PainfullySlow

Awesome! Thank you all for sharing this info. It seems I will be picking up some solid motor mounts myself =)

c69vete

My 383 with an air gap intake and 3" filter leaves very little space between the air cleaner top and LT 1 hood. I do not even run a wing nut on the air cleaner. I choose to run a solid motor mount only on the drivers side. Rubber on the passenger side and trans as well.
The solid prevents any lift under acceleration and the rubber helps cushion the torque, so for me it is a win-win.

Gunfighter13

OP do not do this your frame will thank you......

2mnyvets

Has anybody running solid mounts seen any distortion in the 3/4 cylinders or cracked a block? In one of the prior posts there was a claim that solids caused his block to crack. Looking at the mounting position, I can see how that could happen. The shock that the rubbers absorb is transferred to block and the frame with solids. I am not opposed to using any of the three types of mounts, but I am going to start with rubbers because that has the least risk. $500 is cheap compared to my numbers matching big block and frame. If the rubbers do not work out I will go to polys than then to solids.

Vette5311

I use rubber mounts with a torque limiting turnbuckle on the driver side. Getting the best of both worlds

OldCarBum

Harley has been building motorcycles for over 100 years using solid motor mounts.
Most hi performance sports bike manufactures engineered the motor to be part of the frame and most of the super bikes I’ve owned put out more hp than most stock Corvettes.
Drag racers use solid motor mounts and if they were cracking blocks I don’t think they would use them nor would NHRA allow their use.
I read the same post as you and would contribute his comments as either a fairytale or someone who had a cracked block from a separate contributing factor.
If you have a stock motor I would use a good quality rubber or poly motor mount.
If you modify the motor to put out extreme high torque, then I would go solids.

v2racing

I would agree with this and add that it is possible that someone could have had a block with a flaw in it that ended up cracking at the motor mount and then to them and others this meant this will happen to all blocks, which is obviously not true.

Mike

Gunfighter13

Urban legend/myth. Never seen it happen and no one I know has seen that happen because of solid motor mounts.

2mnyvets

. That is my point. Those engines were designed to take those loads. I don't know that the GM engines were. I believe you may have been the OP of the post that got me thinking about this. I went down and looked at my block and I don't see any good way to get the forces from one side of the block to the other. The loads go from the motor mount through the water jacket, somehow get transferred from the outside of the water jacket to the inside of the jacket, through the bearing bulkheads, back through the water jacket on the other side and finally to the other motor mount. Most of those loads appear to be in bending and tension on cast iron, which doesn't like to be pulled or bent.

When I see phrases like... it stiffens the frame, … it acts like a spreader bar,.... it is more responsive.... don't put a solid mount on the transmission, I know that I moved loads from one component to the other. Obviously, the loads are not significant enough to cause a catastrophic failure under normal abuse. To your point, they would be banned by the regulating bodies if they did. But, is there a long term effect such as block twisting? What happens in an accident?

I have no strong feelings about this, I am just wondering out loud and wondering whether anybody has seen any secondary failures that can be associated with the solid mounts?

PainfullySlow

While I agree with the thought process, I am not sure that I would be quoting HD as evidence of quality design or high performance :-p They shake like a bitch with solid mounts. Anyway, what you said made absolute sense and it was the final straw on this camels back that convinced me to ditch my poly engine mounts and go with solids =)

Gunfighter13

Posts like this just make me laugh........

OldCarBum

Exactly my point, HD V-Twins are not a hi performance application at all but on the older V-Twins they vibrated like a B and they never had a failure in the engine or transmission cases with the solid mounts.

v2racing

Well this is not entirely true. I've seen lots of broken engine and transmission cases on the old Nuckle, Pan and Shovels, but it was always because the mounting bolts were loose. A lot of people never check bolts and loose motor mount or trans mount bolts always ended up with broken cases. If they were kept tight, they didn't break.

Mike

DaGuvner

When I dropped my new 383 (420 hp) with headers in I went with new factory mounts. Months later well after break in. I did a brake torque burn out and heard an awful sound. Turns out the high torque 383 broke the bond of the rubber in the left mount allowing the left side of the engine to lift enough to send the fan into the top of the radiator shroud and destroy it. Happened very quickly.

Bottom line, solid mount left, rubber on right. I think the softer rubber mount in the right helps to offset the slightly higher vibration the left solid mount generates. The right mount is compressed under acceleration so no tear possible.

Lesson learned and mind is at ease now.

Vette5311

This exactly why I have a torque limiting turnbuckle on the driver side. Rubber mount and engine lift protection. Best of both worlds.

Gunfighter13

That was the standard for a car with any horsepower back in the early days before there was solid mounts.

Vette5311

Yeah I remember when GM came out with a cable looped from exh manifold to upper A arm cross shaft but it was kinda loose and only worked if motor mount separated.

OldCarBum

Back in the day we welded a chain to the frame and any bracket we could get to.
Seemed to work.