Hey everyone. Whats a good way to tell your motor mounts are bad?  I've always had a grinding noise when I really get on the throttle in first gear and torque the engine up. Tonight I took the hood off...and floored it in first gear. My engine flexed quite a bit, and it sounded like the grinding noise is coming from the front of the engine near the fan. The alternator looked like it jumped up about 4-6 inches.  Is this normal?

I got under the car and checked out the mounts. From visual inspection, nothing looks wrong. All bolts installed and torqued...bushings look a little worn...and the welds between the frame and mounts looks good.

Shane, the engine will move when you hit the throttle, but 4-6 inches movement on the alternator isn't normal. It sounds like your fan is hitting the shroud, which would leave a mark. It also appears to me that you do have a bad mount. Hopefully Joel will offer more expertise on this. Mounts aren't that hard to replace. 

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Shane here is a link that might help you:  http://www.mobiloil.com/USA-English/MotorOil/Car_Care/DIY/Replacing_Your_Engine_Mounts.aspx

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Shane, you also need to check your transmission mount.

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My left motor mount broke and raised the engine enough for the alternator bracket to hit AND crack the hood. I have a spider crack about the size of a golf ball - it kills me every time I look at it.

  Make sure you get the correct motor mounts for a 350 Corvette and not a 305 Corvette. A few people have received the wrong mounts only to find out there are two different mounts for a 63-82 Vette.
Good Luck and post if you have any problems!

if there's nothing hitting the shroud, it could be a water pump or other belt driven component starting to wipe a bearing...LukesVette2009-01-11 13:55:01

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Yeah...after closer inspection...motor mounts are BOTH shot
I'm looking at the polyurethane bushings from Jegs (Energy Suspension part #355-3-1114G).  They measure 2-5/8'' Width x 1-3/4''Height. Does this sound about right to you guys? I would take mine off now to measure, however the "Red Dragon" needs to roll under its own power to a buddy's house to put on the hooker headers and side pipes tomorrow .

I was gonna go with solid mounts...but with a fiberglass body...I didn't want to run the risk of torquing the frame and cracking something.

Shane, I went with these from Summit Racing. They worked fine....  http://store.summitracing.com/partdetail.asp?part=ENS%2D3%2D1120G&FROM=MG

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Corvette440hp:  Thanks. I just ordered the kit. I've figured out how to get the motor mounts in with the floor jack and block of wood (thanks again for the link)...any helpful tips for the tranny mount?

2 5/8" is the correct width for my 82, 350 - what I received was 2 7/8" which was 1/4" to wide. The height was the same with both.

Mid America did completely take care of this mishap and issued me a full refund with return postage.

Phill:  I've always had great experience with Mid America. However, I doubt I will ever order from Ecklers again. I ordered a center console arm rest...2 months and the paint has started to peel. It looks like they took a black pad and coated it with latex paint. More recent, I bought a radiator expansion tank from them...after the a$$-pain of pulling out the old and installing the new...i've noticed it has a crack in bottom of the tank.  Ecklers is quickly approaching my "F-em" list.

[QUOTE=shanes79]Corvette440hp:  Thanks. I just ordered the kit. I've figured out how to get the motor mounts in with the floor jack and block of wood (thanks again for the link)...any helpful tips for the tranny mount? [/QUOTE] All that you need to do, is to support the transmission, remove the monting bolts on the transmission bracket mount, and remove the transmission frame cross member. 

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The way I found out about my broken motor mount was I opened the hood reved up the engine and watched the motor try to jump out of the car. You will eaisly be able to see it. It will also make a bumping noise on the broken mount as it moves up and down. Worked for me. Gene gs77vet2009-01-13 13:48:31

Thanks fella's.  I was hoping the mounts would show up today.  No dice.  They should be here tomorrow (according to the UPS tracker site, they are in a town less than 50 miles from here) .

I will post pics of the new mounts once they are in.

In the mean time...I was able to get the Hooker Super Comp headers and pipes installed on the car.  I have links to some pics. The aluminum rocker panel covers rub against the new headers...So I didn't install them yet. (missing from the pics). I will machine them down this weekend and reattach.  Thanks again for everyone's help.

http://i36.photobucket.com/albums/e47/usaflyboy9/P1000459.jpg
http://i36.photobucket.com/albums/e47/usaflyboy9/P1000462.jpg
http://i36.photobucket.com/albums/e47/usaflyboy9/P1000466.jpg

Shane, the pipes look good 

Looks way nice!

This is what I did to my rocker panels to make them fit perfect. The Hookers seem to fit a little bit differently from C3 to C3 so customizing may be necessary for most.
I also painted these rockers the stock black; I think the black also helps the pipes to stand out and not be lost in the shine.

Phil:  Those look great. Did you use a template at all...or just free hand it?
I agree with painting them black. The buddy that I bought the pipes from recommended it as well.

I  made a cardboard template first, then traced and cut. I left about 1/2" space between the rockers and the headers.