Carter AVS Lean Spot

[kawahonda]

What's your thoughts on step up springs? Going softer is basically going leaner. Pink spring is rated at 7" vacuum (14") and is closest to my vacuum in drive.

[RUNCHARGER]

I would leave them.

[Chryco Psycho]

 

[kawahonda]

Going to have my dizzy guy take another look at my distributor. I'm starting to question 14 initial. Usual "around city", "peeling out" stuff is fine, but get that engine really spinning on the highway and floor it (best way to add "load)...I'm STARTING to think I hear some very faint pinging. It's intermittent and has me questioning my self, which is already a decent sign to back off 1 degree: tells me I should reduce it to 13. Kinda weird running a recurved distributor at 13 initial. I'm going to ask my guy if it makes sense for him to reduce mechanical down. No reason this car shouldn't be playing at 15-16 initial, and for it to be completely safe at that.

For your enjoyment, here's some videos I took today after rod change.

"aggressive" foot during dead stop:

Doing a little burnout....It used to take a lot of effort (having to load engine a lot, and hope for no stumbles). Now it was just a quick and easy thing:

These videos may seem weak, but It was running so lean where doing any of that consistently was a chore and by chance. Ignore my stupid voice of excitement, but I was very shocked at the difference these rods made compared to the last rods (which made a positive difference too).

[kawahonda]

I was watching an episode on Tony's Garage, and he mentioned something interesting. If some cylinders are burning leaner/richer, then it's common to change jets that are corresponding to those said cylinders. I was thinking about that! May be good to keep that in mind and mark/document plugs after another 50 miles.


1         3
1         3
2         4
2         4

front

1 = passenger side, secondary
2 = passenger side, primary
3 = driver's side, secondary
4 = driver's side, primary

If one whole side is showing leaner cruise readings, I'd assume that probably means a metering rod change only if a cruise reading.

In practice, it's probably much harder than it sounds though and requires you to isolate cruise vs WOT for readings. Interesting though, and explains why the awesome literature that was posted a few pages back shows a tuned 340 having offset jetting/rods.

[Chryco Psycho]

On a dual plane intake the jet listed would not affect the cyl in you diagram ,
so you would have #1 4 on the same jet

[kawahonda]

INTERESTING. See, that's good for me to know.

1 and 4 = same jet (that means both primary/secondary systems)
2 and 3 = same jet

That would make plug readings much more interesting....

[Chryco Psycho]

Follow the path of the intake you shoudl be able to see which runners are connected together

[kawahonda]

Is it true that WOT jetting (secondaries) can only be checked by the "turn-off" method and cutting the plug to look at base of insulator?

[Chryco Psycho]

Basically yes , idling down can add or remove color , however we know you are lean so you have felt the difference in changing the primary side with different rods so you should be able to feel if it is improving by richening the secondary side also & use the plug color for backup

[kawahonda]

Maybe as I wait for my distributor to get back from Hillside for a diagnostic/check-up, I'll throw these 100's in.

Carb started with .096 (ECS spec)

changed to .098 awhile ago. Prob still lean.

.100 prob isn't a bad idea.

[kawahonda]

I'm looking to REALLY nail in the pump shot.

I noticed today that I have some slight throttle movement before I see fuel come out. It's pretty slight, and I've only tried with a slow motion of moving the throttle.

If I wanted the pump shot to happen a fraction of a second quicker, is that raising, or lowering the stem? I'm assuming the best possible setup is if you simply just put ANY motion whatsoever, even slight, you should see fuel come out of the squirters.

I remeasured my stem at it's 11.5mm. Factory measurement I think is 11.2.

[Bullitt-]

You may get desired result by adjusting/shortening the linkage to the accelerator pump

  The hole closer to the carb body I believe delivers a quicker complete shot as it doesn't have to move as much for full travel