What is the optimum air fuel ratio for our trucks? I have been getting conflicting data. Mine is right at 12.5 at WOT.?????

 

11.8 - 12.2 is my opinion, but it all depends how far you are pushing it. I think spray'n Rob02 is mostly in the mid 10's.

-Mark

 

Optimum A/F ratio is 14.7 that there is the laws of Chemistry.

Unfortunatly, the risks of going lean (computer can't react as quick as you can when you open the throttle etc...) and lots of other issues (gas is often used to cool the cylinders) means that the best A/F ration for our trucks is around 12.5 but that will vary based on tuner and opinions.

Coldie

 

11.8-12.0

 

Coldie beat me to it! "Optimal" AF is 14.7, or stoic. However, on our trucks, that figure changes depending on your mods. With mild timing and a roughly stock truck, I don't think mid-low 12s would hurt anything. But a pulley-ed truck should command mid to high 11s, depending on other mods. A nitrous truck should see a lot less timing and more fuel depending on the shot and whether it's a wet or dry system.

Again, notice how much I'm using the term "depending"....

 

I thought that the 14.7 was optimum for emmisions? I guess I am safe. Thanks guys

 

The optimum A/F ratio is probably what the truck is as stock.

I think the better question would be :

What are the optimum A/F ratios for X degrees of timing??

Timing has everything to do with melting down when running too much.........when also too lean.

I have a 4# pulley without a chip................am I taking chances?

I don't think so. I have stock timing. I seriously believe that my A/F's are the same as stock. Yes it has been on a dyno.

Just my .02 cents worth........now gimme some change. LOL


P.S. I'm going next weekend to tow my '37 GMC 2.5 ton truck, 500 miles. I'll let ya'll (dats Texan if'n ya didn't know) know if I melt any pistons, or spit any of my original 60,000 mile plugs also.

Oh, BTW, I'll be going from 5700' alt., to sea level, and to 7400' altitude, and ending at 5700' altitude.

Rock & Roll Baby
-----------
Rick

There is NO nothing listed in my sig, so FO.

 

Good luck with the tow. Seems ironic that the ford has to tow the chevy!

 

Well.......mission acomplished!!!!!

No Chip.........4lb. pulley.........and no spit plugs.........burned pistons, or plugs...........no burned, or broke anything.

Please don't try this at home.!!!! I'd have to say that my A/F is fine.

---------
Rick

NO SIG.

 

I prefer 11.5 or somewhere within 0.3+- of there...I would rather be safe than sorry. I have ran that with a 6#, 4# and a 2#

-dennis

 

12.5:1 a/f is fine on a n/a engine, on our trucks it's living on the edge.`

 

okay I have no detanation issue ,16 degrees of timing. and the A/F was done in the tailpipe? gonna have a bung welded on and run with a LM1 next time but I think I may have my chip "richened" Thanks Guys!

01ArrestMeRed: Thats a solid old truck and big. You making a ro;; back out of it?

 

I'm also running 16 degrees. I haven't dynoed yet. My understanding is measuring at the tail pipe gives about .5 leaner reading than actual A/F measured close to the exhaust port.
What are your mods?

 

What is the timing and A/F on a stock Lightning?

I've never heard what the base is.

TB

 

'01's wife here.............. he's at work.

That truck is completely rust free. It has 22,000 original miles on it. The truck was purchased new by Esmeralda County, NV after all the pipes in town froze one very cold winter. The truck was used to haul water. It has spent its entire life there. The lack of rust is due to the extreme dry conditions in Goldfield NV.

We have everything for it, including 1 brand new swing out turn signal. The original engine froze one year, but we plan on putting a diesel in it. A roll-back is part of the plans for the truck.

You will never see another one. Most were scrapped during the war. About all you see of that vintage is the 1/2 ton trucks.

To me, that truck is just way too cool.

Yes the truck was seriously overloaded with the '37 on the trailer. Unfortunately, you do not know this till you put it on the trailer as specs (weights) are not available anywhere that we have been able to find. However, the biggest problem was that, due to the length of the truck, you are not able to position it any further back on the trailer. Thus, you do have alot of tonque weight. We know it is real heavy from the fuel mileage. The truck only averaged about 8mpg towing it home (vs 10mpg when we were towing an 8500lb load the same route).

Like usual though, the L didn't mutter even one little complaint............. she just pulled. :o) She's a hell of a truck.