Carb issue

[Alex240z]

1st and 6th spark plug. Weird that I’m running rich but the engine won’t start unless I fully push down the pedal. I’m completely lost. In the mean time I’m going to get a new pair of plug cables 

[Alex240z]

hello! Some "progress." So... I guess I wasn't getting spark on all engines. I was getting about 3/4 cylinders max. Which is great to know cause I drove the car like that. Sweet. In a way makes sense why the front carb was always running lean while the rear carb wasn't doing much because it was the front 3 cylinders that were getting sparked. I got myself a new set of spark plug cables and put them on. Haven't had the chance to actually try the car out because its final's week. Another thing I got done was putting the original needles back on (n27). I was running m43 needles I got off a kit because thats the only way the engine would run. They were a couple of mm shorter than a n27 needle. Then I tried a n54 needle that also came with the kit. Hopefully I've have better luck with the n27. Also I found a method to set the float with the jet is turned down 10 turns so I'll try that out. Wish me luck. 

[AK260]

Well done you! That is great progress indeed!

I’ve spent an unholy amount of time playing with carb needles and springs. The strange thing is, I would have said that N27 may be too lean for your engine, but then someone here in the UK found they worked great on a 3.1L stroker! Go figure! Unless you have a wide-band AFR sensor / gauge fitted, you are forever guessing. But with a stock engine, the N27 set up richly or SM set up 2-2.5 turns down, should serve you well.


Good luck with the finals.

[Alex240z]

hello! it's been a while. Unfortunately I got caught up with work and other matters. I finally got some progress and discovered other things. My carbs are finally working! I ordered a 14mm color tune kit and I was able to dial in the carbs to idle around 800 and I got them to run a little rich at higher rpms. I found out something however which I don't know about. I did all the tuning on the carbs with the vacuum advance off. The second I put the line back onto the first carb the car started "tweaking out." Started misfiring and popping in the high rpms. The distributor is a single point kind and I do have a dual point laying around. Just don't know how to convert my electrical for it. Thanks for any input. 

[Mark Maras]

 I always tuned my carbs with the vacuum advance connected. Leaving the hose off will act the same as a vacuum leak, on that carb, and the mixture will change when it's all hooked up. I'd try retuning the carbs with the v. advance hooked up. Why do do want to install a dual point distributor? Personally, I prefer single point distributors.

[Alex240z]

34 minutes ago, Mark Maras said:

 I always tuned my carbs with the vacuum advance connected. Leaving the hose off will act the same as a vacuum leak, on that carb, and the mixture will change when it's all hooked up. I'd try retuning the carbs with the v. advance hooked up. Why do do want to install a dual point distributor? Personally, I prefer single point distributors.

Under my impression I thought dual point would give a better spark. After some research it seems like it was made for emissions. I’ll retune the front carb and see if it makes it any better. Wonder if that was the cause of the pops under load. 

[Alex240z]

So I tuned the car. Doesn’t help that I’m colorblind (a bit) so the color tune is a bit hard for me to tell. I think it ran lean because the engine was bogging when I test drove it. Temp gauge goes all the way up when I drive the car. Probably dead. (I hope) I richened the carbs a half turn then it started popping so I’m going to lean it out an eight or more. One thing I’m curious about is the float setting. I have a 4 screw and the setting for 70-71 carbs are 13/32” but I set mine at 9/16” which is for 72. Not sure if this could be a cause as well. 

[Mark Maras]

The easiest method to verify (set) the float level, I've found, is remove the domes and pistons. Raise the nozzle screws up to the top and then turn them 9 1/2 - 10 turns down. The fuel level should be at or near the top of the nozzle. That puts the fuel level 3/8" (recommended) below the carb bridge. Close is good enough. No need to get obsessive. 

[Alex240z]

2 hours ago, Mark Maras said:

The easiest method to verify (set) the float level, I've found, is remove the domes and pistons. Raise the nozzle screws up to the top and then turn them 9 1/2 - 10 turns down. The fuel level should be at or near the top of the nozzle. That puts the fuel level 3/8" (recommended) below the carb bridge. Close is good enough. No need to get obsessive. 

Only issue with that method I found is I have a plate under the locking nut that stop it’s from going lower. I don’t know if it was set wrong or what because it’s adjustable. But if I try to do 10 full turns (not sure if it’s half or full) it just stops around 4 1/2. After a search of 4 screw carbs I couldn’t find one with the stopping plate. 

[Mark Maras]

 Is the stopping plate removable? I remember something like that on a set of 4 screws I had. If I recall correctly, it was removable so one could remove the nozzles.

[Alex240z]

1 hour ago, Mark Maras said:

 Is the stopping plate removable? I remember something like that on a set of 4 screws I had. If I recall correctly, it was removable so one could remove the nozzles.

I’ve been able to remove the nozzles without taking it off. Only thing it really did was stop the adjustment nut from going lower then it was set so it doesn’t come off the thread. Which the spring already does I believe  

[Mark Maras]

The spring definitely holds the nozzle screw in place. Can you remove the stopper plate? As I recall it is screwed in.