[LenCaverly]

One of the reasons people have problems with blocks splitting is because the introduce chassis stress at the weakest part of a pontiac block , you also transfer all of the torque from the engine to the mounts. the proper place to transfer all the torque from an engine is the bell housing flange (the strongest part of the block), and allow the side mounts to flex and also the transmission mounts. So on a standard non tube door car a solid mid plate ,standard rubber engine mounts and standard rubber trans mounts will allow you to make more power and stress the engine block less.
Len C

[Mike Kasparian,Sr.]

Good post , while restoring the car I was planning to go with a midplate this time .

[gman005]

I run a front and mid plate.

[70 bird]

Front and mid-plate is the way to go but I have 10 years at 700+hp on IA solid mounts.

Do as I say not as I do!

[Tom Vaught]

Yah! But your little 700+ turbo street car doesn't make any power!!! (;>)

Tom V.

Happy New Year to you, my friend.

[70 bird]

Originally Posted by Tom Vaught

Yah! But your little 700+ turbo street car doesn't make any power!!! (;>)

Tom V.

Happy New Year to you, my friend.

Thank you Tom, and a happy new year to you and your family!

[BruceWilkie]

Originally Posted by LenCaverly

One of the reasons people have problems with blocks splitting is because the introduce chassis stress at the weakest part of a pontiac block , you also transfer all of the torque from the engine to the mounts. the proper place to transfer all the torque from an engine is the bell housing flange (the strongest part of the block), and allow the side mounts to flex and also the transmission mounts. So on a standard non tube door car a solid mid plate ,standard rubber engine mounts and standard rubber trans mounts will allow you to make more power and stress the engine block less.
Len C

Agree! Twist TO the block NOT THROUGH it! Hard to open a jar if only turning the lid!
Midplate should have fore/aft limiter though.

I really dislike the front plate/trans mount only scheme.

If running a front plate with your mid plate (instead of side mounts) it wouldnt hurt to use mount cushions on it.

IMO with a solid mid plate the 55-58 timing cover mount(bottom center of cover) would work well too. It mostly would serve to support the nose weight and its pivot center would allow any chassis flex forward of midplate to have least effect on front of block. Looks like it would help limit fore/aft movement as well. Think modern aluminum cover is strong enough to do this.

[Dragncar]

I used to Run the factory big car mounts. Then decided to "upgrade" and bought some Mighty Mounts. Engine moved more with them than stock.
So I made elephant ears out of 1/2" aluminum plate. Stopped all movement. Dont know how fast someone has ran them. Not sure I want to find out.
Next engine is going to need proper mounts/plates.

[Old Man Taylor]

I have elephant ears on mine. The car has run 9.76 at 138.

[BruceWilkie]

I used a chain and stock mounts for years... factory head bolt with a stud on it and chain bolted to frame...set chain up just slack enough to not vibrate the car when cruising. 10years no issue...3910-3920 typical race weight and very consistant 1.52x 60's. (11.78/114)

When car was just a 13 sec car ran stock mounts no issue...when it got in mid twelve range...Cut a good light then bang... lifted throttle and "oh sh*t it's jammed"... was fun getting back to pits... I had unjammed it at turn off but it was still holding throttle way above idle. Start, slam into gear, cut motor, then coast, all the way back. Back in pits was able to get motor back in position and linkage back in order...safety wired broken mount and drove home gently. Lessons learned the hard way.

[Johnny406]

I'm wondering if I'm playing with fire as I'm running solid front mounts and a Energy Suspension trans mount. My block is bottom filled but...

[Half-Inch Stud]

My opinion has always been that a Mid plate is necessary to take-up (react) the Transmission case reaction TQ and shaft TQs, and shift shock, so the Block didn't have to.

Mid-plate & Front plate with rubber or stiff engine mounts should be best to keep the block from being twist in half like a Pislbury dough tube.

[Tom Vaught]

Originally Posted by Half-Inch Stud

My opinion has always been that a Mid plate is necessary to take-up (react) the Transmission case reaction TQ and shaft TQs, and shift shock, so the Block didn't have to.

Mid-plate & Front plate with rubber or stiff engine mounts should be best to keep the block from being twist in half like a Pislbury dough tube.

I posted some years ago about a video I saw at work of a engine block painted white with 1 inch Checker-board squares painted on the sides of the block.

Two (very high speed) video cameras were used to take images of the squares and their movement under different load conditions for verification of modeling tools used to design a block.

The block was attached to the dyno with the typical "elephant's feet" side mount attachment (soft factory mounts used)on the side of the block and a rigid mount on the block blow proof flywheel cover which was a rigid mount. Much like HIS deal above.

The block was moving all over the place at most load conditions. Not so much under just rpm conditions but very much so under dyno load conditions (like racing down the drag strip). So I agree that the soft mounts along with letting the engine move ahead of the fixed Mid Plate is the way to go.

Tom V.

ps If you use a rigid front plate and tie it to the J-Bars and drop the car hard after a wheel stand don't be surprised if the block is not happy, especially an aluminum block.

[taff2]

I've got a 1/4" T6 ali midplate,fore/aft limiters and elephant ears coming off the timing cover,I believe the separate ears flex just enough to compensate for the inevitable chassis flex on launch,much like the early single rubber mount under the timing cover would(not as much obviously). A one piece front plate across the full width of the block along with a mid plate would effectively make the engine a stressed member of the chassis,and every chassis twists slightly on launch so there could be potential for block twist in there somewhere. I've been 8.90's on this set up with 1.34 sixty foots. Most of the 1.34 60ft's were with the previously n/a combo that used the weak 557 block too.

[twooldgoats]

BOP aluminum front plate bolted solid to chassis, All-Pontiac aluminum mid plate bolted solid to chassis, poly trans mount, no fore and aft limiters. No problems after a ton of eight-second passes and several seven-second passes. I set up the four-link with a long instant center so it leaves lazy with a 1.17 60-foot--that reduces stress at the launch and keeps a lot of stress off the wheelie bars. So far, so good.

Jim

[Bob with the 66]

Really interested in advise for my build. 66 gto back half, 4 link car, original frame and cradle up front. 12 point cage with front j bars. I have the All Pontiac steel front plate and steel mid plate.

With the plates I planned on using solid engine mounts from butler as my limiters and a stock factory rubber trans for my Aluminum 535 block with a t-400 trans with t-brake.

I'm new to this level of build, what do you think, will I be OK?
Bob