Daytona poor running...

Terry, this is only an opinion but, I would agree on that it sounds like carburation too. excellerator pump concept but, in the reverse of what you are saying like they are starving the mixture a bit, too lean. You would think that those MSD boxes would keep those plugs clean in just about any combustion environment. I wonder if cam timing could be off? Just thoughts, Regards, Vern

 

Is it still using points to trigger the MSD's? Or did it get switched to an optical system?

 

I vote carbs.

The cam timing is an interesting point but you dont get any tougher Ferrari motor than the Daytona and timing just does not change without a human involved. It will retard slightly over time with chain strech but all in unison and not by a whole bunch in any event.


I think the thing to do would be to get a really good look at the function of the accel pump operation. If it has gotten some dirt in the system the pump nozzles are small and several may be clogged, non return valves may not be working. Pump diaphrams shrink and start leaking with age etc. Look it all over.
Float levels do change, ck those too.

 

Terry, sorry I was thinking from my old holley carb days on the acc. pump deal. How about float level in the carbs maybe they are too high or sticking.

edit whoops Brian beat me to it.

 

Just for laughs also get a good look at all the progression ports and probe them to be sure they are not blocked.

Does not fit all the symptoms but some similar ones.

 

What heat range are the spk plugs and brand?


Have the carbs ever been completely rebuilt dissassembled?

If the butterflys are not perfect with the progression ports you'll get a stumble on take off.



Sounds like a carb sync issue such as mixtures, linkages or possibly float levels.It takes some real skills to tune 12 Webers maybe get a mechanic more familiar with them.

 

I agree, check the plugs for proper heat range. Too cold a plug is going to get wet and miss when the accelerator pumps richen the mixture.

 

Concerning the accel pumps you can check them by getting a small vial or plastic container wrapped in wire, give 2 shots of throttle and measure the appx amount of fuel for consistency in each, should be around 8ml fuel if I recall.

Its interesting the car was in tune then out, carbs shouldn't just go out of tune unless bad fuel deposits from sitting or air leaks from somewhere , lead plugs, throttle shafts.

 

The inconsistency is the clue here I think.

Are you sure your fuel supply is trustworthy..... ie, water either in your tank or even from the outlet you buy it?

 

I had a six carb alloy 275 that did the same thing for 20 years. Never did get it to run 100% unless I featherd the throttle slightly. Always thouht the car was over carburated even though it was stock. It did run better without the air filter & just velocity stacks( the same velocity stacks I sold you a while back).

 

I know they are not the same Webers, but do the carbs on your car have the air bleed jets in them like the carbs on boxers do? (I might need a little help on the correct terminology here, as I’m still new to Webers.)
When my car was exhibiting the same symptoms as yours, I found a tiny bit of something in two of these jets. After blowing them out, and cleaning the fouled spark plugs, the car ran like a top again.

 

For my 77 308, going from a 6 heat range plug to a hotter 5 plug appeared to get rid of a slight miss-fire, an oily fuel smell and a sooty exhaust.

I think Ferrari recommended colder plugs expecting their cars to be tracked or at least to use a lot of high power. With modern road conditions, speed cameras and so on, this is sadly not possible much of the time.

It maybe that the hotter plugs just perform better with not perfectly adjusted carbs.

In any case there seems to be no disadvantages in going to a hotter plug. Pre-ignition or pinking is apparently not a problem with these low compression engines (Daytona also?).

Richard

 

Those are the idle jets John, the air bleeds have a nut on them.



I agree on going to a hotter plug bp5es, the traffic is probably what fouled your plugs a hotter plug will prevent this.

 

Thanks J.P. like I said, still learning.
So in my previous, substitute ‘air bleed’ with ‘idle jets’.
Whatever they are, getting the tiny pieces of whatever out of them made a tremendous difference, and I assume it might well pertain to Daytona carbs as well?
John

 

Nah, from what I've read BP5ES is the best plug for older V12 Ferraris, BP6s can foul, according to the experts quote "a colder plug is the sign a wanker worked on the motor", this was from Tony P in Forza also agreed byPatrick Otis.

I am thinking of going to a BP5ES in my BB as well from a BP6ES, I avoid driving in town so haven't had a fouling issue especially since I replaced my wires with Beru Porsche 911 style screw on extenders but I think they are better as the plug runs a bit hotter so it keeps things clean.

 

Depending on what cross reference manual you read, the original champions cross over to an NGK 7 or 6.

I used 7's for years until I came to Oz and leaded fuel dropped out the market, and since then use 6 as std fitment, 7 in high compression engines (used to use 8's) and 5's in city cars.

5's on track or in competition will melt the tips.

Examine the plugs closely, or even post close up photo of the tips here... oil contamination, bad fuel, overheating of tip (wrong plug for use/timing) etc can be quite easily identified.

Check NGK website too, for photo's.

 

Get away from ES, try EY.

Same price, grooved tip.

 

Terry,

I had the same after a major service of my (ex)Daytona. WWoC checked everything and could not solve the problem. Later it turned out to be a tank of bad gas. Maybe you want to check this.

 

I would clean the idle jets just in case. Easy to pull and clean.

I would also get a buddy and check the timing on each bank and see if the mechanical distributor advance is advancing.

Easy stuff to do yourself if you are a little handy.

Good luck.

Drew Altemara

 

I had a similar problem on my '78 308, I looked down the carbs while holding the throtle at 3500 and saw fuel dribble from the accelerator jets. The cure was to clean the check valve in the accelerator pump circuit.