Gentlemen,

I was checking the stall on my converter and bang, I broke the motor mount on the drivers side. I was holding the brake and started to give it the gas. The RPM's were coming up to around 1500 and then she surged. My cam is supposed to come on at 1500. At that point the motor mount broke and the fan started hitting the shroud. It definitely could have been my technique but the end result is the same, motor mount is trash.

How much HP will a stock motor mount take? My 327 isn't wild by any stretch, about 320HP and 350 TQ. Did I just get a bad mount? I've done a search on this site and read every post on motor mounts but none indicated a HP limit. I called my local parts store and he said all stock SBC motor mounts are the same and are made by one of two companies in the US and then sold under different labels. I even read one post that said that one guy used the mounts from his 283 on a 454.

my car launches hard with very little tire spin and it will actually flex enough to put my 200R4 tranny in the next gear down. I had been noticing this for thew last few weeks but never thought it would brake which leads me to believe that it wasn't my stall testing technique that was totally to blame.

Any help would be appreciated. I thought about a solid mount on the drivers side but I don't want to deal with alot of vibration. Polyurethanr is also an option on that side.

Clyde

My driver breaks the left motor mount and is has only about 275 hp. It will do this in only a few months. I put a poly mount on just the left side and haven't broke it yet in over a year. I bought two but only used one so I have an extra. It is part number 3.114G (http://www.jegs.com/cgi-bin/ncommerce3/ProductDisplay?prrfnbr=874&prmenbr=361). New in the packaging. Email me if you are interested.

any one know of any potential issues as far as using solid MM's?? I am using Moroso solid units on my fresh motor.

Westy, I have solid mounts on my 468, only thing is a little more vibration, but hey, if I wanted smooth I'd drive my wifes chevy venture mini van.Good Luck, Jeff

Torque breaks motor mounts..not HP ;) :D
I run a solid mount on the drivers side only,stock on passenger side.

Pat,

I sent you an e-mail. Thanks.

Thanks for the input from the others but if the poly will work, then i'm not ready to go to the solid yet.

As for what breaks the mounts, I understand the TQ vs. HP principle. No offense but I think we get too picky on here sometimes.

Clyde

The local speed shop guy swears by the poly mounts and has not had any returns or broken mounts reported. He told me that if I could break the poly trans mount I bought off him, he would give me a new one. No warrantee from the manufacturer, so he stands by them, anyway. He is a straight shooter and he isn't just trying to sell stuff, for all you cynical guys out there. He is a gear head just like all of us, and he owns a sweet 68 Chevelle convertible.

Even if you use the poly mount, if it has no provision for limiting the engine in the event of a failure, you should install a limiting strap between the block and the frame.

Excuss me BUT I thought all replacement OEM rubber mounts GM sold for use in our old cars were clamshell type that couldn't come apart even if they did break????

I know I never took my car in to get both my broken ones replaced when I got my warrantee/recall letter way back when.. I drilled a hole through the halves and just bolted them both back together AND they worked fine!!

pdq67

There are at least two different mounts. The interlocked one didn't fit my car. The ES Poly has an interlock molded inside of it.

PDQ, my rubber mount separated completely.

Clyde, I got your email.