Small block motor mount question

[Duster360LA]

I'm looking for some clarification as I prepare to put my 360 Magnum into my 74 Duster. I know there are RH and LH specific motor mounts and I found a set in the parts boxes that came with my Duster. It appears from looking at both the old and new rubber inserts that the bolt holes are different sizes. One is .5 inch in diameter, while the other is a bit over .6 inch diameter. Is that correct?

 

[Dana67Dart]

Perhaps you can post a photo of what you are talking about

 

[Scody21]

As you should have a “spool” motor mounts. Which Rockauto has new ones…

 

[RustyRatRod]

Probably just the difference between two aftermarket mounts or a factory and aftermarket. But pictures wouldn't hurt. If they are factory, they will have part numbers stamped on them somewhere.

 

[tonysrt]

I looked for the correct spool mounts for a 360 a few years back at Rock auto and they only had mounts for the 318. I checked with the company that distributed them and they only made the 318 mounts.

 

[Duster360LA]

As requested, I have some photos. It may be difficult to tell the difference between the .5 and .6, but a half-inch bolts fits snugly in one mount and is fairly loose in the other.
First two shots are of both ends of the new rubber inserts that came in a parts box with the car.

Next two shots are the two new inserts next to a new LH mount I got from Classic Industries (RH mount has been on backorder for 3 months).

Final photo are the old mounts that came with the car (which originally had a 318).

 

[luvmopars]

Bolts should be the same size. I would think they are China junk mounts made wrong

 

[luvmopars]

I do have a left side NOS mount. 3817233

 

[RustyRatRod]

Bolts should be the same size. I would think they are China junk mounts made wrong

That ^^^ is your answer.

 

[Duster360LA]

Thanks everyone, I'm ditching what I have and ordered a new set from RockAuto - we'll see what they look like.

 

[luvmopars]

Thanks everyone, I'm ditching what I have and ordered a new set from RockAuto - we'll see what they look like.

most likely may come from the same vendor

 

[Duster360LA]

Pretty unbelievable that such a common part isn't well made and readily available.

 

[Big.J.007]

[FOR SALE] - 73 up sb spool motor mounts

 

[cudamark]

You sure it's not just the rubber slag making one tighter than the other?

 

[Duster360LA]

I thought of that - before I started this thread I got my calipers out and measured the inside diameter at each end, scraping away any excess rubber material. One is .5 on the nose and the other is .623.
The motor mount bolt is 1/2 inch - any larger of a bolt diameter won't fit in the engine mount slots on the K member.

 

[Dana67Dart]

doesn't the bolt clamp the spool mount between the ears of the body mount? in that case the bolt hole ID is not very important

 

[Duster360LA]

That's correct, but the notches in my K member "ears" are half-inch wide, so any larger of a bolt wouldn't fit - unless I carve out the mounting notches (which I don't want to do).

 

[Dana67Dart]

That's correct, but the notches in my K member "ears" are half-inch wide, so any larger of a bolt wouldn't fit - unless I carve out the mounting notches (which I don't want to do)

If the standard bolts are 1/2" and the hole in the spool mount is 0.6" there is no reason to up size the bolt. That was my point

I would never suggest modifying the car to fit a part.

 

[Needswork]

A short while back I purchased spool engine mounts for a slant 6 from RockAuto (Westar brand I think). The ones I received were made in India and were the poorest quality I've ever seen. Instead of a tube for the bolt they used a piece of square tubing (probably 3/4 inch tube, maybe larger) and slightly smashed it on it's side to make the "hole" smaller. But it was still way larger than 1/2 inch. They went in the trash. They didn't cost much so I didn't expect much.

 

[Duster360LA]

Just a quick update, I got my Rockauto mounts in and they are western, made in India. At an initial look, they appear correct and reasonably well made. The best option I have so far, but I have a little more time to look around.

Picture shows them with the worn-out mounts that were in a parts box with the car.

 

[TF360]

I ordered a Transmission mount a few years ago, and it was made in China. The quality was not so good. Found another one that was made in Taiwan and the quality was much better

 

[dust44d]

The 360 left side mount has a wider bushing to fit into the k frame mount.I found only 318 mounts being repopped and they noted that washers needed to be used to fill gap,so basically they are 318,narrow mounts.

 

[cudamark]

The 360 left side mount has a wider bushing to fit into the k frame mount.I found only 318 mounts being repopped and they noted that washers needed to be used to fill gap,so basically they are 318,narrow mounts.

The '73-6 A-body 318/340/360 K-members are all the same, so they have the same width rubber section of the mount. It's the engine bracket section that is different between the 318 and the 340/360. The 340/360 brackets are narrower on the driver's side.

 

[lemondana]

Energy Suspension makes nice Poly inserts for these. But you need to leave the bushing shell in the mount. I use a propane torch-heat the shell and bushing very well and the bushing will pound out with a big hammer. Then you need to clean the id of the sleeve, probably using the torch some more. And they sell these on Rock Auto cheaper that any other place. If you can stand to use poly. All currant mounts are junk!

 

[H22A4]

I ordered a Transmission mount a few years ago, and it was made in China. The quality was not so good. Found another one that was made in Taiwan and the quality was much better

I had the same experience with Anchor (2512) brand transmission mount. The inner diameter of the bushing for the crossmember bolt was smaller than the diameter original bolt. Frustrating stuff indeed.