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454 swap motor mount alignment issues

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cookieman77

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I’m in the process of rebuilding my 78 k5 and doing a 454 swap.

Recently I’ve been readying it for paint and bodywork and I was going to test the motor.

However I ran into issues with the motor mounts not aligning. I’ve tried the old ones from the 305 and the ones that came with the 454. Unsure what the 454 came out of but I figured if the sbc mounts from the previous engine didn’t work then surely I’m doing something wrong.

I’ve tried putting the inserts the other way in case I had them flipped but still nothing. (Still not even sure what the correct way is

It’s starting to get on my nerves a bit, any ideas or solutions?

This is the closest I’ve been able to get it so far.

0F0B254F-312C-4BB4-A7A2-09E441B32F43.jpeg

D63393F5-91C6-47D8-96C9-43A1BA2FFD0A.jpeg

354DED76-88C8-4859-94B2-67E237EF780A.jpeg

3545E2DE-EAC2-4F88-BE7A-B7303039C747.jpeg
 
There are small block saddles and big block saddles. Ran into the same thing when we put the 8.1 in the first time. Larry had some extras in stock and we could see the difference.
 
cheavyk10 said:
My '84 305 had these triangle spacers from the factory that went between the block and the motor mount bracket : View attachment 473835
Might be worth a look
Click to expand...
I’ll take a peek when I get home but I don’t think mine had any.
ZooMad75 said:
There are small block saddles and big block saddles. Ran into the same thing when we put the 8.1 in the first time. Larry had some extras in stock and we could see the difference.
Click to expand...
Not sure what you mean by saddles. Like the mount that connects to the block? Or the mount to the frame?
 
I know that the square body cans that bolt to the engine are different than the cans for a GMT 400 IFS truck. I found that out when putting a 93 TBI motor in my 81 C10. Tried for way too long to get it to fall into place. Cleaned up the 305 cans, and bolted them to the TBI 350, and everything fell into place instantly.
 
You need to reinstall the triangle plates on the engine side as well if you use the small block brackets. They were used for a reason. I bet the motor fits with them installed.
 
ZooMad75 said:
I’m talking about the block side.
Click to expand...
That’s what I figured; just making sure. Do you have part #s for ones that should fit?
kennyw said:
You need to reinstall the triangle plates on the engine side as well if you use the small block brackets. They were used for a reason. I bet the motor fits with them installed.
Click to expand...
I don’t have the triangle spacers. Double checked the 305 as well in case they were stuck on.
 
First off, apologies for the repost (not sure if this is against the rules or not but I didn't see one).
My last post of this got little traction and gave me little info so I'm trying again.

I’m in the process of rebuilding my 78 k5 and doing a 454 swap.
I recently ran into issues with the motor mounts not aligning. I’ve tried the old ones from the 305 and the ones that came with the 454. Unsure what the 454 came out of but I figured if the sbc mounts from the previous engine didn’t work then surely I’m doing something wrong. I’ve tried putting the energy suspension inserts I have the other way in case I had them flipped but still nothing. (Still not even sure what the correct way is to be honest)

Last post I was told to reuse the triangle 305 motor mount spacers on the block but my engine didn't have any.

I think it's an issue with the block mounts, so part #s would be very much appreciated if I am correct and need to replace those.
Otherwise correct me on that.

I really don't have much time to work on this entire project until summer so even hiccups like these set me back a while so I need info ASAP


This is the closest I've gotten so far.
1714876178678.png1714876417987.png1714876698968.png1714876965255.png
 
I would say line them up with the frame holes first. Then line them up with the engine mount main long bolts second. Leave the frame mount bolts loose so you can line up the engine main long bolts. Then tighten everything down.
 
What's holding the clamshells together in your pictures? The poly is basically oversized and usually the shell has to be compressed. That's why they give you zipties, but using bolts works better. Some people tack weld the clamshell shut. The normal procedure is to install both clamshells to the crossmember with the bolts still loose, then maneuver the engine with the jack to slide the long both through. The 2nd side is harder, of course, and you may need to use a long prybar. Can you get a helper?

At least this way, you verify that the brackets fit on both the engine and the frame.
 
Blue85 said:
What's holding the clamshells together in your pictures? The poly is basically oversized and usually the shell has to be compressed. That's why they give you zipties, but using bolts works better. Some people tack weld the clamshell shut. The normal procedure is to install both clamshells to the crossmember with the bolts still loose, then maneuver the engine with the jack to slide the long both through. The 2nd side is harder, of course, and you may need to use a long prybar. Can you get a helper?

At least this way, you verify that the brackets fit on both the engine and the frame.
Click to expand...
They’re tacked together in my pictures. Snugged them together with bolts then welded.

I do have a friend who can help but we didn’t get very far on our last attempt.

I’ll have to try again next weekend.

It just feels like I have the wrong mounts on the block because it’s consistently off by a bit without me wrestling for an hour or more.

Should I try to use the BB mounts that came with it or the ones from the 305? They’re obviously different but both seem to be off by the same distance.
 
Did a 305 even come in 78 k5. I bet the engine was changed and support plate brackets were left off. What trans are you running ? I would bet if your truck was originally an automatic with full 4x4 it had support rods to the flex plate inspection cover from brackets under the mount buckets.

www.ebay.com

GM transmission and transfer-case support rods | eBay

Support rods from engine mounts to torque converter cover. With bellhousing to transfer-case support rod. Transfer-case rod is 34" long. Rare set, very hard to find. You will need to measure the distance between the bellhousing and mounting holes on your transfer-case BEFORE ordering to verify...
www.ebay.com

leaving these pieces out changes the angle on the drive line, also the front dampener can be very close to the front cross member, possibly even rub on.
 
Wes Harden said:
Did a 305 even come in 78 k5. I bet the engine was changed and support plate brackets were left off. What trans are you running ? I would bet if your truck was originally an automatic with full 4x4 it had support rods to the flex plate inspection cover from brackets under the mount buckets.

www.ebay.com

GM transmission and transfer-case support rods | eBay

Support rods from engine mounts to torque converter cover. With bellhousing to transfer-case support rod. Transfer-case rod is 34" long. Rare set, very hard to find. You will need to measure the distance between the bellhousing and mounting holes on your transfer-case BEFORE ordering to verify...
www.ebay.com

leaving these pieces out changes the angle on the drive line, also the front dampener can be very close to the front cross member, possibly even rub on.
Click to expand...
Vin # says it was a 78 with a 305/th350/np203 which lines up with what used to be in the truck.
I’ll be running a th400 instead though
 
When I was putting the 5.3 in my 77’ with ORD comp mounts the holes didn’t line up at all. I ended up loosening all the bolts that hold the engine crossmember in and using furniture clamp (in the spreader position) and opening the frame a touch. Then once the bolts were in and snug I thightened everything back up. I did have to pull the engine one more time for the low ac bracket install and had to redo it all over again. All cars and trucks have metal under tension and the unfortunate part is you usually figure it out when you cut into it. Good luck
 
The motor mount area on these trucks has a lot of pieces that can move and a lot of variations of pieces that get put in there with little change in all the matching parts. Don't feel like your situation is special, lots of people fight this stuff. It's pretty normal.
 
When I installed a set of these ORD Competition engine mounts is was one hell of a job. I had to leave all the bolts loose, in order to get everything to line up for the main long bolts, and then get my hands into the tight space between the engine and mounts to tighten everything up after the long bolts where in. I am glad I did the job because the almost brand new stock clam shell style engine mount on the right side was completely collapsed with less than 10,000 miles it.

full


This was condition of the right side clam shell engine mount (pictured on left side). It was cracked and collapsed after less than 10,000 miles on it, and the engine is just a stock 200 HP 350 crate engine.

full
 
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I ued the diy4x comp mounts. Love them, not trouble putting in. Guess I got lucky.
 
I run the ORD mounts on my small block K10 as well. I found out the hard way that the factory triangle pieces do not work with the ORD mounts. Once I removed them everything dropped right into place. I will be getting a set for my K5 soon. IMG_20240208_102612251.jpg
 
Are those Stainless Allen head cap screws ? Kinda soft for and engine mount bolt. I was able to use the brace plates between the engine and bracket.
 
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