popping through the exhaust at 4500 rpm or so.. HELP!

[motorman7]

It is so dumb, that I would be ashamed to admit it unless it is the actual problem.

Yes, suspense thrillers keep the audience enthralled

They do, that's what keeps me hooked to this thread. Perhaps we can drag this on for years .

[Diseazd]

It is so dumb, that I would be ashamed to admit it unless it is the actual problem.

Yes, suspense thrillers keep the audience enthralled

Like the time I put a new set of Nissan points in my Z and it wouldn't fire...........drove me crazy...... till I noticed they put a small piece of paper between the points for protection. Cars run better when they have fire to the plugs!

[Zedyone_kenobi]

OH no, much worse...

I will know if I am a total moron in about 3 hours.

[Mike W]

Leon,

Thanks for the nice comments about my throttle setup and the return springs. A few other comments that might help you out.

1. The springs that you saw in the last pictures that I posted are no longer on my car. These were springs and brackets that were made for the 40 DCOE (and that I purchased directly from Pierce Manifolds where I also purchased the carbs) but unfortunately they only work on one side of the carb (unless you decide to modify them like I did so you can use them on either side). Although I liked how clean the installation was with these, they ended up not working for me as they did not provide sufficient return strength to always get my engine back to a normal idle (900 - 1000 RPM's). I think that a part of this was due to the fact that I could only use 2 springs for the 3 carbs and that I had to locate the springs in a different place on the return arm than what the original design intended. Much of this was due to the nuances of my particular installation. The pictures that I have attached to this post represent the latest version of my return spring setup.

2. The throttle cable setup I have has evolved over time. I originally bought a complete setup from Top End Performance (who apparently does a lot of aftermarket stuff for Z's) and this included a special bracket that attaches to the 4 bottom screws on one of the 40 DCOE's. The rest of the seup from them was fairly generic other than the attachment mechanism at the pedal. This did require a slight modification to the pedal, but it was not a big deal. Since then I have changed out the cable to one from Lokar. The Lokar cable is much more substantial, is done in polished stainless steel (so it looks a lot nicer) and has much better attachment hardware in general. You should be able to see this in the attached pictures. The Lokar P/N is TCP-1000HT and I purchased it form Jegs for about $70. I did reuse the carb bracket and the pedal fitting that I originally purchased from TEP. I really like the look of this as well as the performance. It is a much beefier setup than the one from TEP as well.

3. Finally a plug for Dave Cerutti. Dave has developed a really nice throttle linkage setup for the Webers and he fabricates these in billet aluminum. He even went as far as to make me a special arm that I use just for the throttle cable assembly. Again you can see it in the atttached pictures. They look great, are easier to adjust, and in my opinion are a lot sturdier than the standard throttle arms that typically come with aftermarket Weber setups. He is a great guy to work with and has a fabulous product. I believe that he has advertised these in the classified section of this site.

If you would like to try the older return springs that I used prior, just let me know and I would be happy to send them to you to see if they will work for you. As I said, they are a very clean design and made for the DCOE's, but I just couldn't get them to work in my setup. I find that one of the finicky parts of the Webers is throttle return and I have had to go to a couple of fairly strong return springs so they work in my setup.

Let me know if you need anything else. Would be happy to try and help you out.

Mike.

[Zedyone_kenobi]

Update: no luck with what I thought I did. I am not a moron, my setup is fine. Still popping through the exhaust

Looks like motorman will get his wish! Haha

[Zedyone_kenobi]

Still waiting on carburetors. MSA was out of them. I did look up and join sidedraft central. Very cool website. I will post what my carbs come with out of the box for reference. Blue, I will let you know if I get 151's or 152's.

[240260280z]

But... if ZT proved the carbs then it ain't carbs.... good chance you will have a similar problem with any carb.

[Zedyone_kenobi]

I take the car out and get the the car to sit at 16.8:1 with it popping and sputtering, then I slam the choke all the way back and the AFR drops to 12:1 and the car takes off like a rocket ship.

Whatever is going on, my car is NOT getting enough fuel. Or it is not using the fuel in a manner that is 'normal'.

If it still has this issue, then we can definitively say it is not the carbs.

I do believe that Ztherapy gave them a look at. But I am just not sure how in depth they actually looked for issues. I think he drove around with them, but heck I can drive around with them for 2000 miles and the car will run like a top. You have to search for this failure. I casually drove with this going on for over a year before I noticed it. Now that I know it is there, I feel it constantly.

I may be wrong, and I will admit it if I am, but I would bet a shiny new nickle that Webers solve this.

If I am wrong, then consider this the most expensive test of a theory in the history of Z cars.

Edited March 26, 2012 by Zedyone_kenobi

[LeonV]

Have you tried experimenting different needles heights, as I mentioned earlier? Might as well...

[Zedyone_kenobi]

I scooted the sm needles further in and the car barely idled it was so rich then it leaned out again and popped. I also verified my coil is getting 13+ volts during engine run

[LeonV]

This keeps pointing to a vacuum leak, at this stage. Popping occurs at the point of high vacuum and higher-than-idle fuel demand, and it gets better with more fuel. Seems like the mating surfaces have been checked, as well as hoses (booster, PCV, vac advance, any emissions hardware, etc.). I suppose you could double check (triple or quadruple at this point?) anything that is exposed to manifold vacuum.

We'll see how the triples respond.

[240260280z]

What if you just lower the jets and tune for ~ 14-15 at cruise... what then happens at WOT and idle?