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I'm racing the double double this weekend at VIR, and have come accross a possible problem while prepping the car. After March's race, I installed an MSD 6al, new wires, new cap, rotor and upon the advice of fellow forum members a colder NGK plug (at the stock Honda gap). I had full intentions of taking the car to the Dyno tonight, but alas, my Grand Mother went into the hospital last week and has yet to return (which means my father hasn't returned and he has the truck)... hence no trip to the dyno.
Anyway, I digress... as I am unable to take the car to the dyno b4 it goes to the track Thursday, I was going over my handy work in the garage. (also let it be known I am more mechanically capable, than capped or inclined), and noticed that I have a horible spit and miss at around 4000 Rpms. Now for the life of me, I can't remember if it had this b4.
So, I need some recomendations. Do I run it as is, knowing that I've done nothing other than plug and replace? Does the addition of an MSD box along affect the ignition advance? If so, should I just disconnect it all and go back the to the way it was (and not be p o'd if it has a miss then?)? Or should I just conceed defeat to all and not go race?
Thanks!
hoop
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If installed correctly (and I'm sure it is) the MSD should not cause the miss. Might be the colder plugs. Put in an old set and see if the miss is still there.
Do you miss under load, or is it just sitting in the garage revving it?
Carbureted or FI?
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Ok, can you say frustrated? I talked to the mechanic does some work on the car, and also used to drive it, b4 I bought it. He thinks that the car has always had that "unloaded miss", but wouldn't be surprised if the MSD box was creating some of my problems. He based it on the fact that he had never been able to produce any improved performance on like race cars, but that it didn't mean it wouldn't improve the car.
Nonetheless, we decided that I should disconect the box, and see if the miss was still there (as I couldn't remember if it was there b4 I installed it ).
So, I spend the better part of an hour disconecting the box, and wiring the ignition back the way it was. Now it's magic time, right? I start the car, and let it get up to opperating temps. I take the time to rev the car up, and right when I get to the 4500 rpm range... blap, spit blat! It's still there! dang it! I could've spent that hour doing something more constrructive, like counting the dog hairs under the wine rack, or playing GT4, or awe it don't matter.
So, now I plan to run the car as is Friday, and if I get bored between qualifying sesions... reconect the MSD. Afterall, I've spent all this money on it, I should use it for something more than ballast, right?
If anyone has any advice, or want's to just come by point and laugh, I'll be paddocked near Heather and Bill and the trailer with the british flag.
Jeff, it's a carbed car, and yes it's setting in my garage. As for the plugs, it didn't seem to care cold or stock.
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are you running the blaster coil as well?
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Yes, I'm running the Blaster SS 8207 coil (installed last summer), new NGK's, new cap, new rotor and new Moroso 8mm wires.
:lightbulb: Is it possible, that neither the battery or the altenator is providing a pure 12 volts to the system? My first race car (the Fiat) used a Bosch Jetronic system that requried the most perfect of 12 volts to properly operate. If it had anything less, then the car ran rough.
I think I will run downstairs and put a meter on the battery.
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It might not do it under load.
You always hear that 90% of carburetor problems are ingnition, but this one sounds like the carb to me.
MSDs rarely "partially" fail in my experience. Either they work or they don't. There are no "magic" hp gains from them, but for any old school carbed car the hotter spark helps smooth out variations in the mixture that the naturally imprecise carbs create. Bottom line is that an MSD on a carb'ed car probably provides some benefit.
Anyway, do you have a place where you can run the car quickly up the street and back to test it under load?
I bet you have a fuel delivery problem at that RPM (for some reason). Is it a Weber carb?
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Jeff,
The MSD is good, I just had Tech West check it out. As for the Honda, it is using a heavily massaged stock carb with an Holly jet. Is there a possibility that it might be rich or lean at that rpm, probably. Is there much I can do about it since I couldn't get to the dyno, not much.
Unfortunatley, the first place I will ave to run it is the track on friday.
Maybe I'm wrong, but I still think the thing to do at this point is to run it without and with the MSD, in the seperate qualifying sessions, and way the results. Changing the jet requires grinding it down so it will clear the float door, and I don't think I will be able to do that at the track.
If you have time, drop by. I'm willing to listen to ALL opinions.
Thanks!
hoop
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I agree, run it with the MSD and without.
I had a miss most of last year. Turns out I had bought a slightly incorrect sized distributor cap. Misses always turn out to be something small.
Will the car "rev through" the miss? If so, a miss at 4k isn't too bad. Who races at a4k anyway? LOL.....
I'll stop by and see you this weekend, assuming sh#$ don't break on my car so that I'm working on it all weekend. I had my first "roll off, race, roll on" weekend in a long time at Savannah. Hope my luck holds.
See you at VIR.
Jeff
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What did the voltage test show when you had a meter on the MSD supply at 4500 RPM?
And, what does the meter show alternator output is at 4500 RPM when read at the alternator?
And, what does the meter show on the battery at 4500 RPM?
Ron
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Well guess what? Dad got here, so we could load the car on the trailer. We checked the voltage on the bat., unloaded, loaded and altenator... 12.5v 16.8v and 20v, so all that's fine.
As I rev the car to warm it up a bit and take it down the driveway, Dad says, the carb sounds funny. Hmmm? "It's not feeding fuel right." Well, I can't do anything about the jets now... but what about the float?
WTF? Why haven't I thought of this? Because I'm mechanically capable, not inclined, right? So, I grab the screw driver and back 1/2 a turn out of the screw. Now the car sounds as clean as can be! Can you believe that?
Ugg! So, after registration, guess what I'm doing tomorrow evening? That's right, hooking the MSD back up!
:cavallo:
Thanks for the help! See you guys at the track!
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Excellent!
It did sound like carb to me...
