Ok, my 305 seems to be finnicky or something. If I run regular unleaded in the engine I get this horrible fluttering metalic sound when taking off/accelerating and speeding up from a constant speed. If I run mid-grade, it does not do it near as much and if I run premium it hardly does it at all. Why is this?? I usually run mid-grade all the time, because it just seems to have no power with regular and I cannot afford premium all the time. Also, I have a shift kit which barks second everytime but if I'm getting on it good, it breaks down before reaching third....like it's running out of gas or something....and if I let off the pedal it will shift....wierd huh?

The only mods to my Engine are edelbrock 650 w/electric choke, aluminum intake, hooker headers, crane cam (I have no idea what type as I bought the car with it and was told it had a crane cam), a vacuum advance distributor and the transmission has a shift kit.

Now, if I drive it like it's a 4 cyl so-to-speak, it will shift fine and not break down before 3rd. Also the transmission has always shifted smooth and it's a 700R4. But if I try to take off fast etc.. then it goes into a high rev without shifting into third and nose dives...like it's falling on it's face. Anybody know what might be going on here with both of these problems? People tell me both problems are the carb, but I don't know for sure or where to start.

 

sounds like pre-ignition (spark knock) from too much advance in timing. check timing with a light and report back.

 

well, I seem to have a problem there. How can I adjust the timing correctly when the car used to have an electric qjet and electronic distributor? It now has an edelbrock 650 with a vacuum advance distributor. I've taken my car to mechanics twice and they adjusted the timing to factory spec for an 84 Trans Am 305...only problem is...when they did that each time it ran worse. So, I now have the timing where the car will run good, but it's just not right.

 

You have to play with the timing on your own. It might run better advanced more (since you said they adjusted to spec, which is 0 IIRC), and turning the idle screw down on the carb to bring idle back. Also, double check spark plug wires are in place, and correct from the dizzy. Tried new fresh plugs? Set the gap correctly? Check to make sure you have the vacuum line for the dizzy on the correct port - should be no vacuum on the line at idle (that you can feel anyways).

I just installed a carbed 350, and I think my timing is set at like 12*BTDC at idle - I had to set mine a tad high, and adjust the carb idle lower to compensate, in order to get a better vacuum for my power brakes (due to my cam specs I guess - 'cause at my initial settings I had not enough vacuum for brakes). But, I haven't had to run anything but 87 octane, and I have higher compression due to dome-top pistions.

It's all trial and error, and the best way is to get a timing light, and play with it. I had my light in the back seat, and adjusted timing many times while driving - people thought I was nuts stopping every 2 blocks and whipping out the light and screwdriver. I'll probably have to do it many times again, til I get it right.

Mechanics? There is no such thing anymore - plenty of technicians out there, no mechanics! That's why I never let anyone else fool with my ride - if I can't do it, it don't get done!

 

As far as spark plugs, I usually have to replace those every 3 months as #2 and #6 file out badly..I'm talking complete covering of the end of the spark plug with this brownish gunk which you can scrape off and the plug is fine, but I always replace them anyway.

The distributor vacuum is correct and right now the timing is set by ear, since I don't have a timing tab....since the person I bought the car from seemed to have removed it or forgot to put it back. How hard would it be to put a new tab in there? It seems to run descent but only on 89 octane and best on 93 and I still get the fluttering effect in high accleration...not to mention the breaking down of the engine before shifting to third. What causes that anyway??? Anybody?? I explain the breaking down more in my first post of this thread for anyone who can help me with that.

Now the problem is, if I knock the timing back any less than where it is now....there is absolutely no power and it hestitates horribly. I don't know, sometimes I think the engine is just tired, but it seems to have good compression. It has 133,500 miles on it though.

As far as mechanics..oh yeah, I usually do things myself, but that was an attempt to see if a fresh eye could get it in time since one of the guys claimed he was good at setting the timing by ear...and he did a descent job, but after about a month, it went back to it's old ways..which I attributed to the distributor moving since he forgot to tighen the hold down. Well, that guy went out of business so I never got to take it back to him.

Oh yeah, and when I discovered there was no timing tab....it got me thinking..how did they adjust my car to spec?? What are they wise guys? I figured both places just did it by ear since I had this done right after I first bought it and then discovered later that hmmm... the tab is missing. They don't just fall off do they?? I don't think so. This problem has been ongoing for 2 years and still can't get this engine right. It's a good thing I don't drive it every day.

 

The "fluttering" and "falling on it's face" - maybe this is a different problem. Have you checked the tranny fluid? Maybe the TV cable needs readjusted? My thought was - maybe the car is running ok, but it reaches it's peak before the tranny is shifting. My 1990 RS will act funny when it needs tranny fluid (I have a leak I have't taken time to fix) - it "flutters" when downdhifting on an incline, and if I go too low on the fluid, it'll act like it doesn't want to shift, but just kinda hover. Or maybe the TV cable is outta whack and keeps the tranny from shifting.

The high rev sounds maybe the tranny is slipping - best noticed on the 2-3 shift. Maybe not so much a fluid thing, but just a worn tranny - but I'd check the TV cable for sure, and readjust.

Another thought - fuel pressure and fuel filter. Install a new fuel filter if you haven't - I've had them get a piece of trash in them, which settles to bottom of filter, until you gun it, and the trash is forced by pressure, to a place where it clogs the fuel flow. And Autozone/Advance has cheap ($9) fuel pressure guages - get a chunk of hose, some clamps, and cut in a pressure guage on the fuel line and make sure your getting enough - I have my edelbrock set at about 6.5 psi, but edelbrock likes more pressure I read - you'll need somewhere between 5 & 7. I'm assuming if there's an in-tank pump that there's an adjustable fuel pressure reg to bring the pressure down to carb levels.

Timing tab - it is part of the timing cover (welded on), and shouldn't "fall off" - it would be behind the water pump - you have to look straight down in there to see it. If it's gone, then you'll need a new cover I'm guessing, which might as well get a double roller timing chain/gear set ($50) and replace if you have to remove the cover anyways - which may also help - maybe your chain is stretched making a timing setting difficult. AutoZone and others "lend" the balancer pullers, gear pullers, etc.

Part of it may be a simple vacuum leak as well - spray carb cleaner (while it's idling) all around the base of the carb, and around vacuum hoses, and see if the idle increases (make sure none gets sprayed in the air cleaner, as a direct shot will increase idle and make you think you found a leak).

Also check the header bolts to make sure you don't have any exhaust leaks that would "tick" and make noises that you think are spark knock.

Sorry - kinda a potpourri of thoughts here - but my mind works way faster than my typing skills - I hope anything here helps in some small way. I would say start with basics, spark, gas, air. Replace fuel filter, check fuel pressure, double check plug wires correct, and coil good. Test for vacuum leaks. Try to get timing set (start at maybe 6-8* BTDC), then play with timing and idle screws - check vacuum when you get a timing and good idle, make sure you have 12in at idle (for the brakes). If vacuum is low, try bumping timing up 1 degree and readjusting idle screws down to bring idle lower. Get the timing/fuel/idle set where it sounds good without driving it, test/readjust the TV cable, take a short ride, and we'll go from there.

 

You have 2 problems. THe first is, your timing is too far advanced. That's what makes the "metallic" sound. It's "spark knock". Set your timing by backing it off (rotate the distributor clockwise) in small increments, like a degree or so at a time, until it just barely quits doing it.

As far as missing the pointer, I'm betting somebody somewhere along the line in the life of the car, wasted some money on one of those stupid "chrome" aftermarket timing covers. The factory cover had the timing mark welded onto it; but AFAIK, no one in the aftermarket has yet figured out that EVERY Chevy V8 made since the late 70s, is supposed to have that, so they keep churning out the same "universal" junk.

Your description sounds like somebody opened a textbook and copied out the description of "fuel starvation". The fuel supply system can't keep up with the engine's demand for fuel. There's enough fuel in the carb bowls to get the car through 1st and 2nd; but then after a time of WOT operation, the bowls get drained, the fuel system can't refill them, and what you're describing, happens. Then as soon as you come off of WOT for a few seconds, which lowers the fuel demand, the bowls fill back up a bit, and you can go a little more, until they run out again.

The stock fuel system is adequate for well over 400 HP of fuel delivery; so if it was working right, it would be fine.

Most likely your fuel line is restricted somewhere between the gasoline in the tank, and the fuel pump. Most likely, that restriction is inside the tank, especially if the car has sat around for a couple of years out of its life; the fuel line is blocked with dried-up tar-like gunk from old fuel.

Drop the tank, pull the "sending unit", and run a coat hanger wire through the tube. You might be amazed at what comes out.