Okay, here I am with another set of headers, Hedman 68168 with the ceramic coating, trying to fit on the '66 Chevy II/Nova. Looks like it will almost fit on the drivers side, but I'm hard against the shock tower on the passenger side. Pondering the situation, it occurred to me that a bit more elevation on the engine might give me the clearance I need, since the tower tapers out a bit at the top. On a whim, I threw a level across the valve covers, and sure enough, it's low on the passenger side.
So I guess I need to shim (or change out) my motor mounts. TransDapt wants like 50 bucks for two. I don't really want to make my own, and I don't want to use a stack of washers 
Who sells cheap motor mount shims?
Advice?
GaryC83
New Reader
4/14/22 1:16 p.m.
In reply to 1988RedT2 :
Check speedway motors. Pretty sure I've seen them for $15-20. Won't get much cheaper than that for a new part on your door step in a few days.
Okay, sounds reasonable.
Also, on the advice of a friend, existing mounts are solid, which concerns me a bit, as this will be a fair-weather cruiser. I'm concerned solid mounts might make for a fairly noisy situation and transmit vibration. Is there any adjustment in motor mounts, or are they all going to be about the same before shimming?
Solid mounts can be shimmed, I'm sure.
Now, let me tell you this short story. I purchased a 1975 Nova as a front suspension donor for my 67 Camaro project, and mocked everything up using the original worn out GM mounts. I then installed a new set of aftermarket mounts, and could no longer turn the steering wheel because the engine was sitting on the centerlink.
TL:DR- Aftermarket cheap motor mounts are way worse than 45 year old GM mounts.
I'm looking for Curtis to weigh in. I think he may have some expertise here.
Are they clamshell mounts? Or do they look like this...
If they're like the ones pictured, they were pretty flawed from the start. There is nothing really encapsulating the rubber and they can tear. The good news is that you can "egg" the holes that mount to the crossmember and slide the driver's side down and the passenger side up to rotate the engine a 1/2" or so.
And although I know aftermarket ones suck, Rock Auto has the above mounts for $3 each. Since the factory ones sucked as well, it's only $6 to put new sucky ones in.
If you have the clamshell mounts (unlikely unless someone retrofitted them), you can shim the rubber/frame side with washers under it. Just be aware of how many threads you have engaged in the crossmember and be prepared to use a longer bolt. I would also not hesitate for a moment to use aftermarket clamshell mounts. If you look at the design, they can sag and wear over time, but they can't fail or tear. They are completely surrounded by steel like this:
Well, the stock mounts look like your top picture, but what's in there now looks like this:
I'm thinking if I add about 1/2" of height to the passenger side, it might just fix my clearance issues on both sides,
Ah... just read you have solid mounts.
All bets are off. The aftermarket has engineered all kinds of solid mounts. Some just look like factory mounts minus the rubber, others are a whole different critter.
Have a picture?
In case this speeds up the process... yes, it's fine to shim the snot out of motor mounts. I wouldn't do it on an NHRA Top Fuel car, but keep it under 900hp and you're good. Motor mounts are designed on a specific radius relative to the crank. It's more important to shim on the frame side and not the engine side. Not likely you'll notice a difference, but as soon as you move the flex point to a different distance from the block, you have taken it outside the specified radius and you can make the vibes you have even worse.
So, shim between the mount and the frame, not the mount and the block.
In reply to 1988RedT2 :
Then either shim between the mount and the frame, or egg those holes and mount them on the frame using a level before dropping in the block.
My bigger concern is.... why are the mount points off by 1/2"?
Hey, it's an old car.
This is kind of an awkward shot down from the top. Fuel pump block-off plate visible at the front.
Curtis73 (Forum Supporter) said:
In reply to 1988RedT2 :
Then either shim between the mount and the frame, or egg those holes and mount them on the frame using a level before dropping in the block.
If I'm egging holes, then I'm relying on just bolt tension to keep everything in place?
I don't believe I can shim on the frame side. The through-bolt attaches the mount to a fixed point on the front subframe.
1988RedT2 said:
Hey, it's an old car.
This is kind of an awkward shot down from the top. Fuel pump block-off plate visible at the front.
It's hard to tell from the picture but that doesn't look like a factory mount on the frame side either. I'd be rethinking the whole mounting situation and going to rubber.
In reply to APEowner :
The frame side is part of the front subframe. There's nothing to rethink. I just need to add 1/4 to 1/2" to the height on that side, and to me, it looks like the easiest way to do that is to add a shim or shims between the mount and the block.
1988RedT2 said:
Curtis73 (Forum Supporter) said:
In reply to 1988RedT2 :
Then either shim between the mount and the frame, or egg those holes and mount them on the frame using a level before dropping in the block.
If I'm egging holes, then I'm relying on just bolt tension to keep everything in place?
I don't believe I can shim on the frame side. The through-bolt attaches the mount to a fixed point on the front subframe.
Oh... yeah. I was picturing the earlier W-head BBC (348/409ci) and the Caddy 390. They used the same mounts but they were backwards. The flat part mounted to the frame and the "tabs" mounted to the engine. My bad.
Yes, egging the holes requires the bolt tension, but your torque vectors are on slightly different planes. I'll try to draw what I'm talking about
If you egg the holes in the frame side on the green axis and the holes on the block side on the blue axis, you can slide the motor mount down on the block and the holes on the mount slide away from the frame. Then you can see from the orange circle, that's your moment of inertia - the direction the forces put on the fasteners. It's about 45 degrees to the frame side holes and about 90 degrees on the block side holes.
This way you can set the whole thing in with loose bolts halfway threaded in, level the block, then tighten the bolts. If you must shim, I can't see it as a problem to shim off the block seeing as how they're solid mounts. The vibes come from the movement of rubber mounts, but since you have no rubber and no motion, you're going to get the same vibes.
Put it this way... you CAN shim either side safely and it's what I would try first. I'm not sure if you can get enough "egg" on those mounts to get your half inch, even if you do both sides. Its just that if you have rubber mounts you can make some weird harmonics happen if you shim the block side. Since you have no rubber and no motion of the engine relative to the frame, I can't see it would make any additional vibes.
Oh... and make sure you also have a solid trans mount. If one end flexes while the other doesn't, breaky things can happen.
Thanks!
I will have to crawl under there again and take a look at the frame side. Classic Industries does list a frame mount, so it might bolt in. For some reason, I thought it was welded. It could be that the originals got tweaked, or just egged out, and the engine is sitting low on the passenger side.
It's been well over ten years that I put the engine in this thing. It has yet to run. 
APEowner said:
1988RedT2 said:
Hey, it's an old car.
This is kind of an awkward shot down from the top. Fuel pump block-off plate visible at the front.
It's hard to tell from the picture but that doesn't look like a factory mount on the frame side either. I'd be rethinking the whole mounting situation and going to rubber.
I agree. 62 through 67 they had a "tower" on the frame that looked sorta like this:
Curtis73 (Forum Supporter) said:
Oh... and make sure you also have a solid trans mount. If one end flexes while the other doesn't, breaky things can happen.
Disagree here. Ran solid motor mounts with a poly trans mount on my flexible fox body and didn't break anything. It has to give "some".
Those mounts do bolt to the front subframe. Look a lot like this. I'm going to loosen up some bolts tomorrow and see if it's got some movement in it.
In reply to 1988RedT2 :
Looking at them, it's possible they are bolted in upside down or wrong sides.
Ranger50 said:
Curtis73 (Forum Supporter) said:
Oh... and make sure you also have a solid trans mount. If one end flexes while the other doesn't, breaky things can happen.
Disagree here. Ran solid motor mounts with a poly trans mount on my flexible fox body and didn't break anything. It has to give "some".
I just read "my flexible body" and now I can't stop picturing you doing Yoga.
Curtis73 (Forum Supporter) said:
Oh... and make sure you also have a solid trans mount. If one end flexes while the other doesn't, breaky things can happen.
You MUST use a flexible trans mount. The chassis will twist a lot, the engine and trans do not, and the tailhousing is usually the weakest part of the equation.
I have nothing to add other than I put a short deck 496 in a '69 Nova (different chassis, I know), which should have been a bolt in, but it took a bizarre combination of spacers and raised height motor mounts to even get the mounts to line up with the chassis.
