Ignition problems - Driving me NUTS.
Thread Starter
Burning Brakes
Joined: Dec 2002
Posts: 1,069
Likes: 2
From: Sherwood Park AB
Ignition problems - Driving me NUTS.
I have been trying to start my vette for months now... 78 with Q jet, HEI ignition.
I took out the engine and replaced the cam and painted the block. The distributor sat on the bench for a while. I don't think I have any spark. I have the timing light hooked up and pointed through the windshield, and have used a spark tester. Neither one shows spark.
When I first tried, it sparked once, LOUD backfire. Since then I have cranked it over lots and replaced the coil, wires from module to cap, pick up coil (tested bad), module (tested bad). Recently I took the distributor to a shop with a sun (?) machine and was told there was something wrong with the cap, rotor, or coil. Then I replaced the cap and rotor, and even tried a new coil (then took it back). I couldn't get spark at all.
Tonight I used a different distributor; put together with old parts that test OK. It cranked over, then backfired LOUD again.
I have 12V at the coil with the ignition on, the distributor has a good ground (verified when testing the 12V). All new parts in the stock distributor.
In the past two summers and 200 km, I have gone through 1 pick up coil, 2 modules, 1 coil...
Please help me, what is going on?? I would sure like to get it started.
I took out the engine and replaced the cam and painted the block. The distributor sat on the bench for a while. I don't think I have any spark. I have the timing light hooked up and pointed through the windshield, and have used a spark tester. Neither one shows spark.
When I first tried, it sparked once, LOUD backfire. Since then I have cranked it over lots and replaced the coil, wires from module to cap, pick up coil (tested bad), module (tested bad). Recently I took the distributor to a shop with a sun (?) machine and was told there was something wrong with the cap, rotor, or coil. Then I replaced the cap and rotor, and even tried a new coil (then took it back). I couldn't get spark at all.
Tonight I used a different distributor; put together with old parts that test OK. It cranked over, then backfired LOUD again.
I have 12V at the coil with the ignition on, the distributor has a good ground (verified when testing the 12V). All new parts in the stock distributor.
In the past two summers and 200 km, I have gone through 1 pick up coil, 2 modules, 1 coil...
Please help me, what is going on?? I would sure like to get it started.
Thread Starter
Burning Brakes
Joined: Dec 2002
Posts: 1,069
Likes: 2
From: Sherwood Park AB
Originally Posted by DZRick
I've got to ask,
What are you pointing the timing light at?
Are you sure the distributor is in correctly?
What are you pointing the timing light at?
Are you sure the distributor is in correctly?
Timing light: Pick up is around #1 plug wire near cap, power from Alternator (advance display lights up). The light is resting on the cowl, pointing through the windshield. My theory is that I should be able to see it flash me if there is spark.
After the last backfire, I wondered if the distributor was 180 degrees out...
I just looked at #1 exhaust rocker and turned over the engine. The valve closed, I verified the timing mark. I rotated the dampner once more around and both rockers are neutral. The dampner mark is at 0, so I put in the dist with rotor pointing at #1.
Mark
Le Mans Master
Joined: Jun 2005
Posts: 5,447
Likes: 3
From: Syracuse NY
I see what you were doing now, for the life of me I couldn't understand how you thought you could check your timing pointing the timing light through the windshield.
I was thinking that you were 180 out too. Have you checked to see if your 12v source is constant meaning it doesn't drop after you let go of the key.
I'm not much of a mechanic so I'll shutup now and let some of the knowlegable guys help you and wish you luck.
Rick
I was thinking that you were 180 out too. Have you checked to see if your 12v source is constant meaning it doesn't drop after you let go of the key.
I'm not much of a mechanic so I'll shutup now and let some of the knowlegable guys help you and wish you luck.
Rick
Thread Starter
Burning Brakes
Joined: Dec 2002
Posts: 1,069
Likes: 2
From: Sherwood Park AB
Anyone?? TTT
Can anyone tell me what causes a backfire?
Could it be the ignition switch, battery or starting system?
What else, besides the distributor can cause a no spark or intermittent spark situation?
Mark
Can anyone tell me what causes a backfire?
Could it be the ignition switch, battery or starting system?
What else, besides the distributor can cause a no spark or intermittent spark situation?
Mark
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
Have you tried advancing your dist. from the point where it dropped in?And did it drop all the way?Oh and pointing at #1 in the "cap"-correct?
Last edited by ...Roger...; Aug 7, 2006 at 02:06 PM.
Pro
Joined: Oct 2005
Posts: 581
Likes: 0
From: Boynton Beach Florida
Backfireing Is Usually Caused By A Valve Open When It Fires.intake Open It Backfires Thru The Carb, Exhaust Open It Backfires Thru The Exhaust Pipe..also If It Back Fires Thru The Exhaust It Could Be A Build Up Of Fuel, It Happened To Me Once And I Blew My Mufflers Apart..shorted Wire From The Starter To The Coil..just My Two Cents..mike
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Thread Starter
Burning Brakes
Joined: Dec 2002
Posts: 1,069
Likes: 2
From: Sherwood Park AB
Thanks for the replies
Sixfooter: I have 11.5V at the dist, it drops to 9V or less when I crank the starter. I know I need a new battery, but I have had over 12V at the dist before. I shouldn't drop that much when cranked, right?
dwncchs: The rotor is pointing at #1 plug in the cap when the balancer is at 8 degrees BTDC. It is dropped in all the way, engaged into the oil pump. The rotor turns when the engine is cranked.
palazzopl: Backfire through the carb, seems an intake valve would be open. Does that would mean either the dist. is installed incorrectly (I don't think so) or the cam is degreed wrong?
Mark
Sixfooter: I have 11.5V at the dist, it drops to 9V or less when I crank the starter. I know I need a new battery, but I have had over 12V at the dist before. I shouldn't drop that much when cranked, right?
dwncchs: The rotor is pointing at #1 plug in the cap when the balancer is at 8 degrees BTDC. It is dropped in all the way, engaged into the oil pump. The rotor turns when the engine is cranked.
palazzopl: Backfire through the carb, seems an intake valve would be open. Does that would mean either the dist. is installed incorrectly (I don't think so) or the cam is degreed wrong?
Mark
Melting Slicks
Joined: Mar 2006
Posts: 3,342
Likes: 7
From: Connecticut
Mark.... Is #1 pointing to the passenger side, kind of in line with the rear breather/hole on the valve cover?
This is just a very rough estimate of of where #1 should be providing things havnt been moved around too much,
This is just a very rough estimate of of where #1 should be providing things havnt been moved around too much,
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
Originally Posted by rexx78
Thanks for the replies
Sixfooter: I have 11.5V at the dist, it drops to 9V or less when I crank the starter. I know I need a new battery, but I have had over 12V at the dist before. I shouldn't drop that much when cranked, right?
dwncchs: The rotor is pointing at #1 plug in the cap when the balancer is at 8 degrees BTDC. It is dropped in all the way, engaged into the oil pump. The rotor turns when the engine is cranked.
palazzopl: Backfire through the carb, seems an intake valve would be open. Does that would mean either the dist. is installed incorrectly (I don't think so) or the cam is degreed wrong?
Mark
Sixfooter: I have 11.5V at the dist, it drops to 9V or less when I crank the starter. I know I need a new battery, but I have had over 12V at the dist before. I shouldn't drop that much when cranked, right?
dwncchs: The rotor is pointing at #1 plug in the cap when the balancer is at 8 degrees BTDC. It is dropped in all the way, engaged into the oil pump. The rotor turns when the engine is cranked.
palazzopl: Backfire through the carb, seems an intake valve would be open. Does that would mean either the dist. is installed incorrectly (I don't think so) or the cam is degreed wrong?
Mark
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
Originally Posted by rexx78
Could it be the clutch switch on my 4 speed?
I did recently replace the clutch, I had the engine and tranny out.
I did recently replace the clutch, I had the engine and tranny out.
Thread Starter
Burning Brakes
Joined: Dec 2002
Posts: 1,069
Likes: 2
From: Sherwood Park AB
I think so.
Carbon rotor button through the dist cap, then put on the rubber bushing on top. Bolt down coil, making sure two ground wires are connected.
Maybe I have the bushing/button installed wrong?
Edit* Just looked at the MSD instructions again, I have it installed correctly.
Mark
Carbon rotor button through the dist cap, then put on the rubber bushing on top. Bolt down coil, making sure two ground wires are connected.
Maybe I have the bushing/button installed wrong?
Edit* Just looked at the MSD instructions again, I have it installed correctly.
Mark
Last edited by rexx78; Aug 8, 2006 at 05:40 PM.