I'm installing an sbc 350 motor into my 76 el camino.I'm replacing the old ruined stock rubber motor mounts and replacing them with Prothane urethane mount inserts part#7-506.After much fighting with these, i finally got the passenger side bushing installed and the long bolt bracket to fit correctly.The problem is the driver side mount.The bracket hits the bolt hole offset tangs about an inch to high.Bare in mind,these bushings go in the dbl hump,3 bolt clamshell.Has anyone had any difficulty like I'm have using either Prothane,Energy,or any other brand of urethane motor mounts?

do you have the insert in backwards or upside down?
i've never replaced that style of mount since i've never seen them worn out, so i can't really offer much more than that.

I used Energy Suspension poly motor mounts on my big block in a 70 Chevelle and haven't had any trouble with alignment. I did have a slight problem with the oil pan rubbing the drag link at first but was able to put some washers between the block and the mount to raise it up enough to clear. My mounts are a two piece type where you have a plate that goes on the back of the poly part of the mount but I don't know if not having that piece on would cause the trouble your having, are you sure they're the correct mounts for your car?

MRBREEZ

Yes they are installed correctly,not backwards or upside down.If i install the long bolt through the mount and then set it down,the clamshell holes don't line up with the frame holes.Yes MRBREEZ,they're the correct mounts for my el camino.Prothane even sent me a replacement pair to see if there's anything wrong with the first set i bought.Same part number,same looking insert.I think I'm gonna find the Energy ones and see if they work.I f they do,then I'll tell Prothane that their's are made wrong.

Jusr curious, what motor was in the car before?

the previous motor was an sbc 350

Well I installed one of the Energy Suspension motor mounts and lo and behold it works/fits.Ordered one for the passenger side and will have it tomorrow afternoon.Amazing how something so simple could become such a pain in the butt.:hurray:

Yes they are installed correctly,not backwards or upside down.If i install the long bolt through the mount and then set it down,the clamshell holes don't line up with the frame holes.Yes MRBREEZ,they're the correct mounts for my el camino.Prothane even sent me a replacement pair to see if there's anything wrong with the first set i bought.Same part number,same looking insert.I think I'm gonna find the Energy ones and see if they work.I f they do,then I'll tell Prothane that their's are made wrong.
i realize you figured it out, but i'm having a problem visualizing what the problem was.
did you perhaps have the metal part that surrounds the insulator upside down or in the wrong holes in the frame or something?
that style of mount is pretty fool proof, and they last forever- which is why they used them in everything with Chevy V8's rangine from 262-454 inches except Vettes and Monzas from 73-99. i've never seen stockers worn out, and i can't imagine why the stockers would ever need to be replaced with urethane replacements that can only transmit extra vibes thru the chassis and into the car.

The insert can be installed wrong and if it is the bolt will not go through the mount and the clam shell. If you look closely the tabs are not in the same position. The clamshell rests on the tabs and the bolt just keeps the engine down. I know this because my Nova uses the same mount and I made the mistake of assuming they couldn't be installed backwards. When the insert is installed correctly you have to identical mounts, not a right and a left.


http://i80.photobucket.com/albums/j199/64elcamino/77%20Nova%20project/engine/polymounts.jpg

Well good news,the Energy suspension mounts fit absolutley perfect.Trust me,with the Prothane mounts compared to the Energy ones,there is a difference between them.I took some pics of the Prothane mounts with my engine bracket the way it's suppose to fit and you can see that the bolt eyes on the bracket doesn't line up with the bolt hole in the mount.I'll try and get those pics up soon so maybe it becomes easier to understand what I've been going through.As far as installing them backwards or upside down,nope,i had them installed correctly.What i might have to do in the future to make them work is to grind down the offset tabs to make it work.I'm also going to send those pics to Prothane so that maybe they can correct the problem.so now hopefully,you can understand what my headache was.

Glad you got it worked out Dave. The position of the tabs in the mount is crucial. If the metal is formed wrong the mount will be virtually useless. Looking forward to seeing the photos.