Anyone hooked a wideband up to they're datto?

[lynchfourtwenty]

im gettin a wideband an i was kinda thinkin about hookin it up to my datsun before i put it in my car.. figured it would make it easy for me to dial in the air fuel mixture..

 

anyone know what the ideal WOT a/f ratio would be for a carbed l20b? lol

[Duke]

It all depends on what you are trying to tune for. For maximum power, an afr of 12.5 is said to be ideal at WOT. However, that is only if power is what you are looking for. Stoichiometric ratio for gas is 14.7 to one, which is what I would shoot for on something that is daily driven, maybe with it a little richer under hard acceleration. Some searching around on the internet will give you some good articles on tuning with a wideband.

 

After using a wideband myself, I wouldn't use anything else for tuning carbs.

[lynchfourtwenty]

ya my trucks not daily driven, but then its not a race car either, im just tryin to sort out a few things..

 

for some reason she just doesnt have the top end she use to, prolly cause shes tired.. idk.. im doin some adjustments an runnin some tests at the moment..

 

main issue is it doesnt really wanna spin faster then 5000 rpms.. it like its a wall an pretty much just stops turning any faster.. i use to be able to take her to 6500!

[Icehouse]

We used a innovate XD-16 on Dave's turbo L motor after we got it running. Just as Keith said it was 12.5 at cruise and 10 at full throttle. Defiantly rich but worth it once the boost kicked in. :)

[Duke]

ya my trucks not daily driven, but then its not a race car either, im just tryin to sort out a few things..

 

for some reason she just doesnt have the top end she use to, prolly cause shes tired.. idk.. im doin some adjustments an runnin some tests at the moment..

 

main issue is it doesnt really wanna spin faster then 5000 rpms.. it like its a wall an pretty much just stops turning any faster.. i use to be able to take her to 6500!

 

Always remember the old saying: 90% of fuel problems are ignition. You may be surprised at how much little ignition tuneup can help with power.

[lynchfourtwenty]

well heres the run down, i've adjusted the valves, im going to do a compression test.. im gonna get some new ngk iridium plugs for her.. i have a blue streak cap an rotor that arent that old, gonna clean the contacts a tad an they should be good for a long time.. i have even newer ngk plug wires.. now my coil, its old, prolly the one that the truck was born with.. i will look into that..

 

also i tested the vac advance an it works.. im going to check the timing too..

 

an icehouse, those #'s are for a turbo motor for sure!! hehe thats way rich for a n/a motor :P

[Duke]

IMO, don't waste your money on iridium plugs, for older motors like yours they don't do any good. Some normal NGK's (NOT autolites, etc.) are all that you need.

[lynchfourtwenty]

hmmm, i'll give em a try.. shes always liked the iridiums tho..

[DanielC]

you have heard it before, do the basics. Valve adjustment, tune up, that sort of thing.

The L-18 I had in my truck seemed to be a little weak on the top end, when i quit driving it. when I pulled the cylinder head off it, I found a good sized chunk of carbon around the stem of the intake valves, from oil leaking past the seals, and burning there. The chunk of carbon was definitely restricting air into the cylinders.

[lynchfourtwenty]

hmmm i doubt the way i drive my truck that would be possible lol, i also run chevron premium fuel.. i mean its possible but i seriously doubt it.. but ya never know :)

 

also i've only had this head on the truck for 4 - 5 years

[datzenmike]

You've probably seen what a blown gasket does for cleaning carbon off the piston. You can simulate this by slowly pouring water down the carb. The engine must be HOT for this to work. The sudden cooling when the water turns to steam will crack the deposits and cause them to flake off. A buddy used to do this every tune up on his '64 Chevy. He'd put cardboard in front of the rad, uncork the headers and rev the shit out of it while pouring a Coke bottle full of water in. It would steam pretty good and all the black shit would fly out over the floor.

 

 

There are some cleaners that you dribble down the carb while running the motor. You have to get the motor HOT and rev it up as you add it to keep from stalling. Run the whole can till it stalls and let sit 15 min.

 

It will smoke like crazy so don't do in your driveway.

[lynchfourtwenty]

lol that sounds crazy mike, idk if im down to do that lol.. i seriously doubt i have a carbon build up, when i had this all apart everything was clean, no carbon or nothin..

 

 

the cool thing about the wideband him getting is i will be able to hook it up to the laptop, i will also be able to hook it up so it sees my rpms, then i can datalog the info on the laptop and cross refferance the rpms / afr's an should be able to tune it in nicely..

[datzenmike]

14.7 to one is the ideal mixture ratio for mileage economy but hard acceleration sucks ass with this mixture. Hitachi carbs have a power valve that enriches the mixture at WOT. At other times it's much closer to 14.7:1

 

You got a Weber? Don't know much about them or if they even have a power valve.

[lynchfourtwenty]

i think its got something like that, has a lil arm attatched to it an shit..

 

we'll see what happens when i get it hooked up heh, i will post info here..

 

i will fucking revolutionize RATSUN TUNING!

 

edit: yep i got a weber

[hang_510]

lol that sounds crazy mike, idk if im down to do that

using a squirt bottle prevents dumping it in too quickly :)

[datzenmike]

One of those plastic sports bottles might be enough. Too little is a waste of time. Superheated steam will remove almost anything. I've done this before on a motor that was really carboned up. The motor has to be revved up good or it will want to stall when you pour. The water removes a lot of heat so power drops off quite a bit. I don't know if it will clean an intake valve as they aren't that hot.