WheelsUp84z

iTrader: (2)

Ok, i have a couple questions about motor plates and mid plates, hopefully you guys can answer them.

1: when using a motor plate without motor mounts do you HAVE to run a midplate?
2:When using a motor plate, do you seal the plate to the water pump AND block with gaskets on either side of the plate?
3:If you are running a midplate, do you need a specific tq converter to make up the difference the plate spaces the trans. from the motor?

Anyone have any tricks or tips on installing them?

AlkyIROC

1. No

2. Yes. It's usually also bolted to the front motor mount holes also. All GM blocks have the 7/16" mount holes at the front of the block beside the balancer. GM still uses these holes to install engines in 3 and 5 ton trucks.

3. Flexplate spacers are used.

Using motor plates also requires the use of engine limiters. 1 or 2 can be used. The limiter attaches to the side of the engine, usually in an unused motor mount bolt hole then goes forward or backward and attaches to the frame. Motor plates will still flex. The limiter makes sure the engine doesn't move forward or backward from this flexing.

Also use a polyurethane transmission mount. A solid mount will break the tailshaft.

Midplates are a pain in the butt in a door car without a removable transmission tunnel. Midplates are more designed for tube chassis cars. There just isn't enough room in a production vehicle. For my front plate, I welded mounting brackets on top of the frame rails. The plate sits on top of the frame rails and bolts to the brackets with a single 1/2" bolt on either side.

1991z28L98

iTrader: (1)

alkyiroc i know this was a long time ago but what front plate did you use brand and if you could post a picture???

AlkyIROC

Brand?

I acquired some 1/4" thick aluminum and made my own using posterboard templates for the water pump and lower mount holes and cut out around the timing chain cover. This was my second front plate I built. The first was a 2 piece design that only attached with one bolt on each side. This new one is one piece and uses two 3/8" bolts per side.

I welded some 1/8" plating to the top of the frame rails then welded some 2x2" angle to the plating so that the motor plate could attach to it. There isn't a lot of room beside the frame rails to mount the plate low especially on the drivers side. The steering shaft runs right below the motor plate.







The rear plate is a basic competition engineering kit. It was easier than making something. This was my second kit. I had to do some relocation modifications and it was easier to buy a new kit that to try to modify the already cut kit.

1991z28L98

iTrader: (1)

Thanks for the pics and info this helped

DIGGLER

iTrader: (1)

just went through this myself... ugh. twice the pain in the butt i thought it would be. wish i had a plastic engine and trans, that would have been sooo much easier.

1991z28L98

iTrader: (1)

Herd that does the 1/4" though off the the alingnment of the belts any I'm running a serp set up and am wondering if this is something I will run into

DIGGLER

iTrader: (1)

yes. it will push all the accessories another 1/4" foward in relation to the balancer. also, in my case i was working on an LT1. the accessory bracket mounts to the passenger side of the block which is set back about 1" from the rest of the block face. this meant the factory bracket would no longer work, and i had to custom fab an entire serpentine setup to mount on the front of the 3/8" motor plate. alternator, power steering pump, idler pulley, and tensioner. 3/8" plate is a pain to cut if you dont have a vertical bandsaw. i wound up using a plasma cutter on the big cuts, and then dressed them up with the bridgeport and/or carbide burr.

the midplate involved installing the engine/trans and attaching the trans mount to the existing crossmember. i squared it up in the car, made some measurements, and pulled everything back out again. i made the motor plate, and installed the engine, propping the rear of it up on some blocks. i then trimmed up the midplate and put the trans back in/attached rear mount. tacked in the frame mount tabs for front and midplate..... then removed everything again to weld. shot some paint over the welds, and then re-installed the engine and trans.
lol.

also, with the 3/16" midplate, i had to add 3/16" to the pilot of the converter. i made a sleeve, chucked the converter up in the lathe, cut it down and pressed the sleeve onto the pilot. enlarged the holes in the spacers that came with the midplate to accommodate the 7/16" bolts used on the converter.