Base Carb Tuning and the great vacuum leak search.....help (1 Viewer)

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Unless you want to be confused by unintelligible nonsense please refer to my second post in the thread for the actual question.

Sorry for the drabble






Posting this here as well as Dulcy's thread. Feeling a bit stupid. :bang:

Alright, I'm stuck and need some help getting on track. After I bought this rig is ran fine at low elevation but died at my house 8000ft.

Since then its runs well for a time but I've always had trouble getting it to idle near the sever hundred mark. I'll just start from my current position with questions.

Currently
Fj60 with 2f
1. Smog components removed (partial PO, partial me) and idler replaced with man a fre
2. Rushing style recurve on the dizzy done by a mechanic neighbor. he's a good dude but not available much so i don't want to bug him
3. Had some compression confusion earlier but have 100psi + in all cylinders (125 in all but 5 but am counting on some unidentified vacuum leak )
4. Desmog style - Ive run vacuum lines in two versions and can't get idle right (mjweb60 "keeping HAC" and the "how To Desmog" Document )
5. Carb. I have two OEM carbs available . The originals secondary was frozen and has been freed, second was recently purchased used. both seem to currently have all linkage and moving parts functioning .
6. My Dizzy vac advance does not seem to work (pull vac on the advances and the rotor doesn't move)
7. I Know I've got oil pressure so thats a plus
8. Recent fuel filter change , That old bit was full of rust. Plan on changing the tank but want to get it running first
9. Man a fre Plugs in the Air Rail ports and Block off plate in place with gasket
10. At faster than Idle speeds the engine runs with no hiccups can't hear a vacuum leak

Before I go any further, the reason I purchased this vehicle specifically to learn to work on vehicles and would most rather do the work myself. I'd like to do the work myself but as they say, winter is coming, and a baby and I'll need to start splitting wood soon. After that I'm poked for a bit. I am armed with 3 days, and FSM (all three), a Chilton and ok tool Cache. and a 60 minute round trip to a variety of auto parts stores.

I'd like to start over with the whole desmog process and am totally lost.

So...
1. How would you start and go about the process of figuring this out my problems? Please reference posts and or FSM pages as needed.

2. Presuming you can't vouch for your carb at idle (because i jacked with it so much) can I you still set the base timing ? how? Carb has fuel, linkage all turns and moves

3. FSM says start at 2 turns for the idle mixture screw and, the best I can tell says Play with the Idle Speed screw, where should I start just to get base timing going?

4. I know there is a Intake manifold crack problem , Looked under the carb, and sprayed carb cleaned across the area no change in function occurred. anywhere else I can look or other method to use?

5. The only loose hose or connection I can detect is the Valve cover to Air Cleaner connection, Does this matter?

6. I am at about 8000ft and have a function HAC if that matters.

In general, the function of this engine seems like it should be pretty simple. I'd like to be able to figure it out on my own (with your help) and don't feel I'm say enough to quite put it together on my own. I think starting with a good idle would help me figure the rest out.

As mentioned before I've got three solid days to figure this out. If Im still at a loss I'll be limping it to a mechanic.

I would appreciate any help I can get on getting through this process. I am happy to owe you beer or what not and will always pay that debt. Plus think of the joy you'll have knowing you helped an idiot like me.

I'm starting with plugs on all my vac stuff to try to get idle. is this right?

Help Me. Thank you.
 
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Joined
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Messages
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Or for poop and laughs....

Let's pretend you ave a brand new rig with a 2f. You are at 8000ft and have the carb off, dizzy is in and presumably timed correctly (at least to idle) you want to get it to idle before following the whole desmog diagram because of that pesky idle mixture screw.

Where do I start with my carb adjustment and what vac lines do I need vs what can be capped.

I'd like to start here and find the vac leak later.

This way seems easier

Thanks again
 
Joined
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Messages
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May have been misleading but I can't find a discernible crack or leak in the intake manifold.


Working on the static method. Can provide any pictures if the can help.

Test

Test

IMG_2630.JPG
 
Joined
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Sorry, I thought you wrote you knew there was an intake crack. Do you have a mighty vac?

If you post some pics from various angles around the engine bay and carb it would probably help get more input...we all like pics.
 

mattressking

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Do a hot/cold vacuum test.

Aka, once the car is started, fan is off and idling around 650, take an initial cold vacuum reading.

Once you've driven the car, got it nice and warm, take another reading. See if there is variation.

Also note general vacuum reading, if you're at sea level you should see 22inHg at idle and hold there.
 

OSS

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At 8000 feet vacuum should be above about 14 inHg but less than 19.

Spark timing isn't very important at idle. The distributor can be rotated to either extreme within the adjustment slot and it 'should' idle fine. It will idle faster when advanced & slower when retarded. 7° BTDC (factory spec) is when the clamp bolt is in the middle of the base slot.

Not having a functioning distributor vacuum advancer won't be very nice at your altitude, but it doesn't affect idle at all. The outer HAC diaphragm on the distributor does affect idle a bit. Advances the spark 6° all the time when actuated.
 
Joined
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New status. static timing set in the BB. With the recurve. thanks - Mwebfj60 - I'll learn to tag folks tonight

Pics at this point are useless as everything is pulled. I'll work on something

I don't have a mighty vac but I've got an aggressively pulled 100cc syringe with a vac gauge attached so thats nice.

Matressking - I can't get the vehicle to idle under 1500 without dying. Thats my major goal

So with my timing set (static) what vacuum lines are needed to set idle and what can I cap? With everything hooked up I feel there are too many variables to identify a vacuum leak. am I wrong?

Also Where should I set my screws. All I can find in the FSM is Idle Mixture + 2 turns and to fiddle with the idle speed adjusting screw.

Where do I start with the Idle Mixture adjusting screw (out until there is no contact?) , Idle Speed Adjusting screw and fast idle adjusting screw.

Thanks.
 

mattressking

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Messages
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New status. static timing set in the BB. With the recurve. thanks - Mwebfj60 - I'll learn to tag folks tonight

Pics at this point are useless as everything is pulled. I'll work on something

I don't have a mighty vac but I've got an aggressively pulled 100cc syringe with a vac gauge attached so thats nice.

Matressking - I can't get the vehicle to idle under 1500 without dying. Thats my major goal

So with my timing set (static) what vacuum lines are needed to set idle and what can I cap? With everything hooked up I feel there are too many variables to identify a vacuum leak. am I wrong?

Also Where should I set my screws. All I can find in the FSM is Idle Mixture + 2 turns and to fiddle with the idle speed adjusting screw.

Where do I start with the Idle Mixture adjusting screw (out until there is no contact?) , Idle Speed Adjusting screw and fast idle adjusting screw.

Thanks.

If it dies when attempting to idle below 1500rpm, I assume a large vacuum leak without seeing the truck. Shooting blind is tough. Check intake manifold for open ports, there are technically only 4.

1. Opening for Carb (duh)
2. Opening for gas filter (closest to headlights)
3. Opening for Brake Booster and A/C idle up VSV. (Closest to firewall and connects directly to Brake Booster).
4. Carb Insulator elbow that routes to PCV/HIC).

Try and take nice pictures of the engine bay, left and right and center so we can see vacuum routing.

Is it running smooth at 1500rpm or is it rough? Could be a misfire for all I know.
 
Joined
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Central Valley, CA
Fuel cut solenoid aka idle cut solenoid would cause the problem you are having. An audible click when the key is turned on is an easy check. A search will reveal some more in depth checks.

Or your idle circuit in the carb could be clogged. You can pull the ICS and blow some compressed air in the hole. Make sure the little oring is on the end of the ICS.

Towards the end of this thread goes through how I check it.
Aisan Decel Fuel Cut Circuit
 
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Joined
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IMG_2637.JPG
This being the fuel cut switch? It doesn't click when starting . I am unable to test it as per the FSM because there is no green plug but I did pull it, growing the threaded bit and connect negative to threads and positive to the spade . Same result. No click.
 

NeverGiveUpYota

Dare me.
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The intake manifold crack is a problem.
Edited.... my mistake, I see now you said 'no decernible.'
^^^ Right there.
I tried ignoring a crack. It got me nowhere except insanely annoyed and w/ tons of wasted effort.
That's your number one chore.
Guys are guiding you well. I've not forgot about our emails. Let me see what I can do w/ that diz and its frozen screws and that vac adv. I'll luk.
 
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Stumpalama

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You will never get anywhere with that intake manifold leak. you vac advance diaphragm is toast, either plug the vac line to it or use the high altitude diaphragm to get some advance.
 

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