namell87

Just baught an Lq9 for my 70 Nova project. I like the old school look in old school cars. For simplicity I am going to carb this engine. I am curious who is using the distributor kit from gmpp that uses a sbf dist and fuel pump. I know the majority of people use the msd box. Other than popularity of the box. What are the pros and cons of both systems?

The distributor kit seems like it would cost more to install but if money isn't the issue is it worth the money or not? Money is always the issue though that is why i'm asking.

IHEARTLS1

iTrader: (1)

unless you are spinning over 8500 rpm, use the box. everything else is a con with the distributor.

allblowdup

The dist cover system works good enough but you end iether using a mechanical advance or a programable ign box. I have seen a few issues with the fuel pump drive if you intend to use that.(fuel pumps didn't stand up). As far as power goes we have dynoed them back to back and they are within 1 hp of each other. If youi go that route I may be interested in your coil pack for the right price. Were is the middle of the desert.

HPM

From the background in his avatar I am guessing AZ, but I could be wrong. As far as the box vs dist, the box is pretty easy to use and infinitly adjustable. If you want the old school look, relocate the coil pacs behind the motor.

Scoggin Dickey

iTrader: (34)

It is going to cost you a LOT more to do the distributor drive, and it is more complicated.

Pop N Wood

iTrader: (1)

Certain classes of racing require a distributor. That is about the only valid reason I can see for using one.

1994z

iTrader: (48)

why is it more complicated. and cost vs the 6010 box.

ATwelveSec02Z28

iTrader: (17)

The Distributor drive is not for everyone....

Cost: Distributor Conversion - $400 for the cover.
$250 for Distributor
$150 for coil
$200 for 6AL box (cheapest route)
$100 for water pump spacers
$200+ for dampener
And... plug wires etc etc...


MSD 6010/6012 - $300 for the box
$250-300 for coil packs (if you dont have already)
and plug wires etc...

I went with the distributor conversion because the tuning capabilities in the MSD 7531 box far exceed the capability of the 6010 - and for my intended use, those additional capabilities make the conversion worth it.

Scoggin Dickey

iTrader: (34)

Yep, and don't forget bracketry to run any other accessories an individual might need, especially on a street car. Every accessory is going to need a bracket for each one to space them out to match the new offset.

DMMizell

iTrader: (1)

What are the RPM limits of the stock LS crank trigger??
9200 rpm shift points here with a dist and MSD 7.

Dave

ATwelveSec02Z28

iTrader: (17)

An honest answer to that is hard to tell...

I wouldnt doubt that a 6010 using the reluctor wheel could spin that high, but I would be worried about the accuracy of the timing. Im sure people have gone that high with EFIs but mainly using heavier larger external reluctor wheels.

Even with the Distributor, to spin to 9200RPM I would not trust the magnetic pickup in a distributor - youre into flying magnet territory.

Scoggin Dickey

iTrader: (34)

I would tell anyone looking to turn over 8,000 to look into the distributor or an external crank trigger setup.

ZONES89RS

iTrader: (25)

Yea, i dont see any street cars with hydraulic cams needing them, but the solid roller guys that are turning heat, hell yea.

xx_ED_xx

iTrader: (17)

Why if you dont mind me asking?

IHEARTLS1

iTrader: (1)

the stock setup cant deal with processing commands to tell the coils to fire that fast at rpm higher than 8000-8500. most people never spin that high EVER anyway. and if they do, a distributor conversion is the least of their money problems.

Pop N Wood

iTrader: (1)

Has anyone every tried the MSD box at 8000 RPM or higher and noticed a problem?

I know it doesn't mean it can do it, but the MSD box allows the rev limiter to be set as high as 12,500 RPM. I have no direct experience at RPM's beyond stock, but in today's world of digital electronics 8000 pulses per minute is hardly stressing. Plus a multi coil set up is vastly superior to a single coil when it comes to high pulse rates.

I mean, to put my level of experience in perspective I googled the MSD 7531 box and I'm having a hard time getting my mind around how anyone would use all that capability, so I will defer to the experts. But from a purely electronics point of view it seems a digital box with multiple coils that are only triggered by their control pulse (rather than powered by the pulse) would beat a distributor hands down. Where is the weak link in the MSD 6010 chain, the box, the coils or the sensors?

ATwelveSec02Z28

iTrader: (17)

The internal reluctor wheel is one of the down falls...

at those RPM's it will start to give problems.

Look how big the external wheel for a BS3 is....


Pretty simple math, @ 8500RPM the the sensor (24 tooth) will be triggered 3400 times per second. On a wheel that is inside the engine (3-4" diameter) the gaps between the teeth do not give the sensor enough resolution.

As for using the 7531, as stated before - thats not for everyone. I use it for 1 and 2 stage retard, burn out limit, stage limit, individual cylinder timing, and once I get enough data, slew rate limit...

Pop N Wood

iTrader: (1)

Thanks for the insight.

But the engineer in me says the diameter of the wheel doesn't make a difference in the time interval between the pulses. Like you said the pulse rate is just the RPM times the reluctor count. A bigger wheel moves the reluctor teeth at a higher velocity, but they still tic past the sensor at the same rate either way.

3400 Hz, or 8216 Hz for a 58x reluctor, is still a pretty low frequency. I would think being inside the engine could in theory improve the signal quality by shielding the sensor from outside interference.

Maybe the sensor starts picking up signals from multiple reluctor teeth? I could see a bigger wheel helping that.

Seems like the recovery time of the sensor is the issue, but that would be common to either unit. Maybe the stock sensor simply isn't as good as an aftermarket unit.

Has anyone looked at the stock reluctor wheel output at high RPM?

I'm not being a troll, honest. Guess I am just bored at work today.

Scoggin Dickey

iTrader: (34)

As stated, the first problem to come up is the reluctor wheel. The MSD box is capable of more RPM, but the stock reluctor setup is not.

Size of the wheel does matter. Consider the fact that if you have the same number of teeth, say 24, on a bigger wheel, the larger spaces between the teeth is going to make a cleaner signal that is easier to pick up at high rpm. The factory wheel in it's small size is simply going to be a blur.

ATwelveSec02Z28

iTrader: (17)

Here are some pics of a BS3's trigger wheel... (from Shawn @ VA Speed)


Compare that to...


The OEM design also is limited in the airgap which can impact the signal greatly.