Question about engine frame mounts

[csilvy2000]

I picked up a 1973 Mach 1 that is in desperate need of some attention. The car has been sitting since the early '90's. The car was born with a 302 and 3 speed setup. The previous owner was apparently in the process of swapping in a big block mated to a c6 combo. During the swap it appears the frame mounts for the engine were swapped to mounts that fit the big block. I'm not sure about the necessary parts needed when swapping with these cars.

My question is 'are the frame mounts different from a small block 'windsor' to a big block 385 serie?' I have an older 302 without a home and am in the process of swapping it into the car. The big block and c6 units were in the car when I picked it up and are to far gone to consider using without having them completely rebuilt.

Any input is much appreciated. The big block 460 and c6 are for sale if anyone is interested. I'm in northeast Texas, pick up only.

 

[Fordboy71]

Hi. Welcome to the site! The Small block mount is different from the 385 series big block. Small block mounts from ‘64 on up will work fine. Before ‘64 the 260 and (then brand new 289) had offset bosses and used a different mount Altogether.

 

[csilvy2000]

Thank you for your response. Is this an item that is readily available?
Appreciate the welcome. I will introduce my old mustangs in a separate thread. I purchased new engine mounts for the engine, but now need the frame mounts.

 

[Steve McMahan]

Well, not to be annoying, but the mounts on the 73 are different. If you look at any one of the Mustang suppliers, you’ll find their offerings stop at 1972. The 73 uses a clamshell mount that captures the mount in the event the rubber section fails. Something new that was required in 1973, at least that year.

This site shows what they look like:

https://www.mustangsetc.com/73-mustang-302-351-motor-mount-rebuilt-fits-coupe-fastback/
Good luck.

 

[351c1971]

Here are pictures of the 71-72 Fastback Frame mounts. The work with standard 71-72 motor mounts for the 302 and will bolt into the 73 Fastback.

 

[csilvy2000]

Not annoying at all. Thanks for the input. Those, however, appear the mounts that bolt to the engine block.
351c1971, thank you. I think that's what I'm looking for.

The big block frame mounts look very similar, however, the thru-hole that the mount bolt would go through, is more in the center. If my eyes don't deceive me, I believe the small block mounts should have the thru-bolt location more offset.

I know the frame mount has 4 bolt mounting locations, and the big block mounts that are in the car a simple square shape with a single thru-bolt pass thru hole directly in the middle.

 

[351c1971]

I tried the 73 small block frame mounts with my 302 and later my 351 and they do not work with the 71-72 motor mounts. They should work using the 73 motor mounts. In summary, use 73 mounts with 73 brackets or 71-72 mounts with 71-72 brackets.
You can see in attached the pictures that the 73 small block Frame Mounts are very different. You are absolutely right about the thru bolt hole location differences.

 

[csilvy2000]

Wow! You have gone above and beyond. Thank you so much.
I have no desire to make the car a show winning resto. I just want to get the car back on the road and safe. I will gladly use the 71-72 combo if necessary. If that doesn't pan out, I will fabricate something.

Those pictures you posted, are those from a retailer? Honestly, i haven't researched this as much as I should have, but I do appreciate the quick knowledge this site provides.

It would seem to me that three different combos would have to have been offered by Ford for their V8 engines in these cars. One set each for the: 351C engine, small block Windsor 302, and the big block 385 series engine.

If anyone would like the big block 385 series frame mounts, I have them available. I have no use for them.

 

[Steve McMahan]

You can post them for sale in the classified section; please read the rules before you post them there.

 

[Hemikiller]

Just to add some more detail to the above posts, so you don't end up with the incorrect parts.

71-72 coupe/sportsroof frame mounts will work for 302, 351W & 351C in all 71-73 cars. These take the Anchor 2257 mount that's available everywhere and is used from late 65-72. Do not get 71-72 convertible frame mounts, as they take a different motor mount that is not available.

73 coupe/sportsroof frame mounts are different than the 73 convertible mounts. Again, motor mounts are not available for either, so you need to send in cores for a rebuild.


View attachment 1674922702505.jpeg

 

[351c1971]

Not sure where the pictures came from. I believe the frame mounts are only available used.

 

[Steve McMahan]

I did not know you could use the older engine mounts on a 73.

 

[351c1971]

Absolutely, the frame cross member is the same. You can also use the 71-72 Prothane captive mounts if you have stock 2v manifolds. Here is a picture

 

[Don C]

You can also make your own captive style motor mounts:
http://www.how-to-build-hotrods.com/custom-motor-mounts.html

 

[cjstaci]

Wow! You have gone above and beyond. Thank you so much.
I have no desire to make the car a show winning resto. I just want to get the car back on the road and safe. I will gladly use the 71-72 combo if necessary. If that doesn't pan out, I will fabricate something.

Those pictures you posted, are those from a retailer? Honestly, i haven't researched this as much as I should have, but I do appreciate the quick knowledge this site provides.

It would seem to me that three different combos would have to have been offered by Ford for their V8 engines in these cars. One set each for the: 351C engine, small block Windsor 302, and the big block 385 series engine.

If anyone would like the big block 385 series frame mounts, I have them available. I have no use for them.

Pm me as I am interested in the 429 frame mounts.

 

[csilvy2000]

Thanks for the information. I purchased the '73 engine mounts before realizing all the ins and outs. So the two options I look into are fabricating my own frame 'brackets' or coming across some used to match the new engine mounts. Or keep my eyes out for a 71-72 combo.
Thanks again everyone!

Cjstaci, bare with me and I'll respond to you.

 

[Bobby]

Prothane 6-503-BL Black Urethane Motor Mount Kit https://a.co/d/e6XCcY7

Here is a new engine mount for your 73. Nobody makes the frame pedestal that I know of.

 

[Hemikiller]

Prothane 6-503-BL Black Urethane Motor Mount Kit https://a.co/d/e6XCcY7

Here is a new engine mount for your 73. Nobody makes the frame pedestal that I know of.

Those do not fit '73, the listing is incorrect. One reviewer even noted they didn't work on his '73.

 

[351c1971]

Just to further clarify, Prothane 6-503-BL Black Urethane Motor Mount will NOT fit a 73 with 73 frame brackets or 351c 4v exhaust manifolds.

However, if you use 71-72 small block frame mounts (and cut off the tab per Prothane instructions) and have stock 351c 2v exhaust manifolds (not 4v) they WILL fit. This is exactly what I have in my 73 Mach 1. It even fits fine with the stock manual transmission linkage. They will also fit with the 302 small block.

BTW, when I called Prothane technical support, they were not aware of the difference between 351c 2v and 351c 4v exhaust manifolds. I sent them pictures of my installation and they thanked me for my help.

You can't always believe what you read, and the unwritten context is important to understand. A few pointers, when you shop for the 71-72 frame brackets, look for the 90 degree tab and verify that are not from a convertible.

I hope this helps.

 

[csilvy2000]

Good information. The '73 introduced a few changes in several aspects of the car. It's getting a 302 that I picked up recently. While looking into the engine, I put a new oil pan on and took a inspection of its internals. Looks as though it has very little usage since a rebuild. The crank is 10/10 and the pistons are 30 over. Has 351W heads, though I didn't notice the year. ARP head bolts were used, that's nice. Aluminum aftermarket intake, still has a single point distributor.

Unfortunately, the exhaust cam lobe on cylinder 4 is flat. May try my luck with another cheap flat-tappet or go ahead and go the roller route.