Glass Cars, Grounds and Ignition questions

[POPS]

Don't be confused.  If you are not using a data aquisition system Odoms suggestions are fine.  If you are using one do what I suggest and you will be a happy guy, its very simple to implement.  If you want you can call me at 714-269-9645.
POPS

[dieselgeek]

Interesting post.

For anyone who is building or rewiring a car from scratch, I suggest picking up the Bosch Automotive handbook.  There's but 2 pages on proper electrical systems design for cars that carry sensitive electronics, those two pages alone are worth 10x the price of the book in my opinion. 

One thing that's not covered in the replies to this thread, that should be, is the phenomenon of power coupled noise.   There's a good diagram that shows what Bosch recommends for powering and grounding various systems in an electronically-managed engine (which applies to datalogging systems even on carb'd engines), after looking at it and then taking a look at a brand new Chevy pickup, I changed how i wire cars and have yet to encounter a noise issue with any of my electronics installs.

[Cajun Kid]

This is just an awesome site and great group of folks.  My problem seems resolved... I do not have any fancy electronics,  Just a battery, a dist. a coil and a MSD box (other than lights and guages etc..)  The ground suggestions seemed to solve the weak ignition problem and fully solved the slow starter turnover.

Well going back in the shop to figure out how to make some door handles and bleed the brakes again.

See you all this weekend.

Charles

[RichFox]

I don't know much about electrical stuff, but I have been told that with an MSD you should run an alternator to matain enough voltage for the unit to properly operate. You might wnat to check that out with someone who knows what he is talking about.

[836dstr]

Rich,

I heard the same thing!

You are right about MSD units needing enough voltage. I think performance starts dropping off below 13.5V. You can get by at Maxton and El Mirage if you have a good and fully charged battery, use push vehicle electrical to help start the race engine, and only make a few runs.

I put a small alternator on our car for Bonneville and it worked great.

Tom

[thundersalt]

We run 2 group 24 deep cycle batts (80 amp hours,650 cc amps) a 12 watt,3/4 amp solar panel mounted on the rear package tray and no alternator. We most of the time keep a 6 amp charger on in the pitts. There is a volt meter in the car and it has never dropped below 13 volts even on a 5 mile pass. The ing. is a MSD 7AL with a crank trigger. This system seems to work well for us. We never started it after WF until May right before we pulled the engine to inspect. Never had a charger on it all winter just solar sitting in the shop under a skylight and it still fired right up showing about 12.5 volts.

[Cajun Kid]

I do have a small  Denso style Power Master  alternator.. I like the solar power option to help keep a charge,,, for the June event in the heat at Maxton that may be a good idea to keep the battery charged and allow a small fan in the cockpit so I don't bake while in line all suited up.

Thanks  for one tip that leads me to another door of speculation  LOL


Charles

[ddahlgren]

You might want to note for maintainence that virtualy all failures on a car or bike that once worked fine is a ground wire that is corroded, almost never a + lead of any voltage. I have often wondered if bolting on a sacrificial anode like on a saltwater boat might fix a lot of things.
Dave

[Cajun Kid]

Dave,  good Idea.

Well got the new car down the track for two runs.  Not bad for it's debut. No ignition problems, the better grounds did the Job...

Thanks to all who gave me greats ideas and solutions.

Charles

[krusty]

Charles - I was the old fart wrenching the red #906 C/GMR this weekend past; sorry I did not have a chance to stop by and introduce myself. I wire race cars and hot rods for (part of) a living, and I'm nearby in Salisbury; I'd be happy to help you with any problems and/or questions. I would have posted on this earlier but I was overwhelmed with car prep!    vic

[Cajun Kid]

Vic,  thanks  for the kind offer,  I do understand how busy you must have been leading up to this past weekend and also while there,,, we have been the same way..

I live in Midway just outside of Winston Salem,  but also have an office in Salisbury on Jake Alexander..

Like to meet you sometime,,,

Charles

[krusty]

Charles - My schedule is somewhat flexible as I work from my home shop; sometime when you're down on Jake Alexander give me a call and we'll get together for coffee, a drink, a meal, or whatever. Or come on down to the shop, I'm probably 8 miles south of you (just north of 152 between China Grove and Rockwell. 704/798-5421.   vic

[JimL]

Put the negative lead of your Digital Volt-Ohmeter on the battery ground post (with meter set on DC Volts), then put the positive post anywhere you've a questionable ground.  Power up and see how much voltage you read....should be very very small (less than .1).  It may look good on a resistance check, be be no good under actual load.  (NOTE:  During starter cranking you could see .5 volt but not really have a big problem....depends on wire size and length)

To check a circuit under load, for example the wire to the coil + terminal, use this test.
1.  Disconnect terminal wire and connect it to the probe end of your 12V test light.
2.  Connect the clip of your test light to good ground or battery negative post.
3.  With voltmeter on DC volts, put the negative DVOM probe on the battery positive post, and the positive DVOM probe at the test light probe (BEFORE the bulb).
4.  Read the "voltage drop" on the voltmeter.  Again, this should be very small.  If it's reading more than a .1-.2, you have resistance in the circuit UNDER LOAD, even if your ohmeter says NO resistance.  The ohmeter doesn't push enough amps through the circuit to identify corroded copper or broken strands.

Hope this helps....the salt sure tears up our wiring!

Regards, JimL

[Hans Blom]

Vic, good job with the 906 at Maxton...now get offline and get that car prepped! Just kidding, I hear you have a schedule conflict for August???  Hans