I know nothing about a distributor and ignition system. I googled and used the search here and learned a few things but I still have a couple of questions. I've pulled the stock motor on my 72 and I'm going to drop in a 383. It was suggested to me that I replace my distributor and ignition system in the process. I remember seeing somewhere though that I can't just get any distributor. I was told I have a mechnical drive tach. Vs. what? Electric or optic? I was also told that a distributor would be a lot more expensive due to the mech. tach. If this is the case can it be converted? Is it even worth it? I think I found a good setup, just wanted to make sure it would run in my car. Will this work?
-CR

http://cgi.ebay.com/ebaymotors/Chevy...spagenameZWD1V

 

Some Tachs like yours is mechanical, driven by a cable off the side of the distributor. Others are electrical, driven by a wire on the coil. You need a good HEI style distributor with a Mech tach drive, or one like you posted.

 

I am running the stock dist on mine. I have a Crane HI6 box that is a big improvement over the stock system. It is fired by a set of HD points. It also has a rev limiter on it whch I have used many times. I had the stock dist recurved for about 75 bucks and the box cost me about 150. It takes my motor to 7000 rpm without a miss.

 

Okay - I just went through this whole ordeal and have learned a TON!! I had the original points distributor as well and had wanted to upgrade to Mallory distributor with mechanical tach option. A Mallory distro and col were only about $350 but it was on back order for almost 6 months and still not available to date!! In the process of waiting (months) I had a lot of guys steer me away from Mallory and towards MSD. I also learned from a Mallory tech (over the phone) that they were having issues with the new Mallory distributor and thus the back order issue!

So - I went MSD. The downfall to a MSD setup is two fold - cost and the box! Close to $600 for the distributor, box, coil and MSD wires. However, I've read a lot of this forum and two engine builders steer me HARD to a no fail MSD setup, especially if you have a built motor. So...I went MSD and it's great!!! I bought everything through AtlanticSpeed.com.com and saved about $75 over Summit pricing.

I'd suggest a the MSD Distro without the vac advance, however MSD has a mechanical advance only option and a option with mechanical/vacuum. The vacuum advance may give a little better gas mileage but two engine builders have talked me into a mechanical advance only. The mechanical advance only MSD distro is part MSD - 8571. MSD-8572 has both mechanical and vacuum advance options. Both of these distributors work with Corvette mechanical tack drives. You will also need a MSD box, go with MSD 6200 ($165) if you have an automatic. Go with a MSD 6AL box if you have a 4-speed. With a strong and costly 383 you may want to go ahead and pic a MSD 6AL box anyway, it's got a rev limiter so if you miss a gear and high rev or break something then the 6AL box will protect your motor!! The rev limiter box runs about $225! You can get a MSD coil (MSD-8200) for about $35 and MSD Wires for about $80.

Trust me - you can read for days about ignition and distribution, I did, and in the end the survey said MSD all the way. However, if you want to keep a stock look and avoid a box you will need to pursue different options. I bet if you call your engine builder he'll say MSD without thinking twice about it.....

MSD - 8571 (Mechanical Advance Only w/ Corvette Tach)
MSD - 8572 (Mechanical/Vacuum Advance w/ Corvette Tach)
Call the guys at Atlanticspeed.com and ask for their ebay pricing and they will meet with free shipping!

 

Jegs has a MSD set up 4 the same price but it also includes the plug wires.....#121-85551K.........Jerrylee///

 

Your tach is what requires the mechanical tach distributor, of course. You may be able to swap your mechanical tach for an electronic one like I have on my '80 and go with a electronic tack HEI distributor with a high voltage coil. You will also need a tach filter if you convert.

Does anybody know of any tach swap incompatibilities between mechanical tachs and electronic tachs?

 

here's 4 or 5 fully self-contained hei dist WITH MECH TACH DRIVE ...all of em are under $300 ... includes coil ... no box needed.

http://motors.search.ebay.com/hei-tach_W0QQfromZR40

You can also get the same dang thing direct from Star Performance for under $180 (P/N 9200TDR) star 1-800-625-9454

 

The swap into 74-back C3 requires an elec tach from 75 thru 77 C3 ... by the time you you acquire a good working 75-77 tach ... and go to the big hassle to R&I it (take dash panel apart) ... you'll wish you'd spent your $180 on a 9200TDR dist from star or similar.

 

There's no reason to replace your stock distributor - it's a very good unit and it will perform well in any engine. If you want to upgrade your system with something that works very well, simply run a good set of points in your stock unit (like the NAPA CS786) and add an MSD-6AL box to it - this will give you all the ignition system power you will ever need, and it will run exceptionally well. Then, re-curve your distributor to bring in its full timing at 2500-2800 rpm (using springs from Mr. Gasket kit part number 928G) and install NAPA part number VC1810 vacuum advance control unit. Set total timing to 36. You will not get a better running ignition system than that.

 

I've been saying that for a year now but everytime I do it's like banging my head against a brick wall and no one like to believe it.

If your distributor is operating correctly, is within correct tolerances, and set up properly and you have a good set of hi-tension points a points distributor does a great job.
The original pointsdistributor in my '65 has been rebuilt perfectly and I can bury the tach at 7500 rpm with no problems, no points float, no break-up, and she starts instantly on the first try whether hot or cold no matter if she has sat for 5 minutes or 5 months.
What more could you possibly ask for in an ignition system?

If your distributor isn't working perfectly, instead of spending $200-$600 on the latest hot-rod, go fast parts like an expensive MSD set-up spend $100 or less and get your points distributor rebuilt to correct specs and it will run great for you.
The money you save will cover the cost of replacing points once a year or so for the rest of your life and still have plenty left over.

 

Is the MSD-6AL box where the rev limiter comes in?

 

The 6AL has rev limit capability (not that I think you really need it). The 6A does not. I've been racing since the early 70s and I've never used a rev limiter (and I've never lost an engine due to an over-rev). I run the straight 6A on my own car with an original distributor with points.

 

Thanks for clearing that up.

 

Is the fuel burned better and more efficiently using the multispark devices? It looks like it and similiar products work at the lower RPM (<3000 RMP).

Does the multispark improve combustion and fuel ecomonomy on cars that aren't being raced?

Does it improve performance on daily drivers and weekend cruisers?

Do you have to make any modifications to a Stock HEI distributor? I already have a high voltage ACCEL coil.

Are they worth the ~$175.00?

 

My 72 LT-1 has run 12.28@117MPH with a Delco Iron distributor and Pertronix Ignitor ignition but, what do I know? (I know there are lots of other places to spend $$ to improve HP! thats what I know.)