Hi all I was driving home the other night from a cruise and my engine suddenly stalled. I was coming to a stop light and while slowing down it cut out and wouldn't start again. It turns over but doesn't even seem like it even wants to start. I changed the condenser and points thinking that might be the problem but it wasnt. I also thought it might be the carburetor so I also had that totally rebuilt (it needed a good rebuild anyways). After turing the engine over for 4-5 seconds, gas starts spitting up out of the carb. It did this before the rebuild also. What should I be looking for if it is the timing? FYI I have a 1970 Z28, 4-speed with the original LT1 350. I appreciate any help and thanks in advance.

Ryan

 

Is the gas spitting up out of the vent tube? If so, that is due to trash in the inlet needles. When it's a big piece of trash, the vent will spew like old faithful. When it's a small piece, gas will drip out of the boosters. Either way, the excess gas will flood the engine and prevent it from starting.

Does it have a good spark? If so, that would indicate carb is the problem. Either way, the spitting gas problem has to be fixed or you can damage your engine. Gas pouring in the engine will wash out the rings. Worst case scenario: you can have so much gas sitting on top of a piston that when it comes up to the top, the incompressible gas will hydraulic the cylinder and bust a rod, maybe other stuff too. Like your irreplaceable block.

Your engine should have a factory Holley. One of the things I really like about Holleys is that the needles pop right out the top. To verify your fuel levels, just remove the brass sight plug that is located on each bowl on the passenger side. Fuel should just be dribbling out. If you get a river of gas, there is trash in the needle. If too much flows out, but not a river, float is probably just out of adjustment. But in your case, it's probably a nice chunk of garbage.

I don't like the stock brass inlet filters that Holley uses. Their area is too small, so they plug quick, and they have a spring behind them, so when they plug, pump pressure forces the filter back to allow gas in so you can drive home. But then you get a trashy needle. I ditch the inlet filters and install a good inline filter. More area and no possibility of trash being forced into carb.

On older cars the gas tank can have a lot of accumulated crap and rust. When I bought my 71, I had lots of problems with trash in the fuel lines until I dropped the tank and gave it a good wash out. Luckily there was no rust. If yours is rusted, there are tank coatings available. I think POR makes some.

 

Angel thanks for the detailed post. When I had my carb rebuilt I put new everything in it including needles and seats. I also installed a brand new in-line fuel filter before attempting to start the engine. All the gas that has been pumped to the carb is gas that has run through the new filter. I am thinking it has to due with timing or something inside my distributor. I am goign to look into the timing more. Is there anything that should be lining up on the flywheel to indicate timing or TDC? I have a ruler like measuring device with the letters "A", "O", and "R" just above the flywheel, along with a notch mark on my flywheel. Sorry I forgot to add that my carb is not the OEM carb but is still a Holley 780 vac. sec.

Thanks again
Ryan

 

Pull a plug wire off and lay it (or hold it with some insulated pliers anything but your fingers ) about 1/4" away from a good ground then crank the engine. You should have a good hot spark. If you have spark, and fuel, and air it should run (unless youve lost compression or the timing chain which sounds unikely). If it does not run, make sure the distibutor is at TDC #1. Pull out #1 plug and stick your finger over the hole while turning the engine over by hand. When you start to feel air being forced out past your finger look at the timing mark on teh balancer and get it to TDC. THen pull the distributor cap off and look at where the rotor is facing. Should be at #1 wire. People often install distributors 180degrees out.
Good Luck.
CoryM

 

Thanks for the replies! Yeah I have spark on all 8 wires. How do I make sure the distributor is at TDC #1? Is that the same as seing where the rotor is pointing? How do I make sure the mark on the balancer is at TDC?

Thanks again
Ryan

 

Your original stall could have simply been the ignition coil over-heating. That happened to me once while cruizing at low speeds for a long time, as for all the gas spray ill leave that up to the experts.

 

I misunderstood (I think) when you said "spitting gas out of the carb". You may be right that it is out of time.

To check for basic time setting: pull #1 spark plug. Disconnect power from coil. Have someone crank engine (picks, not steady cranking) while you hold your thumb over the spark plug hole. Just as you start to feel compression building, tell your buddy to stop on the cranking. #1 piston should be approaching tdc firing. At the front of the engine, bolted to the driver side of the timing cover, is the timing tab. Clean it and mark zero with white paint. On the harmonic balancer should be a thin slot cut on the outer diameter.

If you stopped the cranking in time, the mark should be before the timing tab. That is, coming around from the passenger side toward the tab (engine rotates clockwise when viewed from the front). Pull keys from ignition. Set a socket on the big bolt in the center of the crank pulley (5/8" if memory serves) and turn engine cw till timing mark on balancer is aligned with timing mark on tab. Paint balancer mark white too, when it is in a clear spot.

Your engine should now be on #1 tdc firing. Pop distributor cap. Rotor should be aligned with #1 spark plug terminal. If not, rotate distributor to get it close, then finish setting timing with timing gun.

Other possibilities: the distributor cap retention on these distributors suxx. Make sure it is seated correctly and the hold down tabs are in their notches all the way. What did you set the points at. Rough is .019" with the points sitting on a peak of the distributor cam (the one with 8 peaks that opens and closes the points).

Rotor might also be on 180 degrees off after reinstall. It has a round peg and a square peg, but it is possible to put it on wrong. Ask me how I know.

 

Just for an update, earlier today I went out and messed with this situation a little. I took out the #1 plug and had my brother turn the engine over so I could feel the air pushing out past my finger to indicate TDC (on the #1 hole). When the air pushed past my finger the rotor was pointing at the #1 plug wire...which is where it is supposed to be....correct?

Is the mark on my flywheel supposed to be at the "O" when the #1 plug hole is at TDC if it has not been advanced/retarted or had a timing jump? If it is supposed to line up then my timing must haved jumped or slipped because the mark on my flywheel isnt in line with either the "A" "O" or "R" when the #1 plug hole is at TDC.

Thanks for any insight
Ryan

 

That is right. You don't use anything on the flywheel for timing purposes.

 

here is a silly question; did you set your floats? sounds to me like serious flooding not timing. My camaro did the same thing and it turned out to be too high a setting in the floats.

QUESTION How do I adjust the fuel level on my carburetor?

ANSWER 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 approximatly 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.

 

Ya, if you got fuel and spark it should run unless something ugly happened. Next thing to do it hold your foot to the floor while cranking it and try to clear out the excess gas. You may have to clean/replace your sparkplugs if you have a miss when it lights.
Seen a few guys do that, fix the problem then flood the engine and think they still have problems. I may have done that once or twice too .
CoryM