Alright fellas, here's a question which may have more to do with opinion rather than facts, but here it is:

Whether a 400 is built to 434cid or not, would it be better to use solid steel mounts vs. the stock rubber mounts, vs. a motor plate, in a street/strip car?

I've been making mounts for mine, and as I look at the rubber mounts (302 truck mounts turned upside down and 45 degrees) I think they might work, and then I look at them again, and I think they'll come apart under the torque of a launch. But if I go solid steel, I'm looking at road vibrations. Would the trans mount have to be solid too? or would that not matter?

 

In my mud bogger, i replace the factory motor mounts at least once a season, granted the motor is fairly heavily built. If you are running hard solid mounting would be ideal, or another option is to build mounts using rubber or poly leaf spring style bushings.

Also the tranny mount HAS to match the engine mount or else they will see different forces, flex differently and something will break.

 

Thanks, that's what I figured on the trans mount.

The lower half in my pic is part of a mount with poly sandwiched in between the metal halves made for 302/351w/c. If there was a way to use the upper half I would. I may still try it, but with everything set in place, I could make solid mounts with the dimensions already there.

Would polyurethane be the best?

 

I say solid at engine. I once broke a tranny housing because my engine mounts broke. they were L and L 460 engine mounts. It was an expensive lesson. new motor mounts and had to replace the c-6 housing and I had almost $2500+ into c-6 at the time. My frame was flexing hard (f-150) and things just broke in a bad situation. If you go solid on engine or atleast a urathane bushing need to do something similar to tranny. Basically tie the frame together. Box the frame to help prevent some of the frame flex if suspension has little flex. I now have since linked the front suspension and flexes way better and forces the suspension to work instead of frame taking the abuse. Just more stuff to keep you up at night.