[freddybob64]

I have noticed a gas smell on the dipstick of my 355. I have changed the fuel pump, makes no difference. The level of oil does not change. I am running a Holley 3310, the engine builder put it on and it was used. It has 66 primary jets. Does this sound like a carb problem or something else. The car runs fine just a little worried about the smell of gas in the oil. By the way I am running a stock mechanical fuel pump from autozone. Any help would be appreciated.

 

[Dave427]

Sounds like the carb is running way too rich then. Does it start like its flooded after sitting? A leaky power valve could leak fuel into the intake after sitting a while. Or the carb could be boiling after you shut it off. You are off the stock jetting by 6 sizes. I would purchase a 670 Street Avenger if your 355 is mild.

Dave

 

[freddybob64]

Dave, the power valve is fine. By looking at the plugs if anything it might be running just a tad lean. As far as mild or hot I really don't know, it has a Howards solid roller 582/582 lift and 246/246 duration @ .050. I did find the intake bolts pretty loose, could the gasket seal on it be a problem or do you think it is over carbed. I did check the float levels and had to adjust the secondary as it was to high. I have the idle mixture screws out about 1 turn and my timing is set at 16 initial and 34 total all in by 2500 rpm. I am running a 4.5 power valve, I have about 9 inches of vacum at idle with car in gear. Any more help would be appreciated.

 

[Dave427]

With your intake bolts loose if anything you would be sucking oil into combustion chamber from the lifter galley. Sounds like a pretty hot combination with that solid roller. The carb you are running should be in the ball park , its just jetted a little strange. Stock jetting in the primary side is 72. I would think you should be closer in that range. Make sure your carb is not boiling over after you shut it off.

Dave

 

[engineguy]

Fred,

If the plugs are reading "a tad lean", that rules out most carburetor problems. If fuel is dripping from the carburetor while sitting, the engine will be hard to start and you will see a puff of black smoke immediately after starting.

Check the fuel pump. Ruptured pump diaphram will allow fuel to be mixed with the oil, even though your pump is fairly new.

 

[freddybob64]

Not meaning to sound like a dummy but is a stock mechanical pump wrong for this combination? I have seen high performance mechanical pumps advertised would this be a better way to go?

 

[Dave Hopkins]

The obvious options are;
1: Defective fuel pump. You say its new so not likly the issue
2: Carb running horibly rich, you say the plugs are tan so not likly the issue
3: Leak at the intake gasket, you would also have erratic idle and oil consumption
4: Carb leaking gas into the manifold when the engine is shut off, it runs down into the combustion chambers and runs past the rings. With 1-3 95% eleiminated I say its time to start looking at this used carb. Some will say run the engine until its hot, shut it off and look into the carb and watch for gas drips. Only problem is its likly you will not see any and think your good to go when the problem is right there so first I would look at fuel pressure. Holley makes a nice pressure regulator for abt $40, has 3 1/4NPT fittings (1 in, 2 out). Plumb that in with a gauge and set it. What ever I sugest will start a debate, I want mine to run impecable and am never on the throttle more than a couple seconds so I set it at 5, 7 would probubly be fine for a Holley, If your spending the day at the drags you might go higher.
If that does not fix it you need to get into the needle & seat & float level area.

 

[Dave Hopkins]

Another option is fuel tank pressure buildup! Absolute nessesitiy that the tank is freely vented in and out! Someone may have added a check valve on the vent line to stop gas from overflowing onto the ground after fill up and that is causing tank pressure to raise in the heat and sink the floats in the carb!

 

[freddybob64]

Just took the car out for about a 20 minute cruise and it runs great. I have to think it is something in the carb that the guy did before I got it. I know he ran it on an engine that he ran NOS through, and I don't know what else he may have done to it or how long it might have sat before I got it. Seems like I have been fixing this guys screwups ever since I put the engine in. Thinking I may just get a new carb. Is a 770 street avenger the way to go or the 3310 like I have now, or down size. All the info is greatly appreciated.

 

[LS7]

FWIW Fred I have noticed this as well, more so when the oil is hot, at room temperature not as noticeable. My combo is similar to yours, solid roller, 780 Holley, plugs look perfect.