[HoosierBuddy]

I told you guys my problem with my 289 was the carburator! Or, maybe I said something closer too, "I'm pretty sure it's not the carb."/forums/images/icons/blush.gif

In any case, as my earlier posts stated, my 289 wasn't wanting to wind out past about 4800 RPM. I decided it was the ignition, and specifically the fact that I had my Pertronix wired up "the easy way"...i.e. 6V at the coil instead of 12. I cleaned up my plugs (they didn't look dirty to begin with, really). Then I unhooked the 6V wire to the distributor and hooked up a jumper off the positive side of the battery in it's place. Test drove it. Didn't make a bit of difference.

So, I pulled the air cleaner and had a look at the secondary sight glass. I couldn't see a fuel line, even when I rocked the car, so I knew that it was either way too high or way too low. I unscrewed the secondary float seal and found the float was screwed all the way into the fuel bowl. In fact it was so far in I couldn't even grip the outside of it to adjust it out. So, the secondary fuel bowl was dry as a bone.

[The specifics are: Holley 4160, 600 cfm. Fairly new carb. I put it on about 4 years ago. Has about 12,000 miles on it.]

Why did the float get adjusted that far in, you ask? Well, because after I put my engine together I was getting a bad surge at idle, which I finally determined was related to the secondary fuel bowl level. I adjusted the secondary float in until the surge went away. I had no idea that I had adjusted it that low!/forums/images/icons/mad.gif

Evidently, the surge went away once I had the fuel completely shut off to the secondaries.

So, tonight, I reset the fuel level to the center of the sight glass, or maybe just a hair higher. The surge returned immediately. The idle bounces from 500 rpm to 700 rpm at idle. When I drop it in gear it gets much worse, with engine almost dying and then coming back up in a cycle every couple of seconds.

But, at highway speeds, the engine pulls like a log truck all the way to 5800 rpm, where the tranny upshifts, and it gets with the program in the next gear.

So...for now, I've adjusted the idle screw up to make the car idle at about 1000 rpm in neutral or 800 in gear with the brakes on. That tames the surge a lot, but it's still there.

It seems to me like the secondaries are leaking gas into the engine somehow. But then again, it was me that said I didn't have a carb problem to begin with...so bear that in mind!

What should I do next?

Phil

 

[CantedValve]

This is probably of no consequence, but there should be a thin metal plate between the block and the metering plate... if this is missing gas will POUR into the secondaries. Since your car is RUNNING, I doubt this is happening

 

[Guest]

Fuel level should be just to the base of the sight window. Too high and the secondaries will be tipping in

 

[Billgear]

Amazing what a couple of extra barrels will do! Fuel level should be at the bottom of the sight glass, just a little bit makes a huge difference.

 

[Art]

Is your vacuum advance hooked to the ported vacuum fitting? Does the engine surge with the vacuum hose off?

 

[66coupe289]

Follow Billgear and SuperCJ and set the floats to the bottom of the site glass. You should be able to have the site glass out and not have gas pouring out when the car is running. If you bump your fender with your thigh to rock the car and gas comes out, you have got it right.

Remember to set both the primary and secondary floats this way.

 

[My427stang]

This is how I'd attack it.

1. Set both float levels to just barely at the bottom of the sight hole while the motor is idling, like someone else said, it should only come out of the hole when you rock the car a little

2. Set the timing with the vac advance unhooked and plugged, good place to start is 12 degrees, pretty safe number for small blocks

3. Leave the vac advance plugged and set the idle speed as low as you can. dont go crazy, but on AT cars, put it in gear and if it doesnt stall its OK, Ford specs are best. What you dont want is for the transition circuit in the carb to feed fuel at idle because you have the idle too high

4. One at a time, turn each adjusting screw (sides of the carb) in until it starts to stumble, then back it out slowly until you have the highest idle, then do the other side

5. Reset the idle speed, then do the mixture screws again, they may be exactly right, but if they were way out of adjustment to begin with and your idle speed setting changed after adjustment, its better to fine tune a second time

6. Check the vac advance line and see if its got vacuum to it at idle. It shouldnt, if it does, find another port at the base of the carb that is dead at idle (ported vacuum) There is a big debate on ported vs manifold vac, but bottom line, unless you have a big cam, its best to use ported vacuum, manifold vacuum doesnt hold idle timing as steady, ported vacuum shuts it off and lets you use whatever you set in the distributor and then timing comes on as you need it

With that you should be in good shape carb wise. Other things to thing about, if you have a bad float in the rear, it could be flooding the motor and by cranking it down you shut fuel off to solve the surge

Also, if your vac line had vacuum to it at idle, often old Ford distributors will short out when the advance plate turns, however, you have an old dist with new wiring and no points, so the likelyhood is low. Pull the cap though and check to make sure no wires frayed, it can be a tough thing to diagnose because that advance plate is always moving and the problem is rarely consistent

My bet is float adjustment and the other carb adjustments though

 

[Guest]

Take the secondary float/needle assembly out and make sure that the needle moves freely. I had a similiar problem with the needle getting stuck because the pressure on my Aeromotive pump was to high and forced it stuck open and lower the floats helped the problem but didn't cure it, took it out checked and cleaned it, adjusted float and it works fine.

 

[mstngjoe]

Sounds like you're on the right track.

I'll have to admit, I didn't consider the rear bowl might be empty. *G*

 

[Nedcrane]

The secondary throttle shaft has a stop screw that holds the throttle plates slightly open at idle position.It may be open too far,pulling fuel through the secondary booster at idle.This would explain why lowering the float level stopped the surging.Pull the carburetor,drain & flip it over and back this screw out 1/2 turn and try it.There's an exact spec on this but I can't remember what it is on a holley.Autolite 4100's spec is 3/4 turn past initial contact of the screw with the the throttle plates completely closed,but I don't if this spec is the same on a holley.Hope this helps...Let us know what you find...