new motor mounts don't have enough spread. 71 SB.

[Chris Cherrison]

I have two sets of motor mounts. One pair of the locking type and another pair of the non locking type. Neither pair seems to have enough spread to line up with the mounting holes on the frame bosses. Also, the locking pair, which is supposed to be the correct pair for my car, the ears are so far apart that there is a 3/8 inch gap front to rear over the boss.

Any idea what is going on here? Cheap motor mounts? One pair is from India, the other from China, but I got both sets at reputable corvette parts suppliers. The old ones fell to pieces in my hands when I pulled the engine and I chucked them in the trash so I have nothing for comparison.

Thanks
Chris

[jim34671]

Re: new motor mounts don't have enough spread. 71

Chris,
I've been down that road before with mounts that fit too loose.
I ended up shimmimg the gaps with a buildup of washers equally on both sides.
It's tricky to do...(mine a 70 LS5).
Some people simply go ahead and leave the gap while tightening hard on through bolt in hopes that it closes this gap,but I didn't feel comfortable doing that.
I don't think a proper fit mount even exists nowadays.
I'm sure you'll get further responses from others on this one.
Jim

[jim34671]

Re: new motor mounts don't have enough spread. 71

Chris,
Further to me earlier response,I remember using quality grade washers equally on each side of mount,thus to center mount to frame.
I had to "adhese" the washers together and use a magnet to hold in proximity while someone tapped bolt through.I may even had to put a better chamfer on through bolt to ease alignment through washers.
Jim

[David H.]

Re: new motor mounts don't have enough spread. 71

New GM mounts are Part Number 6258154. They are more expensive than the discount houses, however, they do look like the originals and they fit properly.

[Chris Cherrison]

Re: new motor mounts don't have enough spread. 71

I think I wasn't entirely clear in my post. While the mounts fit loose over the bosses that is easily addressed with a couple of washers, tho I would like to find mounts that fit correctly. The primary problem is that the holes wont line up. It appears that I need to put some spacers between the mounts and the block in order to get the holes to line up. And that is not a good solution. Its as if the frame suddenly spread apaart about 1/2 inch while the motor was out, but of course its the mounts, not the frame.

I may try the GM mounts.

Thanks
Chris

[Joe L.]

Re: new motor mounts don't have enough spread. 71

Dave-----

Yes! The current GM SERVICE mounts are configured a little bit differently than most 70-82 originals, but they fit perfectly. Also, they are the strongest mount available on the market. These mounts will also work for all 63-69 applications which originally used a non-locking mount. However, for Corvette applications, the lower "V"-shaped RF shields have to be modified (or, the 70+ style shields used).