Front plate limits

At what level of horsepower should a racer add a rear engine plate? Right now I'm running a front plate and an altered mount on my C6 with a stock trans x-member. I have limiters on my engine bolted to the k-member so the engine can't work the plate front to back. They are bolted to the block where the stock mounts would normally be.

At any HP where your using a front plate.

The transmission bellhousing, stock or aftermarket was never intended to support the weight of the engine and hold up against the rotational torque of engine and transmission.

Side mount engine mounts cradled the engine and supported 100% of the engine weight and a good 30% or so of the trans weight. The transmission bellhousing only held the trans to the engine. With just a front plate and a trans mount, your now holding 100% of the engine weight and trans weight with the bellhousing, and trying to resist the rotational forces your applying. Its not a matter of if, just when its going to break.

you need one now imo.

as stated thats asking a lot of a front. plate to handle.

This is what I was thinking about, I see an awful lot of cars running the same setup as mine at track but I they are small blocks. It's something I would like to address this winter with some kind of rear plate setup. I guess I'll have to make a spacer for the converter too.

I just spoke with a friend who runs a fox body with a 521/glide. His engine is out and he has a mid plate so I'm going to stop by for a look. He has a carb pan under his cowl hood do I might as well gawk at that. Fresh engine from Circle R just delivered that I'd like too drool over too...LOL

Would I be better off to fab up solid motor mounts to carry the weight and keep the front plate for added support? After looking at my car tonight a rear plate would be a PITA with my super comp headers. 

Have you looked at your friends rear plate yet?

It isn't the same as the front plate.

Mine is steel, and isn't much more than about 3" tabs that stick out from the side of the engine to bolt to the tabs on the frame rail. Everything else from the piece went into the scrap heap.

2 1/2" primaries into 5" collectors dumping just past the fire wall, so my headers are under the tabs.

Side mounts on high HP stuff can cause issue with block distortion, lots of forces working on the block, and that rotational load at the "stock" mounting points can cause issue

I hope to go down to his place tomorrow, he's about 10 minutes away. I was looking at some .090" and .100" plates online last night, I see what you are saying about the tabs being small once you clear the headers. I'm going to have the engine out to paint the car this winter so I might as well put the mid plate in then. I started mocking up for my cowl fed carb air pan last night, fitting the hood nicely so far in cardboard..... 

I don't run a mid plate. Never have. I run a front plate strut rod limiters and a trans mount. Never had a issue.

Barney wrote:I don't run a mid plate. Never have. I run a front plate strut rod limiters and a trans mount. Never had a issue.

I didn't for a long time, but added a rear truss when I built the 580 inch engine............ It runs from top of frame rail to top of frame rail above the top bell bolts and bolts to the top two bolt.

You have any pic's of the truss?

Yes but photo bucket is actin a fool tonight, I will try again.

BigRigTech wrote:I hope to go down to his place tomorrow, he's about 10 minutes away. I was looking at some .090" and .100" plates online last night, I see what you are saying about the tabs being small once you clear the headers. I'm going to have the engine out to paint the car this winter so I might as well put the mid plate in then. I started mocking up for my cowl fed carb air pan last night, fitting the hood nicely so far in cardboard..... 

 When you get ready for a mid plate, I can help if needed. Here are a couple of links....
https://www.429-460.com/t13876-bbf-starter-locator-plate-and-steel-mid-plate?highlight=mid+plate
Custom plates are no problem.
Thanks,
Keith Fulp

Wheelie58 wrote:

BigRigTech wrote:I hope to go down to his place tomorrow, he's about 10 minutes away. I was looking at some .090" and .100" plates online last night, I see what you are saying about the tabs being small once you clear the headers. I'm going to have the engine out to paint the car this winter so I might as well put the mid plate in then. I started mocking up for my cowl fed carb air pan last night, fitting the hood nicely so far in cardboard..... 

 When you get ready for a mid plate, I can help if needed. Here are a couple of links....
https://www.429-460.com/t13876-bbf-starter-locator-plate-and-steel-mid-plate?highlight=mid+plate
Custom plates are no problem.
Thanks,
Keith Fulp

Custom is not a problem Keith is the custom man if you ever see the 58 you will.under stand what I am saying he has built alot of custom parts on it.

Cool, I'll keep that in mind.

BigRigTech wrote:You have any pic's of the truss?

Sorry it took so long............. But this works fine and plenty of room for your headers too.

Great Idea and easy to make. No concerns about it only grabbing the top two bolts?

So far so good been that way about 6 years.............. 

Ok, your putting down more power than I am so I guess it works....LOL

Is the truss welded or bolted to the body? I can't tell from the pics.

A 3/8ths plate is welded to the frame and the truss bolted to it.

That's what I thought I was seeing. Just trying to decide what to do this winter. Thanks for the quick reply.

I think I had issues with the engine "working" the plate this summer and the engine would leak a tiny bit of water when it cooled down on the drivers side of the plate where it met the timing cover. Nothing serious but I would like to add the 2nd plate or strut