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I'm collecting parts to put my C3 back together, and I'm trying to decide what to do for motor mounts.
I don't know if I want to run solid mounts because I'm worried about vibration (maybe they are not that bad?), but would prefer something more robust than the stock interlocking type. I have mounts like this on both my trucks, and they are much more robust than the factory interlocking style. Is there anything like this out there for a Corvette?
https://www.offroaddesign.com/competition-style-motor-mounts-for-73-to-87-gm-small-block-or-big-block.html
Last edited by kkEdlund; Mar 23, 2021 at 02:31 AM.
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
In your pic , all you would nned is the solid plate if thats they way you wanted to go. Did you have an issue with tearing the polyurethane in the interlocking mounts? I know I used to tear up motor mounts alot years ago, but I havent had an issue with my corvette, even with racing it at the drag strip or doing stupid stuff while cruising the beach. Usually break something i the rear end first
Check a post by GUSTO14 2/2/2018. Rubber mount with thru-bolts. Drill thru rubber and steel on the other side. Chamfer entry side for tapered bolt head. Tap threads for 3/8” bolt in the other side. Tack weld bolt to threads if you don’t want a nut sticking out.
My near-stock small block was breaking the drivers side mount every few thousand miles. Switched to Energy Suspension poly mount on driver side and left the still-intact pass side rubber mount because I was feeling lazy and non-committed to changing OEM look, as it is a low-mileage all original. My other Vette got polys on both sides. I cannot tell a difference driving either car except the one with polys goes a lot faster (lol-other mods). The instructions did say to provide shielding from exhaust heat to prevent melting.
I didn’t read about using the thru-bolts until after installing the poly mounts...next time.
The referenced post shows a picture of heavy duty BB mount that comes with a bolt thru the rubber on the drivers side.
I went with Moroso solid motor mounts.
I’ll never need to worry about breaking one and there is nothing to deteriorate over time.
We went the same route in our 79 after my son broke the rubber mounts twice (I probably don't want to know how, but he went thru a set of tires in under 4000 miles too. ). We didn't notice any additional vibration at all. We do still have the stock rubber transmission mount.
From: Arizona - If you don’t know CFI, STOP proliferating the myths around it...
Originally Posted by HeadsU.P.
I don't race but, have Solid Moroso Mounts and never looked back. Its the only way to fly.
You do not want your engine moving even a fraction with the close clearance of fan & fan shroud.
Another vote for solid mounts. You won't get vibrations, more wives tail stories about vibrations that keeps on going... Have been running them for a number of years and NEVER looked back after breaking old style mounts several times.
Last edited by Buccaneer; Mar 23, 2021 at 03:03 PM.
Bradleyb66 makes two good points above!
1. Driving style can put a lot of added punishment to the motor mounts. Adding torque and horsepower is another contributing factor, but if you drive it hard, even a stock engine can cause the mounts to fail.
2. If you do go with solid motor mounts, “Do Not” install a solid transmission mount.
If you decide on rubber or poly mounts, buy the best, because this is one of those times that it really makes the difference in the quality.
Anything you buy in poly, make sure it’s from Energy Suspension, they have the best quality poly components on the market.
If you are running headers or plan to in the future, there have been a few cases where the heat from a close header tube has melted poly motor mounts especially on big blocks.
When I replaced my motor mounts I called Energy Suspension and their representative stated they have had several instances where header heat has melted their poly mounts.
Thats what sold me on solids.
I've always been a big fan of solid mounting an engine and have had several street vehicles with motor plates (front and mid plates). The noise and vibration has never been an issue (to me).
I have consistently found (across f-bodies, BMWs, trucks, jeeps, etc) that the transmission mount is always the one that makes the interior buzz. Over torquing a poly transmission mount will make everything buzz, but I've had some vehicles that just couldn't be run with anything but a rubber trans mount (even with solid motor mounts). The key is to always make sure the engine mounts are as stiff OR STIFFER than transmission mount. If the transmission mount is stiffer than the engine mounts, you risk breaking the transmission output shaft housing.
I'm in the process of swapping a 454 (BBC) into my 79 and it's getting at least a mid plate. I may do a front plate if I can effectively contour it to not be obnoxiously obvious, otherwise I'll just do solid side mounts (still with the mid plate). I'll be running poly at the transmission.
Motor mount options
). We didn't notice any additional vibration at all. We do still have the stock rubber transmission mount.
