FJ55 f engine Carb tune issues (2 Viewers)

[Tomba]

Aisin carb dated as the correct model for the year(1972) based on the SOR site. Rrecently rebuilt. after a few fixes, I thought I woud attempot to fine tune things. Was planning on doing a lean drop idle adjustment but whne I attemped to use the mixture screw it had no effect on the idle speed. Upon looking further I also attempted to adjust the idle speed screw which, to my supprise wasnt even touching the tab below the screw (that was all the way in) that adjusts the idle connected to the linkage. Turns out the only way I can adjust the idle is by tensioning the throttle cable which i know is incorrect. Seems to run decently aside from an exhaust manifold leak. the installed vaccum gauge show decent vaccum too. checked for vac leaks with starter fluid..
i did not remove any linkage when I rebuilt it and from before and after pics, shows it was reassembled the same way.

Any thoughts on what might be the issue(s)?

 

[Pighead]

Are you sure that that screw is the idle speed screw? It might be the choke idle speed screw...

 

[Tomba]

Are you sure that that screw is the idle speed screw? It might be the choke idle speed screw...

I believe so, I identified both and adjusted what looked like the idle screw , not the choke one. The 1st pic shows the choke idle screw. the one I said dosent touch the tab is facing the head. this pic attached shows both , the idle speed screw on the left.

 

[Pighead]

Ok, my 10/73 carb linkage is completely different. I can't see my idle speed screw, i have to feel around for it with a screwdriver. Thought maybe yours was hiding as well

 

[Tomba]

Ok, my 10/73 carb linkage is completely different. I can't see my idle speed screw, i have to feel around for it with a screwdriver. Thought maybe yours was hiding as well

View attachment 3393464

hmmm ok. Let me take a closer look ...

 

[65swb45]

If you look down the carb and see gas dribbling out of the primary emulsifier, that will explain why the idle mixture screw has no effect. The idle mixture screw has no effect on the primary. You have to back EVERYTHING off until no gas dribbles out of the emulsifier.

If you cannot get the truck to stay running without gas dribbling out of the emulsifier, then the idle circuit is either plugged (happens very easily) or there is insufficient vacuum to draw gas through the idle circuit.

15” is insufficient.

See Post #10

76 TLC Aisin Carb help

Figured I'd kick this over the fence this AM. Having trouble dialing in an OE 76 Aisin Carb. De-smogged original 2f. Looks like its loading up. Double checked for vacuum leaks. New solenoid, fires up at full choke, runs ragged for a minute or so, half choke smooths out, 1/8 choke purrs...

forum.ih8mud.com

 

[Tomba]

Ok, my 10/73 carb linkage is completely different. I can't see my idle speed screw, i have to feel around for it with a screwdriver. Thought maybe yours was hiding as well

View attachment 3393464

yep, mine was hiding under that seconcary counter weight , same spot as what you showed. Thanks! Able to adjust idle w throttle cable loosened up. now.

 

[Pighead]

Good.
Sometimes even a blind Pig finds an acorn

 

[Tomba]

If you look down the carb and see gas dribbling out of the primary emulsifier, that will explain why the idle mixture screw has no effect. The idle mixture screw has no effect on the primary. You have to back EVERYTHING off until no gas dribbles out of the emulsifier.

If you cannot get the truck to stay running without gas dribbling out of the emulsifier, then the idle circuit is either plugged (happens very easily) or there is insufficient vacuum to draw gas through the idle circuit.

15” is insufficient.

See Post #10

76 TLC Aisin Carb help

Figured I'd kick this over the fence this AM. Having trouble dialing in an OE 76 Aisin Carb. De-smogged original 2f. Looks like its loading up. Double checked for vacuum leaks. New solenoid, fires up at full choke, runs ragged for a minute or so, half choke smooths out, 1/8 choke purrs...

forum.ih8mud.com

Idling now but the low vaccum still is an issue. ISsthe only way to address that chasing down the leak? If so soukds like I'll need to replace my manifold gasket. I can get the RPMs down just below 1k but the vaccum is low (11-13) and as a result runs but sometimes dies.

 

[65swb45]

Read some FAQs. Work on dwell, timing and valve adjustment before fussing with manifold gaskets.

 

[Pighead]

Sometimes, advancing the timing a bit can increase the manifold vacuum AND stop it from dying so much...

 

[Tomba]

Sometimes, advancing the timing a bit can increase the manifold vacuum AND stop it from dying so much...

Thanks . tomorrow I am gonna check points, plugs and timing. I havent replaced any tune up parts yet so I think I might start there although cap looks in decent shape and so did the plugs but all new basic tune up items might be a good idea.

 

[Tomba]

Good.
Sometimes even a blind Pig finds an acorn

 

[Tomba]

ok, so I moved onto adjusting the valves. I adjusted the 1st sequence of valves in the pic below at TDC. very easy. how can I align the cam so I can do the remaining valves, 4,6,8,10,11 12. IT says to rotate crank 1 full turn which would put me back in the samne position. "align timing marks" does this mean on the BB? Thanks

 

[ToyotaMatt]

ok, so I moved onto adjusting the valves. I adjusted the 1st sequence of valves in the pic below at TDC. very easy. how can I align the cam so I can do the remaining valves, 4,6,8,10,11 12. IT says to rotate crank 1 full turn which would put me back in the samne position. "align timing marks" does this mean on the BB? Thanks

View attachment 3406250

maybe this is related ?


Post good clear up close pics of yours ?

thanks

.
.

 

[Casey E]

One full turn doesn’t put you back in same position. Turn the motor over one rotation after your first adjustment, the other set of exhaust and intake valves will be ready to be adjusted, just like magic.

 

[Tomba]

Of course its related to the issues but, I'm still going through and adjusting valves. checking the poiint gap etc. heres a pic of my rebuilt Aisin.
I have a feeling the idle channel may be clogged tho. This unit had only 300 miles on it before it was parked for a few decades...

 

[Tomba]

One full turn doesn’t put you back in same position. Turn the motor over one rotation after your first adjustment, the other set of exhaust and intake valves will be ready to be adjusted, just like magic.

Thanks .I'll give that shot..

 

[ToyotaMatt]

Of course its related to the issues but, I'm still going through and adjusting valves. checking the poiint gap etc. heres a pic of my rebuilt Aisin.
I have a feeling the idle channel may be clogged tho. This unit had only 300 miles on it before it was parked for a few decades...

View attachment 3406349

remove your IDLE screw

- see if the TIP is perfect CONE or no ?


- use carb clean down the empty idle screw bore


blow out compressed air using KID GLOVES here


report back any difference ?

this 5 minute thrik may help

 

[ToyotaMatt]

Thanks .I'll give that shot..