'71 LQ4 / 4L80E Mid swap ?s

[DjS71]

I've thought and read too much, brain fade is setting in.

CTSV Pan, $30 ebay plates (this design)

I had to wrestle the damn thing in there like nobodies business, I'm not sure if the plates were too thick and caused the holes on the mounts to be a little out of alignment or this old heirloom truck took more of a beating than my uncles are willing to admit, but it was a nightmare. Anybody come across this before? I read somewheres (but don't see any of the common designs that utilize it, so that might answer my own question) that people will drill the actual motor mount bolt holes (not the plate to block bolt holes) 3/8in lower to combat this problem. Would this have a negative impact on driveline angle?

The other issue i'm having currently is with the trans mount. I've got the CPP trans crossmember but it A: doesn't line up with any holes to use as a pilot or locator and B: the ebrake cable sits tense right against the forward face of the mount.

I'm thinking I got what I paid for in mounts and that the most sensible way to remedy this is to get a set of mounts that place the package 1" back towards the firewall. That should take care of B for sure, and possibly A.

Might be able to get the machinist @ work to make me some, but I want to hear your opinions on the offset bolt hole conspiracy first. Also, if you guys have a measure handy, get a confirmation that the block holes from top to bottom are 3.125 and not 3.070 (78mm), not sure .055" will make or break it but I won't be near the truck for a couple days to measure.

Thanks for your time, fellas. Sorry for the night shift ramble.

-Dan

EDIT: Looks like edelbrock ones might use that offset trickery

[BR3W CITY]

When we put the engine in, we bolted the plates to the engine, then started 1 long bolt from the plates to the motor mount (engine still suspended 1-2"), and slowly lowered the engine into place using the long bolts to guide it down. If we wouldn't have done this, I would have had to slightly flex the passenger side mount down to start a bolt.
*This is the case in my truck because we used I6 stands from the 66, which were not designed "even".



In my case, the whole trans xmember was unbolted from the truck and slid a few inches so it aligned correctly with the new trans mount (4l80e and 4l60e/00r4 use different mount styles).

[dec010974]

Hello to all and DjS71. Don't sweat the small stuff. No LSx swap goes without a few growing pains. I've done so many swaps, and they all had their issues. Keep wrenching and when your cruising down the road with your LSx swap 1971 c10, you'll be smiling from ear to ear. I had to lower my engine using brew city's long bolt method. You should've seen how I bolted my th400 to the lQ4. Just know that a hoist with different length tranny bolts ranging from 2-6 inches makes simple machines. Good luck.

[dec010974]

BTW, I used LSx adapter plates, stock engine mounts, and the V8 frame mounts. I have a set of V6 frame mounts but I like my engine to sit forward so that I could get to the sensors such as oil pressure sensor, camshaft sensor, tranny bolts, etc.

[DjS71]

Originally Posted by BR3W CITY

(4l80e and 4l60e/00r4 use different mount styles).

I'm coming from a 3OTT, this is the trans xmember i have and it came with this mount Har har "$34 Value!" sells separately for $23... Is there a height difference on the mounts or is it just the 4L80 single stud vs the two bolt setup here? FWIW, the mount bolts up to the trans okay.

I'm using the stock V8 stands, and Now that I think about it, the oil pan was a little close to the brake lines on the back of the engine crossmember for my liking, so I might go ahead and try the setback mounts to fix that, and then see where it puts me for the rest.

Thanks so far, guys.

-Dan

EDIT: Looks like the carshop inc. plates use that slight offset as well, think i'll give them a whirl.

[truckdude239]

i used dirty dingo slider mounts with the stock 71 engine mounts engine went right in. now i had to drill the holes for the trans crossmember but that was it mine went in like the truck was made for it

[BR3W CITY]

They were similar in height, it was the 2-bolt vs 1-bolt thing that was the difference. Since I was focused on getting the engine angle correct at that point, i didn't pay attention to any physical height difference in the mounts, but if there was it was very minimal, as nothing stuck out to me.

[Jon01]

IDK which mount plates you have but I too used the cheapo Ebay ones. I think mine were $40.
Here is what I used:
http://www.ebay.com/itm/LS1-Conversi...9b05e0&vxp=mtr
Mounted plates to motor and mounts/stands to plates then dropped the whole shebang in. No issues at all.
Also used the CPP trans x-member to go from 3OTT to 4L80e. All of my holes lined right up. If you moved the motor forward a different amount though yours wouldn't. No biggie, just get a good drill bit.

[DjS71]

Jon01 - Those plates are more or less what i'm trying next, so we'll see if it takes care of the trans issues. It'll definitely take care of the frogs hair clearance at the brake lines.

Thanks again folks, will report back after I get those plates switched out.

[DjS71]

OK, the 1" set back plates fixed all my problems. trans holes line up, plenty of clearance up front. Still had to unbolt the top of the perches, but it didn't take much to get them back down once the mounts we're started in the perches. SO the plates i linked in my first post did not work out for a LS on '71 perches w/CTSV pan.

Take heed to what others say about the cheap hardware that comes with the ebay plates, I stripped both of the flathead allens that sit under the mount. I coated them liberally with swear words and got them out, but sheesh. They we're labled 10.9 and i used a fresh bit, still stripped.

Thanks folks.

-Dan