OK so it's time for me to drop in my short block which is a small block 400 into my 84 Trans Am. So where can I find motor mounts to fit the swap? Also keep in mind that I'm expecting upwards of 500 hp/tq so they need to be strong as well...

Thanks
-Jim

 

Same as stock motor mounts...try polyurethane mounts if worried about breakage.

 

i have a 406 with 500+ hp....it has stock mounts that i installed new with the motor.....no problems so far....

 

All SBC V8 engines are externally the same. The same motor mounts can be used but as mentioned above, get rid of the factory rubber mounts and use some poly mounts.

 

Um, no they’re not the same.

Early ones are completely different, and later SBC’s (mid 90’s) got a 4th boss on the driver side of the block and the engine side bracket could be mounted 2 different ways with different mounts to clear different accessories/cross members. That being said, most late 60’s through early 90’s SBC’s used similar engine brackets and then chassis mounts depended on the application (mostly there’s a late and early style that were similar but different heights).

As far as stock vs poly… I’m not sure that poly is that much stronger. The big problem with poly is that in a hot engine bay (especially if you’re running a power adder or headers with a tube really close to the mount) is that they are not very tolerant of heat… when you get them warm the poly runs out like it was jello. Personally, I would run stockers unless you’re expecting them to be oil soaked (which will kill them quickly, which also will not hurt poly at all), and if those prove not to last either add a torque strap or go to solid mounts (which btw happen to be incredibly street able. If your car already has a good rumble, loud exhaust… you probably will not notice the difference in harshness, but you do notice the difference in rigidity of the front end since the engine block becomes part of the structure of the front suspension).

 

I'm running a 400 sbc that pushing about 400hp with stock motor mounts for over a year with no problems.

 

i've got poly ones and they bolt the same as my 305 did.

 

moroso also makes solid ones for our cars.

 

I have the Moroso Solid mounts. They're great for drag racing.

 

A few years ago, thinking was that solid mounts were not so good because they caused block distortion over time. Has there been new evidence disproving this?

 

im going to disagree with mike because we're only talking about THIRDGEN FBODYS.

they're all the same.

and ive never heard of a poly one melting. esp in a 3rdgen app... if you run your turbo setup on it or somthing, perhaps, but not under normal useage.

 

i haven't heard this but i have heard that solid mounts whether they be tranny or motors are hard on the transmission case.

 

That's what I've heard, but only if the frame is flexing. SFC's assumed for any performance 3rd gen application.

 

I don’t know that there has been any real evidence either way. In a high hp application I could see the pull on the driver’s side causing some case distortion, but you’d have to be making some serious power.



Are you talking to me? If so, it’s Mark…



assuming that you’re running what came in it.

It’s pretty common with long tubes.