I just go my msd ignition setup in. It's a msd pro billet dist. 85551, Blaster SS coil and msd 6 digital box. I asked the msd tech guy which plug and gap he recommended and he said to run a autolite 25 plug and gap it at .60. This seems kinda high to me and I want to see what you guys think. Here's my current setup...

350
292H cam, 244 duration/.501 lift
Dart Pro1 aluminum heads 2.02/1.60
Air Gap style intake
Mighty Demon 750
700R4 with 3500 lockup stall
4.11 posi rearend

I've been on here for about 5 hours looking at old threads about setting the right advance curve using the different springs. From what I gathered I'm going to start out with the 2 blue springs and go from there. What area should the base and total timing be in with a combo like this? Does anyone have any recommendations or experience with a similar setup? Also, the car stumbles or dies when nailing the pedal from dead stop but does fine when normal acceleration and cruising. Could this be a accelerator pump/cam issue? It runs rich right now, I'm going to tune on the carb once I get the ignition put in. I'm going to be purchasing a wideband air/fuel ratio guage in the future, is it necessary to have one for each side of the engine?

 

Anyone have any advice? I plan on installing the msd stuff in a few hours when I get off work.

 

Yes that is very high and it will run up the # of misfires. 35 to 40 should be more than fine

 

I disagree. .035-.040 is what I run for my turbocharged setup, and that's to prevent blowout. He has strong ignition components, so I would give the .060 a try. The larger the gap, the more compete the burn. If you notice a high rpm miss, then back it down to .055 or .050.

 

I'd run around .040. I ran .035 on my n/a 383 and it was fine to 7K. 0.060 seems large, especially for a 350 with a cam that big and good heads. Your gonna be spinning that thing, so keep gap tighter.

I dont see any need for a performance motor to run more than .045" gap.

 

Say I use the 2 blue springs and the red bushing, what does it mean when it says the red bushing is 28 degrees? Does it mean it won't advance past 28 degrees?

 

yes.

i have run a 45 to 50 gap in a 406 small block. it ran low elevens in a third gen. that is running a good cap and rotor as well as a good coil. without a power adder it will be ok. .060 is too much as we had problems there. but good fuel and a .050 gap worked the best.

 

you could do 60 if you check your plug gap more often, it can grow quick with a hot ign system.

45 is the right choice

 

Well, I went with the 2 blue springs and red bushing. I put some new plugs and gapped them at .50 to start out with. I got the distributor in but ran out of daylight. Tomorrow I will hook up the box and coil and see how it runs. When I took the old HEI out one of the screws for the rotor was all the way out and the other was half way out. The rotor was loose, just flapping around! Should be able to tell a big difference after everything is hooked up. Do yall recommend a base and total timing for a setup like this? When I got TDC, the #1 piston was all the way up. My question is after the piston is up and stops moving you can keep turning the motor over about 6 degrees before the piston starts to move back down, so is TDC as soon as the piston is at the top and stops moving or after it reaches the top and right before it starts to travel back down? Or is it to small of a window to worry about?

 

https://www.thirdgen.org/forums/tech...ing-notes.html

 

You find true TDC with a piston stop.
Basically, a bolt through the spark plug hole. Turn the engine forward BY HAND until the piston contacts the stop. Read the degrees. Roll the engine backwards until the piston contacts the stop. Read the degrees. Split it in half. That's true TDC.
I run .060 gap in my machine.
I'm of the school that you run the widest gap you can, but with cautions. Too wide and the coil arcs internally. New coil time. At VERY high RPM, if you get a miss from blowing out the spark, then you need to close it down.
The wider gap, the better low end through mid range performance.
Too narrow, and you get a low speed miss. Might not even idle.
There's a pretty wide range that will run the engine, probably .010 to about .120 or so.
Summary: Too narrow, low speed miss. Slightly low(er) total output. Too wide, high speed miss and possible internal coil damage.

 

Didn't get to finish the install today, I will try tomorrow. I was thinking, I put the 2 blue springs and red bushing in and if I run 15* initial + 28* advance, it will be 43* total in at about 3700-3800 rpm. Thats to much and to late right? I'm not sure how much initial I will need with my cam profile. I was wondering if I should change out the red bushing for the blue? That would give me 15* initial + 21 advance with a total of 36* at about 2800-2900 rpm. I've read of people running anywhere from 16* to 24* initial. What area do you think my initial timing should be in?

 

My mill likes 10 degrees initial.
If the engine windmills and just won't catch, you need more. If it bucks, you have too much.
It should just run away from the starter when it's "right."

 

10-12 initial
all in by 2500

 

ok, sounds like I need to switch out the bushing.

 

I'd run as much timing as possible at idle and the least amount of mechanical to get a MAX of 36* degrees all in. You have an 18* bushing right? Run it. Plugs gapped 35-45.

 

Yeah I have a 18* bushing. 2 Blue springs with 18* bushing and 16* initial will give me 34* total, in at 2500-2600 rpm. That sound good to go with?

 

Well I finally got to finish installing the MSD ignition set up. Went with the 2 blue springs and blue bushing. I was planning on having 14*-15* initial with 21* mechanical advance with a total of 35*-36* total timing. It didn't work out that way. When I set the initial to 14* and adjusted the idle it would cut out on me when reved up and was running kinda ruff. I advanced it till it smoothed out and dropped the idle down. The only thing is it's showing around 30* inital now?? I drove it around and it's running good and smooth. Starts right up even after it's heated up. Should I put the timing back to 14* or so for the initial and the try doing some adjusting on the carb? Also, I put some new Autolite 25 plugs in and they are a little longer than my old ones and a couple of my wire boots are barely touching the header. Is there a good short plug to run? I know of the accel shorty header plugs but haven't heard good things about accel on here. Thanks for the help!

 

First thing I'd do, is confirm that what you think is TDC really is !
Balancers have been known to slip.
Second, long reach plugs in short reach heads is a no-no.
The threads will foul, and you won't get them out !!
( not to mention exposed threads can cause pre-ignition. REAL bad )

 

yea the threads thin edges will super heat fast n be like a glow plug in effect, soon as the gas hits it, its fired off before the plug can fire.

 

So using a short plug is no good?? "long reach plugs in short reach heads", is that what the accel header plugs are considered, long reach plugs? Or are you talking about the Auto Lites? Should I just keep the autolite plugs and try to put something to block the heat on the boots? I had my #3 cylinder wire tested at the speed shop because when I took the old ditributor out it had had a bad discoloration on the cap like it had gotten to hot. The wire ended up being bad so I had them make me a new one. I don't know what would cause that. I haven't ran shorty plugs in this motor it just the last ones were a hair shorter than the auto lites, just enough to keep the wire boot from touching the header.

 

So can you get the same type of plug in different lengths?

 

/snip/
We ( OK, me ) may have misunderstood. A long reach plug has 3/4 inch of threads, and a short reach plug has 0.46 inch of thread.
The Autolite 25 is a projected tip short reach, so this isn't an issue.

I now believe you were talking about the plug wire end, not the threaded end.
BIG difference !
In that case, I might look for a lawn mower plug that has the same wrench fit, seat, reach, and heat range. There may be one, and lawn mower plugs typically are VERY short on the wire end.
You may have to call a plug manufacturer and ask, because this isn't typically done. They will have the knowledge and experience to tell you if such a plug is available, and if it's a good or bad idea, and why.

 

sparkplugs.com

is a great place, it gives full specs on a plug, will even tell ya all the different stuff it fits.......