jonbill

Bkr7e seem the best compromise on mine. Doesn't melt at high revs, doesn't foul at idle. It's a 14mm hex because my plugs are 5mm further in than normal.

At least you've got one working one to compare too, and a good book. On my Dellortos the problem with the accelerator pumps is always the one way valve gets gummed up if the carbs aren't used for a while and sit with fuel in them.

There might also be throttle stops per carb. This is a good book on setup. https://www.amazon.co.uk/gp/aw/d/1845849590/ref=dbs_a_w_dp_1845849590 I'd start with making sure the throttles are closed at rest and adjust the linkages so all 3 throttles start to move at the same time. Idle mixture screws I think should be a couple of full turns out from fully closed (but not sure of this, I don't have Webers). Have a look down the bore of each choke in turn as you open the throttle briskly and you should see a squirt of fuel going toward the engine. (3 pumps should be plenty for cold start even without choke, too many pumps will flood it). If the carbs are reasonably assembled and no big air leaks at manifold it really should start like that.

The left one is for the crank case ventilation pipe (although it looks small in that photo? ) and the one on the right is the block coolant drain. It should be just plugged in normal use. (although I have see one with a secondary electric pump extracting from there)

Imperial and US ounce are the same I think. Wiki agrees https://en.m.wikipedia.org/wiki/Ounce I think we just deviate on how many ounces are in larger units like pints and gallons. An ounce is 28.3 g, so 24oz is 679.2g

If the colour of the plugs is OK, and it really is backfiring through the inlet, I'd suspect the ignition timing.

+1, they definitely have to be in the diff first, and it's much easier to do it while the diff is on the floor out of the car.

There's an explanation of Z7 here: https://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=4017 I liked it better when there was some mystery.

Kameari sell larger valves. I'm sure many others do too, but I like Kameari stuff. https://www.rhdjapan.com/search/engine/nissan_fairlady-z_s30-l28-10-1971-08-1975/model/nissan_fairlady-z/car/nissan/category/cylinder-head-and-valvetrain_valves

I'd agree. Definitely get a decent pump, get a decent regulator and see if you've still got a problem or not. If there's still a problem, at least you'll be sure where the problem isn't.

I've used Holley Red and Blue pumps and I found them both ferociously loud and rather unreliable (correctly positioned at the level of the bottom of the tank). I wouldn't recommend them. I'm currently using an old quiet Bosch 4 bar diesel pump out of my BMW. I've got an Aeromotive FPR that regulates it down to 2.5 psi and I'm very happy with it. I haven't read the whole thread but I read the first post and I'd say if it's going lean almost immediately at 3k in 3rd when you apply load, I don't think it's the fuel supply, it would take a few seconds to use up the float chambers. I think your needles are too lean. Are they the ones that came with the carbs? Apologies if you've been over this.

I use a length of box section bolted to the block to lock the flywheel:

[emoji102]

Fwiw, I always lift mine with ratchet straps round the engine rather than chains. I've got very limited height in my garage so I need to get the leveller as close to the engine as possible.

Where do you even get 99 Ali? Mine is happy with 95.

Thanks. It's very far from perfect but it gets a bit better most years.

That'll be you then Ali [emoji28]

I swapped to an s13 fs5w71c gearbox about 3 years ago, just because it came up cheap and I fancied learning how to rebuild one. I'm using the original 3.7 r200 but put a Quaife in last year, which shaved about 0.3 seconds off. I think next on the wishlist is the AZC or TTT drop links & dog bone kit for the rear suspension mounts. I think I have some movement back there on hard starts. And I do have a finned diff rear cover I'm looking for an excuse to use.

Thanks. I'm sure I'll post quite regularly now I've said hello.

I don't actually know - it was on the car when I got it. Its certainly low, I have to repair it most years. It's also very big, but painting it black made it stand out less which I like.

No, 1/4 mile [emoji4]. Its an L28 taken out to 2.9 with a modified P90 head and a big cam. Triple Dellorto carbs, zstory race exhaust. Its been about 3 years of fettling but it runs nicely on the road and the track now. The engine bay has a lived in look.

Hi Mark, best time is 12.97 @ about 106 mph. I'm sure there's better to come, I'm only just getting the hang of a decent start.

Hello, I've been reading the forum for a long time and I'm overdue introducing myself. I'm Jon, I'm in the UK and have had my 260z since 2002. For the most part I've been keeping it in good standard shape but for the last few years I've been in a bit of a performance improving cycle prompted by a bit of drag racing. Hopefully I can stop soon. [emoji102] Here's a pic of it.

I have a 20 year old mr2 with 3 sensors and 20 year old modern engine management electronics. The first sensor measures the output of cylinders 1 & 4, the second measures the output of cylinders 2 & 3 and the last measures the aggregate after the catalytic converter to judge whether the cat is working or not. I believe this is representative of multisensor setups. Each sensor is trusted to measure its bit independently. Sensors of course do fail. The management system strategy for this is to constantly cycle mixture up and down a bit to check if the sensor reports it. If it doesn't it reports a fault. There's no reason to not believe a single sensor and controller and gauge will report reasonably accurately the average AFR of the combustion chambers it's monitoring.

Thanks. Funnily enough, it doesn't - it mainly depends on the chemistry of the fuel and air mixture which hasn't changed for a very long time. I'm sure there are conditions in which the accuracy is compromised significantly, but it's not within the normal degradation of an engine say in the first few 100k miles of it's life. That's why many of the spark ignition cars of the last 20 odd years are still on the road passing their emissions tests using this technology to regulate their fueling.