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Big Block Motor Mount Confusion...

The Butcher

The Butcher

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Texas. In a van, down by the river!
I posted some of this in my The Wife's Dually thread in the The Driveway, but thought I might get a little more visibility over here. I'm combining some parts from a few K30s into one, and ran into an issue with the motor mounts. Here are the specifics:

I have a 1982 K30 4x4 frame, that originally had a diesel engine in it. Somewhere along the way a 454 was installed in it. I cleaned up and painted the motor mounts that came off this frame, and was planning to use them for the swap. I found out yesterday they do not match the mounts that are attached to my donor 454.

The donor 454 is from a 1984 K30 4x2 frame. The Prothane mounts I bought appear to fit the mounts from the 4x2 frame, but not the 4x4 frame. The mounts that came off the 4x4 are smaller than the BBC mounts from Prothane. I'm guessing maybe the mounts that were on the 4x4 are either from an SBC, or maybe they are the original diesel mounts.

My question is how do I get the BBC mounts from the 4x2 frame to fit on my 4x4 frame? The hole spacing is wrong. I don't mind trying to drill new holes, but they come real close to overlapping the holes that are in the frame side of the 4x4 frame in such a manner that it will likely be tough to get a new hole drilled without falling into the holes that are already there. If I place bolts in the upper holes of the mount, then the end of the mount hangs off the bottom of the frame side mount. Any suggestions?

The pics below show the size comparison. In the first pic, the freshly painted mount is out of the 4x4 frame (these were bolted to a 454, but I'm guessing they are not 454 mounts). The second pic shows the frame side on the 4x4 frame. The third pic shows the frame side on the 4x2. The last pic shows the mounts that came off the 4x2, but placed on the 4x4 frame. The holes don't line up.

IMG_6828.JPG

IMG_6924.JPG

IMG_6923.JPG

IMG_6918.JPG
 
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I may end up having to do that, but I already have the nice new Prothane Poly mounts for BBC that I would like to use. Otherwise I'm going to have to return these Prothane mounts and order new ones which is a PITA. I'd like to use the larger mounts if I can, and blasting and painting these is easy, but it might be a pain to alter the mount on the frame.
 
Curious about this since I will be swapping a 454 in place of a 350. Plus I have 2wd brackets original to the truck that I plan on swapping out in favor of 4wd mounts.

Looking at RockAuto for an 89 R3500 2wd which is what my truck was originally versus a V3500 4wd. The difference in motor mounts appears to be 454 vs 350 not anything to do with 2wd vs 4wd. I wish they had dimensions on the part info.
 
I used SBC prothane inserts on my BBC/K10. One thing I never knew until recently was that the BBC pedestals that bolt to the frame are different than the SBC. The holes are in different locations on the pedestals which explains why my pedestals were redrilled by the PO. I'll see if I can find the thread where this was discussed.

Hoss7979 said:
Other option could be the DIY4X ones, I've looked @ those a few times......
Click to expand...

That's what my setup has.
 
skunked said:
here is some chit chat about the mounts

https://ck5.com/forums/threads/6-2-454-engine-mount-to-frame-brackets.325894/
Click to expand...
Thanks for this. The pic on the second page of your drilled out mount is probably what I will have to do unless I can locate a BBC K30 frame mount as it appears they are longer than the SBC K30 mount. My frame mount appears to be like what you had in your truck, which I assume is an SBC mount. My concern now is where to drill the holes on the frame mount in order for the motor and trans to still line up. Is there that much slack (1/2" or better I would guess) or room for adjustment on the trans mount to allow the motor and trans to all line up properly in their mounts if I move the holes up like that? I assume yours was that way, so there must be, I just don't want to drill holes and then not have the motor and trans line up properly. Or do you just shim the trans mount up if you need to?
 
I don't think it makes much of a difference to be honest, I would drop the motor in with the trans and t-case bolted up and mark the position of the motor mounts on the pedestal. Then remove the engine and drill the holes in the pedestal where the mounts sat.
 
o.k. 1 better who has both sets ?

make a template of the pattern and post it up so anyone else who runs in to this can just print it out and transfer the holes and drill them out .

this would be cool to have info wise .
 
I don't know if you'd be interested but I have the engine crossmember, and all of the mounting stuff minus the part that bolt to the block. Would let them go cheap.
 
sweetk30 said:
o.k. 1 better who has both sets ?

make a template of the pattern and post it up so anyone else who runs in to this can just print it out and transfer the holes and drill them out .

this would be cool to have info wise .
Click to expand...

It would but it looks like you could eyeball it pretty easily based on these pics :dunno:

MAXMAN said:
OK, In the first pic you will see mount and pedestal in 85 k20 sbc suburban. Second pic is mount and pedestal out of 84 K30 bbc. Notice how much closer the bbc mount is to the small hole in the pedestal. Much higher that the sbc!

View attachment 205407

View attachment 205408

View attachment 205409
Click to expand...
 
mrk5 said:
You said in that thread you were going to get back with how the DIY4x mounts worked on the small block brackets, but you never did. :what:
Click to expand...

I like keeping you guys in the dark :D

It didn't line up as well as I would have liked it to. I made it work but I had to loosen the ORD crossmember and the pedestals to squeeze the frame rails together with a strap. Then I could start the bolts and pull it together with the hardware. I'm not done messing with it, the engine is coming out again so I can box that front section of the frame.
 
So because the mounts bolt on higher up the brackets the were too far away? Is that why you had to squeeze the frame rails together?
 
mrk5 said:
So because the mounts bolt on higher up the brackets the were too far away? Is that why you had to squeeze the frame rails together?
Click to expand...

I didn't re-drill my brackets so it's not that. If I took a 4 degree axle shim and slid it between the mount and the pedestal on each side it would have made up the difference.
 
skunked said:
I didn't re-drill my brackets so it's not that. If I took a 4 degree axle shim and slid it between the mount and the pedestal on each side it would have made up the difference.
Click to expand...
Was there the same issue with factory mounts that had been made to fit by drilling the new holes in the frame mount? That's what I'm concerned with if I go that route.
 
The Butcher said:
Was there the same issue with factory mounts that had been made to fit by drilling the new holes in the frame mount? That's what I'm concerned with if I go that route.
Click to expand...

The other frame and engine bolted together with ease (using the drilled holes) which is kind of funny because that K10 frame was hammered. Cracked, bent and repaired multiple times but I could swap out an engine mount easily.
 
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