Motor mount thickness

Kern Dog · Feb 3, 2021

I am getting ready to put the original 383 back in my project car and the motor mounts that came off of the engine look to be in decent shape. I have new mounts I can use but there is a noticeable difference in the thickness of the rubber portion.

These are the mounts that I took off of the engine before the rebuild.

Here are the new aftermarket mounts:

Kern Dog · Feb 3, 2021

The stock mounts were 1 1/2" and 1 1/4". The aftermarket ones are both 1 1/8" .
I've looked at a few other mounts in my stash, they are all a little bit different. The thinner the mount, the lower the engine sits in the chassis and the higher the tailshaft of the transmission sits. It may not be much. I am more concerned with header fitment. If I were using manifolds, I wouldn't worry at all. Sometimes there is a small difference between the headers clearing and them hitting.
My question is....Does anyone know what the correct thickness is supposed to be?

Islandkent · Feb 3, 2021

Going to go check for you right now Greg. Mine are stock. Back in a few.

Islandkent · Feb 3, 2021

Here you go Greg. My pair are 1 3/16 Here is a shot of mine.

91r/t · Feb 3, 2021

They were probably all different even back then from the factory....one supplier's were 1 1/2" and others were 1 1/4" haha!

493 Mike · Feb 3, 2021

You have enough stud length on the mount to add shims if the is a clearance issue.
Mike

F4R/T · Feb 3, 2021

KD that was a good question, I’m looking for dated NOS for my 70 RT... I’ll measure mine tonight to see what they come up as I have ones that are originals.. they show age but not ripped or torn that I was going to use, they seem thinner.

ruffcut · Feb 3, 2021

I think I would measure from the thru hole to the top of the mount for comparison. Might be more accurate. IMO RUFFCUT

Big Bad Dad · Feb 3, 2021

May have been a large production tolerance?

oldkimmer · Feb 3, 2021

The motor torques to the passenger side so that mount ends up getting squished a little. That’s my thoughts anyways. Kim

69B7RR · Feb 3, 2021

View attachment 1063969

Kern Dog said:
The stock mounts were 1 1/2" and 1 1/4". The aftermarket ones are both 1 1/8" .
I've looked at a few other mounts in my stash, they are all a little bit different. The thinner the mount, the lower the engine sits in the chassis and the higher the tailshaft of the transmission sits. It may not be much. I am more concerned with header fitment. If I were using manifolds, I wouldn't worry at all. Sometimes there is a small difference between the headers clearing and them hitting.
My question is....Does anyone know what the correct thickness is supposed to be?

KD...both of my original part numbered insulators measure 1 1/4”.....69 RR.....LA plant build.......both right & left have same part #2536121, however the right is also marked KF-733, & left KF-7.........hope it helps ...Jim

Carcinogen · Feb 3, 2021

This would help explain why my steering cross link rubs oil pan. (72 Sat w/440 conversion)

Went out and verified I have shorter mount.

Now need to find out who makes taller mounts.

Kern Dog · Feb 4, 2021

69B7RR said:
KD...both of my original part numbered insulators measure 1 1/4”.

Thank you. I figured that something was strange. Your OEM mounts are the same as what I have on my red car and what came off this car, more or less.

69B7RR · Feb 4, 2021

Kern Dog said:
Thank you. I figured that something was strange. Your OEM mounts are the same as what I have on my red car and what came off this car, more or less.

No problem. Your posts have helped me in the past.....

67MPRFAN · Jun 5, 2021

493 Mike said:
You have enough stud length on the mount to add shims if the is a clearance issue.
Mike

I know this is a old post but you guys rock with your information, I ran into this problem today when trying to install my engine

Motor mount thickness

Kern Dog

Life is full of turns. Build your car to handle.

Kern Dog

Life is full of turns. Build your car to handle.

Islandkent

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Islandkent

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91r/t

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493 Mike

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F4R/T

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ruffcut

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Big Bad Dad

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oldkimmer

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69B7RR

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Carcinogen

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Kern Dog

Life is full of turns. Build your car to handle.

69B7RR

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67MPRFAN

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