what's going on there, anyone else have two pipes? never seen that one, looks cool
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Vacuum Line Tips (1 Viewer)
- Thread starter JamesM
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I'm glad I don't have emissions laws to deal with 
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That's the POS 1/79-7/80 downpipe. Uses the double downpipe from a 20R engine. Should be adequate for a 4.2L engine... Not!beaufort-fj60 said:
So, the first desmog upgrade on that truck is a 1981-newer downpipe and no cat.
The cat. is gone but since the rest was in good shape I decided to keep it. I have another 40 in progress with no downpipe so I'll follow your advice when I get back to that buildup. Will the 81 downpipe clear a PTO driveshaft?
PabloCruise
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I would start by getting the emissions manual for your '78
It will have the Fed, Cali, and High Altitude vacuum diagram schematics.
What I did is tackle each system individually. I made copies of each system from the manual and took the stack of copies out to the 40 with me. After each system was done, moved on to the next one. I replaced all the vac tubing. After I did this LandPimp posted a pert # for a bulk quantity of Toyota tubing. Cruiser Dan could prob hook you up with the manual and the bulk tubing in one shot - save $.
Good Luck!
It will have the Fed, Cali, and High Altitude vacuum diagram schematics.
What I did is tackle each system individually. I made copies of each system from the manual and took the stack of copies out to the 40 with me. After each system was done, moved on to the next one. I replaced all the vac tubing. After I did this LandPimp posted a pert # for a bulk quantity of Toyota tubing. Cruiser Dan could prob hook you up with the manual and the bulk tubing in one shot - save $.
Good Luck!
PabloCruise
SILVER Star
FJ40Jim said:
I would be interested in the second option - what systems are bad/hinder performance and what systems to keep (engine runs best with these)
Thanks Jim!
bump for bare bones
PabloCruise
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FJ40Jim said:
Jim, if you are still tuned in to this topic, I'd like to hear your opinion on which systems to keep vs get rid of. My '78 fed spec 40 would be my favorite example. Assume no emissions criteria - goal is peak performance/efficiency...
Thanks!
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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).
EGR
AIR
HAC
TP
vac retard
The good systems:
PCV
vac advance
Evap
Decel fuel cut
HIC
Dissy vent
That my $.015 (darn inflation).
PabloCruise
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Always a pleasure to read and learn when you are posting Jim...
By AIR, you mean the air pump and rail?
Thanks!
By AIR, you mean the air pump and rail?
Thanks!
I agree that the TP doesn't increase performance or efficiency, primarily because it maintains a higher idle when decelerating thus probably using more fuel. But if you're going to keep the evap system, I'd keep the TP too and reduce that god-awful smell of over-rich deceleration exhaust.FJ40Jim said:
Just my $.01. IH8hydrocarbons...
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AIR= Air Injection Reaction system.PabloCruise said:
HAC is bad?
Jim,
If you tune into this one again tell me why you include the HAC on the bad list. I assumed that having it automatically lean out the mixture and advance the timing at altitude would improve performance and cause no ill effects at low altitude. Since I'm going for minimal clutter under the hood I'd like to better understand your logic. If I ditch the HAC should I just cap the second vacuum tube on the distributor ?
Jim,
If you tune into this one again tell me why you include the HAC on the bad list. I assumed that having it automatically lean out the mixture and advance the timing at altitude would improve performance and cause no ill effects at low altitude. Since I'm going for minimal clutter under the hood I'd like to better understand your logic. If I ditch the HAC should I just cap the second vacuum tube on the distributor ?
PabloCruise
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FJ40Jim said:
Since we are back to this one, can anyone refresh my memory on what HIC is?
TEQ
Tigger
High Altitude Crap or something like that.
My rig has it. It is one of those round valve thingys with 3 or 4 vacuum tubes coming out of it in different directions. In my case it is mounted low on the engine block just above the starter.
My rig has it. It is one of those round valve thingys with 3 or 4 vacuum tubes coming out of it in different directions. In my case it is mounted low on the engine block just above the starter.
I have an emissions manual and will try and copy it to file soon and pass it along, might be a week or so. Remind me.
Kenn
Kenn
sorry for the repost I wanted to subscribe to this thread
HIC vs HAC
I've been studying the emmissions manual in my attempt to properly desmog my 79.
HAC is the high altitude compensation. Above 3900 ft it adds about 5 degrees of advance and opens a fresh-air vent into each venturi to lean out the mixture. It's all based on a bellows device that's inside the HAC valve so it doesn't tie into the computer or anything else.
The HIC is the system that sends warm air from around the exhaust manifold into the aircleaner until the engine warms up. A temp sensor in the bottom of the aircleaner closes a valve when things get warmed up which cuts off the vacuum supply to the valve in the intake snout. That valve then returns to it's normal position to switch the incoming air to the cool supply beside the radiator. This system is also not connected to the computer or anything else.
The HAC is missing from my 79 and I was planning to reistall it until I noticed that Jim C. listed it as a "bad" system. I hope he chimes in to explain the negative implications.
I've been studying the emmissions manual in my attempt to properly desmog my 79.
HAC is the high altitude compensation. Above 3900 ft it adds about 5 degrees of advance and opens a fresh-air vent into each venturi to lean out the mixture. It's all based on a bellows device that's inside the HAC valve so it doesn't tie into the computer or anything else.
The HIC is the system that sends warm air from around the exhaust manifold into the aircleaner until the engine warms up. A temp sensor in the bottom of the aircleaner closes a valve when things get warmed up which cuts off the vacuum supply to the valve in the intake snout. That valve then returns to it's normal position to switch the incoming air to the cool supply beside the radiator. This system is also not connected to the computer or anything else.
The HAC is missing from my 79 and I was planning to reistall it until I noticed that Jim C. listed it as a "bad" system. I hope he chimes in to explain the negative implications.
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HIC is Hot Idle Compensator. A system on 78-87 USA 2F to maintain/raise idle speed when underhood temps are high. On 78-80 a valve, external to the carb. On 81-87 2F, HIC is built into the air cleaner HAI valve.
HAI is hot air intake. That's the preheat hose on the aircleaner snorkel on 73-newer Cruisers. W/ a stock exhaust manifold bolted to the bottom of the intake manifold, it is redundant. A useful accesory w/ headers, especially in cool climates.
HAC is Hi Altitude Compensator. A system to bleed extra air into the fuel circuits of the carb at high altitudes, thereby leaning the mixture. Standard on US cruisers, 79-87. A nice idea, but the HAC valve is cheap POS plastic widget that fails too frequently. Since most people don't operate from sea level to above 4K feet frequently, a more robust solution is to jet for local altitude.
HTH
HAI is hot air intake. That's the preheat hose on the aircleaner snorkel on 73-newer Cruisers. W/ a stock exhaust manifold bolted to the bottom of the intake manifold, it is redundant. A useful accesory w/ headers, especially in cool climates.
HAC is Hi Altitude Compensator. A system to bleed extra air into the fuel circuits of the carb at high altitudes, thereby leaning the mixture. Standard on US cruisers, 79-87. A nice idea, but the HAC valve is cheap POS plastic widget that fails too frequently. Since most people don't operate from sea level to above 4K feet frequently, a more robust solution is to jet for local altitude.
HTH
