I need some help. I can't for the life of me figure out what is wrong with this setup. I have a rebuilt 250 6 that I am putting in my Fleetline. Ok this motor has never run for me. It is a 72 250 that I bought and sent to the machine shop for a rebuild. Everything is new or rebuilt (new from auto parts store). I first started off with a Pertronix Ignitor II and Flamethrower coil in a rebuilt distributor. I was getting no spark there so I exchanged the ignitor module because it didn't fit right on the dist. and the clearances would not stay at the required air gap. New Ignitor fit well and clearances stayed fine. Still no spark. The car has no wiring in it yet. I had originally hooked an ignition switch up and only had wiring to starter and distributor. I then eliminated the ignition switch and went to a direct wire from the battery to a toggle switch to the + side of the dist. and bump starter with trigger. Still no spark. I removed the Ignitor and put the points back in it. Still no spark. Changed the coil to a cheap house brand. Nothing new. I start investigating the dist. I was getting a spark at the points when they would break. So I put the timing light pick up on the coil wire and it lights up when it pulses. Ok, so I am getting spark to the coil wire...I exchanged coil wire, cap and rotor. Checked continuity on cap, rotor, wires, coil. No change. I exchanged the whole distributor which changed the points and condensor. measured inside cap, rotor height, verified rotor button was touching cap. Set points and verified #1 placement by removing valve cover and watching rockers. No change. Rotated dist while trying to start. No change. I then pulled the coil wire out of the cap and the spark would jump 3/4 of an inch to the block, the spark color is orange. Weak spark? Moved the ground wire on the block, sanded and bolted down tight. Checked the voltage at the + and - side of coil. 11.6 volts. Hmm. changed the coil to an old Jacobs I had here. Still orange spark, 11.8 volts. This is where I am right now. I get 12.6 volts at the dist. + side to my ground on the block. Change the positive wire to a bigger gauge? I haven't found listing for a ballast resistor on a 72 Chevy truck on a couple of websites and at the store (<<not surprised here). My 72 manual doesn't mention the resistor either. Do I need one? For such a simple system, it is sure kicking my ass. I know it is probably something easy that I am overlooking. Sorry for the long post I don't know where else to look. quick recap 2 Ignitors 3 coils 2 distributors 2 coil wires 2 caps 2 rotors 2 sets of points 2 condensors new grounds keeping battery charged between sessions Signed, No Spark and Frustrated.
You say there is good spark from the coil. Plug it back in the cap & see there is spark at one or more of the plug plug wire holes in the cap. Is the wire resistor wire? Is it old or new? Is the plug reach too long & the pistons have hit them & they are closed up?? Moved the ground wire on the block, What ground wire are you talking about?? How can I check the plug wire hole in the cap? Stick a known good wire into a plug wire hole with the coil wire plugged in the center of the cap, spin the engine with ignition on & see if the wire from the plug wire hole will spark to the block.
If I understand correctly you have a good spark from the coil and none at the spark plug? So the problem must be in the distributor cap, rotor, plug wires or spark plugs. New plugs correctly gapped? Dist cap clean, not cracked? Good rotor? Plug wires tested good? Are the spark plugs laying on the engine (grounded) when you test for spark?
The ground wire I speak of is the negative battery cable to the block. I thought I had a bad ground. Painted surface. Relocated it to the head and sanded it down. I don't think any of the wire is resistor wire. everything is new. Some of it is twice new...meaning I have swapped it for different new. I pulled a plug and it looks perfect and gap is still .035. How can I check the plug wire hole in the cap?
I have spark out of the coil. How good is it? I can't tell. Yes it is all new and gapped per spec. I checked continuity on the cap and rotor. My guess is the spark is not strong enough to jump the brass terminals but is strong enough to arc to ground?? The spark is getting to the top of the gap. That's where I lose it.
sonofabitch. I have 0 compression. I put the other coil wire in the number one hole and it will arc to ground. I did that test yesterday with a plug and the plug wire and the plug never sparked against the block. It did just now. I pulled out the compression gauge and much to my disappointment...discovered a bigger problem.
Well at least you have a spark from the coil so now it's time to figure out why it isn't getting to the plugs at the right time to fire the fuel/air mixture when the the piston is at top compression. We are assuming that you did: 1. bring number 1 cylinder up on TDC on the compression stroke and have the timing mark lined up on the engine? 2. set the distributor in so that the rotor is lined up with the number one spot on the distributor cap when the cap is inon stalled on the distributor. 3. put the wires in the cap in the correct firing order in the correct clockwise rotation? 4. You did set the point gap at .019 with the rubbing block of the points on the tip of one of the distributor lobes? I've had more rigs drug into me that wouldn't start with the points gaped wrong than any other cause outside of defective parts. 5. I believe you did say that you wired the coil with the hot wire from the battery to the + side and the wire to the distributor connected to the - side which would be correct.
You wrote the no compression post while I was writing post #8 so now it appears that you need to figure out why you have no compression. First step on that is to pull the valve cover and check to see if the rockers are adjusted right. If the machine shop assembled the engine and adjusted the valves I'd be having a serious discussion with them as to how the valves were adjusted at this time. If you or your helper adjusted the valves I'd be backing the nuts off and resetting them.
The machine shop installed the bottom end, cam and pistons. I bolted the head on and adjusted the valves. I followed the procedure in my shop manual for sequence and tightness. Actually I would have expected them to be loose instead of too tight because the procedure said a full turn after zero lash and I did half a turn past zero lash. I will check the valves this afternoon and report back. Thanks for all y'alls help. Posted using the Full Custom H.A.M.B. App!
I've gotten into the habit of dropping new hydraulic lifters into a coffee can of oil and letting them sit for a while then pushing the plunger on each one down several times with a pushrod to prime them before putting thineem in the engine. If your lifters were dry you may have bottomed the plungers out and are holding the valves open. Pretty much the same if you had tightened a set of solid lifters a half turn past 0 lash.
I did this on a 292 Chevy a couple of years ago and ended up with no compression just like you have. I too followed the manual and ended up filling the exhaust with raw fuel and blowing a muffler apart. Scared me, the wife, the dogs and the neighbors all at the same time. After I stepped back a little bit and cleaned my drawers, I backed off the valves all the way and started over. Started right up at that point and I felt like a dolt. You can start the engine at the point where the rockers are just starting to take up lash and then adjust later. What Mr48chev said above is a good point and probably another small part of the problem. Sounds like you are methodical enough in your approach, but if you're spinning a fresh build over too quickly, I'd suspect valve lash issues. Keep plugging away, you'll get it.
Yeah I asked a couple of people if I needed to soak the lifters and was told I didnt need to. I slapped a little assembly lube on them and installed. Posted using the Full Custom H.A.M.B. App!
I must confess at one point in this several day exercise I had pulled the cap on and off and checked this and that and looked over and shook my head... The rotor was sitting on the dash. Posted using the Full Custom H.A.M.B. App!
Thank You for everyone's help. I got it running after re-adjusting the valves. Note to self: go with your gut and don't listen to certain people anymore...and check your grounds first!
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