365 RUNS BADLY WHEN HOT

Just out of curiousity, how is your charging system?

When I first bought mine, it had a similar problem. It turned out that neither alternator was working. The previous owner kept it on a charger all the time, so the battery would start out fully charged, and as it went down, you would see this.

 

Might as well replace the distributor caps and rotors

 

It could be that your car doesn't run badly, but it overheats. Overheating can cause pre-ignition, among other problems.

john

 

Hi Stuart

My first thought would be to re-check the float levels and then make sure the jets are clear. I know that the carbs have been rebuilt but although very robust the tiniest error can have you scratching your head for ages! Did you have the carb bases redecked and/or are the throttle spindles worn? You could be sucking air in there. Also check both camshafts are on time.

Good luck

Colin

 

I'd suspect the coil breaking down when it gets hot.

 

What you can also do is to run your car in a very dark garage and check for sparks in the ignition system. If you see some fireworks you know the problem.

Good luck and have fun

 

Coil was my first thought also about what would be most likely to fail with heat. You mentioned the coils are new, but maybe one of the new coils is faulty. You could try temporarily installing the old coils as a test.

This might be a crazy idea, but maybe you can tape a sound recorder above the exhaust and separately record the driver and passenger sides while it's breaking up at high RPM to isolate the problem to a bank.

If it breaks up on only one side, then it is probably ignition related since there are separate circuits for each bank. If it breaks up on both sides, then it is probably fuel delivery related or it could be low overall voltage level weakening both sides of the ignition.

One strong possibility is vapor lock making it difficult for fuel to flow when the engine compartment gets hot. Have you tried turning on the electric "booster" fuel pump when the engine is hot enough to break up?

 

...investigated the possibility of vapor lock. I had a VW of all things with the same symptoms and it was due to vapor lock.

 

carb, vacuum leak?

 

just flip the "A" autoflux electric fuel pump switch to eliminate that possibility.

the description of Stuart's symptoms are just like those I had when I bought my QM; one of the coils was in its death throes; not totally dead, but on its way. Are these Bosch "blues"? I would remove and bench test even though they are new.

 

How did it run before you changed all these parts? Recentily I've had a run of bad condensers.

 

Hi Stuart, if your valve clearances were too tight, higher engine temp would change engine performance. Otherwise, seems like you've replaced all the ignition components already.

Norb550 has a good question.

john

 

I don't know if the have a Pertronix electronic conversion for these, but they are wonderful. They take the place of points and are dead on once you set it up. Even makes up fro a slightly worn distributor.

Perry

 

Also, they are self contained under the distributor cap. Can't see that it isn't stock, and can be put back easily when required for cocours events.

Perry

 

Sounds like the engine is a touch too rich. It needs less fuel, the hotter it is. Suggest you either try one size smaller main jets OR two sizes larger air correctors and see how it is.
Chris

 

Make sure you have proper spark plug gap. Stick with copper plugs.

 

after having read the post from it's inception.....

....And please, posters shouldn't take my question negatively/as an assault on your manhood/etc...

But, as a rhetorical question:
outside of quips best associated with experiences which have mostly/can be described as:
"in my own experiences..."

How many posters are actually:
Professional, "automobile mechanics???"
I'd really like to know...

My guess is...almost none?

 

We are all professional mechanics, in our own little minds!
Or we could be just trying to help as best we can.

Hopefully the OP has sorted it out by now, and won't be needing, my very unprofessional advise.
Ps At least One of the posters, rebuilds vintage Ferrari engines and cars.

 

335s:

I do not work on Ferraris for living, but I live to work on Ferraris. I love working on my cars even more than driving them or showing them.

What is the point of your question?

Last I checked this forum was for hobbyist and enthusiasts. Mechanics and other service providers are immensely welcome (and much needed, like our DWR46), but this is not a commercial forum.

A fellow owner asks other fellow owners for help realizing he'll get some good advice and some bad advice, but the choice is his and so is the risk. We all talk, we all learn, as is the intent of this forum.

I personally would be ecstatic if there were as much posts and discussions surrounding technical issues as there are surrounding “what are Ferraris worth” discussions.

We do not want to discourage people from contributing to these kinds of threads.

Thank you.

john

 

Vintage owners have "been there done that" for most of the problems that occur with old cars. Many owners are "hands on", but even those that aren't usually find out what was wrong when when they have it fixed, so even less technically savvy individuals can still provide valuable feedback. There is no substitute for experience. An excellent mechanic that doesn't have vintage Ferrari experience can provide a lot of theoretical input, but they are unlikely to know that, for example, flicking on the booster fuel pump will cure a vapor lock condition (which I still think is the most likely cause of Stuart's issue). We all learn when everyone shares their experiences.

 

Sorry, dear Mr. Monma, but I'm just one of them! One time, having learned that NGK (copper) plugs worked best, I installed a set, but forgot to "double-washer" them, with the result that they bottomed out and mashed the outer electrode shut against the central electrode. Just one more thing to think about.
Now back to your regularly scheduled program.

 

It is very clear that you have no idea what the vintage section is all about.