No Spark from my Daves Small Body HEI Conversion
August 14th, 2014, 10:44 PM
#1
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Join Date: Oct 2009
Location: Lansing, MI
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No Spark from my Daves Small Body HEI Conversion
My 1965 Cutlass just quit running tonight as I was taking the wife for a cruise. I got the car running over a week ago, and have been on several rides since then to check things out. Everything has been fine, so I decided to take the wife out for dinner in the Cutlass. On the way home it just quit on us while driving along. Had to have it towed home and now the wife isn't to hip on going anywhere in it anytime soon.
I am using one of the Dave's Small Body HEI conversions of the original point type distributor. For those unfamiliar, this conversion involves him mounting a 4-pin HEI module underneath the distributor housing and adding the reluctor and coil pick-up to the inside. You get to keep your small original distributor yet have newer HEI components. Previous experience with HEI's leads me to believe the 4-pin module has gone bad (already?). Most of the time its heat or a bad ground that take out those modules.
I won't get to start troubleshooting this thing till tomorrow. However I have some thoughts to put out there and ask others for their ideas. The module picks up its ground through the two screws that mount it to the housing. I believe the distributor housing is grounded by the fact its dropped into the block and held it place by the hold down. I was thinking of installing a "jumper/ground wire" from one of the module mounting screws to the same spot I connected the neg bat cable to the block. That would give what I would consider an absolute ground to the module. Since I don't have the module off yet, I can't tell how much heat sink grease was underneath it. I have read many discussions about how important that is, and to make sure you have the right stuff for it.
The 12 Volts for the module power comes from the original ignition wire. Dave's instructions advise you to cut the original resistance wire approx. 1 inch from the firewall bulkhead and splice in some #14 wire to the coil positive. That way you are not using the current limiting wire that was needed for the points ignition. I had 12.6 V at the coil positive last time I checked. I will of course check that I still have it there.
So, what is the best stuff to use on the back of the module to make it last? Is there a particular 4-pin module that some of you have had better luck with than others? I don't know what brand Dave uses, or if I will even be able to tell that when I get it off of there. My local Advance Auto has a tester for these things, so I know I can at least get the one I have checked out. What else can I look for that could cause an HEI ignition failure?
I am using one of the Dave's Small Body HEI conversions of the original point type distributor. For those unfamiliar, this conversion involves him mounting a 4-pin HEI module underneath the distributor housing and adding the reluctor and coil pick-up to the inside. You get to keep your small original distributor yet have newer HEI components. Previous experience with HEI's leads me to believe the 4-pin module has gone bad (already?). Most of the time its heat or a bad ground that take out those modules.
I won't get to start troubleshooting this thing till tomorrow. However I have some thoughts to put out there and ask others for their ideas. The module picks up its ground through the two screws that mount it to the housing. I believe the distributor housing is grounded by the fact its dropped into the block and held it place by the hold down. I was thinking of installing a "jumper/ground wire" from one of the module mounting screws to the same spot I connected the neg bat cable to the block. That would give what I would consider an absolute ground to the module. Since I don't have the module off yet, I can't tell how much heat sink grease was underneath it. I have read many discussions about how important that is, and to make sure you have the right stuff for it.
The 12 Volts for the module power comes from the original ignition wire. Dave's instructions advise you to cut the original resistance wire approx. 1 inch from the firewall bulkhead and splice in some #14 wire to the coil positive. That way you are not using the current limiting wire that was needed for the points ignition. I had 12.6 V at the coil positive last time I checked. I will of course check that I still have it there.
So, what is the best stuff to use on the back of the module to make it last? Is there a particular 4-pin module that some of you have had better luck with than others? I don't know what brand Dave uses, or if I will even be able to tell that when I get it off of there. My local Advance Auto has a tester for these things, so I know I can at least get the one I have checked out. What else can I look for that could cause an HEI ignition failure?
August 15th, 2014, 12:52 AM
#2
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Join Date: Jul 2012
Location: Vancouver BC
Posts: 2,848
Are you sure its ignition and not fuel supply?
I would talk to the person that supplied the distributor if it is the module and look in to a warranty claim.
I would talk to the person that supplied the distributor if it is the module and look in to a warranty claim.
Last edited by Bernhard; August 15th, 2014 at 12:58 AM.
August 15th, 2014, 10:33 AM
#5
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Join Date: Jun 2014
Location: Battle Ground, WA.
Posts: 171
If it is defective I'd suggest the Mallory Unilite conversion. Still get to keep your stock distributor, can use the stock coil or an aftermarket, and no having to worry about dielectric compounds and additional ground wires. Just two screws (the one that held your points in place) and three wires (one to ignition, one to ground and one to the coil)
Scott
Scott
August 15th, 2014, 10:10 PM
#6
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Join Date: Oct 2009
Location: Lansing, MI
Posts: 269
Figured It Out
Turned out to be a fried HEI module. It was a matter of finding out why it got too hot. As I said, this conversion involves mounting a GM 4-pin HEI module to the underside of a points type distributor housing. Dave drills/taps two 8/32 holes for the module and machines the spot its going to sit nice and smooth. In his own instructions he describes how there are two plastic alignment pins on the module that must be nipped off in order for it to sit flush on the "new" area set up for it to mount on.
Well, when I pulled the distributor to look things over it was apparent that those tabs had not been removed from the module on my conversion. You could see some daylight under the module and it was tilted to one side with only the edge of the heat sink resting on the distributor housing pad he had made for it. I took the module to a Advance Auto for a test and it showed BAD. Just so we new the test was OK, they tried the $23 BWD Select replacement module and it showed GOOD. I nipped those tabs off of it, smeared the heat sink grease on the bottom of it and screwed it in place. It now sits perfectly flush on its spot. It should dissipate heat as designed now.
I called Dave, and even though I have heard horror stories about how hard he is to contact, he actually called me right back. He was adamant that he never forgets to nip off those tabs, and he gave me many trouble shooting tips to try to figure it out. I told him I had the distributor right in front of me, that the tabs were still in place and holding the module away from the base...He seemed rather incredulous. I didn't want to make a big deal out of it, I figure he has been doing this a long time. If my distributor is the first and last one he ever makes a mistake on, good for him. I fixed it quite cheaply and pretty darn fast, and I doubt I will have any more problems with this thing from here on out.
Well, when I pulled the distributor to look things over it was apparent that those tabs had not been removed from the module on my conversion. You could see some daylight under the module and it was tilted to one side with only the edge of the heat sink resting on the distributor housing pad he had made for it. I took the module to a Advance Auto for a test and it showed BAD. Just so we new the test was OK, they tried the $23 BWD Select replacement module and it showed GOOD. I nipped those tabs off of it, smeared the heat sink grease on the bottom of it and screwed it in place. It now sits perfectly flush on its spot. It should dissipate heat as designed now.
I called Dave, and even though I have heard horror stories about how hard he is to contact, he actually called me right back. He was adamant that he never forgets to nip off those tabs, and he gave me many trouble shooting tips to try to figure it out. I told him I had the distributor right in front of me, that the tabs were still in place and holding the module away from the base...He seemed rather incredulous. I didn't want to make a big deal out of it, I figure he has been doing this a long time. If my distributor is the first and last one he ever makes a mistake on, good for him. I fixed it quite cheaply and pretty darn fast, and I doubt I will have any more problems with this thing from here on out.
August 15th, 2014, 11:22 PM
#7
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Join Date: Sep 2010
Location: The Hudson Valley
Posts: 21,183
Sounds good, glad you got it fixed!
As I like to say, It's always something simple, and that goes double for HEI.
Weird that he forgot to trim the tabs, though.
Hopefully, your wife doesn't hold a grudge for too long.
- Eric
As I like to say, It's always something simple, and that goes double for HEI.
Weird that he forgot to trim the tabs, though.
Hopefully, your wife doesn't hold a grudge for too long.
- Eric
August 16th, 2014, 01:39 AM
#8
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Join Date: Oct 2009
Location: Lansing, MI
Posts: 269
I might take advantage of her pessimism about the reliability of the "old Olds". It could be a chance for me to go to the Woodward Dream Cruise later today all by myself! She would want to head for home long before I would anyway. I got the ignition fixed quick enough that I had time to finish installing a AM/FM CD Pioneer head unit. Now I even have tunes! The exhaust is a little loud since I have not got the complete over the rear axle duals on the car yet. Right now its a set of old "Purple Hornies" header mufflers that I have kept over the years just so I could start cars up after putting on headers. If I was 19 like I was when I got my first 1965 Olds 442 I would probably like the rumble. Trouble is I'm 59 now, and its just kind of annoying.
August 18th, 2014, 08:18 PM
#10
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Location: Red Oak, Texas
Posts: 2,999
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