Fresh Rebuild wont start
I just rebuilt a 383 chevy motor and it will turn over but not fire and run. I can't seem to understand why this is happening. I know my timing is right and I know the during order is correct. What do I need to do to fix this problem?
Re "firing" not "during"
Sorry wrong word I meant firing not during!!
Is your distributor 180 degrees out possibly?
I can only assume that you have visually confirmed that the spark plugs are actually arcing and that you have fuel present in the cylinders. The only thing left to investigate is the timing. This can only be confirmed by removing the number one plug and turning the motor until compression starts building in that cylinder. Then continue rotating the motor until the timing mark lines up with desired setting or TDC (should not be more than 15-20*). Then check to see if the rotor is pointed to the #1 cylinder and #1 plug wire position on the cap. If it is not, you can restick the distributor to achieve this position or relocate your plug wires to follow the firing order from the rotor position. Most of us have installed the distributor 180* out at one time or another and is the most obvious problem.
fresh engine no start
here are some tried and true reasons that i have seen over the years for a no start on a new engine.
-plug wires installed wrong as to direction of rotation on the distributor. they were all installed in the correct firing order, just the wrong direction of rotation for the distributor. pull the cap off the distributor and turn the engine over in the normal rotation, keep an eye on which way the distributor shaft turned and compare to the way the wires were installed.
-distributor cap missing the electrode in the centre to contact the rotor. lots of spark from the coil, just not making out to the plugs.
-distributor not in the right position by 180 degrees, or just too far retarded. too far advanced usually makes the starter work really hard on every compression stroke. almost like the battery is going dead.
-ground wire missing from the ignition coil in the HEI distributor, or one of the wiring terminal plugs at the distributor is faulty so contact is poor, usually this means no spark or poor spark. check them all for good clean terminal connections.
-distributor pick up coil wires are damaged. those little wires from the pick-up coil in the middle of the distributor, under the rotor. just give each wire a little tug, gently, and see if they tend to stretch. if they feel stretchy at all then usually the wires inside the insulation are broken and can cause intermittent spark, or no spark. the insulation on the outside can look pristine.
-bad ignition module.
-wrong spark plugs-usually too long and the ground electrode gets bumped by the pistons and closes the plug gap. don't laugh, I've seen it more than once.
-no fuel. carb was never primed after install, so it takes a lot of cranking to fill the carb before the engine actually sees fuel. I have also seen a new fuel filter that was plugged from the factory.
-too much fuel. sometimes the carb can get dumped upside down when the engine was removed. the "stuff" in the bottom of the carb gets sloshed around and can cause the inlet valve to stick open, so the carb overfuels.
-I have also seen guys install a new timing cover with the timing marks in the wrong place for their engine's vibration damper.
-the vibration damper outer ring can slip so the timing marks are not correct. if the rubber on the damper looks like it is all squishy you may want to take a close look at it. don't want that coming off "at speed".
-first thing to check-do you have spark. put an old plug on one of the wires and then ground the metal part of the plug against the engine. have somebody crank the engine while you see if spark jumps the plug gap. nice blue spark, not the orange kind. be carefull if there was a fuel leak or anything flammable spilled around the work area. always a good idea to have a fire extinguisher handy, just in case. also, always keep the air filter in place when you try to start, in case of a backfire through the intake. obviously if no spark you gotta fix that first.
-next thing to check- do you have fuel. with the key off, lift the air filter lid and crack the throttle, you should see fuel spirting out of the accelertor pump nozzles (this is a carbed engine i assume). next, pull a spark plug and see if it is wet, too much fuel if it is (assuming you had spark). if it is dry, not enough fuel. while you have the plug out, make sure the gap is good. maybe you have the wrong plugs (too long of reach) and the gap has been closed up by the piston. seen that before too.
-next thing to check is the timing. like previously mentioned, all of us have done that one before. maybe the distributor is not in at the right place. most of the time if there is a problem the distributor is 1/2 a turn out. first you need to find top dead centre for the number one cylinder. pull the number 1 spark plug and turn the engine over by hand. you need the number 1 piston to be as close to exactly top dead centre as feasibly possibe, on the end of the compression stroke. if you have a compression tester you can put that in and you will know when the piston is coming up on compression stroke by watching the gauge. if a compression tester isn't available, I have seen a really long slinny screwdriver used in the spark plug hole, just be very carefull so it doesn't get jammed up. another way to tell involves taking the valve cover off and watching to make sure the valves are both closed for number 1 cylinder. when the piston is at the top, at the end of the compression stroke, check to see where the distributor rotor is pointed. it should be directly at the plug wire tower for the number 1 spark plug wire. also check to see where the timing marks are on the vibration damper compared to the pointer. if the piston is at top dead centre and the timing marks are not indicating the same, as in "0", then now would be a good time to remark them so you can be correct when you set the timing. speed shops sell a piece of tape for this purpose, new ponters are available as well. also, if your vibration damper is suspect, mark the backside from the centre out, so both the inner and outer parts get a reference line across them. you can tell if things have "moved" after the engine has been ran for awhile if the reference lines don't line up anymore. once you have determined and marked top dead centre, back the engine up, by hand about 20 degrees. then roll it ahead again to the correct timing mark ( this will make sure that all the "slack" is taken up in the internal components). now set the distributor so the rotor points directly at the number 1 spark plug wire. this can be done easiest if you simply felt marker a line on the outside edge of the distributor, stright down from the number 1 wire. then, when you take the cap off so you can see the rotor, all you have to do is shoot for the felt line. re-assemble everything and try for a engine start.
-if you have checked all this and it still won't start, try a compression test. could be that the cam timing is out of whack or the valve adjustment is too tight. does it whirl over really easy when you hit the starter? does it "pop" through the exhaust or intake when you try to start? does it smell really gassy when you crank it? you may have to dry the plugs out if you didn't have spark but did have fuel.
one more thing. if you have had an overfuelling issue, be aware that there could be raw gas in the muffler and exhaust system. when it does start it can cause a fire out the tailpipe. i have talked to guys that have caught their ride on fire from that, or backfiring through the carb and catching the underhood area on fire.
good luck and keep us posted
I did'nt read all of DSravens comments but this happened to me ONCE, I had the rocker arms/lifters screwed down too much causing no compression. Take a compression test or back the adjusting nuts off a little and see what happens.
Everyone was right thank you. My distributor was 180 out and she purrs thanks again!
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