79 308 choke?

http://www.ferrarichat.com/discus/messages/256120/184538.html

 

The use of the choke is not nessasary in most cases (45 degrees F and above) . The choke is extremely rich and will foul spark plugs. Normal starting proceedure when cold :turn key on 1 minute to let fuel pump run , depress accelerator pedal 2 full strokes , hold the throttle 1/4 open , turn key to start and hold rpm's 3000 for 1 minute. A properly adjusted engine will idle slightly below 1000 when cold and 1000 when fully warm.

 

Is it possible that the choke can be partially on one bank of cylinders and not on the others. The reason I ask is that I seem to be getting very fouled spark plugs on one side and not on the other.

Regards,
JP

 

"Is it possible that the choke can be partially on one bank of cylinders and not on the others." -- Yes, it's possible (so worth checking IMO). Each "bank" has it's own choke linkage connection to the choke cable so they could be out of sync relative to each other.

 

The bigger problem is "washdown". Fouled plugs are easy but if you get fuel mixing with the oil you have a lot bigger problem!! If the choke does not fully disengage (and from what I'm told this is common) you'll be dumping extra fuel in creating "washdown".

This was the first lesson my Ferrari Professor taught me!!

 

Would this explain why the spark plugs were in really bad shape on the back bank. How does one check to see if the choke cable is sticking.

 

does anyone here need to use choke on cold start up ?

I have never used choke on gina ('80 gts) and during carb service this winter the choke cables will be disconnected.

cheers, d

 

No choke....Press the pedal four times and crank that baby up.....

Amusing that I picked the car up from a clutch job and one the dash lights was glowing amber, I could not recall what it was, checked the manual it's labelled as "spare" WTF??

Then realized the tech, not used to the car, had set the Choke to ON, illuminating the lamp indicator!

1977 308GTB

 

JP -- This illustration shows the choke lever on the 40 DCNF carb. You'd want to make sure that main cable and the interconnecting rods are working together such that the choke lever on each carb is in its fully closed position when the choke lever handle in the cabin is in the "choke off" position. Your problem could be that the carbs are just poorly tweaked up, but ensuring that the choke levers are working correctly is something that would be done first anyway. Good luck...

 

Thanks for the picture. Now of course the front carbs choke position are fine, (but then I figured it would be as the spark plugs from the front look fine), now how on earth do you see the rear carbs choke position. Are carbs positioned so that the rear carbs choke is inside the 4 or facing the front of the car. Something tells me I have to remove the airbox, and according to the archives this means taking the hood off. If this is the only way to check the cable, then I will have to wait until I get over to the dealership later this month. Pehaps the air box can be lifted just enough to view these cables....BTW what is holding the air box down, i can't see any actual connection to the car. If there is some other way....please tell me how.

Thanks, I think I am finally on to something.

 

JPL,
All four carbs are oriented the same way, as shown in Steve's drawing, when viewed from the back of the car. I can easily see the choke mechanisms under the lower edge of my stock air filter box. I'm assuming your 79 has the same air filter box as my 78, you should be able to see the all the choke mechanisms with little difficulty.

 

You will be able to inspect the mechanisms of the left (driver's side) chokes with the airbox on, but to see/adjust the right side chokes, the airbox has to come off. Heck, while it's off might as well synch the carbs. (It's easy!) The chokes don't need to be super fine-adjusted, just make sure that when the lever is in the off position, they are all OFF for sure. If they don't engage perfectly together, no big deal.

It is not necessary to remove the lid (hood, never know what to call it) to get the airbox off, although with my car ('77) it is necessary to remove the prop stand so I can actually lift the lid just a little higher than it allows the lid to go normally. On cars with hydraulic shocks instead of a prop stand, I'm not sure if the lid goes high enough, but you can unbolt the shocks at one end I'm sure to gain a little extra.

I find it interesting that everyone says not to use the choke but they all recommend 2-4 pumps of the pedal, which causes the accelerator pumps to squirt a ton of raw fuel into the throats of the carbs. This is in effect a "super mega choke" and accomplishes the same thing. Ferrari put a choke on the car for a reason--it makes it start better when it's cold! I use the choke when cold, don't need to pump the gas, and then just get the choke shut off as soon as the car starts. This does not foul the plugs more than pumping the gas a couple times. I have no plug fouling issues. Besides, if your plugs are consistently getting fouled, I would suggest that you have an issue much larger than just using the choke to start it. (Like, it's too rich in general, your plugs are too cold, or you just aren't driving fast enough!!!)

Birdman

 

Well that's a good point Birdman!

Maybe just two or three pumps! LOL

FYI the airbox is mounted from inside to the carbs with four nuts washers and brass bushings EACH. Be careful and don't drop any! That's a lot of little hardware and I re engineer the air box mounting in my mind to fall asleep at night.

It would sure be nice to be able to remove it more easily!

Once set properly though, the carbs need little attention.

 

NGK BP5ES, a little hot perhaps, but my engines old and needs a little help!

 

IME 1 or 2 half-squirts was plenty for a cold-start if followed by some additional intelligent feathering after it fires (but that's on a daily driver -- perhaps if a car sat a couple~few weeks it would need more encouragement). It is a crude, big dose of fuel, but there are no spool valves involved that can stick open .

We always make these things such black-and-white issues. If using the choke mechanism is working for you -- viva-la-difference -- you just might include giving the spool valves a little attention/TLC in your major or between-major services.

 

Remember, if you do remove the air box, there are 16 brass bushings under the air box pushed into the rubber gaskets for the trumpets. Make sure you count them all, as I lost one inside one of the carb throats!!

 

That's what I was trying to warn about...what a pain!

 

I ended up sticking my fingers under the box to feel for the choke levers. They are fully closed.

 

It's not necissarily the fuel at start up but the chance that the chokes may not fully dis-engage after start up that is the greater concern. If you wind up dumping extra fuel in after it's started that creates more problems than just fouled plugs!!

Like someone else said if it works for you Great!

 

I guess that you need to use the choke often enough that it won't stick. It's like anything on these cars...use it or lose it!

 

I was advised by several mechanics to not use the choke, as it tended to foul plugs, and generally create problems. Usual starting procedure, two quick pumps of the gas pedal, crank and feather throttle after it catches. I usually would feather the throttle for 10 seconds or so, until the idle became steady. Warm start, I would just slightly dip into the gas pedal. Hot or cold, the car always started right up.

I would also agree that if you have been using the choke with no ill effects, then keep on...

Dave

 

Based on responses from this list, I didn't even install a choke or cold idle mechanism when putting on new 40DCNF-12s (one less thing to break); Amazingly, it always started and idled just fine after two prime shots, even in sub freezing weather. Runs just fine after a 30 - 60 second warm up and driving with judicious revs until up to temp with no stumbling. Webers are amazing.