Vacuum Line Tips (1 Viewer)

[Mickey Plunkett]

Mixed advice on HAC distributor vacuum

I've heard from some that you should just cap the HAC vacuum port on the late model distributors while others suggest that you should T off the line from the advance port and feed that vacuum to both fittings on the dist. Anyone want to weigh in on which is best?

 

[yotamotive]

JimC,

Noticed that you list TP on the bad systems list. My 78 fed smog FSM lists TP as the Throttle Positioner. Also noticed in the FSM under the choke breaker diagnostic section that this diaphram seems to be the the same one as the one shown in the overall picture called the TP. In another post about 78 fed desmog you wrote:

"The round spaceship thingy on the rear of the carb is the Choke Breaker diaphragm. CB should be connected to any manifold vac source. Typically a 1,2 or 3 port vacuum fitting on the intake manifold in front of the carb."

So are you saying CB is bad and should be removed, im confused? Seems like CB would be a good thing. Thanks a bunch!!

The bad systems, that hurt efficiency and/or reliability are:
EGR
AIR
HAC
TP
vac retard

The good systems:
PCV
vac advance
Evap
Decel fuel cut
HIC
Dissy vent

That my $.015 (darn inflation).

 

[FJ40Jim]

Typically, the engine wants 34-36 degrees max timing.

The typical 79-87 dissy has:
23 degrees of cent advance
6 degrees HAC advance
18 degrees vac advance.

If the base timing is 7, and centrifugal is 23 and HAC is 6, that adds up to 36.

18 more degrees of vac advance on top of that would be a bad thing.

HTH

I've heard from some that you should just cap the HAC vacuum port on the late model distributors while others suggest that you should T off the line from the advance port and feed that vacuum to both fittings on the dist. Anyone want to weigh in on which is best?

 

[FJ40Jim]

CB is good and necessary.
TP is an extra bit of linkage on the CB diaphragm on some years.

Keep the CB, ditch the TP linkage. That way, when throttle is lifted, the engine will slow the truck down.

JimC,
Noticed that you list TP on the bad systems list. My 78 fed smog FSM lists TP as the Throttle Positioner. Also noticed in the FSM under the choke breaker diagnostic section that this diaphram seems to be the the same one as the one shown in the overall picture called the TP. In another post about 78 fed desmog you wrote:

"The round spaceship thingy on the rear of the carb is the Choke Breaker diaphragm. CB should be connected to any manifold vac source. Typically a 1,2 or 3 port vacuum fitting on the intake manifold in front of the carb."

So are you saying CB is bad and should be removed, im confused? Seems like CB would be a good thing. Thanks a bunch!!

 

[mr_manny]

In an attempt to cleanup all the smog stuff...I installed a 77 carb onto my 72 intake.

The install was the easy port, only needed some heat sheald trimming and swapping the base studs.
Looking much nicer then having all that EGR stuff

As far as recommended vacuum port configuration:

Venturi port at the top and the Choke Breaker Diaphragm ports should be routed to Manifold Vacuum.
Everything else is plugged.

What do I do about that electronic (solenoid?) item on the back of carb (towards firewall)?

I am also running an HEI dizzy...any assistance is appreciated,
manny

 

[bsevans]

what diagrams where you using?

I have the emissions book that covers all versions of 78 FJ40s. It is a good investment as it walks you through testing the individual emission components to see if they are properly working. This info is still available from Toyota Publications. I got the toll free number from the parts department at Desert Toyota in Tucson, AZ.

 

[PabloCruise]

What master cylinder is that?

 

[bsevans]

What master cylinder is that?

92-94 Landcruiser, I have F & R disk brakes and this unit already has the setup for four wheel disk brakes. I found that on my rig an external proportioning valve was not required.

 

[PabloCruise]

MAJOR TOPIC DRIFT:

Is there an 80 series MC that does disc front and drum rear for 40's/55's?

I know the topic comes up, but search was tough for me...

 

[mr_manny]

shouldn't the Venturi port at the top and the Choke Breaker Diaphragm hold vacuum?
I tested the port, and found that id does not...are these things serviceable?

 

[bsevans]

Can not see where you got the diagram for a 78.

 

[Pin_Head]

What do I do about that electronic (solenoid?) item on the back of carb (towards firewall)?

Manny,
The solenoid cuts off the fuel to the idle circuit when the power is off, so it won't idle unless you hook it up to the key on ignition circuit. there should be a black wire with a yellow stripe near by. If not, hook it to the black wire with yellow stripe that goes to the voltage regulator.

 

[mr_manny]

thanks Charlie, I figured out the solenoid after talking to Trex.
Did you checkout the Rubithon pics I posted in the trails section?

I also found that Kragen has a carburetor diaphragm for the 77 2f secondaries available for only $15.
LC stuff is never in stock...will have to order one.

 

[LXGXFJ]

I am about to be going through all of this on my '78. PO had a few lines disconnected for whatever reason. I think I can get it back together with the above diagram, but, there are some lines that go to the thermostat housing that I'm not sure of yet...

FJ40Jim...... very nice carb rebuild. Thanks.

I will look to delete the bad systems and keep the good ones.

 

[eperry0303]

I'm with F-Junker on this one. I have a 3/79 40 that has been desmogged by PO and I'd like to finish the job by removing everything that doesn't actually help the truck run better. Anybody have an informed suggestion on a bare bones vacuum setup

Did you ever get completely de-smogged? I just bought a 3/79 FJ 55, the smog pump is burned up, and rather than replacing it I'm thinking about de-smogging, but need to start from scratch. Ant suggestions?

 

[F-junker]

I plugged the manifold and removed everything except the port for the PCV and brake booster. I made a desmoged carb out of two earlier 76-77 carbs and then used a 79' carb spacer with no egr port to eliminate another hole to creat a vacuum leak. I would recommend just pony up and buy a non-usa carb from someone or from $or maybe, you can remove so much crap from the engine bay it will blow your mind. I'll take a picture for you if you wish. the only vacuum line I have is for the vac advance! Sweet!