Motor Mount Perches?

[Jack15T]

Hi Folks, I have been trying to replace the Motor Mount Perches in my 1971 Chevy K20 Pickup. The VIN number states the truck came with a V8. Some previous owner stuffed a 454 in it, using the what I think is the original Crossmember and Perches which should have been for a Chevy 350. The 454 is hitting the firewall in two places. I want to move it forward but I cant find replacement perches. Mine are badly worn. Does anybody recognize these? One picture is the crossmember and the other picture is the Perch that came out of the Truck and the other Perch is what LMC sent me for a Small Block V8. If anybody can ID my Crossmember and Engine Perches I would greatly appreciate it. Cheers, Jack

[Grumpy old man]

Lock Doc picture

[Jack15T]

Thanks for the picture. None of those look like mine. There are no other holes in my frame that would suggest a different crossmember and the ones in your picture won't even come close to bolting up.

[Mike C]

You have a four wheel drive truck and all of the other perches are from 2x4 trucks. Move the entire crossmember and mounts forward. Unlike a 2x4 truck, the suspension is not attached to the crossmember.

[Jack15T]

That's what I planned on doing but my Perches are pretty worn. I would like to replace them. Any idea of a source? I tried Brothers, LMC, Classic and a couple of others. No luck.

[Jack15T]

Well, I found the perches on page 149 of the 67-72 factory assembly manual. Still doesn't help me any as I don't have a part number or a source for them.

[71blksuper4x4]

To my knowledge, they aren’t reproduced. What is the worn area you speak of?

[tj1970cst]

The hole on your mount isn't that bad. The big block trucks had a larger hole than the small block trucks.

[Jack15T]

The 71 K20 didn't come with a big block. I believe it was an option on the C models. Supposedly my perches are for the small block 350. I'm thinking there should be a bushing or something to take up the space around the skinny ass bolt that goes through that hole. The other perch is much worse than the one in the photo. I held the new engine mount up to the old perch and it does seem to fit marginally okay, but it sure leaves a lot of room for slop. I would think the GM engineers would have come up with something a little better. That being said I just finished tearing down my NP205 transfer case and rebuilding it. I'm not sure what planet the guy was from who designed that case but clearly no thought was given to rebuilding it. Thanks, Jack

[notsolo]

These were from a 72 K5 Blazer 350/350...NP205 transfer case.....can post in for sale section if your interested....LMK

[HO455]

It is possible that square body BBC perches were used as they may have junk yard items when your truck was converted.

[Jack15T]

Anything is possible with this truck.

[Jack15T]

NotSolo, Do you still have the perches? Jack

[68isgreat]

Reviving this thread because I'm getting ready to install a small block in the above 4x4 perches in my 68 k10. The OP references the large hole on the perch that the small motor mount bolt goes through. Am I supposed to just use a large, thick fender washer for the motor mount bolt in that hole? Just curious what the correct solution is.

Thanks

[Orefactory4x4 swb]

There’s some listed in the parts for sale on the forum right now, I’m thinking it what your looking for

[68isgreat]

Originally Posted by Orefactory4x4 swb

There’s some listed in the parts for sale on the forum right now, I’m thinking it what your looking for

Thanks! I've replied to his post. Here's what I have now, and I'm not sure how the engine is supposed to attach. I have new rubber flat mounts attached to my new crate tbi small block, and this is my crossmember:



I'm not sure if I need a separate perch that attach to the top of this, or if my flat rubber mounts just attach to this crossmember as is using a bolt and large fender washer in the large hole? Not sure how this is supposed to work. Any input is appreciated.

[Orefactory4x4 swb]

I’m not sure, but that doesn’t look like what I have in my factory 72 k10 350.
I’ll send you pics if you need some

[RustyPile]

Originally Posted by Orefactory4x4 swb

I’m not sure, but that doesn’t look like what I have in my factory 72 k10 350.
I’ll send you pics if you need some

Motor mounts were completely redesigned in 1972.. Pictures of your mounting system won't help him..

[57taskforce]

The upper part of the crossmember goes under the top of the frame rail. From there the engine rubber mount bolts to the crossmember via the big holes at the tops of the upper brackets in the crossmember if that makes sense. See my old picture above for mounting on the crossmember to the frame.

In the picture in post 14 you can see where the rubber mount was rubbing on the upper crossmember brackets below the big hole. The mount just lays on the crossmember and bolts into place. I believe they were 7/16 bolts and washers if I remember right. It’s been a few years since I replaced all that on my truck.

Edit*** All you are seeing in this picture referenced earlier in this thread and reposted here is the disposable rubber mount still bolted to the crossmember and unbolted from the engine. That’s the same mount you can buy at NAPA, orielly, autozone… whatever your auto parts poison is. I think you are overthinking the setup a little bit.

[68isgreat]

Originally Posted by 57taskforce

The upper part of the crossmember goes under the top of the frame rail. From there the engine rubber mount bolts to the crossmember via the big holes at the tops of the upper brackets in the crossmember if that makes sense. See my old picture above for mounting on the crossmember to the frame.

In the picture in post 14 you can see where the rubber mount was rubbing on the upper crossmember brackets below the big hole. The mount just lays on the crossmember and bolts into place. I believe they were 7/16 bolts and washers if I remember right. It’s been a few years since I replaced all that on my truck.

Edit*** All you are seeing in this picture referenced earlier in this thread and reposted here is the disposable rubber mount still bolted to the crossmember and unbolted from the engine. That’s the same mount you can buy at NAPA, orielly, autozone… whatever your auto parts poison is. I think you are overthinking the setup a little bit.

I definitely was! Thank you very much.

[57taskforce]

No worries, it’s easy to do. K trucks can be a bit of a pain to keep up with as far as changes year over year. They didn’t get some of the changes that the C’s did as things went on.

[RustyPile]

Originally Posted by 57taskforce

No worries, it’s easy to do. K trucks can be a bit of a pain to keep up with as far as changes year over year. They didn’t get some of the changes that the C’s did as things went on.

In those years, I was a GM dealership mechanic.. What I remember most was all the cars and trucks that came in with broken motor mounts.. Around '69 or '70, Chevrolet issued a TSB about broken mounts.. Later they issued a "full blown" recall.. The fix was to install a cable device that wrapped around the UCA shaft and bolted to an exhaust manifold bolt. What I also remember about the Ks was all the cracked frames around the steering box and motor mount brackets with holes worn through from the rubber getting soft and allowing the mount edge to rub against the bracket.. Some of this happened while the vehicle was still in warranty.. By 1975 - 76, I had advanced my skills and no longer had to deal with heavy line repairs..

[68isgreat]

Originally Posted by RustyPile

In those years, I was a GM dealership mechanic.. What I remember most was all the cars and trucks that came in with broken motor mounts.. Around '69 or '70, Chevrolet issued a TSB about broken mounts.. Later they issued a "full blown" recall.. The fix was to install a cable device that wrapped around the UCA shaft and bolted to an exhaust manifold bolt. What I also remember about the Ks was all the cracked frames around the steering box and motor mount brackets with holes worn through from the rubber getting soft and allowing the mount edge to rub against the bracket.. Some of this happened while the vehicle was still in warranty.. By 1975 - 76, I had advanced my skills and no longer had to deal with heavy line repairs..

Wow, you are the guy to talk to. Thank you for posting.

[Orefactory4x4 swb]

Here’s some pics of mine. It was a truck needing a lot of work, but I’ve done it all from top to bottom. From metal work lift paint wiring and on. Myself on it all.
Can’t wait to fire it up soon.

[Orefactory4x4 swb]

You can zoom in on the mounts