240z SCCA vintage race car, restoration

[AydinZ71]

Hi all!

 

Restoring a rusted 240z series 1, SCCA vintage race car. Car last raced in 02'. Currently rebuilding to group EP spec's. I figured id start a new thread summarize my plans and progress. Il just add progress photo's to this thread. Thanks for reading!

 

 

1. Engine: L24

1. 1. Block – OEM bore, stroke. OEM materials. Not modified

   2. Head – N42 core

      1. Modifications:

         1. polished bowls. Valve seat de-shrouded. Minor reliefs cut around seats, but within ID spec of gasket. Chambers polished and de-burred.

         2. Deck machined to reduce chamber volume to 38.5cc's. Piston-deck clearance is -0.35mm, so with a fel-pro gasket (1-1.25mm), it should net a static CR of 10:1

         3. Intake ports matched and polished within 1” of mounting surface. Same on intake manifold.

      2. Valves – OEM intake. Exhaust and seat are custom turned down to 33mm (L24 spec)

      3. Valve springs: Custom single bee-hive, with custom machined narrow steel retainer

      4. Cam: Exhaust and Intake are symmetric. 320 duration, 234 @ 0.05. 0.500 lift. 109 overlap

   3. Carbs: Stock SU's. Will purchase SM needles

   4. Exhaust:

      1. MSA 6-1 header w/ O2 weld bung, Eastwood header paint, and fiber wrapped.

      2. Anticipate using Borla XS straight-through muffler. Will consider adding resonator if I have room.

      3. Materials acquired for full 2.75” 304SS exhaust

   5. Ignition: Distributor with electronic pick-ups. This came with the car, so not familiar with it. Looking into crank triggered ignitions system for better resolution and tuning. Standard coil, NGK spark plugs and wires.

   6. Racing dampener/pulley

   7. Stock flywheel.

   8. Remote oil filter w/ copper/AL oil cooler mounted in front of radiator

   9. 3-row radiator

   10. No radiator fan at this time

   11. Notes:

       1. since class rules allow 12:1, intent is to install domed pistons during the next block rebuild. 10:1 with existing flat-top pistons should currently work for 91 octane.

       2. Will use wide-band O2 to log A/F with SM needles to gather data points for needle modification.

2. Transmission – series 2 240z OEM Nissan 4-speed

   1. Clutch/Flywheel: Have not pulled transmission since purchase, but presume OEM.

   2. OEM driveshaft

3. Differential: 17' Subaru STI helical LSD, 3.545

   1. Half-shafts: Datsun restomod custom CV shafts with integral diff input shafts for STI R180

   2. Have a spare 4.11 R180 but have not ponied up the money to transfer the helical center section.

4. Fuel

   1. 12 gallon poly/aluminum fuel cell with steel support bracket. Came with two fuel output ports and one vent. I recently installed a level sending unit so I no longer need to use a dip stick.

   2. Dual (redundant) low pressure fuel pumps with outboard check valves, leading to single Y header. 3/8” galv/steel fuel hard-line being installed in tunnel. -6 AN fittings and new nylon/SS braided lines throughout for connection from hard-line to fuel cell and carbs.

   3. Generic FPR set to 5psi, feeding SU floats. Currently dead-heading but im looking into the need to install a return line.

5. Brakes

   1. Proportioning valve installed in tunnel, protruding into center console for access while driving.

   2. OEM rear drums

   3. OEM front calipers. Cross-drilled rotors

6. Suspension

   1. OEM hubs

   2. Struts sectioned with Ground Control coilovers. Eibach springs 350lb/in front, 300 rear

   3. Koni 8610 RACE adjustable shocks

   4. Ground Control custom bolt-in camber plates

   5. Urethane bushings throughout

   6. Rear has Apex Engineering control arms (got a good deal on offer-up)

   7. Rear sway bar

   8. Front is OEM at this time

7. Wheels – Diamond steel racing wheels, 16lbs, 15X7”

   1. No tires mounted on racing wheels at this time

8. Chassis

   1. Race prepared, lightened, and all trim/accessories removed

   2. 8-point “NASCAR” style cage. Door sectioned with only outer surface remaining.

   3. Chassis reinforcing

      1. Custom rocker reinforcing, utilizing 14 gauge axially and 20- gauge for stiffening ribs

      2. rocker to over-fender frame reinforcing (tube)

      3. Tube steel reinforcing between roll cage termination on fire wall, through to strut tower.

      4. New passenger seat mounting supports. Mounting point 1.5” above floor panel.

      5. Custom extension of floor panel stiffening support, through to unibody subframe directly behind floor panels.

   4. 2X corbeau 1-piece racing seats

   5. Fire suppression E-pull installed, with fire bottle mounted behind passenger seat on floor panel.

   6. expired 5-point harness

   7. solid/welded rear strut bar. Custom made, removable front strut bar

   8. 11lb Braile AGM battery with custom SS battery box, mounted behind passenger seat.

   9. Fiberglass rear hatch

[grannyknot]

Looks like you've put the work into your plan, that sounds pretty complete, looking forward to some pics.

[AydinZ71]

40 minutes ago, grannyknot said:

Looks like you've put the work into your plan, that sounds pretty complete, looking forward to some pics.

I have a complete play-by-play on Instagram @240z_restomod

 

Naturally, most people I respect (including myself) have mixed feelings about social media so I created this page  It’s just so convenient to use, I overcame my misgivings.

 

Here are some photo’s of what I’m working on right now, and the completed passenger compartment. I also added a pic of a steel tube section that connects my passenger floor pan support with the rear subframe crossmember that holds the front of the rear control arms. The passenger seat supports connect to the tunnel on one side, and the inner rocker on the other end. 
 

do posting videos here work well for folks? If so, I have plenty of those! 

[AydinZ71]

Here is a try at a video. Let me know if it works well! 

[74-370LSZ]

Video works great. Would love to see a breakdown on triangulating the front. I've been told that and heavy frame rails (apart from caging it) are 2 most effective strengthening mods you can do.

[AydinZ71]

1 hour ago, 74-370LSZ said:

Video works great. Would love to see a breakdown on triangulating the front. I've been told that and heavy frame rails (apart from caging it) are 2 most effective strengthening mods you can do.

 

I have not performed any analysis or modeling. I spent a bunch of time speaking to other folks who have raced (some competitively, and successfully) with S30's. Beyond that, I am using intuition as a mechanical engineer. The important thing to consider is that Every addition of material has 2 components to consider: 1) How effective will the addition be to the aiding/resisting existing stress/strain of the body. 2) how much weight am I adding in the process. 

 

The most efficient means to reinforce the existing body is to determine where the most flex/strain is taking place, and brace that point from another point that is already well reinforced. The roll cage is by far the thickest/heaviest structural support on the car, so adding bracing that translates stress back to the cage is an efficient way to add rigidity. The gauge of steel used on the S30 unibody (both for subframe shear walls) was very thin compared to modern sports cars. The means of attachment was also poor, as they are mostly lap joints with resistive spot welds holding things together. Not many gussets, ribbing, etc. Its just stamped steel spot welded together. With that said, I am blown-away daily at how elegant and well thought-out the design was given the lack of CAD modern resources. The subframe really is an elegant and beautiful design, with some potential improvements with the benefit of hindsight. 

 

On the passenger side you see one short tube I added to brace the rocker extension to the upper subframe (which also happens to be the air duct for the passenger cabin vent). This was convenient since it also attaches to the roll cage terminal at the fire wall mid-way. The second support is from the end of the roll cage terminal on the firewall to the passenger strut tower. The strut towers (all four), along with the tie-rod mounting box (the thing I just finished) are going to be seeing the largest force inputs from breaking, cornering, and changes in inertia. 

 

I could do a video explaining what I was thinking if there is interest. Also, by no means am I a professional. There are certainly more efficient and improved ways of adding rigidity. Still, I am happy with the results so far. 

[AydinZ71]

Fuel cell is back in. Fuel lines are complete through the transmission tunnel. Now I can finish the brake lines and get the rear suspension back on. 

[clarkspeed]

That is where it should go. Everyone usually mounts the cell at deck height which never made sense to me. Then you have to separate it from passenger with a big ass box or bulkhead design. Drop it down a little and you not only lower center of gravity, but your metal cover solution becomes so simple. I like to cover the hole with an aluminum or steel plate and then put a small 10x10 or so electrical box right over the filler cap.

[AydinZ71]

I like the box idea! Yeah this fuel cell is as low as it should go. About 2” below the rear valence. Only thing lower is the exhaust.

 

I have a large aluminum cover now with butterfly self ejecting fasteners. I’d like to put down a seal to keep some of the fumes out after refueling. 
 

Appreciate the encouragement! 

[AydinZ71]

Taking the cowl “box” apart, replacing rust, and eliminating most of the structure, and replacing some sections with steel tube. 

[AydinZ71]

Update:

 

took a deep dive And removed most of the cowl chimney/box. Starting to make templates for the replacement steel. 
 

In the rear, I just need to put in the replacement brake lines and I can reassemble the rear suspension. I finally assembled the struts (thanks for all your help!) and made a neoprene gasket to keep the oil-fill from oozing. Also helps cushion the shock against the gland nut. 

[AydinZ71]

Rear brakes and proportioning valve in. 

[Ironhead]

Very interesting project.

 

I for one would like to see some higher res photos posted.  Hard to discern details with the size you are using.

[AydinZ71]

1 hour ago, Ironhead said:

Very interesting project.

 

I for one would like to see some higher res photos posted.  Hard to discern details with the size you are using.

thanks! Gosh I’m not sure how to adjust the res of the photo’s uploaded here. I can try e-mailing them to myself and uploaded from a computer instead of from my phone. The pictures themselves are huge files on the iPhone. 
 

Here is a vid I posted on IG today. Got my rear suspension in thanks to the helpful folks here at HybridZ @JMortensen, @jhm, @Ben280 And more 

[JMortensen]

Maybe I'm missing something, but it looks like your coilover sleeves are longer than the strut tube. Shouldn't be like that. The Koni bumpstops will compress a lot, and you'll smack the camber plate into the sleeve if you bottom it hard enough. Easy to trim down the sleeves and put the cut end on bottom so they don't look terrible.

[AydinZ71]

50 minutes ago, JMortensen said:

Maybe I'm missing something, but it looks like your coilover sleeves are longer than the strut tube. Shouldn't be like that. The Koni bumpstops will compress a lot, and you'll smack the camber plate into the sleeve if you bottom it hard enough. Easy to trim down the sleeves and put the cut end on bottom so they don't look terrible.

yeah I was looking at that and a bit confused as well. Of course, I have not adjusted the ride height at all yet, just got them in. I adjusted the perch until the spring fit snuggly into the top mount. Il throw some wheels on and adjust the height before I cut the sleeve, but I agree it looks like they would need to be cut. 
 

I wonder if anyone else experienced this and needed to cut the sleeves. Il also double check that the sleeves for the front are the same length as for the back. 

[JMortensen]

I bought super long ones for mine and trimmed them down. My first set were Ground Control. They had 4" adjusters. I set them up by putting the adjuster all the way up on the collar, then setting the perch so that the adjuster just touched the bottom of the spring, figuring I wouldn't be ever be preloading the springs. Looks to me like if you did the same you might have the perches welded on substantially lower.

[AydinZ71]

3 hours ago, JMortensen said:

I bought super long ones for mine and trimmed them down. My first set were Ground Control. They had 4" adjusters. I set them up by putting the adjuster all the way up on the collar, then setting the perch so that the adjuster just touched the bottom of the spring, figuring I wouldn't be ever be preloading the springs. Looks to me like if you did the same you might have the perches welded on substantially lower.

Unfortunately, I followed the directions from GC which called for the perch to be 7” from the bottom of the strut tube for the rears  

front call for 10”

 

I wonder if anyone else has had this issue with the GC weld-on kit. I might e-mail GC just to check if I did something wrong. Otherwise, I agree the solution would be to cut the AL sleeve. Too bad I can’t do it on the car 😂

[AydinZ71]

I just measured and the adjustment sleeve sits almost exactly 1.5” above the top of the strut gland. Il pull the sleeves off and cut that amount off the sleeve. Bummer GC’s dimensions are off. Now I know to consider the length of the sleeve, and not just follow their measurement for the perch  

[JMortensen]

Was thinking my first set from GC in '95 or so had 5" adjusters. Just to clarify. Looks to me like you might run the spring to the bottom of the adjuster without getting the ride height you want. You could grind the perch off of the strut tube, but that's a hassle. The other solution is to run a shorter spring. Shortest spring that doesn't coil bind is always the best choice because it's lighter and it will resist bending sideways when it compresses. I started off with 10's, worked down to 8's and now run 7's, but I also have super stiff springs and run very low, so don't need 6" of travel.