Adding HAC Back Into Desmogged 2F (1 Viewer)

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So @4Cruisers, would you have any idea if I could use BVSV2 for this? BVSV1 on mine has the nipples broken off but BVSV2 is good. I believe these two BVSVs operate at different temperatures so might be asking for rough idle during warm up cycle.
I'd have to check, but I think the temperature ranges are different enough that it might not work well.

I was able to salvage an otherwise good BVSV1 that had one broken (outer) nipple. I carefully drilled down into the plastic at the nipple and force-fit a section of brass tubing into the hole, along with a bit of Super Glue. I then slipped a very short section of larger diameter tubing over that to act as a sleeve, so it extended over a bit of the plastic nipple just below where it had broken off. I slathered the outside of that with some epoxy. It'll probably hold up OK because there's really no force of it.
 
So with the world unable to get anything done, I finally was able to get my hands on a vacuum pump tester. I tested my distributor pots and neither one holds vacuum. So looks like I am screwed. I have read some of the thread on dizzy pots and attempts to get advance working. Seems that there are single pot options available but for HAC I'd need dual advance to work. Unless someone has a recent way to solve this, I guess my project is dead. Seems there is some way to do this through RockAuto but not sure how well it works:

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Would appreciate ideas at this point. Thanks in advance.
 
The vacuum applied to the distributor vacuum advancers is a continuous force, not a one-and-done event. If the vacuum is stronger than the leak, the diaphragm will still actuate.
It depends on how fast the leak is. A slow bleed of air shouldn't effect it's operation significantly.

I read a thread here a long time ago of a guy (can't remember who) who had his distributor rebuilt by Cardone and they fixed both of the vacuum advancers too. So that's an option.
 
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The vacuum applied to the distributor vacuum advancers is a continuous force, not a one-and-done event. If the vacuum is stronger than the leak, the diaphragm will still actuate.
It depends on how fast the leak is.

Yeah I couldn't get the needle on the vacuum pump to move. Looking through FSM now to see if there is a flaw to my testing. Do you need to apply vacuum to both advancers at the same time via T-fitting to properly test this. I was doing one at a time. Maybe I need to cap one while testing the other? FSM has this to say:

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FSM seems to show both ports being tested at once but not sure. Thanks for the help.
 
Each port should individually hold vacuum whether or not the other port is open or capped, I just verified this on one of my two good spare FJ60 advancers. I was planning on selling at least one of them, PM me if interested.

I've tentatively identified an option for a new NipponDenso dual diaphragm advancer (with HAC), that's next on my list of vacuum advancer R&D projects. This morning I'm finishing up the installation of a new a single diaphragm vacuum advancer in a '79 2F electronic distributor. Once that's done I'll jump on the dual diaphragm project.
 
So funny enough, I just got off the phone with @ToyotaMatt (thanks very much for the time Matt), and he actually mentioned your name @4Cruisers in possibly being able to help me out with this. Sending PM now. Thanks.
 
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OK so @4Cruisers got me going with the advance pot. Thanks again for this.

Having trouble confirming the arrangement with the BVSVs.

Purple BVSV - P/N: 90925-05035 - This is the lower BVSV in the Thermo Housing - Still available from Toyota
Pink BVSV (changed to Blue perhaps) - This is the upper BVSV in the Thermo Housing - P/N: 90925-05046 - Discontinued.

For this I think I need to use the upper BVSV. My upper one is sealed well but the nipples are broken off. The lower BVSV is unused in this setup. On mine the lower BVSV has the nipples intact but leaks so I am going to most like replace it with a plug. I don't think the lower can but used in place of the upper because it operates at a different temperature. At this time there is not really a replacement for 90925-05046?

Can someone check me on all this? Thanks in advance for the help.

Edit: After doing some digging, I think I have the P/N right but the locations in the housing reversed:

Purple BVSV - P/N: 90925-05035 - Upper
Pink BVSV (changed to Blue perhaps) - 90925-05046 - Lower

I know dumb stuff here but mine are all faded so cannot tell really from what's on mine what goes where.
 
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So I went to remove my vacuum advance pot today and discovered its not easy without actually removing the distributor from the engine. Oil cooler is smack dab in the way of the head of the screw to be able to get a driver on it. Mine won't budge no matter what is done. Is the way most folks do this by pulling the distributor out of the truck? Or is there some slick way to get this done with the distributor still installed?

I got my cap off and without detaching the original advancer can, I tried to move the advancing mechanism in the distributor to see if it would pull back. It doesn't budge. Not sure at this point if the advancer is locked up not allowing the arm to move and thus not allowing the mechanism inside the distributor to move or if the mechanism inside the distributor is locked up and that's why the advancer became blown out. Is the mechanism inside the distributor supossed to rotate freely. Should I normally be able to pull back on the arm inside the distributor and have it move freely? Thanks in advance for the help.
 
OK spoke too soon here. I was finally able to free this set screw holding the pot on:

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I also checked the advancer mechanism. Here's how mine looks/moves?



Is this how its supposed to move? It doesn't move very much based on how much the advancer pot can move so assumed the dizzy mechanism was broken/locked up somehow. It prolly does not need to move much but seems like it should move more than this. Sorry the video is not the best. Would appreciate any feedback here. Thanks.
 
Here's what I came up with:

Had a question here @4Cruisers on your diagram. You have the Dizzy vent going to the air cleaner via a VCV. The hose that runs to the air cleaner off the VCV should go to what port on the air cleaner. My air cleaner has two ports on it (which I assume is not unique to my truck). One on the top of the cleaner, which is where I believe the VCV hose should go, or the one on the bottom of the air cleaner. Or should I T this hose and send hoses to both ports? Maybe plug the one underneath and just run to the top port?

Also, for the HAC ports, the vacuum line that gets T'ed off going to gas filter, HAC, and distributor secondary advance, there is something labeled 'check valve' coming off the gas filter line. Is this a generic valve or a specific Toyota part? See diagram below:

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Thanks for the clarification.
 
Had a question here @4Cruisers on your diagram. You have the Dizzy vent going to the air cleaner via a VCV. The hose that runs to the air cleaner off the VCV should go to what port on the air cleaner. My air cleaner has two ports on it (which I assume is not unique to my truck). One on the top of the cleaner, which is where I believe the VCV hose should go, or the one on the bottom of the air cleaner. Or should I T this hose and send hoses to both ports? Maybe plug the one underneath and just run to the top port?

Also, for the HAC ports, the vacuum line that gets T'ed off going to gas filter, HAC, and distributor secondary advance, there is something labeled 'check valve' coming off the gas filter line. Is this a generic valve or a specific Toyota part? See diagram below:

View attachment 2287223

Thanks for the clarification.

OK NM on the distributor vent. I looked again at the desmog guide and see now it goes on the top port. Bottom goes on the PVC T-fitting. My T fitting was capped. PO made a real mess of things.

The check valve confirmation would be helpful though. Thanks in advance.
 
Air cleaner port is on the passenger side of the air cleaner housing, IIRC it sticks out horizontally towards the inner fender just under the lid.
 
IIRC it's the small check valve just above the thermostat housing area, the two-color one almost exactly in the center of the photo:

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Part Number 90917-10038, NLA. Do you have that check valve? I have a spare if you need one.
 
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OK @4Cruisers sorry for the beat down here. I realized I don't have the EGR port on the carb plugged to anything. I forgot about it. Looking at your diagram you have this circled listed:

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Is this to mean this should be T'ed off and sent to the EGR port on the carb or should I just plug the EGR port on the carb being desmogged. One of the desmog guides has the EGR port on the carb going to the BVSV where the advancer goes in your guide. I think I can do either but wanted to make sure. Thanks in advance.
 
I'd cap off the EGR port on the carb.

The following excerpt from the "Dizzy FAQ" may shed some light on why the EGR port is used with vacuum advance in some desmog guides.

"Cal Spec and High Alt carburetors do not technically have a true advance port on the carburetor base. They only have an EGR port and a manifold vacuum (or Throttle Positioner) port. Toyota used said EGR port to supply the vacuum signal to the Cal/High Alt distributors whereas the Fed Spec carburetor base had a dedicated "Advance" port and an EGR port and TP port. Whether or not there were significant differences in the location of the EGR ports in the throat of the Cal/High Alt carbs vs the location of the advance port on Fed Spec carbs (which, again, had both) is something I have never bothered to investigate. My general understanding of these carbs is that the EGR port is higher up and therefore comes in slightly later in the power band."
 

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