"that's where you need to be for all the emissions stuff to work"

Uhhh... no.
There are always unburned hydrocarbons regardless of mixture, NOX formed by too much temperature, CO by not enough oxygen etc.
Doesn't work, and they don't use it.

_________________

"wide band closed loop thing"
Wide band is the more modern (=$$$) exhaust O2 detector for feedback, can auto-correct mixture comfortably below 12-1, I don't know how far. Closed loop just means the system provides a signal back to itself ("How'm I doin?") and makes changes as required.
The reason lamda systems are deprecated is that the signal strength indicating rich/lean fades out a lot below 14-1, so the diff between 12 and 14 is almost undetectible. However: once you know what jet gives you 14.7 (fairly accurate), you increase the flow area (metering rod) or size (main jet) by... wait for it.. 17.6% to get 12.5-1 mix (14.7/12.5).

20-1 requires very hot intake air, hot water jacket, 55-60 degrees advance, very tough to set up - probably not practical except as an experiment.

By ram pipe you're talking about the entrance to a Helmholtz resonator as an air cleaner can? Tune for 180 f/s gas speed at power peak - it's smaller than you think, definitely not carburetor throat size. think of the snorkel on an air cleaner - that's what it does.

_________________

thanks!

do you are leanin to the EFI side? (no kidding, just wondering) or you think that carburetion still has something to give?

_________________
Juan Ignacio Caino

Please use e-mail button istead of PM'ing. I do log in sometimes but I'll be answering quicker thru e-mail.

I think the 'get-you-in-the-door' price is higher for fuel injection. This includes the hardware, and then the software to tune it (plus a lap-top if you don't have one)........


But to really get both properly tuned, you really need a wide-band O2 sensor, tach, vacuum gauge, boost gauge (if applicable)............ so you can see what's going on.... Then you can tweak things to see what's happening (jets, bleeds, rods.....).

Being cheap I used a narrow-band O2 sensor with a digital voltmeter (had to then convert millivolts to A/F mix with a handy-dandy graph I found) to tune my motorcycle's CV40 carb..... It was interesting seeing how the mixture changed under various conditions, throttle settings, and purposely going too rich or too lean with jets and needles to see what happens, and when the different circuits (idle, needle, WOT) come into play...........


As an aside, (found it somewhere on the internet), the recommendation was to get your fuel mixture correct then play with ignition timing as fuel mixture as an effect on timing, but timing doesn't have and effect on mixture.

_________________
Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

hey ed

I'm interested in the cheap o2 sensor method... would you send me those charts? measuring mV is within my basic skills... plus about the timing thing, IIRC advanced timing creates an "artificially lean" condition and viceversa.... wich I think means that if you use lot'sa initial timing you can get away with richer carburetion... Anyway I think that this has close limits....

Plus, if you're so kind, wich brand or model or what o2 sensor are you using and where you place it for taking your reads.

_________________
Juan Ignacio Caino

Please use e-mail button istead of PM'ing. I do log in sometimes but I'll be answering quicker thru e-mail.

I did this on the motorcycle, haven't done it yet on the valiant........

You'll need an O2 bung and plug (18mm, summit has them so you can see what I'm talking about)

On the motorcycle I welded the bung on the crossover tube near the front header pipe. It was out of the main flow so it wouldn't obstruct flow, but close enough so it would see the exhaust mix and stay hot.


If you're close to the exhaust manifold (like where the exhaust pipe connects to the manifold) you can get away with a 1-wire sensor. Farther downstream (past the steering) you should use a 3-wire (or 4-wire) heated sensor. Basically where you can weld the bung. Get a plug too so that you can plug up the exhaust and save wear and tear on the sensor when your done testing...


The sensor was a BOSCH (I've had problems with no-name sensors on my truck) and would recommend the BOSCH. It was the CHEAPEST 1-wire BOSCH I could find that had 18mm threads to match the bung. Just about all sensors are interchangeable except for the wiring end, and if you're doing it yourself, the wires don't matter. I also have used a 3-wire BOSCH that I retrofitted to my truck (had to add wires for the heating element) that helped it to run better when it was cold........ The cheapest 3-wire BOSCH is BOSCH 13913 and crossrefs to various fords. (don't have the 1-wire part number handy, but just get the cheapest BOSCH)


I'll need to look up the graph for mV vs A/F.........

_________________
Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

look here:

http://www.datsuns.com/Tech/oxygen_sensors.htm

http://www.geocities.com/MotorCity/High ... ambda.html


Do an internet search for 'lambda sensor' and you'll come up with a bunch of stuff..............

_________________
Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

I was told to not use that kind of balance tube, but connect the vacuum chambers on the carbs instead...
Any thoughts?

Well, if for "production engines" you´re referring to anything that you might wanna want to be able to roll out the garage by its own power, you´re kinda right

This argentinian guru Nestor Penin said once that never is so hard to work on a race car as it it to work on a street daily driver unit... cuz you have to get the extra power yet keep it streetable. No matter if you drive "fast" or "nutsy", a race car won´t do it for you if you wanna get the wife to the wallmart. As a matter of fact, his son, who is dedicated full time to racing engines production, tune and development, doesn´t work on street engines. He sez that's too hard to get right.

Even the dual 1 barrel manifold (I think that Offenhauser markets those up there, sown here there were factory OEM piece on some models) has a balancing tube, less than half the size of one runner, connectinc the plenums and providing PCV port while at it.

_________________
Juan Ignacio Caino

Please use e-mail button istead of PM'ing. I do log in sometimes but I'll be answering quicker thru e-mail.

I wonder if the balance tube was ONLY for the PCV system so that both sides would pull from PCV valve..................

_________________
Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

Unless you need the PCV system like above (or brake booster), I don't see the need for a balance tube.............

You have essentially 2 3cylinder engines with even pulses between each cylinder.


If you could deactivate a carb, then you could have a 3/6 cylinder engine for really good fuel economy......

_________________
Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

I will tend to think that the balance tube is there not only for the PCV connection. Altought is neccesary, I wouldn't think that the balance is for that only reason. I think that at high speeds, you ain't have time for crosspulsing to become an issue even balanced, but on the lower side, a balance tube, while you're minimizing the crosspulsing, it helps to keep the unused carb "kinda awake" so you don't have to overcarburate. That's my poorly educated guess.

_________________
Juan Ignacio Caino

Please use e-mail button istead of PM'ing. I do log in sometimes but I'll be answering quicker thru e-mail.