1972 Float Adjustment ...

[Patcon]

3 hours ago, jalexquijano said:

Lets see if i can explain myself better. Shouldnt the goal of tuning both carbs is to set the float levels to 9/16 or to be able to see the fuel 1mm below the nozzle hole when both of the fuel mixture knobs on my 1972 240z Hitachi round top carbs are set at 2.5 turns clockwise? Car seems to be running find with no misfire either at the intake or exhaust but by dialing the front carb mixture knob to 3.75 and the rear to 3.50. I dont want to get obsessed with the 2.5 starting point but thought that it would be good that both carbs could be dialed equally.

Another thing i noticed is that the car does not have enough power as a fuel injection car when stepping on 1st gear launching from a stop light. Is this also normal? How do i achive more power and response?

Nope!!! The goal is to make the car run good and burn cleanly with your carb setup. I think Mark has done a masterful job of helping you achieve that! The number of turns really isn't that important, and the carbs are not likely to have the exact same number of turns. Little variances in the float level, the float valves and the carbs themselves can cause the carbs to each be set a little different.

These cars new had 0-60 times of between 8.6 to 10.2 seconds. There are plenty of modern cars, even cheap cars that are faster than this and the EFI also helps with the throttle response, because there is less delay and the fuel atomizes better under pressure. Even the 280ZX turbo only ran 0-60 in about 7.2 seconds. That is an average sort of time for a modern car. These are not modern cars and in my opinion there is no reason to try to make them modern cars. If you want it to respond like a modern car it takes a good bit of money and a good mechanic. From previous post I doubt you have an adequate mechanic available.

As for tires you can take the current tire size and plug it into an online tire calculator and it will tell you what size tire you need for a 15" rim so the overall diameter is the same as the 14" rims you have now. That way you aren't changing the drive wheel gearing, so it doesn't reduce the performance

 

[240260280]

try 30wt then 80wt oil in carb damper and stomp on it from 1st gear. See if the power changes.

[w3wilkes]

4 hours ago, Patcon said:

As for tires you can take the current tire size and plug it into an online tire calculator and it will tell you what size tire you need for a 15" rim so the overall diameter is the same as the 14" rims you have now. That way you aren't changing the drive wheel gearing, so it doesn't reduce the performance

This will also keep the speedometer registering the same as it was.

Here's a tire size equivalent calculator;

https://www.discounttire.com/learn/tire-size-calculator

[jalexquijano]

Good advice guys.

[jalexquijano]

22 hours ago, siteunseen said:

I run 15" Rewinds and love them. They're not too big like the the 16"s I bought originally that now hold my 280 off the ground. They work great on the 280 but looked way out of perspective on the lowered 240. Looked like doughnuts on a Graham cracker.

Zed Head, I know zero on gearing and numbers and $^!# like that. I'm sorry. 8^(

The wide 5 from a '79ZX 2+2 works great with the R180. 80mph in 5th turns under 2,500rpm. About 2,200 on flat stretch.

Jalex I'm trying not to be a jack arse but "California Datsun" is your problem I honestly believe.  

I hope you can be happy with your 240 someday. I'll try and help but I think we've "climaxed" with your set-up.

Nice pics of your wheels.

[jalexquijano]

On 7/17/2018 at 9:08 PM, Mark Maras said:

@jalexquijano LOOKIN GOOD. The plugs are definitely lighter than we used to run the "back in the day" but you report the engine is running good so I'd leave it alone. I think the problem with #4 was in the cap, rotor or plug wire connection. #4 definitely looks better now. The lighter plug color could be due to modern gas formulations as reported by others. I'm still curious about that previous lower compression reading. I'm hoping it was a poor test and not tight valves. Any thoughts?

Compression test:

Cylinder 1 ------ 180 psi

Cylinder 2 ------- 182 psi

Cylinder 3 ------- 182 psi

Cylinder 4 ------- 182 psi

Cylinder 5 -------- 182 psi

Cylinder 6 --------- 182 psi

 

 

[Patcon]

2 hours ago, jalexquijano said:

Compression test:

Cylinder 1 ------ 180 psi

Cylinder 2 ------- 182 psi

Cylinder 3 ------- 182 psi

Cylinder 4 ------- 182 psi

Cylinder 5 -------- 182 psi

Cylinder 6 --------- 182 psi

 

 

I would say those are all excellent numbers

[Mark Maras]

5 hours ago, jalexquijano said:

Compression test:

Cylinder 1 ------ 180 psi

Cylinder 2 ------- 182 psi

Cylinder 3 ------- 182 psi

Cylinder 4 ------- 182 psi

Cylinder 5 -------- 182 psi

Cylinder 6 --------- 182 psi

 

 

 Wow, Those are great numbers. Thanks for sharing.

[jalexquijano]

On 7/26/2018 at 12:45 AM, 240260280 said:

 

Mark I don't think it is too far off the mark (pun). In his suggestion: The exposed annular fuel ring will be  1mm higher so it will be slightly richer due to less energy needed to lift the fuel, but the narrower taper of the needle 1mm higher will either have no effect or slightly  contribute a mild leaning as the exposed annular ring will be narrowed.

 

2.5 turns down is simply a recommended starting point  for a factory fresh stock 240z at sea level at 20C.  There are also recommendations for changes to this height for altitude and temperature.  From experience, there are additional changes in fuel height and in needle type to accommodate engine volume changes, compression changes, cam changes, etc.

 

Just adjust until plugs look good and driving under all loads (idle, city cruise, highway cruise, acceleration) is adequate.

 

In addition to changing needles, you can put weights and stronger springs in the carb bodies to make the pistons rise less for the same engine vacuum. This can help tune towards WOT from cruise.

 

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The 2.5 turns is just a base line to get the car idling? Mine is idling at 3 turns clockwise. My engine has been modified to 2.6L and has a shneider 274 camshaft with ovesized pistons. I believe the engine gets better at 3.5 turns. I.have the colortune tool so i can check anyway.

[240260280]

Correct Alex.  2.5 turns down is just the starting point for tuning a 2.4 litre.  A larger engine ( like yours ) will need more fuel so the jet should be lower than 2.5.  Or you can buy richer needles. ?

Edited April 12, 2020 by 240260280

[jalexquijano]

Both of my needles are SM needles.