Front Plate only vs front plate and mid plate
 

At what performance level is both a front plate and mid plate required. I currently have a front plate and mid plate and want to remove the mid plate and leave the front plate. Below is the front plate I am using. Running a TH400 with standard trans mount.

https://butlerperformance.com/i-2445...ALL-FRT-MP-100

I don’t think there’s ever a power level where both plates are not a plus in keeping the motors own torque production from acting on the structure of the block.

I would say that for the best / ultimate stock block longevity that a motor making over 550 ft lbs is a good candidate for using two plates.

Does anyone make round port headers that will work with a mid plate?

You would likely have to have a set modified.

The engine's torque is a fraction of the torque reaction on the transmission housing (the fraction is 1/3 if low gear is 3:1). To [almost] totally eliminate torque stress within the block a person would use just a midplate and concoct a torque-neutral front engine mount which merely positions the front of the engine.

Modify the mid plate. Its not that big a deal.

i didnt think id have any trouble fitting a midplate with my huslers or even a set of dougs. the header drop down lower i beleive.

my problem is being a stick shift car i dont think i coukd clear my z bar and rods..

i hope im not wrong on the header fit. right now im just using mighty mounts and butler front plate. i may have to see if i can trim a mid plate to clear everything as is.

i was gonna add a mid plate once i swap to an auto.

Jack Gifford, would the engine block almost always be "stiffer" than the chassis? If so, then tying both ends of the block to the chassis (with solid mounts) would be using the block to strengthen the chassis....correct?

I would also put a couple bars for 'fore & aft' motion. On my dragster it helps a lot. You'd be surprised how much it moves back/forth. (bent a few aluminum plates. use chromoly now)


:)

With my current headers (Indian Adventures) tubes 3 and 5 one goes under the mid plate and one goes over it. The tubes are one unit and the only way to remove the headers are to remove the mid plate and that requires pretty much pulling the engine. Now they have serious dents in them just to clear the mini starter and the frame. So now I'm looking for a new set of headers and looking for recommendations for a 65 LeMans round port and 1-7/8 tubes. Thanks

How fast are you planning on going ? How does your car 60 foot ?

60's in the low 1.4 range low 10's knocking on the 9 second door. I'm going to order a set of Dougs round port 1-7/8 primaries silver coated tomorrow. I hope they fit I will keep the mid plate. I also will need to lift the engine some to get the pan off the center link. Then I plan to raise the trans up to get the engine closer to level. Might have to cut the trans tunnel near the back of the trans to get clearance. I will probably make a spacer to go between the trans mount and the trans. Not sure how I'm going to patch it maybe I can find someone to fab up a piece that I can weld in.

With the length of a chassis being about ten times the length of an engine, improvement in chassis stiffness would be trivial. Besides, I was responding to steve25's concern with torque stress on an engine.

I have front and Mid in my 69 Bird, just have it welded in after making the brackets on a laser.

I used the All Pontiac Brackets from Butler.

They clear my 2-1/8" Mad Dog Headers without problems. Heres pics without headers.

https://forums.maxperformanceinc.com...1&d=1772544803

https://forums.maxperformanceinc.com...1&d=1772544328

Here's a pic when I had the headers on my Mock Up:

https://forums.maxperformanceinc.com...1&d=1772544802

Headers are well past the turning down stage before the mid plate because they have to clear the factory Oil Filter housing/Filter on one side and the starter and provide access to it on the other.

I'm thinking about chassis flex/twist/torque that will be transferred to the block. If the chassis between the front and mid mount is not as stiff as the block, the block would then be subject to that torque.

Jack, if I understand what you are saying having a front and mid plate will stress the block? What is the recommended installation then? Maybe I don't understand what you said.

Tim & Ashley- please re-read my post #5.

Jack, I totally understand. I'm helping to lead others to that knowledge.

Trans is out. So I took a few pics of my mid plate/header situation and my elephant ears.
The bottom of the elephant ears are un bolted right now as I had to tilt the engine down in the rear to get the trans out.
Engine is in stock location with Mighty Mounts. They are rubber so tilting the engine is not big deal.
But when its all together everything is very solid.

Your headers definitely exit higher than mine. Ill see if I can grab a pic tonight.