Can I reuse old Enginge Mounts?

[Patrick N.]

I am close to putting my engine back on the frame and was not sure if I could reuse my old engine mounts or need new ones?

Is there any clear way to inspect / determine if the mounts are OK -specifically the rubber?

They are the non-locking style for a 68 BB

If I need new, I was planning to source them from Dr. Rebuild-any thoughts are appreciated.

Thanks,
Pat

[Robert G.]

Re: Can I reuse old Enginge Mounts?

It depends on several things. Are you going to show it or drive it? What condition are they in? The ignition shielding may require modification to fit with locking style mounts, though that may only apply to midyears. I'd go with new ones to be safe.

[Patrick N.]

Re: Can I reuse old Enginge Mounts?

Rob,
Mostly for judging and show, it will be driven as well though. Is it common practice during a restoration to swap these out?

I'm not opposed to simply buying new ones to ensure they are good if that is best solution. I don't need a hassle down the road for something as basic as a mount!

Thanks
Pat

[Gary B.]

Can I reuse old Enginge Mounts?

Patrick,

If you want to use the old ones because there are no acceptable reproduction that meet your cosmetic requirements, there are places that will remove the old rubber and replace it with newly vulcanized rubber. This is commonly done with harmonic balancers (e.g., by Damper Dudes), but I recall there are shops that will do motor mounts as well.

Gary

[Edward J.]

Re: Can I reuse old Enginge Mounts?

Pat, one quick note, these mounts are a saftey issue if they are deteriorated, when they do seperate the engine can pick up off the mount under accelaration causing the cars accelarator pedal to stick open.(yes, just like the Toyota problems) . a close inspection of the mounts will tell ya.(the drivers mount tends to be the mount that gets the most wear).

My advice is if the mounts are still good put them aside til your ready for judging. new ones will surely give you piece of mind.

[Patrick N.]

Re: Can I reuse old Enginge Mounts?

Well said Ed,

My mounts "look" ok but I cannot be certain and i'm very aware of the risk if they do fail.

I will source replacements and add them to my list of parts to swap before judging-good plan.

P.S.
small detail, should the motor mounts show orange engine paint overspray? My originals show overspray, but the previous ower had done some painting.

Thanks all!
Pat

[Terry M.]

Re: Can I reuse old Enginge Mounts?

Well said Ed,

My mounts "look" ok but I cannot be certain and i'm very aware of the risk if they do fail.

I will source replacements and add them to my list of parts to swap before judging-good plan.

P.S.
small detail, should the motor mounts show orange engine paint overspray? My originals show overspray, but the previous ower had done some painting.

Thanks all!
Pat

The engine mounts were installed in St. Louis, I believe. Check your copy of the AIM to be sure. If the part number for the engine mounts is called out in the AIM, they were installed in St. Louis.

There was nothing painted orange in St. Louis.

[Patrick N.]

Re: Can I reuse old Enginge Mounts?

thanks Terry, I will check the AIM + part num tonight.

Always great to learn about the details from everyone on this forum-Thanks!!

[Jim T.]

Re: Can I reuse old Enginge Mounts?

Patrick I am still using the original factory installed motor mounts in my original owner 68. It has the 327/350 and not the amount of torque a big block has. They still do the job of keeping the engine in place. With the applied torque on the left mount a person could place the used left mount on the right side since the right motor mount was not subjected to motor torque like the left.

[Michael H.]

Re: Can I reuse old Enginge Mounts?

Patrick I am still using the original factory installed motor mounts in my original owner 68. .

And they will likely last many more years. The original Corvette (and 409 Chevy) mounts were quite durable. Nothing like the mount used for regular passenger cars. The Corvette/409 mount was much different.
I can think of a LOT of broken mounts in pass cars but I can't remember ever having seen one fail in a Corvette.

If new mounts are used, I would definitely use the interlocking style. I wouldn't trust a conventional "replacement' mount available today as they would be designed after the regular pass car mount.

[Erik S.]

Re: Can I reuse old Enginge Mounts?

Now that we are on this subject: can somebody maybe identify these mounts that are from my 68 L71; I would think this is a later style mount right? Planning to re-use; good idea or not? Thanks, Erik

[Ridge K.]

Re: Can I reuse old Enginge Mounts?

I agree with Mike Hanson and others who attested to the durability of the original Corvette/409 motor mounts.
In years and years of attending drag racing events, I've never seen a failure of a factory C2 or C3 Corvette mount.

Having said all that, I found and purchased a NOS set for my own big block '67. The NOS service replacement set is cosmetically identical to the originals that were still on my 46,000 mile car. They cost about, a hundred dollar bill.

Good luck, Ridge.

[Joe L.]

Re: Can I reuse old Enginge Mounts?

Now that we are on this subject: can somebody maybe identify these mounts that are from my 68 L71; I would think this is a later style mount right? Planning to re-use; good idea or not? Thanks, Erik

Eric------


These are GM engine mounts first used in PRODUCTION for 1973 Corvettes and available in SERVICE for all 1963+ Corvettes thereafter. These mounts were sold under GM PART #6258154 which included the GM #330973 mount + attaching parts. The earlier locking style mounts, GM #3980701 and 3990916 were virtually identical.

[Patrick N.]

Re: Can I reuse old Enginge Mounts?

Here is the mount that had me question should I use these again- you can see some cracking on the side. This is the worst of the two, they other lookks reasonable.

My engine is .060" over and a bit more wild cam now so HP and torque may put a bit more stress on the old mounts eh?

Per Jim, Michael and Ridge's comments, it seems like I could use these again -still leaning towards new and swap for judging. I'll post what I end up going with.

Interesting learning though, as I was looking in the AIM per Terry's earlier comment, my mounts are 3886466 which shows under the 327.
427 with AC calls out RPO L36 PART + shim 3910756 (my car is non ac so this should not apply). Other than that callout, it looks like 3886466 was for both 327 & 427 prior to the change to locking style.

[Michael H.]

Re: Can I reuse old Enginge Mounts?

Interesting learning though, as I was looking in the AIM per Terry's earlier comment, my mounts are 3886466 which shows under the 327.
427 with AC calls out RPO L36 PART + shim 3910756 (my car is non ac so this should not apply). Other than that callout, it looks like 3886466 was for both 327 & 427 prior to the change to locking style.

That would be the correct part number for 66-69 for both small and big block. (3796050 for 63-65)

The original mounts can be made into "safety mounts" with a little work. I don't remember the details but it had to do with drilling through the center and installing a limiter bolt. It's been decades since we did this so it will take a while to remember how it was done.
When complete, it was undetectable.