| Author |
Message |
Tim Hogan (Tojo)
New member
Username: Tojo
Post Number: 38
Registered: 4-2002
| | Posted on Thursday, July 04, 2002 - 9:11 am: | |
Had my genius Ferrari expert friend tune the car today. Wow what a difference it can make with someone who has done it a million times does the job. I replaced the spark plugs first, then Gerry synchro'd the carbs in adjusted, the mixtures and found a mystery air leak that I missed.
The carbs do need to be fully rekitted though so that will happen real soon when i do the cambelts, bearings and clutch replacement.
Thanks again all for your helpfull tips and suggestions |
Keith Rudd (Rpmcars)
New member
Username: Rpmcars
Post Number: 1
Registered: 7-2002
| | Posted on Tuesday, July 02, 2002 - 2:24 pm: | |
hoping to help you all out i would start with replacing the plugs as they are probably fouled and will not take to being cleaned well, then remove the carb tops and clean and clear the float bowls, check the jets and passages again and if you have build up in the bottom of the bowls soak in a high quality spray carb clean. re assemble and check. |
Bill Sebestyen (Bill308)
Member
Username: Bill308
Post Number: 260
Registered: 5-2001
| | Posted on Wednesday, June 26, 2002 - 8:24 pm: | |
Pascal,
I guess I don't understand the logic. When the ambient temperature is high, air is less dense and requires less fuel for a given mixture. When the air temperature is cold, air is denser and requires more fuel for the same air fuel mixture strength. If you take a balloon filled with air and put it in your freezer, the diameter of the balloon will be smaller, yet the mass of air in it, will be the same, disregarding leakage. The difference is, the air is more dense, for a given mass of air, and therefor occupies a smaller volume. The bottom line is, more air requires more fuel for the same ratio of air to fuel. If larger idle jets solved your problem, then I suspect one or more of your idle jets were restricted by something or your engine is getting extra air from another source, perhaps a vacuum leak or oxygenated gas. |
Pascal A. J. Maeter (Maeter)
New member
Username: Maeter
Post Number: 21
Registered: 11-2001
| | Posted on Wednesday, June 26, 2002 - 3:07 pm: | |
This may sound a little far fetched but I am finishing the restoration of a Dino and have experienced the same problem as you. The car started fine and held its idle without problem when I bought in Italy, and after rebuild and tune up, barely starts on a good day, fouls the plugs very easily and does not maintain its idle when warm. I spoke to a Weber carbs expert and the first thing he mentioned were the jet sizes. It seems that jets need to be larger in warmer climate countries (Italy) and smaller in cooler climates (UK) primarily due to the air being finer or heavier. We made the change to the idle jets first, and it cured the idle problem. We are changing the main jets tonight which should clear the starting/flooding problem. Go figure. |
Tim Hogan (Tojo)
New member
Username: Tojo
Post Number: 36
Registered: 4-2002
| | Posted on Wednesday, June 26, 2002 - 12:03 pm: | |
Thanks guys for the suggestions. I had a quick look at the plugs before I went to work today and they didn't look that flash. I'm going to clean them tomorrow and see what joy that brings. I'm sure flooding them hasn't helped. The plugs are reasonably new so I don't want to replace them right away if cleaning them does the job. If not new plugs are my next stop. If not the next stop will be the carb rebuild.
One of the guys I work with suggested I crank the car for a minute with the throttle fully open to dry everthing out then start it again. Doesn't sound too good for the starter motor to me what do you think?
I'll keep you posted on my progress. |
Matthew J. Morgan (Kermit)
New member
Username: Kermit
Post Number: 18
Registered: 8-2001
| | Posted on Tuesday, June 25, 2002 - 10:29 pm: | |
Bruno's Right.
With the length of time sitting , the gasoline in the float bowls has broken down into various compounds, including varnish. The carbs may have dried out, which will has been known to be hard on all of the carb's "soft" parts (gaskets, diaphragms, etc.
So the wisest choice IMO is rebuild rather than waste time. You mentioned mufflers. During rebuild would be a good time to rejet if necessary to compensate for different levels of back pressure. The manufacturer should be able to intelligently give you "ballpark figures" . As a general rule, more airflow, more gas flow.
Kermit
|
Gerrit Visser (Gerritv)
Junior Member
Username: Gerritv
Post Number: 74
Registered: 6-2001
| | Posted on Tuesday, June 25, 2002 - 6:04 pm: | |
Hi
For rebuild kits, check on eBay. 'einmaseratifan' often has kits for set of 4 DCNF carbs starting bid @ USD59 plus shipping.
For the other challenges, get your ignition timing setup first then play with the carbs. If the last thing you did was clean the idle jets, then you need to start looking there for whatever ihas made the problem worse. E.g. the o-rings should be lubricated slightly (Vaseline?) so they will seat easily. It is also possible that in cleaning you blew dirt further into the passages. Did you use compressed air? It is also possible that one or more of the jets is not seated? |
bruno bandaras (Originalsinner)
Junior Member
Username: Originalsinner
Post Number: 179
Registered: 5-2002
| | Posted on Tuesday, June 25, 2002 - 10:27 am: | |
I would take the carbs down rebuild,reinstall,then set up from what you said.A rebuild kit is only 40-45ea. for full kit.less for orings only. |
Tim Hogan (Tojo)
New member
Username: Tojo
Post Number: 34
Registered: 4-2002
| | Posted on Tuesday, June 25, 2002 - 9:52 am: | |
Thanks for the tips Kermit. Dialing in the carbs will be the next step when I get the damn thing to start. In my tiredness I forgot about air leaks, but being the pessimistic type, I have my doubts. All the o-rings for the idle jets looked pretty good and I'm sure I didn't damage any. Would that make the difference to allowing the car to start if one of them was damnaged? |
Matthew J. Morgan (Kermit)
New member
Username: Kermit
Post Number: 17
Registered: 8-2001
| | Posted on Tuesday, June 25, 2002 - 9:13 am: | |
It sounds like you need to get your carbs dialed in. First make sure that it isn't an ignition problem.
Sync the carbs, or balance them.
Your Idle mixture should start at 3 turns out to start, adjust to suit from there.
Getting the linkage to work with the carbs in sync can be tricky, a little trial and error helps.
Take care that you do not adjust the idle screws in so far as to cause the throttle plates to start to transition into the intermediate circuit.
If necessary to arrive at the proper idle speed (Warm) on just the idle mixture feed holes exposed. If necessary, drill the throttle plates .040" to allow more air, so that the rpm is right with the idle mixture only. You may go to .060" if necessary, but it is better to start small than to solder holes shut, and redrill smaller. I prefer to drill the hole halfway between the shaft and the idle feed.
Hope that helps. Oh yeah, Check for air leaks first?
Kermit |
Tim Hogan (Tojo)
New member
Username: Tojo
Post Number: 33
Registered: 4-2002
| | Posted on Tuesday, June 25, 2002 - 8:28 am: | |
sorry about the double post I was trying to clarify the car model but my ten thumbs managed to bugger things up |
Tim Hogan (Tojo)
New member
Username: Tojo
Post Number: 32
Registered: 4-2002
| | Posted on Tuesday, June 25, 2002 - 8:23 am: | |
Here's some background for anyone who maybe able to give me some advice.
I've been restoring my 308 for about a year now, and I'm just about finished. The car has not had a proper run for about 2 years now, except for a couple of minutes when I took delivery of it and when the panel beater was moving it around.
I just had a new muffler fitted to replace the crappy and heavy US muffler. (Man these cars sound wicked when you run them without the pipes). When I got the car back I took it for a couple of laps around the block for my first drive. It went pretty well when the revs were up but was idling a bit rough and spluttering when the go pedal was applied and revs were low after changing gears.
I then decided to clean my idle jets, thinking this can't hurt and it would go some way to fixing my problems. The carbies were really filthy on the outside so I gave them a good clean and then removed the jets and cleaned them one at a time.
This is where my big problem is, when I went to start the car it wouldn't. It cranks over gives a bit of a cough and splutter but wont fire up. The accelarator jets are pumping plenty of fuel into throats, and I have good spark coming from my ignition system. The engine does need a good tune up - timing, mixtures and idle speeds, but as the car was running and starting before I can't work out why it won't kick over now.
Any suggestions will be greatly appreciated. |