2f Carb Tuning - Timing - and Vacuum Routing for Desmog

[dannyvp]

I just installed a new Fuji carb. It idles high and doesn’t seem to want to adjust out and it’s running rich. I sprayed carb cleaner all over looking for a vacuum leakbut have not found one.

I thought at one time I saw a guide to tuning one, but can’t seem to find it now.

Any help is appreciated.

 

[NeverGiveUpYota]

Fuji as in the City Racer? Are sure you’ve got the linkage correct, could be flip flopped... I’m thinking the throttle return spring. Honestly I could be way off but that’s my first guess w/o pixs. Mine is all sorts of dissembled so I can’t help what’s so ever.

 

[dannyvp]

Yes a city racer carb. The linkage is correct I’m pretty sure.

 

[dannyvp]

 

[Seth S]

Well if it’s similar to the stock carb then in the last photo the screw with the spring on it is for the choke cable...meaning the speed that the engine idles at with full choke.... and the screw slightly down and to the left is the idle speed screw. And then there might be an idle mixture screw between the carb and the valve cover. There is a process of adjusting the idle speed and mixture screw to get things set right. At least for the Aisin carb

 

[dannyvp]

Well if it’s similar to the stock carb then in the last photo the screw with the spring on it is for the choke cable...meaning the speed that the engine idles at with full choke.... and the screw slightly down and to the left is the idle speed screw. And then there might be an idle mixture screw between the carb and the valve cover. There is a process of adjusting the idle speed and mixture screw to get things set right. At least for the Aisin carb

So your saying my choke is hooked up wrong?
Im pretty sure that's where it was on the old carb. When I adjust the two screws you are referring too, nothing seems to happen.

 

[Seth S]

No i didn’t word that correctly. The screw with the spring on it isn’t for the actual choke cable but it’s the one that you adjust to set the idle speed for when you pull the choke cable all the way out.

 

[gt7058a]

This thread helped me a lot when I tuned my Fuji carb. A vac gauge and tachometer that shows degrees and rpm are also good to have.

First-time lean idle drop...help!

forum.ih8mud.com

 

[dannyvp]

What are those tach’s that you set up called?

 

[Seth S]

What are those tach’s that you set up called?

Just a tachometer you can look at in the engine bay. I have a nice fancy timing light with a tach function. I bet you can find a small handheld tach on amazon these days.

 

[dannyvp]

This is probably important information I forgot to mention. When I pull my choke out and the truck is running, it will kill the engine.

Also the auto store looked at me like I had a third eye when I asked for a diagnostic tach meter.

 

[Maxwild07]

When I rebuilt my carb and went to tune it, I bought an automotive mulitmeter from Harbor Freight. Comes with a clamp that goes around the #1 sparkplug wire that detects when that plug fires. It has some special settings that you wont find on a normal multimeter for getting a digital tach readout. I think it can do dwell and other functions as well but I haven't used it outside of tach and the other normal functions.

 

[gt7058a]

This is probably important information I forgot to mention. When I pull my choke out and the truck is running, it will kill the engine.

Also the auto store looked at me like I had a third eye when I asked for a diagnostic tach meter.

Get a timing light with a tach like this one

https://www.amazon.com/gp/aw/d/B000EVU8J8/ref=ppx_yo_mob_b_inactive_ship_o0_img?ie=UTF8&psc=1

 

[NeverGiveUpYota]

This is probably important information I forgot to mention. When I pull my choke out and the truck is running, it will kill the engine.

Also the auto store looked at me like I had a third eye when I asked for a diagnostic tach meter.

Have you put a vacuum gauge on the truck yet? Get one from HF or wherever and hook it up to the port above the finned brake booster connection on the intake manifold and report back.

 

[bobewans]

I used this video when I tuned mine

Also got a cheapo tach from amazon/fleabay for $10 or something

 

[dannyvp]

Have you put a vacuum gauge on the truck yet? Get one from HF or wherever and hook it up to the port above the finned brake booster connection on the intake manifold and report back.

No I have not.

 

[dannyvp]

I used this video when I tuned mine

Also got a cheapo tach from amazon/fleabay for $10 or something

I watched that guy. I just didn’t have that meter.

 

[LAMBCRUSHER]

back out your idle speed screw till it doesn't touch, the turn it back in till it touches plus one turn. pull your choke cable and then back your fast idle speed screw out till it doesn't touch, then back in till it touches plus one turn, then push your choke cable back in. both of these will need additional tuning- by backing them out now, you rule out the possibility of either them having been set too far in and causing the throttle plate to be open too far at idle. If the throttle plate is open too far at idle, you will rev high and have zero tunability... Next, the mixture screw should have been set at factory and you should not have messed with it. If you haven't, no worries; if you have, you will want to gently turn it in to its stop GENTLY, and then back it out 3 full turns. pull your choke out so the choke plate closes, and the fast idle screw contacts the throttle linkage tab and turn the truck on. since the idle speed and fast idle speed screws have been backed out, you will want to turn the fast idle speed screw in to reach optimal fast cold idle (can't recall spec, but it's about 1200rpms). after the truck warms up, push the choke in, and turn your idle speed screw in to keep a 600-700 rpm idle...Once you push the choke in, you're going to need to be sorta swift to get the idle screw turned in some. The truck SHOULD be able lope down to about 250-350 rpms, just chugging and wheezing, but still running, if there are no vacuum leaks, and the carb is somewhat tuned in. I always find it better to tune UP to idle speed from a lower running speed, as it rules out the plate being open too far, AND it proves the carb and intake aren't leaking...HTH some...

 

[Seth S]

if you have a multimeter you might be able to get a wire clamp kit for it. some meters will support the tach function

 

[4Cruisers]

I have an old dwell/tach meter, similar to this one:

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