Restoration of BringaTrailer 240z - HLS30-35883

[Pat Carr]

Looks like I'll be changing the plate on my '73.

[inline6]

"sticky" throttle linkage has been a problem with two out of two 240z's I have owned.  To go from no throttle to just a little it of throttle, there is noticeable resistance.  I notice that as I try to apply a gentle amount of force, nothing moves.  Then I apply more force and more force, until finally, the linkage "jumps" open and the car jumps forward.  Driving the car to work the other morning for some show and tell, and getting into the midtown Atlanta area during the commute, this issue was extremely annoying.

Yesterday, I worked on all parts of the linkage for the better part of 2 hours.  Everything in the linkage has been examined and lubed.  Adding grease to the auxiliary throttle shaft (5) helped a little.  I disconnected all of the pieces in the linkage and checked each one for issues.  Each piece in the system operates smoothly.  With the gas pedal disconnected, and carburetor linkage return springs disconnected, I operated the connected parts of the linkage.  So, the (5) aux shaft connected to the throttle shaft that slips into eyelet of the bracket on the fire wall, the rod that connects from that shaft to the bell crank, and the rod that goes from the bell crank to the gas pedal.  

 

The only thing I can detect as a potential problem in that assembly, as far as resistance to movement goes, is that the rod that goes through the rubber bellows may be rubbing against the inside of the bellows a bit.  It is hard to tell with the other end of that rod disconnected from the gas pedal.  But I felt some kind of rubbing or vibration coming through the bell crank when operating the linkage.  

I removed the gas pedal and its mounting bracket (which is made of plastic) and put grease on the pivot points.  With that reassembled, I tested movement of the gas pedal alone, and it operated smoothly.  However, when I reconnected the gas pedal to the rest of the linkage, and put the carburetor linkage return springs back in action, unbelievably, I got a squeak at the gas pedal pivot (which I confirmed was unrelated to the spring that is there.  That is what I chased for a good part of the time I was working on this "little" issue.

After I got that quieted down, I decided to do a brief test drive around the neighborhood to see how much better it was.  I was able to control the throttle application a little better, but it's not good enough for me.  Anyone else have luck addressing this?  I have an old recollection from when I dealt with this issue on my other 240z many years ago.  I believe I ended up changing the length of the adjustable connecting rod and that was helpful.  In concept, that would alter some of the operating angles of the system.
 

Edited January 19 by inline6

[inline6]

Oh, while I was doing the test drive, the rear carburetor needle/seat/float failed again.  This, after I was able to drive the car many times, and trouble free for about 100 miles.  I was about a quarter mile from the house, and the engine started to fail to idle.  I wasn't sure what the problem was, so I limped it home.  When I opened the hood, I smelled gas, and saw that fuel was all over the place and dripping onto the header.  

Awesome.  

I decided to take a thin wire and reach down the float vent tube... to tap the float, which in theory, would unstick it.  I tapped the float down and it bobbed back up again.  I did this several times, and could hear the float contact the needle when it would bounce back up.  Bounce, bounce, bounce, followed by tap, tap, tap.  I turned the ignition key and several geysers of fuel came out the float vent. 

Awesome.

I stopped there.  I think I will replace the needle and seat next.  There must be something wrong with it. 

Edited January 19 by inline6

[inline6]

I bought some of this yellow paint to see if it might be close to the stuff that was used in the original assembly line.  

 

 

It was inexpensive, so I thought I would have a look.  Lighting is a big factor in the look from a picture.  But here is an original fastener with paint that is in pretty good condition, along with a fastener that I dipped into the new paint.  My skin color is darker in the picture of the new paint, which tells me the lighting is darker.  

 

I also took a picture in another room (kitchen) with different lighting.  It looks reasonably close in the pictures, but I think is a bit "lighter" than the original paint.

Edited January 20 by inline6

[dutchzcarguy]

I think you scored the right paint.. the old bolt with orig. paint is old AND dirty.. so the new paint looks good for it's job.

[Freez74]

I think the throttle issue is related to the bellcrank on the firewall under the hood.  On my 74 I noticed the the angle from the bellcrank to the auxiliary throttle shaft was somewhat extreme, so I cut the upper arm off a spare bellcrank and welded it on higher up on the tube.  This reduced the angle to the throttle shaft and made it a little easier to control the application.  I got this idea looking at an early 240 bellcrank.

[Patcon]

On 10/5/2024 at 9:08 PM, inline6 said:

am pausing on the seat bottoms for now.  I need to think about how to make them look right.  It is going to require something other than just hog rings to secure wire in the flap to the wire under the Pirelli straps.  More distance will be required to keep the material from being yanked down too far.  

In the meantime, I got the small parts back from the chrome plater.  They came out nicely.  These cost about $250 to have redone.

Who did this chrome work for you? and what are the two flat pieces with the lip?

[inline6]

7 hours ago, Patcon said:

Who did this chrome work for you? and what are the two flat pieces with the lip?

This is the place:
Decorative Metal Coatings
2613 Temple Heights Dr. Ste. C
Oceanside, CA 92056
Tel: (760) 746-3378
Fax: (760) 940-8781
Email: Accounting@DecoMetalFinishing.com

Those plates are part of the ash tray parts.  The plates seems to be something you can grab onto to lift the front of the ash tray out of the console.  I had two sets of ash tray parts done.

[Patcon]

Thanks for that. I have a number of parts that will need chroming. Gas door latches, hatch thimbles, ashtray parts, int door trims. Could get expensive...

I found a company in Marietta. Did you speak to them?

https://www.chromeatlanta.com/?utm_source=GMB&utm_medium=organic

[Patcon]

26 minutes ago, inline6 said:

This is the place:
Decorative Metal Coatings
2613 Temple Heights Dr. Ste. C
Oceanside, CA 92056
Tel: (760) 746-3378
Fax: (760) 940-8781
Email: Accounting@DecoMetalFinishing.com

Those plates are part of the ash tray parts.  The plates seems to be something you can grab onto to lift the front of the ash tray out of the console.  I had two sets of ash tray parts done.

Did you have a good fuse cover? Mine has defects and I will have to figure out how to solve that. There are repros available that aren't very cheap but I am not sure how accurate they are. Some of the used ones are pretty pricy!

[inline6]

The replacement connecting rod for the carburetor showed up in the mail today from ZTherapy.  Thanks @Patcon for suggesting I contact them.  

Unfortunately, the replacement needles and seats did not show up in the mail today.  So, I found myself removing the rear carburetor needle and seat... just to have little look see at it for issues.  Well, one thing led to another, and I found myself on Youtube watching a video someone made about their needle and seat not working properly and causing fuel to gush everywhere.  That person used a Q tip in a drill and some metal polish to polish the inside barrel of the seat.  I decided to have a close look at mine. 

I wasn't able to take a good picture, but you can kind of see from the above one that the inside of the seat bore where the needle sits is not exactly smooth.  So, I grabbed a small section of 1500 grit sandpaper and rolled it around a drill bit which I inserted into this bore.  Using the drill, I smoothed out the ridges on the inside of the seat.  

Then I used a Q tip and some metal polish and a drill to polish the inside of the barrel.  I then sanded the corners of the needle with some 2500 grit sand paper and polished the corners of it as well with the Q tip and metal polish:
I 

After cleaning them, I put the needle and seat back together in the carburetor.  Because I had to take the linkage apart to install the new connector rod, I synchronized the carburetors again. 

Here is something interesting: While I did the standard balancing procedure which included setting each carburetor's set screw so that each carburetor had the same flow at idle, and then screwing in the auxiliary shaft screw (to activate the linkage against both carburetors) and setting the balance screw to have the same flow during throttle application, I also did something similar for the choke.  This is not something I saw in the factory workshop manual.  

For proper choke function, the factory workshop manual provides instruction to set a specified gap between the throttle plate and the body of the carburetor when the choke lever is pulled.  This is to be done for each carburetor.  After this is done, in theory, when you pull the choke lever, the choke mechanism will open the throttle plates on the front and the rear carburetor the same amount.  I did as instructed in the factory workshop manual. 

However, I then started the car with the choke lever slightly activated.  This raised the speed of the engine above normal idle speed.  And then, I checked the flow of air through each carburetor using the Uni-Syn.  Well, the flow was not the same. Similar to the procedure to balance the front and rear carbs when the linkage is activated, I used the Uni-syn flow meter to set the flow between the two carburetors to the same amount with the choke lever in operation (slightly).  To adjust flow I had to shorten/lengthen the connecting rod for the choke. 

After completing this adjustment, when I pull my choke cables to start the carburetors, both throttle plates are opened to a position where both carburetors are flowing the same! 

I never was able to get the chokes working well on my track Z (when it had SU's), but I think this will be the ticket to getting the chokes to operate well on this car.  I will be able to test that tomorrow when the engine is cold.

I did take the the car for brief drive after messing with the needle and seat.  So far, so good!  I hope I have solved the issue with the rear carburetor puking fuel.

Edited January 26 by inline6

[inline6]

23 minutes ago, Patcon said:

Did you have a good fuse cover? Mine has defects and I will have to figure out how to solve that. There are repros available that aren't very cheap but I am not sure how accurate they are. Some of the used ones are pretty pricy!

Regarding the fuse cover, mine was slightly melted.  I found one on Ebay a while back that was decent.  Do not use any kind of thinner on them to clean them up.  The white lettering on them is painted on and will rub away easily.

I am pretty sure that the place in Marietta is the same company.  When I contacted them, they responded from CA.  They said that during Co-vid, the had to shut down the GA location, but that they were the same people.  It was expensive.
 

Edited January 26 by inline6