from h-pipe back, after starting car, now fan is rubbing shroud. engine had to settle when I trailered it. how to fix ? 1. put back on 73 style motor mount and frame brackets. 2. shim between block and motor mount or between frame and frame bracket. 3. modify shroud. I loosened shroud its as low as it gets. ideas?

In the picture below is the wrong combination of 73 frame mount/perch and 71-72 small block motor mount. The left is a 71-72 mount for a coupe/FB and the right is definitely a 73 coupe/FB frame mount. 73 frame mounts do not have a turned-up lip on the lower edge. If it's a 73 vert that you have then neither of these is correct. For a 71-73 coupe/FB the 71-72 motor mount on left should work, if you replace the 73 frame mount with a 71-72 taller version. Your other choice is to keep the correct 73 frame mount on right and replace the 71-72 motor mounts with the correct 73 captive style motor mounts.



Also, the trans mount can affect the engine's tilt some. If the trans mount is not correct, the tilt at the shroud could be higher or lower.



Here is another link to a post on the topic with some measurments...https://www.7173mustangs.com/thread-fan-shroud--31440?page=5



Here is a link to a 360 article on motor mounts: http://www.mustangandfords.com/how-to/engine/mump-1302-how-to-identify-and-choose-engine-mounts

 

[164runner]

rubs on the bottom. I will pull shroud and see if I can notch it, where it sits at bottom in the clips

 

[164runner]

put the mounts and brackets that came on car, back on. raised engine back up. one more problem fixed, on to the next one

 

[rackerm]

put the mounts and brackets that came on car, back on. raised engine back up. one more problem fixed, on to the next one

If you are worried about the condition of the original mounts. The hardtop 1973 captive style motor mounts can be rebuilt. There is a shop that does, but I can't find the info. I have it somewhere. I'll post it as soon as I find it.