AydinZ71

Interesting! With this many folks having the same experience, that kind of rules out mistakes or incorrect clearances. How are your compression numbers?

That is unusual. If there was something specific to the piston that would cause this, your machine shop would have been able to catch it during assembly. The piston is centered inside the bore via your rings. The piston can not contact the cylinder walls unless: 1) Piston installed is too large relative to your final bore. Machine shop would have checked that. 2) Your ring gap is incorrect, which is causing your piston to move around. 3) I have also seen skirt slap from damage due to detonation. Are you using forced induction? Did you experience anything that may indicate your engine was knocking? I have Kameari forged racing pistons in a motor I am building, but the head is not finished yet so I have not run.

Took the kids out to the track. I gotta say, I’m really jealous of the track’s ya’ll have on the east coast. Still, was a great day out at historic Willow springs. event was VARA IMG_0328.MOV IMG_0318.MOV IMG_0315.MOV IMG_0316.MOV

It makes a loud whining noise, kind of like a supercharger. It can be annoying, especially for a street car (which most people buy it for). I have spoken to the designer at Kameari (Mori Kame) and he has not heard of any performance issues. It really serves two purposes: 1) Minor reduction is friction/resistance from the OEM type tensioner. The twin idler uses needle bearings. I mean, squeeezing a few drops of parasitic loss out of a race engine with listed restrictions (class requiring an L-series). 2) Main purpose is to eliminate chain slack on heavily decked heads and alleviate the need for super thick lash pads and thick tower shims. Thick lash pads add unnecessary weight to the moving parts of the head. This part is for racing applications. He sells an adjustable OEM style tensioner for street cars. I bought this for my 3.1L race motor, since I am running 11.5:1 and my N42 had quite a bit removed. Just waiting on Mr. Yoes to finish the head before final assembly. Block is ready and waiting at Mountune (here in southern california).

Hi all! For those of you who have not heard, our friend Greg Ira will be returning to the SCCA Run-Off's this year. In a wild twist, he will be driving Jesse Prather's own personal title-winning BMW Z3! Greg has been my mentor on my EP car restoration for the past two years, one of the best amateur drivers in the country. If you are near VIR on April 7th, come check out the race! @jhm This one's for you! I hope to make-it if I can arrange work and kids, and it would be great to see ya'll out there!

Ah john... now I just feel like a jerk for being a sarcastic ass, hehe ("breakthrough"). Pretty cool for a bolt-on. I steer most friends away from bolt-on's unless required by class rules, but that's kind of snobby. Always good to have options for the full range of skills and driving conditions.

What a design breakthrough…

treadmill time 🤓 got the front flares on today. Can continue bodywork along passenger fender IMG_0261.MOV

Another swap that I personally like is the K24 Honda. Yes it looks kind of silly in that big engine bay, but you will be putting the engine weight behind the front axle. Not sure if that officially constitutes a "mid" engine, but that a huge plus for road racing, autox, etc. You will also be shedding well-over 100lbs of engine weight compared to the L6 with nearly double the power (in NA form!). If you just want a street car, and plan to drive it more like a grand tourer then id go with the 6 or LS. If you want a small, light, great handling Z with more power than you would expect from a 4-banger, K24 might be for you. Only other negative I can think of is.... well... it sounds like a honda. Like all Honda's, they kinda sound like lawnmowers IMHO.

I got them from a local mechanic friend of mine who repairs and builds s130’s and some S30’s here locally. He buys a junker two three times a year and parts them out for his clients. So like most right decisions in life, it may be best to be patient. I may need to pump the brakes on my brakes… we are allowed alt. Front brakes with a 2% weight penalty. When I called willwood they told me to check the most recent GCR and sure enough, they allow alternate material non-oem calipers and rotors up front now. That opens up things considerably. I may need to wait and weight the car to see how close to 2150 I am (soaking wet with driver). My fat ass is around 190, so that’s not an easy task. If I happen to already be overweight, I may need to add little or no ballast and end up with sweet 4-pot lightweight willwoods and a decent diameter rotor up front. Then I can upsize the rears to match. honestly, it’s been raining here so much I was just trying to open-up another work path while I am unable to progress the bodywork. Hate to lose momentum.

That first image with the rusted cylinder wall... this engine needs to be rebuilt. The machinist will need to remove material until the pitting/rust has been completely removed. Then he will match the remaining cylinders to the one they needed to remove the most material from. Depending on how much was removed, they will either use the OEM piston with a larger dia. ring, or up upsize to the next diameter piston + rings. Your valve seals will likely need to be changed too. $1000-$3000 of work and parts depending on what can be re-used. Can you clean it all up and try to run the engine? Sure...buy why. You will have poor compression, will likely burn oil, and all around be disappointing. Is this your OEM original L24? If the numbers match and you like the 2.4L, makes sense to rebuilt. Otherwise, I would toss it and find a running L28. You could get a long block for under a grand, and your SU carbs will work just find with it. Everything else is the same except displacement.

Haha! Thanks John! Unfortunately, I still have to use the 280zx front calipers Darn EP rules, but since the rears were always drums to begin with, the rules are a little more forgiving. Thanks again for the write-up! I actually bought the Skillard AL front dam because it came with an integrated splitter. After unboxing I discovered the front opening was larger (extends lower) than the type-1 air dams on the market. We can't reduce the size of the front rad opening, but I certainly would not want to make it bigger. I decided against hacking it apart, so Its now for sale With the chassis modifications I have, I didn't want to risk another misalignment so I just made it myself out of 6061 AL. Two sheets of 0.04" for the dam, and 0.08" for the top flange. I still need to design-in a way to quickly remove it (probably quik-latches) and an adjustable splitter. I'm just waiting on bodywork to finish so I can throw the front suspension on. and find a reasonable ride-height. I am pulling the car in-and-out of the garage like a wheelbarrow at the moment, and it is more convenient than wheeling it out without brakes. Filler dust gets everywhere, so reassembling the car has been put on hold. I have two front fenders and the drivers door left.

Thanks Clark! Literally the first time I have let them “help” in a long time haha. It’s usually dust, toxic paint, etc. and I don’t have PPE small enough for them 😂

It’s been a while since I made any updates so might as well attach some pics

Thanks jon. You are a resourceful dude. Took me several tries just to confirm the critical specs on rotors. so here is the solution I have cooking: using Silvermine rear willwood 2-piston caliper brackets. They were adapted to the 11.4” Z31 rotor. Later S130 is the same hat height and width, but 10.16”. Il have to drill two new holes closer to the hub to accommodate the difference. And voila, I have a small 2-pot 1.5Lb caliper paired with the right dia. Rotor. The his combo should compliment the tiny 9.92” vented fronts. il have to take a closer look at the caliper bracket. I might save some cash by just making it myself from 1/4”-3/8” 6061.

PS: Jon, how are you Johnny-on-the-spot (no pun intended) with those ZX caliper pictures? That is incredible. You must have a library of stuff at your finger tips. I forget specs constantly haha. You must be very organized

Thanks Jon and CalZ, Yep, so I did more research. It appears the MSA does sell a rear kit that uses the 280zx later year rotor and a maxima caliper. That will work, but I would be losing-out on the Willwood 2-pot weight savings. Since it is sprung weight, this isnt ideal. MilkFab also makes one using the older ZX rear rotor/caliper. https://milkfab-engineering.com/shop/ols/products/s130-turbo-disk-brake-kit-datsun-240z-slash-260z-slash-280z Since the hat height on the later ZX and Z31 rotors is the same (dia different), I could buy a bracket from silvermine for example designed for the larger rotor and just re-drill holes for the smaller rotor and use a small willwood. That assumes there is enough "meat" on the bracket. If not, I'll have to fab my own.

Thank you Jon! Gosh so much misinformation out there. I was told the calipers were the same for all ZX, so this is really helpful. Attached is my spec line. As you can see, I’m stuck on the 252 vented fronts and a ZX caliper, but which ZX caliper is open (so definitely will be using the later year). for the rear, because OEM was drum the EP rules are a bit looser. We are allowed to swap out drums for disks, and the spec line (attached) doesn’t limit this ability. The rear rotor has to be smaller than OEM front (272mm), and we are allowed to use alluminum calipers. Therefore, what I pick for the rear just need to balance well with the 252 vented ZX fronts so the bias (Tilton mechanical screw, seperate masters) is not too-far too the front at the get-go. ideally a 2-piston willwood rear caliper and an OEM S130 rear disk would be ideal. A kit to get the caliper on would be helpful and keep me from wasting more time on fab.

@JMortensen I would go with s130 rear brakes, especially if I can swap the caliper for a lightweight willwood unit. Unfortunately, I can’t swap the whole strut as we have to keep OEM hubs. Not really sure how anyone would know, but better safe than sorry. We have a lot more options in the rear since car never came with rear disks, but we are super limited in the front

Hi all! Seeking some advice from our racer community. Clark, Jon, John, Cary, and the like. Stuck with those 9.92” (252mm) S130 vented front rotors from EP rules, and looking for a rear brake kit. Rotor must be smaller than the OEM fronts (272mm) I was going to pull the trigger on the T3 rear micro brake conversion (265mm) but Mr. EP Greg thinks the rears will be too big relative to the fronts. That would cause my bias (Tilton mechanical) to skew too far to the front making adjustment more difficult. Makes sense to me. I also don’t know what rotor T3 uses which concerns me about replacements. Any thoughts on a rear brake kit that will balance well with the teeny 252mm fronts? I see a lot of brackets and I do for converting the rear calipers to 240sx or Maxima, but not clear what the right rotor spec (car, size) w works with those. many thanks!

I hear ya on putting bodywork on the back-burner. That was my original plan. I wanted to throw everything back on the chassis once the interior and non-body chassis was painted. Once I started doing some filler work, I realized just how much sanding and dust I had ahead of me. I could not figure out how I would manage keeping all that dust from getting everywhere, so I decided to just finish the body before proceeding with mechanical and electrical. Yeah that has been some of the stress of ordering ahead. Two bird in a bush, one in the hand (so to speak). I try to buy what I need 1-2 weeks in advance, but once I pivot directions I end up with a bunch of stuff taking up storage space. Its incredible how much room a disassembled car takes up haha.

Sweet man! Yeah I have had cu-ni tubing and a flare tool sitting in my Amazon outbox for months now 😂 I’m trying to stay disciplined on planning ahead, as I still have several months of bodywork before I’m ready to move on. As you said… dust everywhere. Can’t imagine how I could bother putting anything back on the car given the extensive cleaning I would need yo do later. I have one door nearly complete. Hardest part is matching the contour with the rear quarter panel and fender. Using filler as a last resort, only when no other option is possible (like along a body line). I have the drivers door next, then both front fenders. Rear half of the car has been sealed and primered, ready for block sanding with 220-400-600 il tell you what, doing things “right” is a PITA. Everyone told me to get down to bare metal, but this was a race car before I started resto. You can imagine what shape the underlying steel was.

Here is the check valve without hose barbs. Probably a better installation: https://www.mcmaster.com/product/5492K51

Yes, the way you described the check-valves are correct. I bought them off McMaster Carr. They are enclosed plastic with hose barbs on both ends. I’ll have to look them up again, and il post it. all spring loaded check-valves have a “crack”pressure. It’s the pressure necessary to open the valve in the direction of flow. Just enough pressure to push the spring and allow fluid to flow in the intended direction. This spring creates the back-pressure preventing the valve from being open all the time. I’m just using this tiny amount of necessary pressure to create a “closed” system that operates in a + 0.3psi to -0.3psi range. the plan was to put an air stone on the make-up air (one of two). I just have not gotten around to it. It’s not a big risk, given where the valve is (right on-too of my fuel cell) how Infrequently it opens to let air in, and the downstream fuel filter. So it goes: vent nozzle on fuel cell -> AN fitting 90 to hose barb -> fuel hose -> tee fitting -> short length of hose on 2/3 ports on the tee -> check valves on those short lengths of hose. Check valves oriented in opposite directions PS: before doing this, make sure your fuel cell can handle the little bit of pressure that will build up. I did this by closing off all the nozzles and blowing in one until I hit 1/3psi. Yes, the fuel cell was drained and all residual fuel had evaporated. I am an engineer who works in fuel infrastructure (go figure) but just because it works for me I can’t guarantee it will work for you.

Fuel cell and passenger vehicle gas tanks have the same principles. The main difference is the OEM vent system must comply with EPA regulations that dictate where and how the vent Vapor is routed/treated. Besides the nozzles (feed, return, gauge, etc.), you have a fill port and a vent port. Fuel cell has an a roll-over check-ball in the vent line for safety. Passenger vehicle has all sorts of stuff like carbon canisters, vent connected to the fill port etc. your main challenge is how to deal with the vented gas. If you don’t care about the smell of gasoline vapor filling your car and garage, you can just put a small breather filter on that fuel cell vent port. for those who prefer to manage the vented gas like myself, there are many strategies. Some coil a length of tube connected to the vent port. This creates a volume and restriction for the vented gas to occupy. Eventually, the Vapor cools and condenses back into the tank. I have a different strategy. I use two parallel check-valves made of plastic compatible with gasoline. They have a crack pressure less than 1/3 psi. One is for air make-up, the other for gasoline vapor to escape. Therefore, my fuel-cell is actually a closed system that operates +- 1/3psi. It’s not enough pressure to stress the cell (mine has a bladder), but just enough to keep the vapor from escaping under most conditions. On particularly hot days, pressure rises above 1/3 psi and vents. no more gasoline smell in the car or the garage.