5.3 LQ / LS on 6 cylinder towers

[Willie Makeit]

Hey all!

Found this section of the forum after a google search on LS engines in 67-72 trucks.

Here's where I'm at. Pulled a small block 350 out of a ,67 C-10, It was sitting on the I-6 towers (forward holes) and it was hooked to a TH350 transmission. I plan on using the existing TH350 and would like to retain it's current position in order to keep drive shaft length same and be able to use my current linkage.

Here's the $64,000 question: will the Dirty Dingo "sliding" mounts allow enough adjustment to mount the LS engine on the I-6 towers? Thanks!

title should read LM ... not LQ, sorry.

[Clyde65]

I had mine mounted on the 6cyl perches and it was a tight fit. I chose to use ECE perches and trim my frame rails. I have heard of many that use OEM perches though.

I am unsure of the DD sliders though.

[Willie Makeit]

Tight in the front (radiator) or just along the sides (frame)?

[Matt Cramer]

Not sure there's much of a difference between the I6 and smallblock engine stands for that year. Big block stands have more clearance.

I used a set of short, non-adjustable plate mounts to put an LS on V8 engine stands in the six cylinder position. Trouble was, the manifolds hit the part of the engine stand that sticks up. I ended up cutting that part out, flipping it upside down and side to side, and welding it back in to get enough clearance.

The rest of the setup bolted up just fine.

[Willie Makeit]

Thanks for the info Matt! I'm more concerned with the front to back placement of the engine. I am needing the bellhousing mounting points to remain where they are. I know the I-6 mounts are approx 2.5"-3" forward of the V8 mounts. What I am unsure of: is the dimension from the back of the LS block (bellhousing mounting face) to the motor mounts the same, or close, to the small block engine. Or at least within the adjustment range of the Dirty Dingo adjustable motor plates.

I was under the impression that the I-6 towers were different than the V8 towers, thus the reason for the two different sets of holes. I-6 forward holes and V8 rear holes.

I plan on using the stock rubber motor mounts on the stock I-6 towers then bolted to the DD sliders and if I am reading this right on the DD site, this setup allows for 1/4" more clearance in the up and down plane.

Unfortunately I only have the I-6 towers to work with, so if this setup won't work I'll need to also source some type of hard mounts.

[crazy longhorn]

Originally Posted by Willie Makeit

Thanks for the info Matt! I'm more concerned with the front to back placement of the engine. I am needing the bellhousing mounting points to remain where they are. I know the I-6 mounts are approx 2.5"-3" forward of the V8 mounts. What I am unsure of: is the dimension from the back of the LS block (bellhousing mounting face) to the motor mounts the same, or close, to the small block engine. Or at least within the adjustment range of the Dirty Dingo adjustable motor plates.

I was under the impression that the I-6 towers were different than the V8 towers, thus the reason for the two different sets of holes. I-6 forward holes and V8 rear holes.

I plan on using the stock rubber motor mounts on the stock I-6 towers then bolted to the DD sliders and if I am reading this right on the DD site, this setup allows for 1/4" more clearance in the up and down plane.

Unfortunately I only have the I-6 towers to work with, so if this setup won't work I'll need to also source some type of hard mounts.

On the 67-72 trucks, the I 6 (230/250) stands are 3 1/2" rearward, from the smallblock stands...the 292, does have odd ball stands. The dr side same as the 230/250, but the pass side is moved forward due to fuel pump placement on the 292 engine. The difference tween the 6/250, vs the small block spot is exactly 3 1/2".....now you will note that the bolt holes are 2 1/2 " different on the stands placement, but due to the shape of the stands, it makes up the other 1 inch On my swap, I moved the trans 1" forward, from the I 6 spot, left the 6 stands in place & slotted forward on the holes. I then welded a "tab' to the front of the stands, for the mount to sit properly on the stands. Due to the difference, on the rear of the block....the LS engine will set tighter to the firewall, than the gen I did Stick shift (3 spd), use the auto crossmember under the trans....move it 1 " forward (trans/bell), this will be as tight as you want to be on the firewall! You can modify the stands as I did, or use the V8 sb stands in the rear set of holes on the top (redrill the bottom holes). I used a set of Carshop Inc plates on the block, with a stock replacement urethane mount.....Longhorn

[BR3W CITY]

The towers are similar but iirc the I6 perches were asymetric.

I used the front holes, but modified the front bolt position to accomodate the way I wanted it. I used "Generic" transdapt swap plates. I have good clearance on the firewall on my 66, but the tightest area is on the sides. Because of how low it sits in the crossmember, I have minimal clearance for the headers. I used TBSS headers, even then the clearance is tight.

If I set the engine back just a touch more, the firewall clearance would lessen, but I might gain a bit of side clearance for the manifold exit.

[Matt Cramer]

Now that you mention it, I think one of them is the same and the other is different. I believe they can still be used though.

I used 2010 Camaro manifolds. Those exit straight down and tight to the block. The only clearance issue besides the set-back engine stands was that I had to remake the rear brake line as the exhaust pipe was touching it.

[Clyde65]

The 292 had offset perches, the v8 and i6 ( non 292) have the same perches and I did get these to work, I also had the interference with the header/manifold and the perch. I went with the POL perches like I said and moved them to the rear holes. I can still slide my hand behind the valve cover and firewall. BTW, I did not use the stock LSx mechanical fans tho.

[Willie Makeit]

I got access to a bare block and 5.3 oil pan. I'm gonna mock the engine with these and the I6 towers in the front set if holes.

I'll post what I learn.

P.S. I'll be running the Doug Thorley LS conversion headers and electric fans.

[crazy longhorn]

Originally Posted by Willie Makeit

I got access to a bare block and 5.3 oil pan. I'm gonna mock the engine with these and the I6 towers in the front set if holes.

I'll post what I learn.

P.S. I'll be running the Doug Thorley LS conversion headers and electric fans.

Just a thought or 2...note that the I 6 stands are a tad taller, than the V8 sb stands? Where they are mounted on the bottom, is recessed about 3/16"....moving them forward, will raise the nose of the engine, & 'pinch" the center to center on the bolt holes? I am not saying that it wont work, but IMHO, you can pick up a set of V8 sb stands , for 20-30 bones....I would set them in the rear position, & redrill the bottom hole. After that, you have choices on the block plate (length), depending on how tight you want the engine to the firewall? I will pull my thread/pics up to the top, so you can see just how tight 1" forward, from I6 spot is. Longhorn

[PGSigns]

Get some heads and valve covers to make sure your setup will clear the fire wall. The head on the pass side sits a full 1 1/2" I think further back than the old style small block in relation to the bell housing face. I am getting ready to start this process of getting mine placed shortly.
Jimmy

[slowtruck]

Originally Posted by PGSigns

The head on the pass side sits a full 1 1/2" I think further back than the old style small block in relation to the bell housing face.

I would have never thought that was true, but I just set my 5.3 on a set of 250 mounts yesterday and had two problems. One is the engine is to far back and the other is the cheap adapter pushed my stands to far out to put a bolt in the holes. To get an ok clearance behind the heads I'm going to need to move it 1.5-2" forward.

[Willie Makeit]

Great thinking PGSigns! I just so happen to have a spare set of heads laying around!