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Topic Review (Newest First)
04-19-2010 02:23 PM
eric32 Ok Red I will do what you said. I am not driving my truck the next couple of days but will be getting it out Wednesday evening cause I have to drop it off cause I am getting a new set of rear end gears put it. My other ones has seen better days. I will pick up some 12 gauge wire and hook it up.
Thanks Eric
04-19-2010 10:50 AM
red65mustang eric,
one step one test at a time...

hook up the ground batt to the shell first and drive it...

leave the module alone for now...

re: second/third set of eyes...
it is just too easy for anyone to not see something immediately obvious to someone else causing a fault or could be made better is why I recommended it...
you described the harness plug in connect as "flimsy",,,can be a simple as just improve/better secure that to cure the miss...
that kind of judgement call we can't make over the net and so so darn often it is a simple to fix problem source!!!
(that doesn't need 20 tests to sort out the source)
04-19-2010 10:14 AM
Bill Adkins Actually I have owned a couple of Sun 1115's, the earlier models that were real time patterns rather than electronic sample rate machines, that accompanied with a wide band setup is all thats needed. As far as the dyno goes I worked on two different ones, both in ground Claytons also from a time gone by The later had flywheels to simulate road load and the first was just a load and go machine. Neither were all wheel drive as most of todays but most muscle cars don't have front wheel drive. I'm sure they were both donated to some school and replaced with a detail station LOL
04-19-2010 09:43 AM
red65mustang eric,
that's the type info we need to know up front...

you have tried 3 different dist on this motor and the mis-fire remained the same....
(that's a strong indicator that the fault source is external,,not in the dist at all)

doesn't have to be #12 wire,,,I suggested it because it is easy to work with for good crimp terminals connects...
(got some scrap #14 or #16 laying around and some red terminals go ahead and use it)
it's the quality of the physical connect points that counts and most wires available anymore are less strands per size
04-19-2010 09:43 AM
eric32 Ok on the ground wire I do believe I understand now. So how do I run an extra ground wire from underneath the control module to my battery? Do I take a spade eye connector and take one of the screws out then put the eyelet underneath the screw and put it all back together then? Sorry if I sound stupid here but trying to visualize here how to hook it up inside my cap on the control module.
04-19-2010 09:41 AM
Originally Posted by Bill Adkins
My wife is gonna be ssooooo pissed, now you got me looking for an old scope and a damned dyno

What kind of scope and dyno (distributor "dyno"?) are you looking for- one you have 'misplaced' (as in, have it but don't know where it is) or "looking" as in, to buy?
04-19-2010 09:36 AM
eric32 Ok guys I will do the ground wire test to start off with. I will have to pick up some 12 gauge wire. Yes I did state my Uncle is coming up from Florida and my Dad mentioned he has some testing equipment that has a lot of features to test a lot of different thing's with various types of ignitions. As far as the distributor goes I used one in my other truck from skip white from ebay and that thing runs like a charm and just as good as any auto part rebuild HEI but I guess results will vary. I have used three different HEI's in this truck to rule some other issues out I had with a previous carb issue last fall and they all worked no better then the one I have now. One was a autopart gm reman one and the other was a proform which I sold.

Looking them over I don't see any difference in them or a auto part store rebuild. One from GM might be better or not I don't know with the way they make things these days. Will try that and I don't have the option to bring my truck to anyone to test these things. I need to learn this stuff and be able to trouble shoot this stuff with learning and getting help from you guys or manuals. Maybe one day I can be as good as you guys

04-19-2010 09:23 AM
Bill Adkins My wife is gonna be ssooooo pissed, now you got me looking for an old scope and a damned dyno
04-19-2010 09:23 AM
red65mustang eric,
just my $.02:
alligator clip connect to the dist body is too "iffy" for what we are trying to prove...
(rock solid over kill ground supply negative circuit wiring to cure the miss)
unless you can find a spot where more than just the tip of the tooth only is contacting the dist metal surface...
and the clip does have a very strong spring to really grab and hold secure when actually driving over bumps in the road...

find a machine screw on the body and use a crimp on "U" or loop terminal... for the connect to the body...

don't connect to that middle wire....

just to the dist shell
04-19-2010 09:16 AM
cobalt327 Eric, did you mention someone was going to stop by w/some test equipment, or was that another thread I'm thinking of?

In any event, there's nothing here that you can't do yourself. It will take patience (that you have more of than your helpers, it seems! lol), perseverance and maybe a couple bucks- but this is not beyond your abilities.

Although pulling out the "big guns"- i.e. seeking professional help- would be a short cut to a possible solution, it wouldn't be the same as a "hands on" approach of doing it yourself, w/some suggestions from the forum.

Whatever you decide, I'll respect your decision. If there's anything that I can help with, I'll try to do so- as I'm sure all concerned will, as well.
04-19-2010 09:06 AM
cobalt327 The 4-pin module grounds through the screws into the distributor body. Barring any weird conditions where the screw wouldn't contact the steel sleeve that the screw holes of the module contain, or that the threads of the screws would somehow be insulated from the threads in the distributor body (both unlikely), the grounding of the distributor body to the "-" terminal of the battery w/a jumper cable will be sufficient to eliminate that as the cause of the intermittent miss.

If the module and/or coil is suspect, just change them- there's no good reason to toss the entire distributor. I'd suggest using a Delco module and an OEM coil for testing purposes. But I seriously doubt they will be the cause.

I would also suggest installing a fresh set of plugs before you do any in-depth chasing of the miss.
04-19-2010 08:42 AM
red65mustang eric,
with absolutely no distributor facts available,,,I'm not comfortable enough to tell you to do anything...

there are roughly 20 versions of the HEI electrical/mechanical design sold today...
(my $.02,,some of those are truly "junk" electronics for operating amps and robust design based on my experience)

it had a Proform cap and coil so it might well be just a $57 retail Proform "throw away" dist?????
(not even worth the time to test,,,if it hick ups throw away the whole unit and go get another one or MUCH smarter yet get a better built electronics dist)....

most of the parts chains do carry those proform units,,,carefully visually compare yours to one...

I will having nothing to do with the proform unit because they don't publish any spec's at all (not even a wiring diagram)....
( based on the way low $25 approx replacement ign module cost it is likely only 2-3 amps operating which is 36watts versus stock hei 5amps 60watts for plenty of coil input reserve)
many HR members have reported good results using them on "stock" or very mild motors...
(we live in a throw away society so sell a elcheapo throw away dist is smart marketing)

what you want is a wire direct to the module itself ground pick up point...
illustrations only:
some have a capacitor/condensor screw and do pick up ground from the dist body...
some wire off the HEI lug to a common wire combo module/coil ground...
some have a independent module wire ground ....

anywho,,,more better "0" resistance copper grounds to the batt neg can only help any/all electrical devices on a car and your ign module may/might possibly ground to the dist body....

go ahead and make the jumper (batt neg to the dist metal body) a permanent install,,,if nothing else it will help disappate errant and "weird" electric forms under the cap if they are present (like occasional AC spikes coming from the alt causing the misfire?)...
if it does cure the miss go get the alt tested,,diode may be failing or just a bad diode...

I do agree with Bill,,,the smartest move at this point is to get some experienced eyes to atleast look over the dist to tell you what you do have (to post here)....
04-19-2010 08:14 AM
Originally Posted by eric32
I can use an alligator clip and clip it on part of the body and then too my battery and see what that does so would that work good then?
04-19-2010 08:08 AM
eric32 Ok I understand about the ground strap now. I can use an alligator clip and clip it on part of the body and then too my battery and see what that does so would that work good then? Bill the miss happens at warm up the most but also at cruising at any rpm and it happens in no particular condition. The miss at cruising is hardly noticeable and engine still runs smooth. It does not happen constant it just comes and goes here and there but still happens everyday. Most noticeable at idle. I hope that makes sense. I don't have any place around to be able to measure the air fuel ratio of my carb or anything.
04-18-2010 09:23 PM
Bill Adkins So hows things, been in the mountains for a couple of days and missed so much here. from all I have read I can only say that 30 minutes on a dyno with a sun 1115 scope and it would be Miller time. The next best thing..... although it's not real close would be a wide band o2 sensor. The misfire, is it at a light throttle cruise or just when you pick it up after having had a sort of lax period almost like a coast. It's really hard to know exactly when the problem occurs from here, the conditions in the engine change so dramatically with a slight change in load. You would likely save yourself a lot of grief and time having a performance tech actually drive it so he or she can identify exactly what's going on. You might need to dance around a air bleed or a power valve, if you had a scope you could easily and quickly eliminate any secondary ignition problems and a good scope will also tip you as to a lean condition in the time line. This is however a good detective story.
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