I ended up selling the bumpers on ebay. I posted an add on both hybridz.org and classiczcars.com with no bites. I didn't know about this forum then.

Is there anybody here that could help me with tuning my carbs. This spring I am willing to drive to anybody's house in order to get it done. I have a full jet kit in hand. I have a bad stumble when the throttle gets pinned. You have to feather it to get by it. I have the car garaged in Sutton, MA if anybody wants to spend some boring winter months wrenching. I drove it like this all summer and I would like to fix it for next year.

Stolen from the Atlantic Z Car Club site, credits to them.

http://www.atlanticz.ca/zclub/techtips/ ... /index.htm

Byran Little (the Z guru) had the same stumble problem with his Webers (it's a common complaint) until he had his distributor re-curved to handle triple Webs. The vacuum advance gets deleted and the mechanical advance gets modified to do all the work.

Nobody who does that ever comes back with any more complaints, and Byran's Z flies like a rocket, so it must work.


Frank

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1970 240Z

I have that link saved in my favorites but I have yet to try it.

I am a little unsure about step 6. "6. Adjust the brass screws using a tachometer or mercury manometer for highest idle speed (Best Rich setting is preferred for performance, search the archives, I'm not going over that again)"

I am a complete noob when it comes to mikuni carbs. In fact carbs in general. My last "sport car" was a 1993 Toyota MR2 so I didn't have to worry about carbs.

Also what do you mean by "until he had his distributor re-curved to handle triple Webs. The vacuum advance gets deleted and the mechanical advance gets modified to do all the work. "

Ahh ~ part of the distributor's job is to deliver the spark to each cylinder AT THE RIGHT TIME for best performance. That "TIME" varies, depending on conditions.

We set the timing a few degrees before top dead center (BTDC) on our distributors, but under different loads, the engine can want it at different times. The dizzy makes that happen.

The 'floor' plate inside the dizzy can spin back and forth a little in either direction. When it turns, it sends the spark either a few degrees sooner or a little later than before. This helps the engine develop more power at the right time. We call it SPARK ADVANCE (altho it includes spark retard, too).

Two devices make the distributor's "floor" plate spin in the right direction at the proper time: VACUUM ADVANCE and MECHANICAL ADVANCE. In the 1970s cars, these two devices worked together to ensure a smooth transition from low-speed spark advance to hi-speed spark advance. When everything was working properly, you got seamless transition thru the entire powerband and your engine ran perfectly.

If either of those devices failed to work right, you got hard starting, rough idle, stumbles, flashbacks thru the carbs, no power, overheating, and/or stalls. Your timing simply was a mess.

The VACUUM ADVANCE worked off a tube connecting the dizzy to the intake manifold. When you opened the carbs wide all that air rushing in at once dropped the manifold vacuum, so the spring-loaded 'floor' plate got pulled 'round a bit, advancing the spark until the vacuum built back up again.

The "floor" was also turned by a pair of small bananna-shaped mechanical weights, which were spring-loaded inward. These weights were pivot-mounted at one end and spring-attached at the other, and they spun around with the rotating plate.

Hi engine speed caused enough centrifugal force to make these banana weights "spread" outward against their springs, which changed the position of the 'floor' plate, thus delivering the spark at a different time of advance.

Weber carbs (and probably all other triples) don't depend on vacuum advance for low speed timing. They have multiple venturi and individual jets inside each throat to accommodate that. So the vacuum can be disconnected on a set of trip Webers.

But then the mechanical weights have to be reconfigured to make them deliver the proper spark advance throughout the entire rev band. Modifying the different weights and springs, adding and subtracting times and degrees of delivery is known as RECURVING your distributor (so called because they do it on a machine which shows the RPM and timing curves on a scope as they make modifications).

It's a bench-job. You send them your dizzy and they slap in onto the tester and modify it in a few minutes. Your car stays home. When you re-install your dizzy and cap off the old vacuum advance tube from your intake manifold, you're ready to go.

I seem to recall Bryan outlining this procedure in his great website, THE DATSUNZGARAGE. ( http://www.datsunzgarage.com). I think he used and recommends ADVANCED DISTRIBUTORS in Minnesota: http://www.advanceddistributors.com/index.htm.

And I found an excellent example of some guy driving a Z which has had the distributor recurved to match a set of triple Webers, and I think it sounds wonderful: http://youtu.be/VSYh69ea-x8




Frank

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1970 240Z

Wow that is awesome information. I just sent an email to Advanced Distributors about getting it re curved. I can get over the family feel of this forum. I ma too used to hybridz.org and my350z.com. I mean I love those forums but everybody feels so far away. So far here I feel more connected. Thanks!

I received a reply from Jeff at Advanced Distributors this morning. He tod me that lead time would be three weeks and about $200. I need to fill out a curve sheet. Problem is I don't know some of the information thy are asking. Compression, what type of cam I have and so forth. Now the real problem of asking the wife to spend the money......

Every project has hurdles ~ you just have to take them one at a time. Wives are the hardest (ask me how I know ). They tend to get all involved with worldly things like paying bills, feeding the family, sleeping indoors, wearing different clothes each day, etc.....stuff which isn't all that important to us guyZ. So when we start talking about throwing money on a car they don't even drive, we *might* encounter some resistance. Don't worry ~ after her first Z ride (and thinking all the guys are turning around to look at HER), she'll be easier to convince about your investment.

You might be able to compute your compression ratio here: http://chainganger.co.uk/Page2/Page2.html

Your cam will have some secret numbers scribed into the front bearing, readable when you take the cam cover off. If the car is stock, you can research that info in your Datusn Field Maintenance Manual (or ask here), without removing anything.

This whole Club is awesome. We are a bunch of friends who own Z cars. Most of us know most of us. We do things together, we help each other and we really are sort of a (whacky) family. We care about each others' cars and we have a lot of fun learning new "Z stuff" from each other.

You're gonna have a lot of fun in here.

Frank T

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1970 240Z

"They (wives) tend to get all involved with worldly things like paying bills, feeding the family, sleeping indoors, wearing different clothes each day, etc.....stuff which isn't all that important to us guyZ."

You constantly crack me up Frank! You make catching up on forum traffic every night an entertaining event! Thanks!

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Phil
1981 280zxt - Now in the care my son!
2014 370Z Sports Touring Roadster

Hey, it ain't easy being a Z-guy. We all have stories........

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1970 240Z

Got a present in the mail yesterday....


Hopefully I can get to the garage some time in the near future to install it.

So I have done a few things to the car before I took it home from the garage. I was going to install the new RT diff mount until I realized my existing stock diff mount was in good shape. Turns out the clunking noise from the diff was the two bolts on the back that bolts to the mustache bar were FINGER TIGHT!!! Tighten them up.....job complete.

Also put the interior back in from when I installed the sound deadening. Wow I hate my carpet kit. Definitely putting a new 1 piece carpet kit on the list to buy. Any suggestions out there on what I should buy?

So two weekends ago I took it home but the weather has still been cold and I my body does not like being cold. So driving a car with no heat is not in the cards.

This past Wednesday I had the new exhaust welded in at my mechanics. It consists of 2.5" pipe, a 2.5" glass pack, and a magnaflow muffler topped with a magnaflow tip.

Sounds night and day better. I have a video of the exhaust before that I will be posting but I have yet to make a video of after.

Now the sad news...
The day I brought it back from the mechanic I noticed a puddle in my driveway under the gas tank. The fuel pump is pissing fuel out. I have a new pump at my garage that I will hopefully install next weekend. It is a red holley electric pump that is mounted to the right of the fuel tank.

I will get the videos posted as soon as possible.

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Adam Perry
Datsun 260Z

I went to a the 8th annual WPI car show this past Sunday. I had no idea about it until my buddy called me on Saturday night. Ended up being a pretty decent turnout. I entered in a loudest exhaust competition just to see the readings not because I thought I was going to win...





Here is the video of the entire loudest exhaust competition. It was taken with an iphone so the quality wasn't very good. My car is at 10:56. I ended up getting 111 decibels. The winner was the Barracuda drag car at 122 decibels.

http://youtu.be/AUTuZNu965w

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Adam Perry
Datsun 260Z

Your Z wins the "most distinguished exhaust" award.

Completely different than any of the others, with a deep rich, confident tone. Maybe not the loudest, but certainly "Best in Show".

That makes you wish for a 20-mile-long Jersey barrier against the left lane, as you fly by with the window open!

Frank

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1970 240Z

Its that time of year to get an inspection sticker. I am nor to worried about passing except I have to repair my hazards and running lights.

The issue I am having is the hazards only blink on the driver side which I think I corrected when I removed the console and reinstalled it. I am assuming there was a bad connection at the hazard switch.

The other problem I had was the passenger running light would not work (blinker worked ok)

I investigated the front turn signal sockets and noticed that the previous owner had spliced the 240Z specific sockets when they converted the front ends. The splices were made with solder so they seemed ok but they have seen better days. The wiring at the sockets themselves were in extremely poor condition (lots of corrosion) Just an all around bad connection at the bulbs. I decided to take them apart and re-soldered the leads, filed the contact points, made new grounds, reinforced the wiring and a cleaner tape job.


This picture shows a new hole drilled for the wire to pass through. It was then filed down to made good contact with the bulb.











Old soldered connections cut out and being replaced







It works!

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Adam Perry
Datsun 260Z