Motor Mounts Wont Line Up!

[82chevy350]

Ok guys so I was really hoping to get my 350 into my jimmy Yesterday but ended yup with no luck!
I have a 1978 GMC Jimmy 4x4 and I had got a set of mounts to the motor (clamshells) from a 1981 GMC Sierra 2wd and had bought a set of the rubber frame mounts for my 1982 C10 2wd but decided to use them on the jimmy since im gonna run solid motor mounts. I bolted it all up and noticed one side the hole is about a inch off! Me and dad tried loosing the rubber mounts hoping it would give us enough room. I figured it was gonna be a PITA since the rubber mounts where new. But if just wont line up for nothing. Anyone have any ideas why it wont work? I figured all the rubber frame mounts are the same. We even tried swapping sides of the mounts on the engine it didn't help any. This is kickin My ASS!

 

[89Suburban]

Doh!

 

[82chevy350]

Haha I do know that there are "tall and Thin" and "short and wide" mounts. But figured since the mounts I got are for trucks they would work. I was hoping to get the darn thing in before it got to cold!!

 

[89Suburban]

Somebody knowledgeable on this will chime in buddy, just hang in there. I'll search around and see if I can dig anything up.

 

[MrMarty51]

Is the transmission in and mounted to the cross frame, and, the engine bolted to the bellhousing ????

 

[82chevy350]

Tranny is not in. Seems Like my rubber mounts need to come up

 

[skysurfer]

I ran into something similar with motor mounts recently, the part number showed them to be the correct ones but they didn't line up. In frustration, I drilled out the areas holding the clamshells together and put the new rubber in the old shells, then tack welded them back together. You're dealing with more than just the shells so it might not be as simple as what I was up against.

 

[MrMarty51]

Grind out the hole in the frame mount, the part that is bolted to the frame., into a longer elongation, but, check the position of the stud in Your new mount to the original mount first, see if they are in the same position/location.
You may have also needed the part that bolts to the frame.

 

[82chevy350]

Well when I got the jimmy it had no mounts whatsoever. Im just wondering if there is a difference between mounts on the engine 2ws or 4wd but I wouldn't think so. I may just have to like you said grind out the hole!

 

[chengny]

First make sure it's not an indexing problem. Measure as below:

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and determine if the distance across the frame is the same as the distance across the clamshell bolt holes.

Everything else aside - if the distances are equal, the motor should sit on the mounts (with the bolts installed).

If the distance across the frame seems too wide - are the plates that go between the clamshells and the block installed. These are the brackets for the forward end of the transfer case stiffening struts:

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Having those installed substantially increases the distance across the clamshell bolt hole
centerlines.

 

[89Suburban]

Outfuckingstanding

 

[82chevy350]

The problem is the mounts on the engine are to wide for the rubber mounts. The distance between each motor mount is wider than the frame mounts. When I put one bolt in on the passenger side the drivers side motor mount needs to go in about an inch.

 

[chengny]

When I put one bolt in on the passenger side the drivers side motor mount needs to go in about an inch.

Or the distance across the clamshells needs to be increased "about an inch".

Did you catch my suggestion (and see the images) about the forward brackets for the transmission stiffening struts?

Do you have those brackets installed between the back of the clamshells and the engine block? They are made out of shaped 1/4" plate. When both are installed, the distance across the clamshells at the bolthole C/L's increases by about 3/4".

 

[82chevy350]

No I don't not have the brackets between the clamshells as it would make the problem worse. The distance of the clamshells need to be decreased about a inch.

 

[chengny]

If the clamshells are bolted right up against the block - that's all you can do on that end. There is no way to decrease that bolt hole - to bolt hole dimension. The motor mounts have to be moved out.

But you already know all that - I'm just thinking out loud as it were.

And, without major frame modifications, they can't really move out in the horizontal plane. They need to go further up the slope of the landing plates.

The face of the landing plate is at about a 45 degree angle relative to vertical.

Some math:

You need to increase the distance across the frame (from motor mount hole to motor mount hole) by one inch - right?

That would mean that the bolt hole in the rubber section of each mount needs to be shifted out 1/2".

You can't go straight out (without frame mods) so the mounts need to move up higher on the plates.

To obtain a .5" increase in distance from the centerline of the motor, requires 1 inch of travel up the slope.This is due to the angle of the landing plates (you know the equation - a squared + b squared = c squared).

The mounts are normally bolted to the plates so that the bottom edge of the steel casing (of the mount) is flush with the bottom edge of the landing plates.

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