Motor Mount Confusion!

[kcmash]

Team,

I keep thinking I am ready to install the power train and come across strange new information. I have an original 11/70 build Mach 1 Body with motor perches. I am planning to use the 73 style capture mounts to prevent the motor mount cracking issue. The power train is a 351C 4-V setup with original intake, Holley Carb and Ram Air system. I saw this post the other day.

RE: Anyone change motor mounts on 351C?


The 73 mounts are capured style and are unique to that year. The 73 frame perches are shorter and the mounts are taller to compensate. The motor sits a tiny bit higher on the 73 as well.


71-72 are rubber mounts that look like most older mustang mounts. The frame perches are taller on these than 73 and the mounts are shorter.


Most auto parts stock them, most are made overseas. I think NAPA had some USA made ones. There is also these Lakewood muscle mounts that look promising.


http://www.summitracing.com/parts/LAK-24094/

Is my engine going to fit OK if I use the '73 mounts on my '71 perches?

Thanks!

kcmash

 

[Paul of MO]

I think the problem will be that the holes will not line up. If you get the mounts bolted to the engine then the pins that go through the frame mount wont line up.

If you get the pins in then the bolts on the block will not work.

Trying to find 73 mounts is the issue - Ford is out and is not making them and no aftermarket company makes them specifically for 1973 Mustangs with the 1973 perch.

But this is available - a capture style mount for the older cars. They say it fits 1973 but I would bet it does not. It will fit your 71.

https://www.performanceonline.com/Ford-Engine-Motor-Mounts-Small-Block-V-8-289-351W-Polyurethane/

I do not know why 351c is not listed as all the holes are in the same spots for all small blocks and 351c's from 65 to 72

I have never had a non 73 style mount fail on even on pretty high HP cars.

If the motor mount along with the trans mount are all good I would not worry about it.

- Paul of MO

 

[Don C]

You can always build your own. This way you can select whether you want urethane or softer rubber, and will be easy to replace the bushings.

http://www.how-to-build-hotrods.com/custom-motor-mounts.html

 

[secluff]

Unfortunately the 73 mount is a low demand one year only part. The 71-72 mount was shared with Torino/Montego/Cougar, so at least there was some compatibility with other models (and $$ to be made by parts venders on a multi year part).

I was involved with a group of Ford gear heads who raced and beat our cars within an inch of their lives. The only mount failure was on a 69 428 SCJ Cyclone with throttle linkage (no throttle cable) so that was a "White knuckle ride"(I was driving it)! I NEVER had a mount problem with any of my 351C cars. The mount shown in Paul's link look good and they should work on your 351C although not listed. My 67 289 Mustang used the same motor mount as my 71 M Mach 1 so the mount is the same.

The $129.99 price each may seem a little high, but you'll probably spend more trying to find and purchase the 73 items and still have a 43 year old part. If your really concerned about the safety of keeping your engine in place, I would purchase the mounts listed in Paul's link.

 

[kcmash]

I think the problem will be that the holes will not line up. If you get the mounts bolted to the engine then the pins that go through the frame mount won't line up.

If you get the pins in then the bolts on the block will not work.

Trying to find 73 mounts is the issue - Ford is out and is not making them and no aftermarket company makes them specifically for 1973 Mustangs with the 1973 perch.

But this is available - a capture style mount for the older cars. They say it fits 1973 but I would bet it does not. It will fit your 71.

https://www.performanceonline.com/Ford-Engine-Motor-Mounts-Small-Block-V-8-289-351W-Polyurethane/

Paul,

Thanks for the information. I am very glad I learned this before hanging the engine on the hoist. I have had a couple failures of the original style mounts on this car over the years, so when I found a set of the 73s in a batch of parts I acquired, I just assumed this was a Hi-Po upgrade.

I will check to see if I have the frame side saddles in my parts pile, now that I know there is a difference.

So if the engine sits different, that must mean the fan shroud or at least the radiator mounts are different for 73 also, correct?

kcmash

I do not know why 351c is not listed as all the holes are in the same spots for all small blocks and 351c's from 65 to 72

I have never had a non 73 style mount fail on even on pretty high HP cars.

If the motor mount along with the trans mount are all good I would not worry about it.

- Paul of MO

 

[Paul of MO]

"So if the engine sits different, that must mean the fan shroud or at least the radiator mounts are different for 73 also, correct?"

That is a good question. I have always had 73 mounts on 73 perches but I know I have swapped shrouds and radiators and the like from all 3 years and all 3 body styles and I have never had one not fit. Maybe I just got lucky.

Logic seems to say that if the engine sits higher or lower the fan shroud and radiator would need to be placed differently. Not a big deal as it would be easy to adjust it by an inch or two.

I wonder if under the shroud there is enough clearance for the fan no matter what because I never get lucky.

- Paul of MO

 

[Totalled]

Lakewood made capture style mounts that will work with 71/72. Then there's the urethane mounts.

 

[rocket366]

I read a 71-3 vert engine sits .5 in. lower I think for the belly brace. I don't remember where

I read that and I don't have a vert. Not enough IMO to need different rad mount or

shroud.

Info is from web research so I cant be sure. There was a write-up on Mustang Monthly

that addressed the different perches. (not the fish)

Paul

 

[kcmash]

So I found he other Perches. 1/2 inch shorter and a little different shape than the 71 units. So what does everyone suggest. Use the 73 style captive setup, or order new mounts for the 71 perches and sell the 73 setup?

Not going concourse on the car, just trying to add all the best factory features.

Thanks,

kcmash

 

[rocket366]

IMO

The regular 67-72 mounts are ok unless you are drag racing the car or

it's a manual trans car and you are trying to get second gear scratch

all the time.

The Regular mount failed quickly in my 69 that was drag raced weekly and I

chained the engine down because of that.

Paul

 

[kcmash]

Well, I opted for the 73 setup since I had all the parts. Bead blasted, painted, baked and installed today.

Getting ready for the engine drop!

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