General help with LS3 swap

[GECCO]

Hello all,

I've read through most of the threads and other info here and I *think* I have the answers to most of the questions I'm going to pose....but perhaps there's newer/different/better info out there so I figure I'll ask anyway!

I have a MKIII FFR and I lunched my 347 last weekend

I'm strongly considering doing an LS3 swap, and I'm hoping to pick your brains on some issues. This is a non-PS, non A/C car, so no extra accessories on the front of the motor.

First - Motor mounts. I understand there are a couple solutions for the LS engines and the FFR mounts? One is Forte's, but they require a bit of fabbing (which doesn't bother me), also BRP and Dirty Dingo?

Second - clutch/bellhousing/tranny. The LS3 would come with a flexplate. I currently have a T5 in the car. On the fence about the necessity of a 6-speed.

• Any cable clutch options?
• What would be necessary to use the T5?
• Any way to do this without the expense of altering (shortening/lengthening) the FFR driveshaft? In other words, are there any motor mounts and bell housing combos that would put the tail of the T5 in about the same place it is now?
• Are there any GM tranny options that have a good mid-shift set up? *IF* the driveshaft needs to be modified regardless, *AND* there's a good GM mid-shift solution I may be tempted to go that route.

Headers - I'm assuming I'll have to have them custom made? I'm under no emissions restrictions and would prefer true headers into the sidepipe collector. I doubt there's been enough of these swaps done that someone is mass producing bolt-on headers for our sidepipes.

Oil pan - mmarshall mentioned a champ pan that I'll be looking into, but any other suggestions are welcome.

Any other pitfalls? Mainly in the realm of mechanical, will-it-fit type of things.

Thanks in advance for any help and advice!

[mmarshall]

So here is a list of parts I used to adapt my 10 spline TKO 500 to a LS series engine and drop it in an FFR? Here is the list of what I am using:

1. Bellhousing - Quicktime RM-6037 bought from Mark at Breeze
Lakewood brand | Part #: RM-6037

2. Pilot bearing - Lakewood #15975 adapts Ford trans to Chevy engine. Just call Lakewood tech dept. to find out about specific applications.

3. Flywheel - standard Fidanza aluminum LS flywheel

4. Clutch - this was custom from a local clutch shop, 11 3/4" disc size. You have to use a 4.6 mustang clutch fork and the same clutch cable from the 302 setup.

5. Headers - Hooker block huggers. I brought them out the front of the engine and then they can be made to go anywhere you want. Similar concept to the FFR J pipes.

6. Oil pan - Bat wing pan won't fit. I called Champ and they make a fully baffled 10 QT oil pan for the LS that the designed for jet boat racers.

7. Motor mounts - I had to fabricate these because the block huggers would hit the stock FFR mounts. I cut the FFR mounts off about 1.5" above the frame rails and made some mounts out of 1/4" plate that will clear the custom exhaust. I moved the engine about 2" forward to clear my A/C box and to shift weigh forward. The roadster has a little more room so the stock location may be possible.

Here is my thread on how I did it:
New engine my Coupe

All my LS pics: http://s464.photobucket.com/albums/r...cpZZ1QQtppZZ20

Ok what else do you need to tackle???

Pics:

[GECCO]

Thanks for the PM and the reply!

Here's my general plan so far:

• LS376/525 crate motor and the accompanying GM engine harness/computer/throttle pedal
• I've talked with champ pans about their 10qt pan that you found and will be using that
• Found a bellhousing/clutch/TO bearing kit, but I'll need to do some work to adapt the fork to use the cable since I'm not looking forward to trying to convert the pedal box to hydraulic
• Instead of rebuilding and reinstalling the T5 (which would be marginal behind this motor) I've decided on a GM spec TKO500 with the midshift. This made sourcing the clutch, etc much easier since it'll all be GM spec
• I'm going to use the Fortes motor mounts
• Since the only accessory I'll be running is an alternator, I found an Edelbrock CW water pump and pulley. This will make the serpentine belt path a simple triangle for a cleaner look, though I imagine I'll have to fab my own alternator mount and adjusting rod. No problems there.

My only remaining "big picture" issues are exhaust and driveshaft.

I like your block hugger headers. I'm thinking I'll use those, but have them modified to fit the existing sidepipes. I figure if I have them cut off roughly where the red line is in this pic





Then all four pipes could be fed into the existing collector on the sidepipes, and hopefully (?) this will eliminate the motor mount interference issue? What do you think?

As for the driveshaft, I'll simply take some measurements when the rest is complete and have the existing shaft modified as necessary.

[PSB]

I got my driveshsaft to mate a Ford AOD to a Corvette rearend here: Dennys Driveshaft and driveline parts High Speed High RPM Balanced Steel and Aluminum Drive Shaft Specialist. Followed their directions for measurements, sent in the form, and got a driveshaft that fit perfectly.



Pete

[mmarshall]

I am no expert on collectors so I would ask whomever you intend to have modify them. If you only are doing a high mount alternator then some stock manifolds swapped side to side might work even better. It is possible to cut the flange off Ford 5.o shorties and weld a LS flange on as the cylinder spacing is the same.

I will try to get some pics in the car and see if the spacing will work.

[GECCO]

Originally Posted by mmarshall

I am no expert on collectors so I would ask whomever you intend to have modify them. If you only are doing a high mount alternator then some stock manifolds swapped side to side might work even better. It is possible to cut the flange off Ford 5.o shorties and weld a LS flange on as the cylinder spacing is the same.

I will try to get some pics in the car and see if the spacing will work.

Yeah, sounds like I have a lot of options. I think the first will be to see just how badly the FFR headers would have to be modified in order to work. Second would be to source another set of headers to modify. I guess whatever results in the lowest overall cost and the better looking/performing product.

My work schedule dictates that I probably won't have a lot of time to devote to this until early October....and it's killing me! LoL

[sk8runeg]

Best way to do the exhaust is the get a set of 302 Shorty headers and cut the flange off and weld an LS1 flange on. The should make it possible to mate right up to your j-pipes

[jkrueger]

I used these headers from BBK: BBK-40200, 1 3/4" runners, ceramic coated. From summit they are $400.

JC

[ffr598]

I just finished an ls3 swap in my FFR mk3 a few months ago. I did an ls376/480 crate engine. It was a lot of fun but definitely came with a set of challenges. I would honestly recommend fabricating everything that you are capable and comfortable fabricating. I bought forte's ls mounts, I know he is a sponsor on here but there is nothing special there. They were essentially a "universal fit" that you could find out of a summit or jegs catalog for way less money. They do not bolt up to the ffr mounts and do not locate the engine in the ffr chassis. I ended up just welding mine to the stock ffr mounts. Also the holes in the engine side of the mount were too small and needed to be drilled before installation.

As far as the exhaust goes, I tried to use a set of ffr 351 4 into 4 headers that I got at a discount on this site. My plan was to cut off the flange and weld an ls flange on and viola! Not the case. I welded my engine mounts in place so that the driver side header flange would line right up with the sidepipe cut out in the body, but the passenger side wasn't even close. I ended up fabbing the passenger side header completely and ended up having to do some modifications to 2 of the primaries on the driver side to clear the spark plug wires. For the headers I would recommend starting with a pile of J and U bends. This was the first set of headers I built and it was not nearly as bad as most people make it out to be. I had about 4 hrs in mock up and tacking and maybe another 6 in finish tig welding and cleaning them up.

Hope this isn't too long winded, I would be more than happy to help in any way I can with your swap. It's nice to have some more chevy guys in here. Best of luck with your build!