I have a 12bp with weber 48ida. I tried putting 75idle jets in and I can screw the idle mixture screws all the way down and the car will idle the best like this. I thought that when you tightened the screws all the way down the engine should run way rich and idle rough and kill the engine? Well my idle is fine with the screws all the way down. I tried replacing the mixture screws with new ones' and I have the same result. I checked for vacuum leaks, none found. I tried putting a 70 idle jet and now the best idle is 1/2 turn out from full seat. Does anyone have any ideas what's going on? The only thing I can think of is that someone who had the carb last overtightened the screws and cracked the seat. I remove the mixture screws and looked down with a flashlight to see the seat and I don't see any damage/cracks. Does anyone have any idea's? Wacky- Where you at?

 

Screws in is LEAN. Screws out is RICH. This is only an idle adjustment. THe throttle plates have to be properly adjusted, so when looking form underneath, the throttle plate JUST BARELY (I mean JUST BARELY) exposes the "transfer slot". Its the little slot machined into the side of the carb barrel, near the bottom. THis is to insure you hit the transfer slot and have proper enrichment for throttle tip in when coming off idle. If you got that throttle palte too open, exposing the transfer slot at idle, it will pull fuel through it AND The idle enrichemtn holes. This will make the car really rich at idle, and then you will run circles trying to "tune" the damn thing to idle and not stumble on acceleration.

PS, I cant remember if the 48 IDA has a "slot" or 3 little holes. But thats what you want to look for. Remeber, out is restricting the passage LESS, letting more fuel by, in is restricting it MORE, letting LESS fuel by.

 

I'll check that out thanks. How are the throttle plates adjusted? I thought they are fixed? Do you mean adjusting them via the high speed screw?

 

The throttle adjustment screw, that sets the throttle position at idle. When you screw it in, the throttle opens more and the idle (should) go up. That one.

 

Sorry J, I just woke up. How big are your venturies??

 

46

 

What RPM does the car idle at?

 

I can make it idle as low as 1000rpms, but it's most happy at 1200. I can also see some drips of fuel come up through the venturies sometimes when it is idling.

 

Your float level needs to be adjusted. If your seeing fuel drip from the auxillary venturi your float level is high. Don't change too many things at the same time. If the float level issue is dumping fuel into the engine it will impact your idle adjustment screw changes. Fix the float level then go back to adjusting the idle adjustment screws. Idle should be from 1000 RPM - 1700 RPM depending on how big your engine is ported. If your driving the car on the street lower in the RPM is better for fuel economy if that is what your shooting for.

Good Luck
Albert

 

Albert, I'll double check my float level again. The drops of fuel are not coming from my squirters. I just have some fuel vapor/drops that shoot up out of the carb when the car is idling. I think because of the bridgeport? I think this may be normal? What's the easiest way to check my float level? Last time I checked about a month ago I did the measurement via the carb manual and it was spot on.

 

u never "tighten" the idle mixture screws down. it'll mess up the needle ends and the seats in which u tightened them into.

 

yup on the float level and mixture screw (dont over tighten it). I say let it idle where its happy. Albert said "Fuel economy???" WTH is that

 

Alright thanks for all the help guys. Here is what I came up with . I put the 70 idler jets in and the car now idles really well at about 1200rpm's and my response is instant. My cruise is nice and smooth and is alot crisper. I did notice that the front squirter was dripping just a tad at idle and come up with the conclusion that my fuel pressure was a tad high at 5.5psi and due to running solid motor mounts my float is bouncing just a tad causing the slight dripping at idle. I backed the pressure just a tad and now I have no more dripping and my idle has a nice brap, brap, brap that you just got to love from a bridgeport. Car is pulling really hard with the help of ALbert and Mel. You guys are the bomb. I think I'm almost ready to graduate weber ida tunning school as I am getting the hang of it finally.

 

I have a couple of suggestions so you don't blow your motor. If your running MSD's put the rev limiter chips in ASAP. You should be able to make good power under 9,000 RPM. Purchase the EGT meter and use it. The MSD RPM chips and the EGT meter are way cheaper than blowing your motor. If you need any additional help let me know.

Albert

 

Albert, I only am running one msd 6al direct fire on the leading and stock on the trailing. If I use the rev limiter it will only kill the leading. Will this be enough as I heard it would not? I dont have the cash to buy two more msd's right now, but I am going to buy that egt meter asap. Thanks, the car is running awesome!

 

no but a bolt in your gas pedal will help you not to let the pedal meet the metal. Remember thats how I did my son's first car for a 6 months. He always wondered why his FB wont go past 80mph. I told him that it was electronically controlled.

 

Mel, your too funny!!! That's a good idea though. When my son starts driving he's getting the bolt.