77 Chevy
 

I have a problem that makes no sense. Its a 250 L6 auto. It has spark. All the ignition stuff is new. New fuel pump. New starter. Dump gas into the carb and it wont fire. I took off the carb...and the manifold had gas in it. I pulled the plugs...and they are dry. I dont know what the problem is. It makes no sense. Anybody got any ideas?

Re: 77 Chevy
 

Was the distributor pulled? If yes then it may have been dropped in several teeth off, had that issue with my 350 and it would just turn and not fire. Pulled dizzy, clocked it right, dropped it back in, problem gone!

Re: 77 Chevy
 

Module!

Re: 77 Chevy
 

Got spark. Took the valve cover off...checked valves. No gas getting to the pistons.

Re: 77 Chevy
 

How would you know that by looking at the top of the valves? Turn the engine by hand (well, use a ratchet or something), do you see valves moving? All valves? What about my question about the dizzy - a dizzy that's off by some will still fire just fine (you will have spark), but it will do it at the wrong time so engine won't run no matter how much gas/starter fluid you dump in it.

Re: 77 Chevy
 

Dirt dobbers? Rat's nest?

Re: 77 Chevy
 

I took the valve cover off. Took a screwdriver to the starter and turned the motor over and watched all the valves move. Since this is a straight 6..the starter is right there. Makes it easy to do.

Re: 77 Chevy
 

i wish I knew. I dont see anything down in the intake...and this is one of those 6's that you cant take the intake off.

Re: 77 Chevy
 

I'd say if you dumped gas down the carb, there's your reason for fuel in the intake. But what's odd is the lack of fuel (or even smell) of fuel on the plugs. I've had delt with a couple of cars that were a pain to start after sitting a couple of days and the plugs were always wet from priming.

Granted a straight 6 intake doesn't have the most optimum shape to flow fuel like a V8, but still you should have got fuel to the center cylinders. Besides what new parts you added to it, what was the problem with this engine when you started working on it? Has it been sitting for a long time? Was the carb left of when it sat? N2trux might be on to something with some critter taking up residence while it was sitting.

Re: 77 Chevy
 

The po had done a tune up on it...and it never ran again. So they started replacing parts all over it. I got it thinking they didnt wire it right. i checked the wiring...and it was right. So is the timing. As many vehicles I have pulled out of the weeds...I have never had this problem before. I pulled a 50 Chevy truck out of a field that had sat 20 years. Cleaned the plugs...and points...dumped some gas in the carb...it fired up and stopped. I cant even get this to do that.

Re: 77 Chevy
 

Do you have compression? What is it? The opposite side of compression is vacuum. Need that for the atmospheric pressure to push in the air fuel mixture. It's simple really, must have one to have the other...


Terry:)

Re: 77 Chevy
 

Thats odd for sure. It was running, but the PO did a tune up on it and it never ran since.. What could be done in a tune up to kill it like that? You said you had spark, the plug wires are at the correct locations. Seems strange. One thing I was thinking of was on the straight 6 in my little sister's 79 Camaro. It had a feature that cut power to the distributator if the oil pressure was at zero. That oil pressure sender quit one day and all it would do was crank, but obviously it had no spark, unlike yours.

I'd say before you chuck any more parts at it, double/triple check the distibutator's position. Pull the #1 plug and bump it until it's on TDC. Remove the cap and look at the rotor's position in relation to where the #1 plug wire goes on the cap. If it's not dead on, it may be off a tooth or two. You'll still have spark, but it won't be timed right with the compression strokes.

If you were close it would cough and backfire. If you were way off it might not light at all. It's probable if the PO was floundering after the tune up and replacing parts left and right, the Dizzy might have been removed for some dumb reason. They never got it back in right and compounded the original issue.

It pays to take a step back and revist the basic stuff. Compression? Check, Spark? check, distibutator position and timing? check. Fuel pump work/ Check flow? check....Break it down to subsystems and check individually. Each one has to work for the whole to operate.

Re: 77 Chevy
 

You know I have no idea. I took the distributor out flipped it 180...no start. I am begining to believe compression is shot. The truck only has 138,000 on it. I have never seen a 250 6 Cyl go down like that. I have seen them ran hot...no oil...no water or oil at the same time...and they still ran the next day. The PO had this truck since 79. It wasnt abused.I have also seen these motors go as far as 300,000 miles. So Its going to be a donor truck for my 69. The 69 needs the 5 lug suspension...and disc brakes. I also need the bench seat and back bumper.

Re: 77 Chevy
 

Get a compression gauge and test it. On a staright 6 it shouldn't take more than 10 minutes. That 79 camaro that my sis had originally came to us with a non-running 6 in it. Turns out it was a couple of bent exhaust valves. the PO (another teenage girl) backed it up and hit the tail-pipe on something causing it to fold up almost shut. Then she managed to haul-tail up to 80 mph with it. Those old 6's don't like being corked up like that, explaining the bent valves. We rebuilt the head and it purred like a kitten.

Re: 77 Chevy
 

Why not spray a little ether starting fluid down the carb???

Re: 77 Chevy
 

I even tried ether. First thing after gas. I tried putting gas directly in the cyl's...and it still didnt fire. I was under doctors orders not to be out messing with that thing today...but I did.