My Desmog Keeping HAC Lots of Pics

[LAMBCRUSHER]

How was it before w/ just the HAC advance tied to the secondary can???

 

[Eporter]

The 3 HAC fittings on the carb are for 3 separate circuits. If they were all tee'd together, then connected to a VSV, at high altitude, they would work fine. All 3 would pull in extra air through the VSV as they needed it. But when the VSV was closed, the idle fitting would be sucking, and it would pull fuel in through the other 2 fittings. At higher speed, the primary main HAC fitting would suck fuel out of the secondary....

What is needed is a VSV that when off has 3 separated vac fittings, then when on connects all 3 to a common port (atmosphere). Or 3 separate VSV's powered by one switch.

Could you use one VSV with a T to the three lines to the fittings, and then place one-way valves in each line? That way each line would draw in air, but wouldn't be able to draw fuel out from the other fittings?

Or, are the factory one-way valves not up to that type of a load?

I'd like to figure this out, as I frequently drive from ~50ft. above sea level in Portland, OR up to about 6000ft. at Timberline on Mt. Hood. All that in ~60 miles. And it's COLD up there, which makes for some poor performance and hard starts.

When I used to live at elevation, I would just adjust the timing manually (in place of the HAC) and leave it that way. Made a big difference. This going up and down in elevation makes that more of a pain.

Thanks for the help.

 

[FJ40Jim]

Ok, I rerouted my vacuum to original, ported primary on carb to primary on dizzy, HAC to secondary on dizzy. Got a little knock so I retarded base timing 2 degrees. Then 3 degrees...knock went away. Now the idle is a little rough. Thoughts?

The engine is not operated under load at idle. Idle quality is a cosmetic concern. The important thing is that the timing under operating conditions is spot on now.

To get the idle quality back, recurve the dissy for less total advance, and a slower advance curve. Then it can be operated at 10* base timing and the correct loaded timing.

 

[FJ40Jim]

Could you use one VSV with a T to the three lines to the fittings, and then place one-way valves in each line? That way each line would draw in air, but wouldn't be able to draw fuel out from the other fittings?

An excellent idea.

Or, are the factory one-way valves not up to that type of a load?

The concern would be: will a check valve restrict flow at the small differential pressure in this system?

Try it and let us know.

 

[mwebfj60]

Thanks Jim, I think I will start all of my posts from this point out that way....Thanks Jim.

One thing I finally got my mind wrapped around was that the vacuum doesn't flow through the VCV valves, it just allows the valve to open so the other ports will function. The BVSV valve (on the water jacket) opens to allow the vacuum to pass through it...vacuum switching valve (VSV) versus vacuum control valve (VCV).

Now trying to figure out the HAC valve...mine tests good at altitude and functions fine....at low altitude, what keeps the manifold vacuum from advancing the secondary advance? The FSM shows that port A opens and port B closes. Doesn't the vacuum from the manifold still apply vacuum to the secondary on the dizzy. I know it goes through the check valve but the valve is placed so that air flows through it into the manifold (manifold sucking in)....This is the last little puzzle I have for the air circulation system.

**EDIT** The black and white valve should go the other way, white toward manifold and black toward the tee ***

 

[mwebfj60]

How was it before w/ just the HAC advance tied to the secondary can???

It was a little sluggish on acceleration but idled great. After hooking up primary and secondary and retarding base timing to 6 degrees, it was much more responsive but idles rough.

 

[FJ40Jim]

At low altitude, the HAC valve port B is a leak, allowing the vaccum that's headed to the advancer to leak out through the HAC. The check valve keeps the leakage rate to a reasonable minimum, so not to upset low alt driveability.

See p.3-31 of emissions FSM.

 

[mwebfj60]

At low altitude, the HAC valve port B is a leak, allowing the vaccum that's headed to the advancer to leak out through the HAC. The check valve keeps the leakage rate to a reasonable minimum, so not to upset low alt driveability.

See p.3-31 of emissions FSM.

Got it. I don't like it, but I got it. So my valve is in backwards.

 

[jfnall]

Driver side VCV ----

On the Driver Side VCV - I am running a Weber/Empi Carb --

can #5 that goes to the BVSV on the thermostat housing go directly to the air box, next to #6 on the air box? (I don't have either BVSV on the thermostat housing, both are plugged) does this create the right amount of vacuum for the VCV to work properly or is there a better way to hook up the VCV on a weber desmog?

if you go directly from the "purge" line off the charcoal canister to the adaptor between the carb and the intake, it really effects how the truck runs. too much air i guess.

I'm going to see a Weber guy that knows his stuff next week, and I wanna make sure I have the EVAP system stuff hooked up right so he can make his adjustments off what is correctly routed.

BTW - These are the best pictures and references for a desmog. Thanks for taking time to put these together.

thanks for the advice.

 

[mwebfj60]

The BVSV valve opens when the temp gets up and applies vacuum to the VCV...this opens the airflow through the VCV so the fumes from the charcoal cannister can enter the port under the carb. That is the way I have it figured anyway...I am guessing a workaround without BVSV would be to just take #5 to a vacuum source (egr port on carb) Just guessing and I don't have any knowledge of the Weber setup. Thanks and good luck...hopefully someone with some first hand knowledge will jump in.

 

[FJ40Jim]

#5 needs to go to ported vacuum.
Connecting it to manifold vac will open the VCV constantly, which will cause poor idle.

 

[jfnall]

So with no bvsv or extra port off the carb, what's a good option? To put a bvsv back on?

 

[FJ40Jim]

The BVSV is of secondary importance. A ported vac source is needed.

 

[jfnall]

With a 1 port weber/empi, Is it a bad idea to T off the vac source on the carb port that is going to the dizzy vac port?

 

[mwebfj60]

I don't see why that wouldn't work. As long as your dizzy diaphram is good and your VCV port holds vacuum.

 

[Borick]

FJ60 "How to" desmog doc

mweb - hope you don't view this as a hijack of your thread, but have been looking for a place to post this doc for comment and came across your thread. (I might also cross-post to "My Desmog Thread".)

Anyway, this is sort of a "how to" doc that I put together to desmog an FJ60 2F. Virtually ALL the info came from "My Desmog Thread". It has pictures and labels similar to yours here, and is easy to print out and carry to the truck. I think it's consistent with what you've done.

View attachment How to Desmog an FJ60.pdf

Input/feedback VERY MUCH wanted. I will correct as needed.

I haven't desmogged yet (waiting for carb/dizzy before I dive in), but wanted to post this to get feedback, and also - like you - to hopefully give others a hand.

Apologies again if a hijack.

 

[worldspan]

Well Done Borick. I will look this over and reply to anything i see different than mine. As of now, my desmogged FJ60 runs like butter, idles perfectly, and has no fuel smell from the engine bay whatsoever as i did before.

Great work!

 

[Borick]

Hey worldspan - great! The more eyes on this the better.

 

[scott84]

Awesome work man should be in FAQ!

 

[jfnall]

you might specify that this is an OEM carb desmog. A couple thing are different for not having HAC. or running a Weber/Empi other carbs.

putting in the pics from this thread directly into the PDF to have laying on top the motor would be beneficial too.

This has been needed for quite some time. the other thread has gone on so long, it is more confusing than it needs to be. thanks for doing this.