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In hindsight, we could have gone with new Webers with what we have spent on getting these Mikunis in order. Then we would of had a lot more options to improve drivability. I'm not giving up on them yet. In the spring I'll get time on the "free" dyno and spend some time playing with the low speed jets and look at different emulsion tubes options.

I figured getting it to do more that 1/2 lap before overheating was more important that a video As soon as I have one, I'll post.

The track event was successful as far as the engine is concerned. Engine ran good. Pulls hard between 4000 and 7500RPM (rev limited). Now its a completely different beat to drive, and I have completely change my shift points. AFR didn't budge above 13:1, but was really rich in areas below 4000RPM. Plenty of winter projects to do

I think it is important to use a break in lube with a high zinc content, as well as an oil with high zinc levels. I'm using an Isky CWC grind on my race motor (almost .600 lift), and have had no issues with lubrication or lobe wear. I used Redline break in lube with Valvoline VR1 (high zinc) for initial break in. Then I ran another bottle of Redline break in lube with Brad Penn 20W50. It's just about ready for another oil change, and it will get more Brad Penn 20W50. The cam is internally oiled, and I'm also using a spray bar.

Nice. Check the dimensions before doing anything for sure. If all looks good, you might want to consider Swain coating. Another $300 or so. You have to bore after you have the coated pistons in hand so the clearance is correct. I sent a set of 25 year old Cosworth pistons out for coating and they came back looking like new.

Are you sure it is not fuel? Do you have a wide band O2 sensor on there so you can see what it is doing at 3000RPM? BP8ES is probably too cold for street use. I would not use a projected tip either. I would try B7ES and set the gap to 35 thousands.

Question: Does it run OK? Does it feel like it is missing? What plugs/gap? There is nothing wrong with triggering from the distributor. I've not hear bad things about this system. It is most likely better than the HEI retrofit. I run a 280ZXT distributor in my vintage racer with an MSD. The timing is rock solid. Sure, a crank trigger is more stable, but if what you have is working, I'd stick with it.

If you look at the final pull from the engine dyno, you will see high 12s to low 13s. This is where it should be. Before making any changes to the engine, I did some pull on the dynojet and got AFR reading like what you see in the plot above. I have a feeling that the lambda on the dynojet was reading a few points higher than the very accurate lambda sensor on the superflow dyno (engine dyno). I am putting a new sensor in the dash lambda gauge and will watch it closely at the track. I am fairly sure that I will see high 12s to low 13s with this sensor. I'm running 110 Cam2 race fuel in this engine.

It will run extremely rich. Stock are 180cc/min and have green tops. Find a set.

Jon, these are the old style Mikunis that were modified by the guys at BSR back in the day. The mods cannot be undone. The engine specialist I've been working with can explain in extreme detail this mod and what the limitations are. He is one of the old school guys that did these mods back then. Basically it has to do with the flow through the emulsion tubes. When the flow through the carb is increased beyond a certain point, the emulsion tubes become less effective in controlling that crossover point. He says that the Weber DCO 55mm carbs can be tuned a lot better because of a better emulsion tube design, and the fact that they are designed to flow that much air. He actually thinks that my motor needs more air. He is probably right. If I didn't have these Mikunis, I probably would have run Webers because you can still buy them new and also get parts. You are correct, for a street engine, the venturis should never be removed, but for a race engine with a limited power band, the extra air flow is worth it.

For the compression ratio I'm running (13:1), I really needed to cut grooves for copper wire into the block to get the gasket to seal correctly. Basically it was blowing compression into the water jacket once a good load was put on it. When you have a water shooting out of the overflow tank, and after a few dyno pulls there is mostly air in the cooling system, you can pretty much figure out where the air is coming from. The MLS gasket was the quickest fix. So far it is holding up.

It has Mikuni 44phh carbs with the chokes removed (~50mm). With such large venturis and with the emulsion tubes they have, it is difficult to tune a that lower crossover point where the low speed fuels jets meet the high speed ones. I can try smaller low speed jets, but it may just move that crossover point to where it has a negative effect on the top end. If I run richer high speed jets it will richen it up on the top end, but it will also make that 4k droop even deeper. Would I love them to change the vintage rules to allow EFI? YES! Until then, I'm stuck with not a lot of tunability in that area. Pete

I used the 2mm Kameari one. It's really the only 2mm MLS gasket you can buy. It's loud with the dual megaphones. Earplugs needed when driving it and on the dyno for sure. I'll get try to get an audio clip at the track.

Been chasing head gasket sealing issues. Finally think we have them resolved with a MLS gasket. Made 223HP on DynoJet with leaking head gasket. Now that it appears that the gasket leak is fixed, here is the latest dyno plot: I figure it's making close to 300HP at the crank. Doing a track event in a couple weeks. I'll post the results. Pete

I sold the old Crown stuff a long time ago. Here is a 240Z in Maine that has the kit: http://cgi.ebay.com/ebaymotors/?cmd=ViewItem&_trksid=p3984.m1423.l2649&item=300602822505&sspagename=STRK%3AMEWAX%3AIT#v4-37

Yes, many have turbo'd L24s, including myself. Here is my L24 when it was running the Crown kit (sorry for tiny pic): Here are the original brochures: For this project I am thinking more turbo than NA. Low boost, fast spooling, high RPM turbo. Probably going with a single, modern turbo selected especially for this configuration would be best. Stay tuned.

None of these mods are a good match for the stock EFI (they will work fine with the stock manifold though), period. Sure, maybe you can hack something together with a Z31 ECU and make it work. Or, like I said, you'll be changing head gaskets until or if you can get the tuning right. If you are going turbo in the future, to do it right, you need to run standalone EFI. Now sounds like a good time. Or just do the turbo swap and forget about interim step.

With the stock ECU you will have tuning, and potentially detonation problems. Have extra head gaskets handy. I ran basically the same setup in my track car for 5 year with a Megasquirt, around 26 deg of advance, and a 50/50 mix of 93 and 110 as insurance. Blew a few head gaskets along the way. If the tune isn't right, you will be blowing them too. It made 180WHP all day. If it is a street car, consider a P90 or P79. You can run a lot more advance, and run safely on 91 octane.

First gasket pic from the left looks like there is s some blow by. Unless that is just oil. I would clean the head and block really well, and also have the head checked for flatness.

So I acquired this L24 engine that someone spent some money and time on. Taking it apart, it looks like whoever built it, did a pretty good job. There are signs that it was balanced. This is how I received it: L24 block bored ~0.030" over Arias forged pistons (domed) 9mm L24 rods. E88 head (73-74 open chamber) with Norris 490/490 - 280/280 cam, springs, retainers, lash caps, etc. The head is really the wrong one for the piston dome shape. An E31 or early E88 would have been a better choice. So a I have few options here: 1) Do up an E31 head and build a nice little street NA/mild race motor (might be a good spare for the race car) 2) Turbo charge it and use it in my semi street legal turbo car that has a tiring L28ET. I'm thinking the later. Worth the effort? I figure I'd do something like this: - P90 head (eye brow cylinders, check clearances, etc. Do whatever to make it right). I'm guessing the dome is around 5cc or so. I'd basically shoot for an 8.5-9.0:1 CR. - I can probably locate some RB26DETT turbos and have a manifold and down pipes made. - I'd have a custom turbo grind done. I'm thinking that it would be responsive, and the turbos would spool quickly. What do you guys think, worth it? Or should I just just build an L28 turbo when I need to and do an NA setup with this engine? Thanks, Pete

Definitely head gasket.

What block/head/piston combination are you running? Compression ratio? Stock head gasket? Could be detonation related. Pete

I'm looking forward to seeing the results from your dyno testing. Thanks, Pete

You should look for a set of 280Z shafts. They are much stronger than the 240Z ones. This is what I run in my race car. If you still need some spare 240Z shafts, John at Bad Dogs parts has a bunch of them.

Exactly. We run the SW13 calipers on the vintage racer along with the stock drums because we have to. But to be honest, a 240Z properly setup for the track doesn't need crazy brakes, especially running in groups where huge tires and big flares are not allowed. Make it fast in the turns, and keep it light, and you'll find that getting a whole season out of a set of pads is not that difficult. We have been running the same non drilled/non slotted 300ZX vented rotors for at least three years now, and we have just had to resurface them a few times. What are you trying to say here, that Porsche drivers are especially hard on their brakes? I think a lot of drivers are much harder on their brakes than they need to be. A little more skill in the turns can make a huge difference in the life span of rotors and pads. Pete