Decided to make my own motor mounts for my lq4 swap into an 87 Firebird.

Pros: Cheap, Easy, Fit is perfect

Cons: Time consuming

This style uses an adapter plate and the original 3rd gen V8 motor mounts.

Get 2 pieces of .250" thick steel (4.5" wide by 6" long, rough dimensions)

Get 8 button head M10x1.5 @ 1" length

Get 2 button head M10x1.5 @ 1.250" length

Get 4 M10x1.5 Flange nuts

Get 2 Flat head M10x1.5 @ 1" length (tapered head)

Note: get grade 8 or better on all the above.

 

Measure the hole spacing on the lsx block and transfer this measurement to the steel plate

 

Next drill 4 M10 sized holes in the plate.

Next countersink 1 of the 4 holes that was previously drilled. The hole to be sunk is the hole closest to the front of the engine on the lower level. See below pic but ignore studs for now.

 

Draw a straight line between the the center of the holes on the top row. Get the u-bracket shaped piece of the thirdgen mount and place it on top of the plate. The two holes of the u-bracket go on the top row of holes with the bracket sharing the hole that is on the top row closest to the front of the engine. This is the hole directly above the countersunk hole. Now line up the second hole in the u-bracket with the centerline you have drawn. Mark the center of that hole on the plate. Move down to the one lone hole on the bottom and mark the center of that hole on the plate. Take the plate off and drill the two marked holes.

If you are confused yet im sorry. Study the illustrations and look at your car and it will make sense.

Your holes should look similar to this. Again ignore the studs in the pic

 

At this time you can put two of the 1" long button head bolts through the plates from the back side forward. You must use button head bolts because the webbing on the block will interfere with hex heads. Even so I ground the button heads slightly to clear the block. Now weld the button head bolts to the back side of the plate. Your plate should look exactly like the above pic.

 

Bolt the adapter plate and u-bracket on to the engine block. The 1.250" bolt is for the hole that is shared by the bracket and the adapter plate. Your installed plate should look like this. You can see in the pic below why you need a counter sunk bolt. The u-bracket gets in the way if any other bolt is used.

 

You may now take the 3rd gen rubber section and attach it to the mount with the long through bolt. Place the engine in the car and set it lightly on the sub-frame. Be sure to check for clearance from the engine to the firewall and oil pan clearance at the subframe. Use a marker and trace the holes or the outside of the mount onto the subframe to leave yourself a guide for drilling new mount holes. Remove the engine and drill the holes that were previously marked. Separate the rubber section of the mount and bolt it back onto the subframe.

I made my life easier and welded these bolts from the inside of the subframe. When you go to take off the 3rd gen rubber section you will understand why I did this!!! Place the rubber section on these bolts and bolt it to the subframe. Your new mounts should be a perfect fit, cheap and easy.

 

Here are some things to note:

1. You cannot use the original spot for the rubber section of the mount. Take a look at the below pics and you can see how far rearward I moved the mount. Don't be tempted to share any of the original holes either. I tried this at first and found you do not have enough oil pan clearance.

2. Your passenger side brake line will have to be moved. Take a look at the below pic and copy my routing. Even though it is not bolted down to the subframe you get the general idea of the routing. It was lifted for painting reasons. You will have to bend this line yourself. You bend at your own risk because if you bend to much you will kink the line. Go slow and be patient.

3. Your transmission mount may have to be changed to accomodate where the engine is now positioned. I elongated the holes in my mount. I used the spohn t56 mount so I have no idea how the stock one lines up.

original mount location

modified mount location

modified mount location

 

Odd

You built adapters based on a rearwards located engine and used the V6 mount locations

Most people who run adapter plates buy the stock position set and use the V8 (original rubber mount location) placement on the K-member. You can spot these by the bottom most bolt hole is reused to the LS1 block even with the SBC mount

Yours appear to be 1" setback plus whatever the V6 mounts moved back. Hows your firewall clearance?

 

? Huh. That is interesting. Maybe I did do something screwed up. I used the original mounts of my 350 TPI. I'm not sure about the v6 mounts you are referring to. The second set of holes in the crossmember was indeed for the v6 location but it was just too close too the oil pan to use that location. I drilled new holes rearward of the v6 location. I haven't taken a look at the swap mounts that other people are selling I just kinda threw this together by looking at it. Im sure there is a better way to do this. Just one take on the many I guess. Here is a pic of the clearance at the firewall.

 

Did a search and found these mounts. LOL! I guess there is always someone smarter out there.

 

There are a lot of companies out there selling the plates that utilize the stock motor mounts. Energy's kit is a lot more expensive than most because it includes their poly mounts.

One thing that I like about your setup is that it seems like there might be more room for the a/c compressor because your mounts are mounted farther back on the K-member.

 

They aren't the right mounts for a 3rd gen, either.

$30 for plates and bolts pretty much convinced me to spend a few bucks and save a lot of time (to say nothing about knowing it will be lined up properly when it's time to stab the engine).

 

five7, are you refering just to the energy suspension ones or all the "plate" styles in general. I've been looking at this type (and the 1" back ones) for some time and seem to keep getting mixed responses.

 

The big problem with the plate style that uses thirdgen motor mounts is that it occupies the same space that the a/c compressor needs.

I like the BRP style the best, but they're way too expensive. I think that I've decided to make my own.

I've got drawings for the plates, so I may make a set of those to locate the motor with respect to the k-member, take the measurements I need, maybe fab up a jig or two, and then make a BRP-style set.

Or just suck it up and buy spohn's kit, a new set of clamshells, and a set of urethane mounts... on 2nd thought, when you take that into account, BRP's prices start looking more appealing!

 

I've gotten used to my 3rd gens being A/C-less, and since the plan was to just let this be the weekend toy, the plans were to remove all the a/c stuff and get the a/c-delete air box to make some more room in the engine bay.

 

Just the mounts. The plates are the same.

The plate does interfere with the stock AC compressor mounting. I'll be using Kwik mount plates for Sanden compressor, which mounts up by the head. One belt for everything.

 

Yes I gained about 3inches of extra space for the ac compressor. I am also using the 6.0l compressor which is significantly smaller than the 5.7l compressor. I am pleased with how they turned out. I am switching to a motor plate in the future but this will work until then.