66 gmc ls swap...need help!

[Slammed96]

Hey all, working on dropping a 4.8 into my 66 gmc and having a devil of a time getting it in. I'm using dirty dingo clam shell adapters and have the v8 engine mounts in the truck. When I set the engine down on the mounts I'm off by about a half in on either side, as if the engine is too wide. Anyone else run into this problem?

[Captainfab]

Exactly what 'V8 engine mounts' are you using?

Have you searched for an answer in the LSx swap section of this forum?

[Slammed96]

Originally Posted by Captainfab

Exactly what 'V8 engine mounts' are you using?

Have you searched for an answer in the LSx swap section of this forum?

The precious owner had a big block in the truck, so I'm just going with what was there already. I haven't had a chance to really dig through the other section, made this post from under the truck last night while still trying to wrestle the engine in. I'll do some searching though.

[Captainfab]

If you could post a few pics of what you are working with it help us help you.

Originally Posted by Slammed96

The precious owner had a big block in the truck, so I'm just going with what was there already. I haven't had a chance to really dig through the other section, made this post from under the truck last night while still trying to wrestle the engine in. I'll do some searching though.

[Slammed96]

Originally Posted by Captainfab

If you could post a few pics of what you are working with it help us help you.

I'm trying, for some reason it's not letting me upload them from my phone.

[siggyfreud]

Upload them to a site like Photobucket first, then you can link them here.

[cp_66_c20]

More than likely it's the big block mounts or the clam shells. The both have to be from a small block Chevy because the ls is a small block chevy. There is a difference in the small block and big block clam shells.

[Slammed96]

Originally Posted by cp_66_c20

More than likely it's the big block mounts or the clam shells. The both have to be from a small block Chevy because the ls is a small block chevy. There is a difference in the small block and big block clam shells.

Everything I have found online says the SBC and BBC clam shells are the same. How are they different?

[aggie91]

without pictures it is hard to help, but if you do have big block frame mounts and using the DD adapters, the frame mounts could be your issue. BUT, the BB frame mounts are NOT factory '66 year model parts. Those mounts did not come out till the '67-'72 body style iirc.

LS swaps in these trucks are relatively easy. What makes them hard is the vast assortment of adapters and frame mounts that are out there. Best results happen when you use the adapters and frame mounts from the same source in my opinion.

[Slammed96]

Understandable. The mounts that are in the truck where in it when I came into possession of it. Finally got the pictures to send from my phone to my photo bucket, so here they are. First two are with the engine set down level on both mounts. The measurement is how far off either side is when one of the mounts is lined up. Sorry it took a while, been super busy and haven't gotten a chance to actually get on from a computer.



I plan on getting a set of new SBC clamshell mounts (only $20) because i realize these are a bit worn out. Was trying to test fit the engine to see how far foreword or back it would need to be.

[cp_66_c20]

This might clear some of it up
http://67-72chevytrucks.com/vboard/s...d.php?t=649056

[Slammed96]

Originally Posted by cp_66_c20

This might clear some of it up
http://67-72chevytrucks.com/vboard/s...d.php?t=649056

Good info! The ones I'm using on the engine side are out of a mid 70s small block pickup. I wasn't sure on the rubber mounts if they differed or not.

[Captainfab]

Those engine mounts are '73-'87 style. I can't tell from the pics if the frame brackets are from a C10 or a C20/30. If they are from a C10, that is part of the problem. Those do not fit the early frames correctly without a spacer on top of the frame. Without changing the frame brackets, you will have to search and try and find a set of clamshells that are shorter. That or a different set of Ls engine mount plates like these.

http://www.ebay.com/itm/Dirty-Dingo-...dW3aG-&vxp=mtr

I do not know if these will cure your issue, but they might be worth inquiring about. AZ Pro Performance is a forum Vendor here.


The more I look at those pics the more I am now fairly certain those are from a C10 and they put them on the wrong side, slid them down and drilled new holes.

[aggie91]

I agree with Captain. Those frame mounts may be more of your issue than the clam shells. You might be better off ordering a set of these mounts:

http://www.ebay.com/itm/1963-66-68-6...item58e8ffeb5e

You can still use the adjustable sliders that you already have to set the fore/aft placement of the engine.

[Slammed96]

Another option I've considered is slightly elongation the holes in the frame mounts to allow for some adjustment up and down. I wanted to see other opinions in case the problem was something I'm doing wrong.

[Captainfab]

If you are set on keeping those engine mount brackets, unbolt them from the frame and crossmember. Then bolt the brackets, engine mounts and clamshells to your engine. Set the engine in place where you want it and mark the bolt holes on the crossmember and measure how thick of a spacer you need on top of the frame. You may need to trim the top flange of the frame back a little to duplicate the '73-'87 frames.

[Slammed96]

Originally Posted by Captainfab

If you are set on keeping those engine mount brackets, unbolt them from the frame and crossmember. Then bolt the brackets, engine mounts and clamshells to your engine. Set the engine in place where you want it and mark the bolt holes on the crossmember and measure how thick of a spacer you need on top of the frame. You may need to trim the top flange of the frame back a little to duplicate the '73-'87 frames.

I may give that a try. It's not that I'm dead set on keeping the mounts that are in the truck, more just trying to keep things as budget friendly as possible.

[63C20]

Looks like you need different mount perches

[Slammed96]

The deeper and deeper I look into this, the more I see that it appears the easiest and least headache route to take will be new perches as stated above. Saw some pictures of the remedies for the mounts I have and not a fan. Looks like time for new motor mounts and towers...thanks for all the help and info guys!

[63C20]

like i said, perches