Has anyone had any unusual fit problems with aftermarket motor mounts on early A-bodies?

My ’64 Valiant convertible has issues I never had with any other slant bodies, and I can’t figure out what created the problem.

It’s a stock, low-mileage 225 Torque Flite setup that had OEM mounts when I bought it nearly twenty years ago. Those mounts were tired and deteriorating so when I rebuilt the engine I bought a rebuilt aftermarket set from India. I had tried for years to locate US made parts, but those were the only ones I could find at the time. When the car was in the paint shop, the engine was installed by the shop after they painted the engine bay. I never had my hands on the job.

Everything was okay for a few years, but the refurbed parts were always mushier than OEM so I kept looking for better quality parts without success.

About two years ago, I had a classic restoration shop check out the mounts while having some other work done. Their mechanic said there was something wrong with the way the mounts were installed, and he could only make them fit by adding spacer washers between the brackets and the engine block. However, after a few months, the engine began to shift until the exhaust pipe contacted the torsion bar creating a serious rattle.

I wanted to tackle the job myself, but at the time, I was having health problems and without a lift, I was unable to do it, so I ordered new poly mounts and took the car to a well-respected local mechanic to have them installed. He had nothing but problems and after three hours of frustration, he had managed to shift the engine enough to get a 1/4” clearance between the pipe and the bar but he couldn’t determine why the driver’s side mount didn’t fit correctly. He said there was no evidence of crash damage and the new poly mounts seemed to match the configuration of the India-made aftermarket parts, and he wanted no more to do with it.

The pipe-to-bar rattle is gone, but the hard poly mounts shake the whole car when driving slow or idling at a stop light. I don’t think I want to put up with the dozens of new rattles.

My health is still too bad to try my hand at trouble-shooting but maybe someone has run into a similar problem that is easily recognized and repaired.

Since the poly mounts are so damn stiff, I’m even considering having a local hotrod fabrication shop adapt some later spool type mounts that are readily available!

Many/most catalogs list the wrong motor mount "insulators", for 1966 and older "A" body slant sixes. The correct part numbers should be some form of 2303 and 2304. If you look on Rock auto you will see the problem, if you compare the part numbers for Valiant or Dart, and 1966 older and 1967. It might be that someone installed the wrong insulators (at one time) and they didn't fit, so they changed the engine brackets to get things to fit. I don't know if this is possible, but I do know about the problem with the incorrect part listing. Just spit balling here.
If you look up motor mounts (insulators) for a 65 Dart you will get the correct part number.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

The Poly Mounts came out wrong. I bought a pair from the same guy I believe and the driver side mount don't fit, I had to grind the hole in the cross member wider to make it fit.

Far too firm for my liking anyways, made the whole car vibrate so I removed them and put in some from Rock Auto.

If you look at the details when buying there they will tell you the manufacturer location, I got some for my 64 and they were made in USA and haven't fallen apart yet after 10k miles. Fit like they were supposed to.

B

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Just checked on Rock Auto, none of the motor mounts say where they are manufactured. Fairly certain I got lucky and the box said USA, but I could be misremembering. I'd rather replace a crappy mount every few years than have all the screws in the car loosen themselves from the vibration of the Poly Mounts. Can't believe in my younger days I drove noisy vibrating cars on purpose!
For what it is worth I have had the same mount (It's a westar brand) in for almost 3 years no problems, but I drive like an old lady now so the mounts aren't being abused.

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I had the same exact experience, and when I posted about it, the few people who replied implied I was nuts for thinking they were too rough.
Felt like I was sitting on the ol' cartoon "waterwheel with boots on it ass kicking machine."

Glad someone else is afflicted by the same neurosis as me.

– Eric

It appears I'm not alone with a motor mount problem!

I think I can eliminate the wrong insulator part numbers and/or someone installing brackets from a different year. I'm 99% certain that I removed the original mounts when I first replaced them. I can vividly recall seeing red engine overspray on the rubber, so they were probably OEM. Though I couldn't prove the 38,000 miles on the odometer was original, I know everything on the engine had the original paint and the old man I bought it from said he had done nothing in the 17 years he had it and he bought it from the original owner. The engine ran perfectly with no noise or blue smoke, but every dry seal leaked oil to the tune of about a quart every hundred miles, so I opted to rebuild a '79 Super Six to swap instead of taking the time to rebuild the original.

I wish I had kept the ones I had the local garage replace so I could have measured and compared them with the poly set, as I think the last mechanic only compared them visually. The way he complained about the fit sounds as if he was fighting the crossmember hole location as it looks twisted when installed. If the weather clears up this weekend I'm going to try to get a picture of the driver's side installation.

Thanks for all the info and opinions!

My pass side mount was fine, and I'll likely replace it soon to get rid of more NVH....

The driver side mount was able to go in, but wouldn't sit level till I ground the hole in the crossmember out more. I just wanted a durable long lasting mount and have buyers remorse. Even with a clean fit I would have replaced it for being too firm.

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Are you referring to the mounts Johnny Spiva makes/made? He offered them in different Durometers for various applications. I'll have to look at the set I have for the '63 to see if the bolt alignment is wrong. For racing, the harder poly was appropriate. For a road car, you'd want a much softer poly.

Most of the mounts he was making were for racers early on, so they transmit a lot of energy. Softer than solid, but not remarkably. Great for taming torque for tight pan to K-Frame clearances on goofy racecar deep sump combinations.

CJ

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Part of Tyrde-Browne Racing