The McLeod Mag Force Twin is a seriously beautiful piece, its really sad that it has to be buried behind a bellhousing. I bought it to run it though so it has to go in. This being a twin its a little different from other clutch installations I have experienced.
First you pop off the pressure plate to see the ceramic pucked solid hub disc that's backed up by a floating pin drive center disc. I chose the floating center disc based on recommendations that it would drag less as the clutch begins to wear, allowing me a slightly longer interval for re-shimming the clutch.
On top of the drive pins there are shim stacks calibrated from the factory for proper finger height on the clutch diaphragm. As the clutch wears, shims will be removed until either one of the plates are out of spec or the clutch is worn or damaged to the point where it needs to go back to McLeod for a full rebuild.
I have the strapped pressure plate to keep some of the noise down.
I'm using ARP pro series 12pt flywheel bolts to protect the investment p/n 330-2802
Using the standard clutch alignment tool this is all the further the transmission would engage, I thought I could get away with it, but I no matter what I tried I couldn't get it any closer than the last inch. Finally I broke down and bought the Quarter Master 1-5/32" x 26 spline alignment tool. Its under $50 and well worth it to just go ahead and get it if you're going to install a multi-plate clutch.
Working on a project there are always things that pop up and catch you attention. This is one of them.
Excuse the blurry picture, but you get the idea. There was rust in the former home of the battery tray, an intercooler pipe hole that's too small and in the wrong location for the intake, holes from drilled spot welds, and provisions for a washer fluid tank that's been out of the car for nearly 10 years now. My first problem was no press brake to bend the radius on the panel. So I made a quick and dirty rail for the hydraulic press at work.
I used this in conjunction with a piece of 1-1/4" round stock to make a nice radiused corner. Then used my handy dandy card board templates to make my patch panel out of 22ga sheet metal, the same thickness as the original piece.
After making the panel I cleco pinned and butt weld clamped it in place for weld.
Also, I patched some strut tower rust that I had previously repaired with bondo and stitch welded the front of the car. I figured that with the extra torque the LS will provide the front of this car will need all the help it can get. The first steps to stitch welding are scraping out the seam sealer, then wire brush the remaining sealer out.
Stitch welding is a serious pain, no matter how much you think you've thoroughly cleaned all the bits of rust and seam sealer there will still be some in there. Every time you hit some seam sealer, dirt or rust and pull it into the puddle it burns and makes the puddle pop. You'll have a good run for a few stitches then a few that are terrible where you keep cleaning and trying to get a good weld. A much easier part was making at attaching subframe rail caps. I plasma cut them then used the dimple die to make the holes look clean and tig welded them in place.
The next step will be to repair some rust holes I discovered in the frame rails (frail rails)
So, I'm finally getting back in the swing of working on the car and updating the blog. I had a busy summer and fall with long work hours, mountain biking and spending time with the family. I visited Panacea Powder Coating again and had them coat my timing cover and valve covers. I finally settled on a hammertone bronze color similar to my rims for the parts.
While installing the timing cover I installed the ATI Super Damper. I chose ATI p/n 917277, It's a 10% under drive without an air conditioning pulley and SFI approval. No need for A/C since I removed the evaporator from under the dash along with the rest of the system. I wanted an under drive and the ATI seemed to be the best insurance for my engine while providing under drive.
I've also added -8 AN heater fittings to the water pump. The original stainless steel fittings were pretty difficult to remove. I tried twisting them with a pipe wrench, wishful thinking that they might just forcefully twist out, but no luck there. I ended up up supporting them with a board to protect the waterpump, smashing in one side with a chisel to collapse it, taking pressure off the sides then they popped right out. After they came out it was just a matter of tapping the holes they're already the correct size, the small side with a 3/8 npt and the larger with a 1/2 npt.
After the headers came out for ceramic coating, the engine went on the stand where I promptly tore it down.
The engine had carbon headgaskets, which are nasty. I bought a plastic scraper and some permatex gasket remover and went to town on all the crap they left behind. To get all the left over residue off, I went over the surface with a nylon scotchbrite pad (no aluminum oxide) until all the remaining gasket was removed. After that I used some 2500 grit sandpaper to get the final finish, to give the cometic headgaskets a good sealing surface. Then I cleaned everything over and over again and checked all the surfaces for dirt with my fingertips and then cleaned some more. You can never be too clean when you open an engine. All and all the cleaning took about 3 hours per side.
Then I unboxed all the goodness that the fedex and ups guys had delivered.
Here's the grocery list from above:
- Cometic .040 MLS Headgaskets
- LS6 Valley cover, for its improved PCV system
- LS2 Lifter Guides
- LS7 Lifters
- GMPP Heavy Duty Timing Chain
- Melling High Volume Oil Pump
- GM camshaft install gasket kit
- ARP Headbolts
- ARP Camshaft Bolts
- ARP Cam Retainer Bolts
- Lingenfelter GT2-3 Cam
- Lingenfelter LS9 Blue Springs (hand checked for lift to work with the cam)
Check out the difference between the original chain and the heavy duty one, can you tell which one is which? I consider it cheap insurance when getting heavier valve springs, the HD chain has some serious beef to the side plates compared to the original part.
Also the melling high volume oil pump is more of a preventative maintenance item as well. Its the part number 10296. It comes with the red high pressure spring installed, which I plan to switch out for the blue standard pressure spring. I suspect that the increased volume alone will try to drain the pan, so I'm at least going to start with a little less pressure.
The cam install was pretty uneventful. I discovered that cams are very sharp while I was cleaning it with a bunch of little paper cut like cuts on my hands that I discovered when hosing it down with brake cleaner. I then used some Lucas Oil Assembly Lube and slid the cam into place. Overhead cams (like the SR20DET) are way easier to install, but all and all it wasn't bad. You just have to be patient and careful so that you don't damage the bearings or get it stuck.
Afterwards I moved on to the valve springs. I considered getting a loaner tool, but ended up just buying one specifically made for the job instead. I love new tools anyways. I got the Trick Flow Specialties 90306 from Summit, this tool made the valve spring change simple and quick, its definitely a quality tool.
While I was in there I found something interesting, my 799 heads have what looks like hollow exhaust valves and the intake valve is black oxided, I'm not quite sure what to make of it.
Super easy, just turn the nut down and pull the locks, I had lost my magnet and there was enough room that I could remove and install them with my fingertips fairly easily.
After I finished with that I installed and torqued down the heads.
To get torque specs, patterns, and specific instructions, when guidance was needed, I used these references. The first is free information over the web which is pretty good, and the second is a book I purchased which had great, in depth explanations and some really good information in general.
I did the final test fit on the headers after Dan and guys at Advanced Chassis welded the tubes to the flanges, I couldn't be too careful before ceramic coating. Once that coating is on, its on there and won't come off easily. As always they did a great job and everything came out perfect. They even modified a tube slightly for increased steering clearance. For the ceramic coating I used Panacea Powder Coating, where Mike took excellent care of my headers. Mike showed me a color called blue titanium on his own classic hotrod and I went with his recommendation. The headers turned out awesome. Pictures are hard to do the color justice, its a matte charcoal grey color with a little blue metallic, it makes for a really clean look.
The clutch decision was a big one for me and one that I didn't take lightly. The clutch can have a huge effect on how the car drives. My final decision was to go light to lessen the hit on the tires and let the engine rev faster for the approximately 2600lb car. First I was going towards a 7.25" racing clutch but after seeing a lot of you tube videos with extremely jumpy, light switch like clutches and reading manufacturers recommendations to not even drive cars onto the trailer with them I got the idea that it was a little more aggressive than I want to deal with. Dru Nichols (SicBastard on Zilvia.net) compiled some great information on moment of inertia of clutch assemblies. For those of you not familiar with the term or the concept, moment of inertia in context of a clutch is the idea that the same weight at the same rpm has more energy the further it is placed from its axis of rotation. A good example is a baseball on a string, a baseball on a 2 foot string rotating at 100rpm is only going about 7mph, but the same baseball on a 17 foot string at the same 100rpm is going about 60mph. Enough about the physics and back to the clutches.
Tilton Clutch Assemblies MOI (lb-in^2)
Includes: Clutch cover with diaphragm spring, pressure plates and floater plate(s)
(add 66 MOI and 2.5# to include the button
(add 87 MOI and 3.4# to include a Sonic ultra-lightweight flexplate)
337 9.0” Mantic street dual sprung clutch (33.8#) cool set up!
>3200 11.5"? Stock LS2 flywheel and clutch (52#)
(MOI list thanks to Dru Nichols MD)
I also put together the following list of weights without MOI with a lot of google searches for light weight clutch assemblies for the LS series engines.
McLeod Mag Force 8" dia twin Assembly (Approx 25#, Goes on the scale tomorrow)
Spec Lightweight flywheel w/Al PP Option 11-1/2 dia. (33.4#) (McLeod also offers a similar set-up if you call them)
RPS Street Twin 1/2 Carbon (40#)
RPS Street Twin Full Carbon (36#)
RPS Billet Carbon Street Twin w/Steel Flywheel (32#)
RPS Billet Carbon Street Twin w/Al Flywheel (25#)
After talking with Lee at McLeod clutch and Scott at SPD Metalworks I went with the Mag Force twin. They put together a custom assembly based on the pin drive Mag Force, with a strap drive pressure plate, and ceramic discs.
Here's a video for an example of how I expect it to rev.
In between the header fabrication I made a little patch panel for the front core support and some tension rod bracket re-inforcements. I had a little fun with a dimple die while I was at it. I made the panels out of 16ga steel so they would be strong since the front core ties the two frame/unibody rails together. When welding in the panel I decided to try a product I hadn't before. I got a weld through primer, I was a little reluctant to paint where I was about to weld, but that's how its advertised to work. I sprayed the back side of the panel and anywhere I thought I might have trouble spraying after it was welded together. My reluctance seemed to be correct, where ever the primer was my weld didn't want to penetrate until I had it all burnt away.
Really happy with how the dimple die worked
This part goes in the bottom of the tension rod bracket as a gusset. I also made a cross bar like the Nismo power brace
I had to add a couple dimpled holes where they might be visible, when the car is together.
I tried out weld through primer, it was more of a burn it away with the mig, then weld process. I wasn't impressed.
Also I received a call from Lingenfelter's this week, my valve springs finally came in. I'm pumped, that means I get to take the drive to Decatur, IN and pick up my GT 2-3 cam, valve springs, and Cometic .040 head gaskets. The remainder of parts for the final assembly of the engine.
I haven't posted anything for quite some time now. I had professional help lined up to help mock up the passenger side but he ended up being too busy, so that was a minor set back. I guess the plus side to that is that I still can say that I made them to my design, with lots of helping hands, literally, its nearly impossible to hold all of those tubes into position alone. I wanted to run all the tubes to one side or the other of the steering shaft, but the collectors wouldn't fit through and it wasn't working for the equal length thing either. I ended up running the front two cylinders inboard, and the rear two outboard kind of like the passenger side.
This picture makes me wish I would have taken a picture of the headers outside of the car, the front two cylinders looked like snakes.
Both sides outside of the car.
See the steering gap, I'm hoping its enough, but if I have any problems I'm just going to stiffer motor mounts.
I still need to check the fit one last time on the car before the final weld on the flanges, everything should be good, but once its tig welded all the way around its a lot harder to go back.
So, building motor mounts to stuff a ls1 into a 240sx seemed like a challenge, but it was actually a breeze compared to building headers and attempting to make the tubes equal length. My first length attempt was 32" with the collector just behind the firewall, to maximize ground clearance, it worked great for the two cylinders to the front of the engine, but not so well when it came to the back two, I had to pick one or the other to make the 32" length, then the one that didn't get the length was going to be 4-5 inches shorter which just wasn't going to work. So I went back to the drawing board and came up with some creative tube arrangement to shorten all of the tubes to 28" the shorter end of the recommended length from cone engineering.
Notice the front most tube, its tucked as tight to the block as I could get it and actually enters the collector above the next tube behind it to make it possible to make these headers equal length.
I decided to tuck the front most tube in very close to the block and take the straightest path possible towards the collector, inserting it into the upper opening (rather than the lower opening where it would typically go), tucking the second tube from the front underneath it. With this tangled tube arrangement, I was able to get the first three cylinders within 1/2" of length of each other and the last one within 2", this is not perfect equal length, but I think it will do. I could have squeezed a little more length to get it closer to the 28" goal, but I would have had to have much more aggressive angles, which didn't seem worth it in terms of loss of flow.
Front View
Here's the underside view, there's another new tool under there, an adjustable V-channeled (angle iron) tube tube stand. Between this and the collector holder these are some massively helpful tools. I've built these with a lot of inspiration from Advanced Chassis's shop tools.
The passenger side is now ready for tig welding. The driver side is coming up, so its decision time, I wanted to make it in such a way that it could be installed without removing the steering shaft, but with the difficulty of the passenger side I'm not sure if that will be a possibility.
