Ignition question for blown sbc ???? Help!!!

[sc5080]

I'm getting a lot of conflicting advice lately regarding the ignition for my current project (Sheets & Giggles 23 T nostalgia altered). I am using a 383 sbc, 671 blower, Enderle injection and alcohol fuel. I will be running 15 pounds of boost maximum .. likely closer to 10 - 12 lbs.

The problem is that I am being told that an MSD 7AL will not supply enough spark to keep the candles lit and that I will need to upgrade to (at least) a Mallory Super Mag III. Does anyone on the board have any experience with this?

If I have to upgrade, are there any used mags out there for a reasonable price?

Appreciate any and all feedback.

 

[BlueNorther]

most people run mags in blown applications because they lack a alt/generator and an on board battery.

if you have the voltage, the MSD 7AL puts out enough spark volt to light any gas powered car.

I would invest a dime and call the boys at MSD and see what they suggest.

 

[kenny c]

Isn't Dr. Crankenstein an experienced supercharger man.

 

[kenny c]

Isn't Dr. Crankenstein an experienced supercharger man?

 

[sc5080]

most people run mags in blown applications because they lack a alt/generator and an on board battery.

if you have the voltage, the MSD 7AL puts out enough spark volt to light any gas powered car.

I would invest a dime and call the boys at MSD and see what they suggest.

Already talked to MSD. They were rather non-commital on the issue. As you say, if I was running gas there would be no problem but I will be using alcohol. The folks at Good Vibrations Motorsports who's advice I generally trust advised that the MSD would not be good enough. But they also want to sell parts. Searching the interweb tends to be 50/50 on the issue. One local guy is running the 7AL2 box and HVCII coil with a 14:71 blower and 25 lbs boost on alcohol and claims no problems - but that fellow also breaks a lot of parts. Leaves me in a bit of a quandry as to what I should do considering I already own a 7AL2 box that I used to run in my dragster. I had no problems in that car running alcohol normally asperated but the box failed when I was running blown alcohol in that car. The box is now being repaired at MSD.

 

[BlueNorther]

as long as you have the MSD box already, give it a whirl, if it works, great, if not you can always buy a mag.

MSD's love big voltage, when I ran mine, I had a big battery in the trunk and a 100 amp alternator a local electric shop made into a one wire alternator that charged full blast any time the engine was running. never had a low voltage problem after that. no charging between rounds or even between weekends. (120amp + 16v @ 3000+up rpm)

I wouldn't recommend the full time charging alternator for anything besides drag race only car, would dry out battery in no time, but works great at drag strip.

 

[bob w]

I did some Googling last night and it appears that MSD-10 works but that tuning is easier with a mag.

 

[sc5080]

I did some Googling last night and it appears that MSD-10 works but that tuning is easier with a mag.

Thanks Bob and BlueNorther. Unfortunately the 10 is no longer being made. I'm leaning towards the mag but would sure like to find a way to save a bit of cash on the deal.

MSD choices are 7al2, 7al3, digital 7, Grid System (which is a big $ deal and is a 7 box), or an 8. Also, the strongest coil that MSD makes is the HVC II which has a peak current of 2 amps.

I have an older 7al2 that is currently being repaired at MSD. I would still need to buy the coil (~$200), the distributor (~$250), wires (~$100), 2 step (~$75), and the rpm switch (~$90). Total if I can get away with the 7al2 is $725. If I need an 8 box that's another ~$1200. That makes the total for an MSD system approximately $1900.

Mallory Super Mag 3 is ~($1330) with coil (~4 amps), wires (~$100), tach converter (~85), rpm switch (~90). Total for new mag setup is approximately $1600.

Remember this is all US $. Add shipping, 40% exchange and 13% sales taxes on the total Cdn $ and brokerage of unknown amount and you can understand why I want to make the right choice the first time . Whatever I do is going to be expensive .

 

[bob w]

How about the racing junk site for used parts?

I see Good Vibrations Racing has some used stuff.

 

[ANNAMEL]

454 with 671 blower MSD ignition with MSD coil. No problems with twin 850s. No nitrous though... Good Luck

 

[Dr Crankenstein]

Isn't Dr. Crankenstein an experienced supercharger man?

Yes and No.

Quite a few years back, we owned and ran a fuel funny car... BIG twin magnetos, dual plug heads, two pumps, 32 nozzles and 40+ lbs. boost.

That ^^^^ was a completely different animal and I have no experience with alcohol, except for the drinking variety...

I can appreciate the need for a hot ignition, however. With mechanical injection, the last thing you need is a weak or dead spark. (Think hydraulic lock and your crank "on the floor".)

sc5080, pick up an issue of Quick Times. Your local speed shop(s) should have it and it's free if they do. It's an Alberta publication, Don is a racer and the magazine is heavy on the classifieds.

http://www.quick-times.com/

.

 

[sc5080]

Bob - I've been looking but I'm a little afraid to buy used parts from someone I don't know - especially long distance . Good Vibrations had no magnetos in stock (new or used) when I spoke with them last week.

Annamel - your setup looks pretty cool. I expect, however, that you were running it on gas. Alcohol is an entirely different beast and needs a hotter, longer duration spark to fire properly.

Dr. Crankenstein - Thanks for the suggestion. I had forgotten about Don's magazine. I met him several years ago when I was racing at a National Open in Calgary. He was running a Cobra super gas car back then. And yeah, stock Chevy blocks are weak enough without adding misfire and backfire problems to the equation. It may look real cool but I really don't want to run over the crank (think Magic Muffler Fiat).

 

[jfg455]

I think you are over thinking it. The MSD 7AL will work fine for what you are doing as long as you are using the correct coil for the application. If you said you were running 15-18 psi and going to turn it 8K rpm then I would say go with the mag. You will want to spend time on indexing your plugs to the direction of the intake charge and tighten your gap up to get a good hard spark ball. Run a quality 8mm wire set as well. You won't "blow out" the spark with only 12 psi especially with alcohol. Mags help you by doing 2 things. 1 they run with very little or no power and 2 the faster you spin them the more energy they make. A regular coil set up starts to lose power when you get up into the 7K - 8K range as they just don't have time to populate the coil. Where you are probably not going to turn it over 6500 and are not running an insane number for boost your set up will be fine. Just my $.02 [P

I used to run straight methanol in my WKA Karts so I'm familiar with the properties although they were not blown...

 

[sc5080]

Thanks jfg455. Your response is well thought out and overthinking things is something I am known to have done once or twice in my life .

If I do wind up going to the MSD I will be using their HVC II coil as it appears to be the highest output available at an advertised 2 amps. Plug gap would have to be closed up to .015 to .018 I think but that's the same gap range for a mag.

You may be right as to the rpm where my calculations would indicate just over 7000 at the finish line considering slippage at the converter and in the trans provided the motor makes the power I anticipate (approx 750). Static compression on this engine is 10.25:1. If the car will pull a 3.50 gear on a 29.5" tall tire I should see low to mid 8's at 160 - 165 mph. This should be feasible if the GMC 671 blower will make enough boost without heating the air to much. I am really trying to avoid the temptation to put my 871 on it.

I would pull about 72 - 7300 rpm with a normally asperated injected alcohol setup with a 451" Chrysler wedge at 13.5:1 compression running a 33" tire and 4.11 gears. That combination went 8.0's @ 168. It was when I put my 871 at 9% under on that engine at 11:1 static compression and saw 17 - 20 lbs boost that I ran into problems that may have been due to the 7al2 ignition.

 

[Bamamav]

Mid 8's at 165 mph! That is gonna be moving on! [cl
That would be like a what, 4.5 in the 1/8th? No 1/4 mile tracks around here, everybody races the 1/8th.

 

[jfg455]

If I do wind up going to the MSD I will be using their HVC II coil as it appears to be the highest output available at an advertised 2 amps. Plug gap would have to be closed up to .015 to .018 I think but that's the same gap range for a mag.

You may be right as to the rpm where my calculations would indicate just over 7000 at the finish line considering slippage at the converter and in the trans provided the motor makes the power I anticipate (approx 750). Static compression on this engine is 10.25:1. If the car will pull a 3.50 gear on a 29.5" tall tire I should see low to mid 8's at 160 - 165 mph. This should be feasible if the GMC 671 blower will make enough boost without heating the air to much.

The alcohol will help keep the temps down but I think you will be seeing the 15-18psi down at the big end. Looking at your combo and rpm range I would now say you might be right at the limit of what the MSD will handle. You just might be better off jumping to the Mag and kill 2 birds so to speak. 1: eliminate spark issues by having just a bit too much of an ignition system and 2: it will be ready when you decide to dump the 871 on it and test the structural integrity of the block [cl

 

[sc5080]

Mid 8's at 165 mph! That is gonna be moving on! [cl
That would be like a what, 4.5 in the 1/8th? No 1/4 mile tracks around here, everybody races the 1/8th.

Not quite that fast . It would work out to 5.20's to 5.30's at the 1/8. 5.0 works out to about a 7.90. 4.5 is a very low 7 in the quarter. Very quick figuring is 1/8 time X 1.58 = an approximate 1/4 time.

 

[sc5080]

The alcohol will help keep the temps down but I think you will be seeing the 15-18psi down at the big end. Looking at your combo and rpm range I would now say you might be right at the limit of what the MSD will handle. You just might be better off jumping to the Mag and kill 2 birds so to speak. 1: eliminate spark issues by having just a bit too much of an ignition system and 2: it will be ready when you decide to dump the 871 on it and test the structural integrity of the block [cl

Thanks jfg. That's pretty much the conclusion I have come to although several people are encouraging me to go with the MSD Grid system. Now all I have to do is find a reasonably priced mag from a reliable source.

I'm thinking the 871 will stay on the Chrysler engine. If i decide the small chevy isn't fast enough I can put that in and go run that 4.50 that Bamamav is talking about . That engine makes over 1200 hp on a mild tune up and about 1500 when its set on kill. Enough to keep me entertained anyway!

 

[sc5080]

Made a decision and bought a Mallory SuperMag III from Spud Miller at FIE. Nice folks and great to deal with.