Stuttering engine

[frankie]

Hi all,

I've recently fulfilled a long held ambition and bought a Dax Cobra with a 350 Chevy engine so I'm completely new to this game. I'm no mechanic and am completely confused by some of the definitions I've come across when trying to solve the problem that I'm experiencing.

When loading the engine above 3500 rpm the engine runs rough and seems to be suffering from either an electrical fault or possibly fuel starvation. In contrast when at idle it's running really smoothly. I recently discovered that the distributor was loose and have since had it tightened with the timing being reset and in a renewed effort to resolve the issue fitted a new set of points and plugs. I've also replaced the condensor but still have the same problem.

As you can tell from the above everybody I've spoken to provides a different answer. The distributor is a duel point Mallory with vacuum advance. The carb is a Holley (don't know any more than that at this point) and the fuel pump is mechanical.

I guess I'm at the beginning of a voyage of discovery but wonder if there is anything obvious I'm missing and if so who would be the best people to help.

Thanks.

Simon

[osgood]

Contrary Mary

Simon, could be one of a number of things, fuel starvation as you say, crack in cap or rotor arm or on the top of the coil look for ar-king on all these units. A faulty plug lead perhaps? Float levels need setting up on Holly (two low). Also if the cam is fairly hot it may not like the vacuum advance system, sorry I cant be of more help. Some times in these situations you end up spending heavy do-sh on items that are not faulty but its a process of elimination at the end of the day Eric.

[Miket]

Simon

I agree with Eric, first check the fuel levels, as I had the same problem and this cured it.

Setting the fuel level should be the first thing you do before attempting to make any further adjustments.The float level should put the fuel level just below the bottom of sight plug hole. You will make the adjustment with the vehicle on a level surface and the engine idling. You will first remove the sight plug, then to make your adjustment you will need to loosen the lock screw on the needle and seat. This will allow you to turn the adjusting nut to raise or lower the float level. Each hex flat on the nut will change the float level approximately 1/32". When you have the fuel level just below sight plug hole you will then tighten the lock screw and reinstall the sight hole plug. Make sure you have a shop towel handy in case you have any fuel leaks from the Sight plug or needle and seat adjusting nut.

:tu :tu :tu :tu :tu :tu :tu :tu :tu :tu

[nicklouse10]

Hi Simon,
I recently had a very similar problem on a ford 3litre V6. I changed the fuel filters and bingo, problem solved.
As it has been said, most of these type of problems are solved through process of elimination, I always start replacing the cheapest bits first, like the couple of quid filters etc.
hope you get it sorted.
Nick

[Jaun Huw Nose]

The Holley web site has lots of good stuff on it,you can also download the manual for you carb as a PDF doc,well worth while..
I've just replaced my Holley with an Edlebrock 4150 'cause I got pissed off with constantly tweeking the Holley...
If you're near Herts I can have a look and maybe help clear the prob if you want.

[petecob]

Had the same problem on my 350 chevy,it was the vacuum advance.Put a new one on, been ok.:}

[rocket]

It maybe that the points are gone because the dizzy was loose!

Did you set the timing with the vac pipe connected or off?

Rgds

Roger