No spark to #4 - Problem Solved
- Thread starter Brother A
- Start date
Franchise_24
Well-known member
rollingsculpture
Senior Member
Re: No spark to #4
spark plug gap and gap at pointsv and double ck timing
spark plug gap and gap at pointsv and double ck timing
Barry B./ Ma.
Well-known member
Re: No spark to #4
Could be a bad lead inside the distributor housing. I had that happen once.
Could be a bad lead inside the distributor housing. I had that happen once.
Brother A
Senior Member
Re: No spark to #4
Thanks guys. I did change the plug, checked the gap, re-timed the engine and checked the points gap. I rotated the cam and the points seemed to open equally on each lobe. This is a newly rebuilt H&M engine so I doubt it's a valve but I'll check the compression. I had the distributor apart to replace a bad lower plate. (I should mention that this is a "modern" dist.) and all the leads looked fine. My guess is that a bad lead would effect more than one cylinder consistently. Am I correct with that?
Please keep the ideas coming. Thanks
Thanks guys. I did change the plug, checked the gap, re-timed the engine and checked the points gap. I rotated the cam and the points seemed to open equally on each lobe. This is a newly rebuilt H&M engine so I doubt it's a valve but I'll check the compression. I had the distributor apart to replace a bad lower plate. (I should mention that this is a "modern" dist.) and all the leads looked fine. My guess is that a bad lead would effect more than one cylinder consistently. Am I correct with that?
Please keep the ideas coming. Thanks
Mike V. Florida
Well-known member
Re: No spark to #4
What exactly do you mean "modern"? Just the upper plate or do you also have a "modern" cap with true plug wires coming out?
How and where exactly did you check for spark?
What exactly do you mean "modern"? Just the upper plate or do you also have a "modern" cap with true plug wires coming out?
How and where exactly did you check for spark?
Ron in Quincy
Well-known member
Re: No spark to #4
About 85% of problems are electrical. Today I checked a problem one of the fellows was having: no fire to number 3 and 4, 1 & 2 was firing good. Checked the clearance between the rotor and contacts in the distributor body; 1 & 2 contacts had .025 clearance, 3 & 4 there was no clearance. filed the contacts on 3 & 4 until we had .025 clearance. The engine fired up and ran smooth.
The fellow said he had checked the clearance only on lobe 1 and assumed the other 3 were ok.
Ron
About 85% of problems are electrical. Today I checked a problem one of the fellows was having: no fire to number 3 and 4, 1 & 2 was firing good. Checked the clearance between the rotor and contacts in the distributor body; 1 & 2 contacts had .025 clearance, 3 & 4 there was no clearance. filed the contacts on 3 & 4 until we had .025 clearance. The engine fired up and ran smooth.
The fellow said he had checked the clearance only on lobe 1 and assumed the other 3 were ok.
Ron
Brother A
Senior Member
Re: No spark to #4
Mike,
It's a round distributor cap and the condenser is on the top plate. (I have a Simmons HC head on this motor and the traditional style distributor doesn't fit)
To check for spark I grounded my screwdriver to the head and touched the shaft to the plug wire. I see spark and notice a change in RPM at 1,2 and 3 but nothing at 4.
Ron,
I can't check the rotor to cap clearance on this type of cap. However, I thought changing the cap and rotor out with old spares that I had would cover the clearance issue.
Mike,
It's a round distributor cap and the condenser is on the top plate. (I have a Simmons HC head on this motor and the traditional style distributor doesn't fit)
To check for spark I grounded my screwdriver to the head and touched the shaft to the plug wire. I see spark and notice a change in RPM at 1,2 and 3 but nothing at 4.
Ron,
I can't check the rotor to cap clearance on this type of cap. However, I thought changing the cap and rotor out with old spares that I had would cover the clearance issue.
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1931 flamingo
Well-known member
Re: No spark to #4
Soooooo, what kind of a dist DO you have?? On mine a while back, new dist body from very reputable supplier, ck'd rotor to contact clrnc, each was way off, reinstalled orig body, perfect clrnc's on all 4 contacts. problem solved. new isn't always better.
Paul in CT
Soooooo, what kind of a dist DO you have?? On mine a while back, new dist body from very reputable supplier, ck'd rotor to contact clrnc, each was way off, reinstalled orig body, perfect clrnc's on all 4 contacts. problem solved. new isn't always better.
Paul in CT
Patrick L.
Well-known member
Re: No spark to #4
OK, so it appears that you have a ' modern ' distributor with a one piece round cap ?? What style plug wires are you using?? ' modern ' or flat straps ??
It seems you could have 2 defective caps or a defective plug wire if using wires rather than straps.. Have you looked inside the caps for any cracks or carbon tracking ?? Sometimes carbon tracking can be removed with an eraser..
OK, so it appears that you have a ' modern ' distributor with a one piece round cap ?? What style plug wires are you using?? ' modern ' or flat straps ??
It seems you could have 2 defective caps or a defective plug wire if using wires rather than straps.. Have you looked inside the caps for any cracks or carbon tracking ?? Sometimes carbon tracking can be removed with an eraser..
Richard Lorenz
Senior Member
Re: No spark to #4
I vote for bad distributor body. The number 4 spark sometimes jumps internally to the #3 plug.
I vote for bad distributor body. The number 4 spark sometimes jumps internally to the #3 plug.
Brother A
Senior Member
Re: No spark to #4 *** PROBLEM SOLVED***
As usual, when I'm stumped it's usually something simple.
As I started putting my original cap back on this morning, I noticed that the cap moved when I pulled the #4 wire off. I grabbed the cap and noticed that I could move it without much effort. I bent the cap spring clips a bit to secure the cap more securely.... started her up and to my great relief it was purring like a kitten. I checked for spark on #4, just to be sure, and there it was. That will be the best 4th of July firework that I see this year. I took her out for a test ride and she climbed the most challenging hill on the way home like a race car.
My sincere thanks to all you Barners that chimed in. All those suggestion kept me focused on this.
Steve
As usual, when I'm stumped it's usually something simple.
As I started putting my original cap back on this morning, I noticed that the cap moved when I pulled the #4 wire off. I grabbed the cap and noticed that I could move it without much effort. I bent the cap spring clips a bit to secure the cap more securely.... started her up and to my great relief it was purring like a kitten. I checked for spark on #4, just to be sure, and there it was. That will be the best 4th of July firework that I see this year. I took her out for a test ride and she climbed the most challenging hill on the way home like a race car.
My sincere thanks to all you Barners that chimed in. All those suggestion kept me focused on this.
Steve
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tbirdtbird
BANNED
Thx for the follow-up. we don't get it anywhere near enough to be able to help others
Mike V. Florida
Well-known member
As Tbirdtbird said, here the resolution was something not even suggested. Thanks for posing!!
Brother A
Senior Member
Actually, you guys helped a lot. Ron in Quincy's comment about measuring the gap between the rotor and the contacts in the distributor body was what came to mind when I noticed that the cap was loose. Even though that is not a measurement that I could take on this style distributor cap the same principle applied.