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73 240Z with triple side draft Weber carbs


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I have a question that hopefully some one can answer. The 240z has triple side draft weber carbs, The distributor on the car is still the original point syle vacuum advance unit. I cannot advance the timing enough without causing problems with pinging and hard starting. The 240z runs ok but has flat spots under hard accelleration. Should I look for a Mallory mechanical advance distributor or intall the euro 22100-E3101? My understanding is the 22100-e3101 is a single point distributor with a quicker advance curve.There is not a port on the intake for the vac. line to the distributor.

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I see this is your first post- welcome.

Your question is vague and you need to elaborate more for us to help you.

So you have a 240z - what engine- original?

You can't advance your timing enough for what? You can't make stock specs?

What's your timing at now?

So the vacuum advance is NOT hooked up now?

How does the engine run OTHER then WOT? Idle good?

Describe flat spot.

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  • 2 weeks later...
I see this is your first post- welcome.

Your question is vague and you need to elaborate more for us to help you.

So you have a 240z - what engine- original?

You can't advance your timing enough for what? You can't make stock specs?

What's your timing at now?

So the vacuum advance is NOT hooked up now?

How does the engine run OTHER then WOT? Idle good?

Describe flat spot.

The engine is the L24. The camshaft is a Racer Brown 9/6 E1035. The stock distributor is a vac advance unit. The advance is not hooked up. There is not a port on the intake for the vac line. The timing spec is 10, I have it set at 12. Light throttle and ease into the accelerator the vehicle runs great. If you get on the throttle the engine boggs down briefly, let up and then runs fine. It acts almost like it chokes it self. Idle is fine. Hold a steady throttle at 3000 rpm there is a slight intermit skip. The carbs have been rebuilt.

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First of all, download the distributor information table in this thread:

http://www.classiczcars.com/forums/electrical-s30/34192-280zx-distributor-advance-curve-reference.html

If you are running a U.S. specification points type distributor, the correct static timing is NOT 10! it is 5 for 1970 - 1972 and 7 for 1973. If you are running it at 12, even without a vacuum advance, you will have spark knock above 3000 RPM. And this will rob you of the power you seek.

I made the same mistake early on with my car also The knock will sound like buzzing because of the engine speed, not the clatter you would expect at lower speeds.

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How are you sure this is an ignition issue. Maybe it's carb related. I'm having a hard seeing this as a timing issue unless the mechanical advance is sticking. If that was my Mikunis I would suspect accelerator pumps

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first you do need a good working dizzy, the stock points will not do it for your set up. second webbers are sensitive to weather cams etc . I usually do all my work but I had a difficult time sycronizing the carb especially with a the cam I had, i though I finally had it right so one day I went to Z meet and we were talking about our cars and a person name Bob dimaggio walked by and said your carbs are not right you must have falt spots, he tune the carbs it took him 15 mins and I can not tell you how fast smooth my car became. Latter I found out that Bob raced the 240s had a shop etc. Moral of the story it is difficult for us to tune carbs at idle with a cam unless we have done them for many years and many times .

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  • 1 year later...

Hey y'all. Sorry, I don't know much about forum ettiquette as this is the first one I've joined, but I also have I think the same triple Weber carbs on the 260z I just bought. The guy said that everything under the hood was perfect, but after driving it for a week, I'm seeing that the carb intakes are leaking gas and the gaskets leading into the engine are wet with gas as well.

 

I'm kind of a novice (at the Forum thing as well as owning a datsun/working on my car) so any pointers would be appreciated!

 

I really want to do the car justice!

 

- Josh

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You're running rich, the intake/exhaust gasket might be compromised, and your float levels are likely high. Time to do a thorough check-up. This forum has tons of info on triple Webers, looks like you've been searching so keep it up. ;)

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