73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: Skunksmash on August 06, 2008, 06:19:27 pm
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I have been looking at that MSD distributor, but i have questions as to whether or not it is really worth the extra money. I could save a little bit by getting the stock replacement, but if there is some advantage to one of the aftermarket units, i might get one of those instead. I am open to suggestions on which one yall think is best. This would be for a daily driver truck. (87 1/2 ton 5.7L TBI 2WD. <-- I always put that cause the sticky note says to do so.) And as you guys may know from that other thread, i also intend to pull out every trick in the book to see if i can squeeze out 22 MPG out of one of these old trucks. Just a little challenge that i think might be fun to try and accomplish. And i have heard that some aftermarket ignition systems give a hotter spark. And that will eventually lead to a small MPG gain. If i can do that it will maximize the gains i get from my HHO generator that i intend to build eventually. Anyway, back to the topic at hand, which aftermarket distributor do you guys think would be best for this goal? I would just like to get a few opinions.
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try summits new line of ignition components. They're basically the same as MSD but less expensive and Summit stands behind them.
http://store.summitracing.com/egnsearch.asp?N=700+115+%2D203994&D=%2D203994
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i bought a streetfire msd dizzy w/coil and adj. vac. advance. i love this unit works awesome was only like 150 bucks and the tuning of the vac. advance will help out with gas mileage
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What advantages do yall think these units have over the stock ones? What has been improved upon which is not there normally?
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Getting 22mpg highway out of a stock 87 TBI 350 should be fairly easy. My stock 87 305 TBI is getting almost 23mpg.
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A capacitive discharge ignition system will give much more intense spark and more complete combustion. Timing is more accurate, It works through a higher RPM range, better quality components, better advance mechanism etc. If you look at their dyno results you can see the difference when compared to a standard HEI
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Just out of curiousity, I have a fairly new MSD Pro Billet HEI #8365. Do you think there would be any power to be gained by using a 6AL box rather than the module? And maybe switching over to an external coil? I'm kinda wishing I had gone with a #8361 Street Pro Billet and a 6AL box in the first place.
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Absolutely. Run the cd box. The AL just gives you a rev limiter which you may not need. Run the high output coil also but make sure you are running the msd cap and rotor also. the resistaqnce value in the carbon button is different.
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Do you mean I should keep the current MSD high energy in-cap coil (~ 42,000 V) or use an external Blaster SS coil (~ 48,000 V)?
Man I wish I had gone with a Street Pro Billet in the first place. >:(
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A capacitive discharge ignition system will give much more intense spark and more complete combustion. Timing is more accurate, It works through a higher RPM range, better quality components, better advance mechanism etc. If you look at their dyno results you can see the difference when compared to a standard HEI
Ok thanks for the answer. But what component makes the ignition system capacitive? Or is just all of them being superior?
Also, will this system wear out faster? Will the cap, rotor, and spark plugs last just as long as on a stock system?
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They'll last just as long with the exception of cheap spark plugs. Cheap plugs will deteriorate more quickly. The ignition module is capacitive. It replaces your factory ignition module.
Event- If you are running an MSD HEI and are keeping it then just use the in cap coil for now but don't use a standard HEI cap & Rotor. As I said the carbon button is different and many caps will melt at this point.
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Event- If you are running an MSD HEI and are keeping it then just use the in cap coil for now but don't use a standard HEI cap & Rotor. As I said the carbon button is different and many caps will melt at this point.
OK thanks. I'll have to look into a 6AL box though.
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I have a 6A with an HEI set up in my blue truck for now but will be changing the distributor and coil down the road. I have the 6AL and MSD distributor and coil in my 74. I originally had a modified HEI with the 6AL and when I finally put the distributor and coil in I swear to you the difference was amazing. I was sold from that day forward on MSD. It was worth the $ all day long. I think for the pink truck I'm gonna try the summit brand stuff just to see how it compares.
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Sure, experiment with lower cost stuff on your GF's truck. :D Thanks for all the advice, Vile.
Even though I did hijack this thread from Skunksmash. Hope you found this info helpful as well.
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When you say ignition module you mean things like this, right? The little red box thing. Is that what you mean by 6AL?
http://www.msdignition.com/ignition_1_5900.htm
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That red box takes the place of the ignition control module. A standard ignition module replaced breaker points ignition with a solid state transistor. Instead of a mechanical device (points) that wears out, a pick up coil was used to produce an ac voltage. That signal basically tickles the module to give an on off signal. The module then further controlled the primary side of the coil to induce spark. A capacitive discharge module does the same thing but controlls it more precisely and releases a higher energy surge from stored electrons. The result is multiple spark firing which also insures more complete combustion. It's just an imrovement on your ignition system. It does the same thing but better. It's much bigger because of it's capacitor.
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Skunksmash: This (http://stores.casselent.com/catalog/100_1004.jpg) is the 6AL box (a particular model of the CD box). The only difference between this one and the 6A is a built-in rev limiter that accepts these (http://www.msdignition.com/rpm_10.htm) modules to adjust the redline. Oh, and this (http://dimequarterly.tierranet.com/articles/tech_hei.gif) is the stock HEI module that a CD box would completely replace on these distributors.
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Thanks for explaning that guys. ;D But now of course i have a couple more questions. When that box completely replaces that stock HEI part, what happens to the stock HEI part itself? Does it get removed from the truck all together? Also, what does HEI stand for?
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You remove your module altogether from the vehicle. I know that MSD and MSD StreetFire CD boxes come with a harness that plugs into the place of where the module would have plugged into. Just check out MSD's site, i'm sure they have the installation instructions on their 6A or 6AL box. HEI Means High Energy Ignition.
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Not to hijack, but would a rev limiter will be necessary for a street driven vehicle or should one pay the extra $$ for the pro-tection. I mean, you get valve float at like 5500 rpm or so with stock valve springs, pistons hitting valves sounds like a rev limiter to me. :D
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Not to hijack, but would a rev limiter will be necessary for a street driven vehicle or should one pay the extra $$ for the pro-tection. I mean, you get valve float at like 5500 rpm or so with stock valve springs, pistons hitting valves sounds like a rev limiter to me. :D
LOL. I like the idea of the 6AL because it will do the job when my engine is built up a bit and then needs a rev limiter. And I think a rev limiter is a good idea on any engine if you drive it aggressively or loan it out to your idiot brother who thinks it ought to redline at about 8000 rpm.
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I think we have the same brother.
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Or the idiot buddy who never gets to drive anything performance and you have to let him drive cause you are to drunk. How hard is it to install one of the 6AL boxes, and how do you set the rev limiter?
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They use a plug in module. You just pick the module that you want for example 7500 rpm and plug it in. It's fairly easy to install. Rev limiters really help if something lets go and you are pedal to the metal but not really necessary if you aren't racing.
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Hmm.. well other than a rev limiter, what difference is there between all the various little red ignition modules that they offer? I guess not to much.
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The differences are mostly gonna be the voltage they produce at certain RPMs. And maybe the ease of installation. You can easily put a 6AL on an HEI setup in less than an hour if you have everything lined up.
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The 6A and the 6AL are identical with the exception of a built-in rev limiter on the latter.
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Do you have to completely remove the distributor when you are installing a new ignition module?
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No
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Hm- when you type in "1987" or "1988" ( because of tbi) for the model yr, Summit says their ign. systems are for non-computer controlled carburetor applications only.. I guess a guy could call them to get a better idea of which system to buy.
http://store.summitracing.com/compare.asp?N=700+4294925143+4294839065+4294763302+400304+4294908216+4294925005+4294840140+4294759315+4294872902+115 (http://store.summitracing.com/compare.asp?N=700+4294925143+4294839065+4294763302+400304+4294908216+4294925005+4294840140+4294759315+4294872902+115)
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For TBI
http://store.summitracing.com/partdetail.asp?autofilter=1&part=MSD%2D8366&N=700+400122+4294925008+4294908216+4294908002+4294840140+115&autoview=sku
http://store.summitracing.com/partdetail.asp?autofilter=1&part=MSD%2D8226&N=700+400122+4294925008+4294908216+4294908002+4294840140+4294890813+115&autoview=sku
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And to use an MSD 6-series CD box on the above or stock TBI distributor use this (http://store.summitracing.com/partdetail.asp?autofilter=1&part=MSD%2D8876&N=700+400122+4294842389+115&autoview=sku) wiring harness.
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For TBI
http://store.summitracing.com/partdetail.asp?autofilter=1&part=MSD%2D8366&N=700+400122+4294925008+4294908216+4294908002+4294840140+115&autoview=sku
http://store.summitracing.com/partdetail.asp?autofilter=1&part=MSD%2D8226&N=700+400122+4294925008+4294908216+4294908002+4294840140+4294890813+115&autoview=sku
How is that coil any better than a stock one? I always wondered that. And do you have to run that dizzy with the new module? I am guessing no, but you posted it so i thought i would ask.
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A coil is a step up transformer. The quality of the components and the number of turns of wire dictate the voltage output. A higher output coil shouldn't be used unless the rest of the ignition system has been upgraded.
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Ok. So let's line out what all composes the ignition system. Dizzy, plugs, wires, module, coil... Anything else?
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Your ignition system is broken down into two parts. One is the primary side (control) one is the secondary side (output)
Primary=
Trigger device (pickup coil)
Ignition control module (transistor)
Breaker points for 73-74
Ignition coil primary windings
Secondary=
Ignition coil secondary windings
Distributor/cap/rotor
Igniton wires
Spark plugs
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So really, is a stock dist is pretty much the same as an aftermarket one? I mean if we are going to change the module, anyway... what else is there about an MSD brand dizzy that makes it any better?
Also after looking around at MSD's site, i have no idea what parts would be best for my truck. I don't want their bottom of the line stuff, but i can't really tell what's still safe to be used as a daily driver.
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No, they're not the same
http://store.summitracing.com/partdetail.asp?autofilter=1&part=MSD%2D8361&N=700+400122+4294908216+4294840140+4294925045+4294881256+115&autoview=sku
Race distributors designed for the street.
These MSD Pro-Billet Street distributors are popular routes for people looking for race-proven performance for their street machine. A vacuum advance canister provides improved economy, and the proven MSD mechanical advance mechanism gives you the opportunity to dial in a timing curve to fit your needs. As always, an advance kit of springs and stop bushings is included. The housing features an all-billet 6061-T6 aluminum design for accuracy to within .001 in. An oversized steel shaft is QPQ-coated for low friction, and rides in sealed ball bearings at the top and bottom of the distributor. An extra-long sintered bushing replaces the ball bearing at the bottom for Chevrolet models. This combination keeps the shaft steady, creating accurate spark delivery at any rpm. They rely on a magnetic pickup to trigger the MSD ignition control, which delivers the powerful sparks to the coil. This pickup is extremely accurate and never needs adjusting. The distributors are CARB E.O. approved for use in all 50 states, and are guaranteed to deliver race-quality performance for your ride. These distributors require the use of a separate ignition box, such as an MSD 6, 7, 8, or 10 Series ignition.
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Thanks vile! Now i have a couple questions about the components of such a dist.
1. What exactly is vacuum advance? I am afraid i never really learned about that part.
2. Is the vacuum advance on the stock dizzys in some form? They talk like it is some kind of upgrade, so i don't know...
3. Is there a difference in the cap and rotor somehow? Are the MSD cap and rotor somehow better than OEM quality ones?
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The quality is defintely better.
There's a lot to it but to sum it, vacuum advance allows the timing to change according to engine load. The GM HEI is kind of hokey in it's centrifugal advance and inconsistent vacuum advance. You will be able to dial in your timing more accurately and consistently with an MSD
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Thanks. Just looking to get the best i can that is still safe for street/daily driver. Probly be driving the truck to work and school a lot to begin with, till i get a honda or a toyota gas sipper.
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Oh yeah, i forgot to ask. Are those larger MSD dizzys still small enough to fit up against the firewall in our trucks?
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Yep, but air cleaner clearance might become an issue, as it did for me. If I had it to do all over again I would go with a small cap pro-billet street dist and a 6AL box. Little more $ overall, but a better package, IMO.
(http://i208.photobucket.com/albums/bb247/1985C10/engine07small.jpg)
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The Large Cap MSD's shouldn't be any larger than a comparable HEI.
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Yeah but he says his air cleaner wont clear, which is also what i was kinda thinking. I will just have to go with the one he recommended cause i dont wana deal with all that.