Hey guys...the truck seems very low on power. The original carb was dirty so it was rebuilt. When trying to put it back on, the phenolic spacer broke and caused a MASSIVE vacuum leak. It ran like ****. got that fixed with an EGR plate and gaskets...checked for vacuum leaks, there is none. The car runs like a champ, one pump in the morning and it starts right up, doesn't stall or anything. But it feels much weaker...wouldn't it be stronger now that its running right? What could be the case.

 

have you confirmed the secondaries are opening? on mine the air valve plate was jammed in the carb body and wouldn't open even though the secondary throttle plates were opening...

 

How do I do that?

 

you can take the air cleaner off and make sure you can manually open the air valve plate...or you can blip the throttle and watch to see if everything is opening.

 

Ill probably do that in the morning and check a diagram. Like I said, she runs better than she ever has, and still has power. But she won't burn tires anymore like she would before all of this, and it doesn't feel like it pulls as hard. Also, top speed is down.

 

a video that shows how my carb is functioning cold.

Let me know if there's something wrong.

 

Besides the fact that the 4350 is an abortion of a carb.

Issues.

The clip by the choke cap is for the heater core feed hose to run by to help heat the bi metallic spring in the choke cap.

I can tell right off the choke is not set correctly and it needs "wound up" a bit the choke should close fully on a cold engine. Your high idle is also low.

Did you adjust the idle air screws when you installed it ? Those need to be set after a rebuild

As for the loss of power. Make sure you are getting full stroke on the accelerator pump.


Also did you get your actual carb back ? The 4350 had several engineering/manufacturing issues and no 2 run the same. If you do mange to find one that runs good guard it with your life as about one in ten actually ran properly..

The real solution to fixing the 4350 is to remove it and replace it with a Holley. As that is exactly what Ford did back in the day.

 

I remember that the guy did tune the IAS but I don't know how well. I'm thinking I'm going to have to do it myself which is fine. As for the clip, I knew about that but just didn't put the hose back which is an issue.

 

Good idea to double check it. The 4350 is a fickle carb and I have seen and most never run the same after being rebuilt.
To be honest I don't recall if I have ever seen one after being rebuilt that ran as good or better than it did originally, especially if it was one of the rare good running ones.

Really the best thing to do with a 4350 is to remove it put it away in box and replace it with a Holley or a Carter (Edelbrock) Personally I would go with a Holley, I have never been a big fan of the Carter, but that is me.

 

Carbs are expensive.

There's no reason I should lose so much power out of the thing that I can't even burn tires like I did when it had a massive vacuum leak...

Its pathetic.

 

In the event your carb is well rebuilt and tuned, that carb is a worthless pile. I had one on a '72 T-Bird with a 429. Carb needed a rebuild, but dropped on an edelbrock 1406 in its place and that car really woke up!

As for your truck having more power with a vacuum leak, it sounds like it was tuned to run with the leak, and now that it's corrected it may be running too rich...

Cheap carb cores to rebuild can be found on craigslist. I'm not one to tell folks how to spend $$, but replacing that carb is a must-do unless on a shoe string budget!

 

Wait a minute. Watched your video and yes your choke is not set correctly and the high idle is a bit low to my ears.

Also...how is your distributor's vacuum advance hooked up? Only wondering because that would affect your power that you feel.

Mixture may be set wrong at idle as well. Again my guess is that it's lean. Did you set the idle mixture with a vacuum gauge and the idle speed with a tach?

 

The guy did all of that by ear, but he's a professional who's been doing it for many years. All he does is carbs.

I don't have a tach or a vacuum gauge...

I also don't know where the vacuum advance goes...is that smog equipment? My truck is desmogged. I really need a simple guide that shows how to tune the thing.

 

It sounds like you are not getting full accelerator pump stroke. Check that is is even hooked up. It is adjustable See below for accel pump adjustment.

The 4350 was Fords second attempt at an emissions 4BBl carb. The 4300 was the first attempt at an Emissions carb it was better than the 4350 but not much better. There is a reason Ford abandoned the 4350 after just a few model years and they went to Holley's

 

That would have been a 4300 not a 4350. The 4350 came out in 75. The 4300 could be made in to a decent carb but you ussually had to go beyond just a simple rebuild. It required opening up some of the bleed jets and ports. Some 4300 carbs were ok. Others were just as bad as a 4350.