Topic: H8PVMNT's Aisan 22r Carb Tech /Study

[H8PVMNT]

Wheeling/backroad trip this weekend got me 12.5 mpg.  I could pull on the other Toyota with a 22RE and a 4 cyl Nissan on hills though .

[emsvitil]

So if I follow correctly I am looking for a lighter spring if I want less fuel dumping in there?

Vacuum closes the valve, so yes,    lighter spring will take less vacuum to close.

[H8PVMNT [OP]]

Do you think I have less vac in there after opening up the intake air?  Kind of makes sense.

[emsvitil]

No.   The more throttle you need, the less vacuum.

[emsvitil]

and you loose vacuum with altitude

[Gnarly4X]

https://takemebeyondthehorizon.wordpress.com/2009/09/28/how-to-go-fast-faster-the-math-behind-turbocharging-part-3b-brake-specific-fuel-consumption-bsfc/

Yeah.. I've read this post before.  I think it's mostly voo-doo math, wild speculation, and laced with hypothetical unprovable assumptions.

Gnarls.

[H8PVMNT [OP]]

Um, well yeah.  You never, ever want to think you know everything. This thread is about learning, not knowing though so it's OK .  After emsvitil's prodding I decided I had to investigate the power valve thing.  I took 3 of my crusty parts carbs apart and pulled the power valves.  I had two 22R carbs that both appeared to have been rebuilt and one 20R carb that was all original.  What I found was very interesting. 

The 20R carb power valve is the same except the stroke is about 1mm longer than the 22R one. Other than that they are the same and would swap.  The real mind blower though...  The 20R power valve had a jet threaded in the bottom of it.

NONE OF THE 22R CARB POWER VALVES FROM THE RE-BUILT CARBS HAD A JET IN THEM!

I wondered if maybe the 22R carb wasn't supposed to have a jet, but some diagrams do show one.  I'm guessing the one in most of the rebuild kits omits this information and we all just pop the new power valve in without swapping the jet into the new one.  Holy cow. 

I am guessing this is a very common mistake and the majority of the carbs driving around have the jet missing from the power valve.

I went ahead and pulled my power valve and sure enough, no jet.  The fuel has just been dribbling past the piston in the power valve, completely un-metered!

I checked to see if a main jet will fit, but it will not, the power valve jet has it's own unique threads and is a little smaller to fit into the power valve bore.

So my plan is to install the 20R power valve jet in my power valve and see what happens. 

Learn something new every day.

3 22R power valves from re-built carb missing the jets from the left and the 20R power valve to the right with the jet...

[H8PVMNT [OP]]

I put the jetted power valve in and took a test run.  I don't notice any lack of power.  The only difference is a little hesitation when I let off the throttle went away.  We were hypothesizing that this was caused by a bit of fuel pooling in the manifold and a millisecond rich condition when you let off the gas until it huffs out. This would make sense with the un-metered power valve.

I just topped off the tank so we can see if this makes a difference.

[fireitup]

I put the jetted power valve in and took a test run.  I don't notice any lack of power.  The only difference is a little hesitation when I let off the throttle went away.  We were hypothesizing that this was caused by a bit of fuel pooling in the manifold and a millisecond rich condition when you let off the gas until it huffs out. This would make sense with the un-metered power valve.

I just topped off the tank so we can see if this makes a difference.

I've got a good feeling about this.

[kneedownnate]

Ok, so I've finally done a little work on my setup.  The 22r carb I got (still no idea where my other 2 that used to be in the cab of my parts truck went) had a thoroughly jacked up harness and connector.  One wire was nearly pushed out and the entire cover was broken.  Snagged a complete harness for the choke/idle/etc from the wrecking yard recently and was going to just cut the wires and butt connect it all together, but decided to push the connectors out of the plug on both and put the non-broken one on my carb.  Was a pita but it is back together, and I only had to butt connect the 2 wires to the choke solenoid.

Still gonna be a bit before I get this all on and working, but I appreciate what you've shared in here and am going to use the posted diagrams to see what all needs to be hooked to vacuum and what I can cap off.  Gonna avoid temptation and leave on the current exhaust setup and cam so I can see the true difference between the oe carb and the weber.  The only real change I made was using your idea for plugging one of the passages with a small piece of vacuum hose.  I had out the jb weld and was going to close it off, then decided to do something less permanent for no real reason at all.

[H8PVMNT [OP]]

Well after adding the power valve jet I got 11 mpg on the last tank.  I am hypothesizing that with the aisan carb you can choose power or economy, but you can't have both.  I think the way everything works off of vac that just by opening up the intake and altering the way it draws air makes it so the thing can't meter fuel the same as when you have the stock filter box on.  Shame though because the throttle response is WAY better with everything freed up.

This thing really has the power now, but I can't put up with this lousy of gas mileage. I am going to put the stock air cleaner back on and change the main jet back to the happy place with that.  I will keep the manual choke on if it fits though, that was a nice addition.  I will play with the HAC again.

Then I may be trying something even more drastic.  I'm not telling until I do it though .

[H8PVMNT [OP]]

All righty then.  I put the stock filter box back on and a leaner main jet. Let's see what kind of mileage we get this tank.  I was able to keep the manual choke, it clears the filter box.  I also added a "throttle positioner" from a parts carb which basically cushions the throttle from slamming shut and allows enough air to clean off any extra fuel when you are in decal. 

It is WAY quieter with the stock filter setup .

[Gnarly4X]

Have you tried this yet?

Double Gnarly Air Filter Mod.... two stock air filters stacked.


Gnarls.

[H8PVMNT [OP]]

Not yet.

[emsvitil]

11 mpg.......

Not what I was expecting...


 

[emsvitil]

Maybe the power valve is stuck open for some reason

[emsvitil]

I think you should tap into the O2 wire and measure the voltage with a digital voltmeter and see what's going on......

[kneedownnate]

Don't half ass it with a double stack stock filter, there are options for a taller single filter.  I will say, though, I tried the taller filter and didn't notice any difference in power or the ability to climb the hill to work any faster.  I have a stock size k&n to run when I get mine set up and have considered running a modified stock box setup with a larger intake tube

[Gnarly4X]

Don't half ass it with a double stack stock filter, there are options for a taller single filter.  I will say, though, I tried the taller filter and didn't notice any difference in power or the ability to climb the hill to work any faster.  I have a stock size k&n to run when I get mine set up and have considered running a modified stock box setup with a larger intake tube

kneedownnate,

Anyone can have a different experience, and every engine is different.

You got it wrong. It’s not half ass, it’s 2X assed.

I made that very simple and expensive modification after adding a DT header and bigger exhaust.  It took me about 30 minutes. The two stock filters was a smart-a$$ed idea because they are readily available, the top one filtered more so just replaced the top one with a new one and moved it to the bottom and the bottom one to the top.. another smart-assed idea.

The modification increased air flow and was very noticeable at freeway speeds, a really smart-assed idea.

Regarding K&N filters, I would NOT put a K&N filter on ANYTHING I own… to me THAT would be a “half ass” idea.

Gnarls. 

[H8PVMNT [OP]]

I think you should tap into the O2 wire and measure the voltage with a digital voltmeter and see what's going on......

I need a wide band and an O2 sensor.  This is early 22r stuff and there is no O2 sensor on it.

[H8PVMNT [OP]]

This open filter was my attempt at the same thing.  I wanted to make it easier to change jets, clean up the engine bay and answer the question "What is the minimum I can run and still have this carb work?"

In my case I did notice a difference, first in throttle response, then as I dialed it I'm a bit more with the fatter main jet acceleration improved, pulling hills got easier and I could buck a headwind better at highway speed.  The more power I got though the less mileage and consistency I got.

Also notable was less drivability.  It was more rough and raw with the open filter.  This was both fun and annoying.  Also with the open filter it was really super loud.  Like I need earplugs when taching it out up a hill loud.



What I think, if that if you free things up this much, it changes the way the intake air flows enough to effect the amount of vacuum realized and since all the piggyback systems on the carb run off vac, nothing works quite right.  Well it works well for power, just not for economy.

So you can take all that off and it's no big deal, but then we have the power valve thing.  I ended up trying two different power valves, one with a slightly softer feeling spring, no difference.  Both sealed up just fine off the carb. The deal that pushes on it is working fine and moves freely.  The we even added the power valve jet which surprisingly was detrimental to fuel economy.  I have an idea that with the open filter and associated tuning the power valve may just end up opening up way more.  The jet just made it squirt harder, kind of like when you have your thumb on the end of the hose.

You have much more air available with the open filter, so you can re-jet for more fuel, which feels good so you are in it more.  With the stock filter there just aren't as many reasons to stay on the gas as much .

I filled up and put the stock stuff back on, put in a 112 main jet, which the leanest I have successfully ran.  We will be running a test tank on the same commute I have been testing on, same fuel, and see what we have for gas mileage.  If it's still porking the gas, I will revisit the power valve thing and maybe get a rebuild kit and replace the auxiliary accelerator pump.

On the upside the 112 jet pulls hills a little better with the stock setup.  My favorite in the stock filter setup is the 116 jet, it accelerates better and the plugs read the best on it. With the open filter, the 118 main jet feels better than anything else.

My ultimate goal long term is a setup that can deal with our constant head winds, pull my hills on the way to work at 55 or better and gets 15 mpg or more consistently on 87 octane without pinging.  Add to this list pulling around a heavy 4runner on 35s and I don't want EFI .  Piece of cake right?

[Gnarly4X]

H8PVMNT.

Where are you now with cam timing?

Gnarls.

[fireitup]

If it's still porking the gas, I will revisit the power valve thing and maybe get a rebuild kit and replace the auxiliary accelerator pump.

H8 mine was porking gas and having some really odd acceleration/idle revving issue.  Noticed some gas smelling fluid coming from the AAP BVSV vacuum line and swapped the line out for a clear tube. Found this...

https://youtu.be/zyWfNoZn67s

So I am guessing that my AAP Diaphragm is blown out and fuel is getting sucked into the vacuum system.  Maybe you are having a similar issue? 

Ended up breaking the plastic nipple off the BVSV so I'll need to find a new one of those as well as rebuild the AAP.

OR

I could delete the AAP all together!  The short time I had to do research last night it seems to me the AAP is only there to force more fuel into the accel nozzle when the engine is cold.  Might try it as "cold" ambient down here usually means ~40F for like 10 days of the year. Doesn't take long to warm the engine up...

[H8PVMNT [OP]]

H8PVMNT.

Where are you now with cam timing?

Gnarls.

I left at at 1 degree retarded, that was the happiest place I found.

[H8PVMNT [OP]]

H8 mine was porking gas and having some really odd acceleration/idle revving issue.  Noticed some gas smelling fluid coming from the AAP BVSV vacuum line and swapped the line out for a clear tube. Found this...

https://youtu.be/zyWfNoZn67s

So I am guessing that my AAP Diaphragm is blown out and fuel is getting sucked into the vacuum system.  Maybe you are having a similar issue? 

Ended up breaking the plastic nipple off the BVSV so I'll need to find a new one of those as well as rebuild the AAP.

OR

I could delete the AAP all together!  The short time I had to do research last night it seems to me the AAP is only there to force more fuel into the accel nozzle when the engine is cold.  Might try it as "cold" ambient down here usually means ~40F for like 10 days of the year. Doesn't take long to warm the engine up...

I pulled the AAP vac line off and no fuel was there but that clear line trick is genius!  I may try to get ahold of some today and see what I can see.

[H8PVMNT [OP]]

Tried the clear line and the AAP was leaking.  I replaced it with a fresh one I had in a rebuild kit and now it runs terrible!  Maybe the new one leaks more, I don't know.  I'll have to get back to you on this...

[Gnarly4X]

.....
OR

I could delete the AAP all together!  The short time I had to do research last night it seems to me the AAP is only there to force more fuel into the accel nozzle when the engine is cold.  Might try it as "cold" ambient down here usually means ~40F for like 10 days of the year. Doesn't take long to warm the engine up... 

hhhmmmmmm.... I think you will find that the Toyota engineers knew what they were doing when designing in the AAP.

Gnarls.

[Gnarly4X]

I left at at 1 degree retarded, that was the happiest place I found.

Hi H8PVMNT,

So, what you have experienced parallels what my DD software shows.... 1 or 2 degrees of cam timing retard produces more power in the 22s with the cam profiles I've tested, both in torque and in HP numbers.  Which also is puzzling to me because retarding cam timing increases high RPM power.  Advancing cam timing increases low RPM torque.  So does that mean that our butt-dynos can more easily "feel" the upper RPM change? 

Or is my Engine Analyzer software producing "foo-foo data"?

That's why it's been interesting to me that the very often promotion of buying an adjustable cam gear to "correct" retarded cam timing caused by the change in deck height after machining the block or head.

The adjustable cam gear is a very useful tool, but perhaps not "required" for a .020" or less change in deck height. 

Gnarls.

[fireitup]

So I effectively deleted the AAP... Pulled out the old diaphragm and cut a ~27mm diameter circle of gasket and inserted it into the carb side of the diaphragm.  Reinstalled the diaphragm and spring to keep pressure on the gasket and capped off all the vacuum lines from the AAP BVSV.

This puts it in an "always closed" state which is the state it should be in with a warm engine.

Definite improvement from before when it was leaking but still notice a very slight hesitation when hard on the throttle around 2300RPM. Also get the hesitation, but more pronounced right after startup, which I kind of expected since that was this things sole reason for existing.

Filled up the tank so I'll try to get a MPG reading for H8PVMNT's archive here.  Might be worth fixing it back to stock and getting a MPG comparison as well at some point.

[Gnarly4X]

I left at at 1 degree retarded, that was the happiest place I found.

Hey H8PVMNT,

I forgot to ask you.... when you retarded the cam timing, did you re-adjust your ignition timing?  If so, how much change?

Gnarls.