I am trying to install a set of Schumacher Poly Locs on a Big Block. I have been fighting with these mounts for hours. I originally used a stock set with a torque strap behind 530hp. I never broke the drivers side but I noticed the passenger side was starting to tear along the part were they mold it to the metal. The mount was still okay but I figured I would replace them with a set of Poly Locs. I installed them and removed the torque strap. I can't get the passenger side to sit flat on the k-member. The driver side is resting on the k-member properly. If I get the passenger side to sit flat on the k-mount the transmission poly mount will not line up and the transmission tail shaft it not centered to the hump in the floor. If I force it to the drivers side with a piece of wood it pulls the passenger side mount off the k-member and no longer sits flat. I am ready to go back to the stock mounts. Can anybody shed some light on this issue.

Maybe not helpful to your situation, but are the Poly Lock types thicker than your original mounts?
I considered the Poly Locks but thought that they would aggravate my already dicey hood clearance issue.
I looked at some parts store replacement mounts and found that they appeared to be about 1 1/8" to 1 1/4" thick. The mounts in my car are thinner than that by a noticeable amount. My LH side is an interlocking type and looks to be about 7/8" thick. I can't recall if it was rubber or urethane. I used a quality NON interlocking RH mount that actually failed first. That surprised me since I don't recall hearing of a RH failing before a LH mount. I replaced the broken RH one with an OEM spare I had laying around. It ended up causing the drivers side of the engine to sit lower, resulting in header-to-steering box contact.
Anyhow, it may be that your replacement mounts are too thick, causing a misalignment.

https://board.moparts.org/ubbthreads/show...e=6#Post7987159

check the thru bolt that goes through the insulator. Mine was just hitting the block and would not allow it to sit correctly and get all the bolts thru. I struggled for a few hours before removing the mount and seeing a mark on the block. cut the bolt down about 1/4 inch or so and it slipped right in. I almost Lol

The poly mounts are thicker than the ones I took of the motor that could have something to do with it. I had a look to see if anything is touching the block and I don't see anything. It looks like the passenger mount has to come forward. Could the engine mount be installed wrong on the block? I know the poly locs aren't as flexible as the rubber ones. Maybe the problems has always been there but more noticeable now with the poly. Is the k-member adjustable? Could I loosen the bolts and move the passenger side forward ?

The trans crossmember will let you move it side to a little, depends on how far you have to go, but you could loosen the 4 bolts and the one on the trans rubber mount and try it.

If the metal bracket on the engine block was put back on the same way it came off, the problem is with the new mounts themselves.

Guys thanks for all the info. If I am running poly engine mounts, what should I use for the tranny mount? Should I run the aftermarket rubber or run the poly tranny mount from Schumacher? Anybody ever use the tranny mount from Schumacher?

I had the same problem. after 1/2 day I got them installed.
After one weekend at the darg strip they melted at the passenger side.
(some inches away from the headers). Right now I am running only one at the
driver side. Would never buy them again. I think the HD from Mancini are
a better option. Personally I would not use any tranny mounts in PU
unless your chassis is ultra stiff. I would be afriad to brake the trannys neck.

I used them on my 67 440, and they work fine.. Only noticable difference is more engine vibration throughout the car vs the stock mounts I replaced em with..

I have finally fixed the problem with the passenger side mount. I spoke with Schumacher. They were very helpful with the problem. They recommended moving the hole on the passenger bracket forward. I reamed the hole forward a 1/16 to 1/8 of an inch. Re installed everything and the mount fit perfect and the tranny lined up perfect with the floor hump. Looks like the k-member perch must be slightly out. This explains why my passenger side rubber mount broke before the drivers side.

Just wanted to give some feedback after using the Schumacher mounts. The engine doesn't move much like it use to. You do feel very small amount of vibration, but I expected a lot more. The rear view mirror at certain rpm's does vibrate a tiny bit, and looking in the mirror the lines in road do move a bit. All in all I am very happy.

I have 'mitymounts' in my '71GTX and have had no issues. These are positive locking mounts that appears to mimic the dimensions of the stock mounts. They are made by DynaTech Engineering, LLC. You can check them out at www.mitymounts.com.

Thanks for the link! I think I'll get a set.

I also used the Schumacher mounts for a 496 in my GTX. No issues whatsoever. I'm very happy with mine