I read through the swapper guide and a bunch of old posts, most with dead links to parts.

Two real questions here:

1) All the swap guides say you need a new transmission cross member, but this appears to assume running an LSx transmission. If you are jus swapping an LS/5.3 into a thirdgen using motor mount adapters, does the location of the bell housing mounting surface change? I'm using a TH350 transmission, so I guess I'm asking does it push the transmission forward or move it back or keep it in the same spot?

2) What are the ideal swap brackets? The market is flooded with brackets - some convert the LS to a SBC type, others convert the car to an LS type (i.e spohn). Which ones are the best and why? I'm using a tubular spohn k-member.

-- Joe

 

For the most part, engine mount swap brackets align the plane of the flywheel housing to that of stock 3rd gen. Holley Blackheart is an exception, the plane is pulled forward. There might be other exceptions but this is the one I know of for sure. I think maybe NVH is reduced if you use LS mounts with the rubbers on the engine side. I have solid mounts and couldn't even tell the difference so I'm not a good judge of that apparently.

Your trans crossmember options are very limited since you're doing a non-standard engine / trans combination. I would just call the trans crossmember manufacturer and ask what engine mounts were used during development of the product. These decisions are coupled together in your situation.

 

I built my trans crossmember a few years ago. I didn't like the off the shelf TH350 crossmembers . I run two 2.5" pipes along the transmission, not traditional thirdgen routing. I can re-work the crossmember, but I was curious if the adapters would change the location of the transmission.

My LS1 driveshaft is already close to being short with a 9" tail TH350, so if the transmission moves I may need to get a custom length shaft.

-- Joe

 

I also and running solid engine mounts (UMI). They offer more clearance than the clamshell ones. As quick mentioned, the holley crossmember does move the plane (a half inch if I remember). Does your K-Member have fixed mount stantions? Or can you bolt on any number of mounts to the pads?

 

I would avoid Spohn LS engine mounts. I tried using these on the engine side and UMI LS swap mounts on the k-member side. The Spohn mounts made my engine sit about 3/8" lower on the passenger side no matter what I did.
I swapped out the Spohn mounts for UMI solid ones and they worked much better.

 

The Spohn K member has the smallest pad that only mounts the SBC bushing:



So when I asked them for help, they said they don't offer a mount that works on their K-member. Basically, Spohn sells mounts that create LS pedastals, they don't sell kits to convert LS blocks to SBC mounts.

My buddy has the ITC mounts which are adjustable, but ITC says because the way they sandwich the bolts together they do not work at the 'zero' position, or where the factory bell housing should be.

I'm looking at these on Amazon, which appear to be quite adjustable and would negate the need for the SBC clamshells as they appear to mount directly to the bushing:



-- Joe

 

I see you're running those eBay strut mounts. I would immediately abandon them. I ran them for 2200 miles and they bent really bad and jacked my alignment up. The only thing good about them is the center section. They are beefier there.

 

They have been on the car for about 12 years. I haven't checked the alignment in a while but I probably should..

 

Wut ........ I'm impressed. Mine buckled in no time.

 

Where did they bend?

I'm not a huge fan of these by any stretch, but at the time they were what was available when I had the car apart.

 

 

That's impressive! Does this car pull the front wheels off the ground on launch?

 

Ha, it doesn't. I think its just a combo of stiff front end, koni's set too tight, and R compound tires.

 

Oh is this a coil over car?

 

Nope. Standard strut set-up, just with aftermarket stuff.

 

Got me. I'll have to check mine with a straight edge later haha.

I think I'm going to go with the flat steel LS conversion mounts. I may end up needing to move the engine forward anyway for downpipe clearance.

 

.....and what ever happened to this story???