Tcheairs38655

Bought a 66 a few months ago with a very nice RHS 383 Stroker setup, Hedmans and side exhaust. The car came with TWO MSD 6L systems (2 coils also) installed and switchable on a toggle inside the car. When I asked the previous owner WHY, he said that one of them was a backup. Sure enough, on startup and at idle RPM, one of the systems backfired a few times (through the exhaust) while cruising to the gas station. I switched systems and the car starts and runs smoothly.

My question is, do I really need the (apparently unreliable) MSD systems and if not, what would be a good reliable replacement. The engine has Dart heads and a roller cam and is capable of 7K+ RPM, but I don't ever drive the car to that limit, maybe 6K just for "kicks" every now and then.

Thanks in advance for your responses..

DansYellow66

I don't know why people continue to buy their crap. Over on the Cobra forums that's probably one of the major technical questions - why has my MSD system failed, or why is it all corroded inside the cap, or etc, etc. I think MSD stands for "May Suddenly Destruct" at any moment.

cv67

Take them out and put a good quality HEI in keep it simple.
(have an msd now myself)
EVeryone wants to think they need an msd they dont.


hes got 2 of them with a switch doesnt sound like he trusted them very much

If you got way too much overlap, lots of boost, nitrous maybe. YOu simply dont need it, one more thing to go wrong.

Crunch527

I have used MSD reliably for decades...I prefer it actually...I hate setting points...been there and done that...

wmf62

points and a Capacitive Discharge box, points never wear out that way (well, maybe wear on the rubbing block...(

Bill

Tcheairs38655

Summit offers a MSD HEI distributor with a built in coil. Does this make sense? Or does anyone have a better idea..I need a tach drive however for my 66.

wmf62

just a good old fashioned corvette tach drive distributor with points... always worked, always will...



Bill

j_66chevelle

Contact Davis Unified Ignition (DUI) and they will build a HEI distributer with your engine specs. Don't just buy a generic distributer unless you plan on curving it your self. They do excellent work and you have the reliability of HEI.

Nowhere Man

Simple yet effective

TCracingCA

One if you know the parameters (connections are good) and you have a malfunction, you can take out that redundant unit and send it back to them for testing! I would generally always lean toward a coil first as a suspect part, prior to the solid state Electronics!

Anyone that calls this stuff junk, really is ignorant to what they do! If you have a stock and slow piece of crap, ya all you need is an old point distributor.

On the switch box, check the seating on those connectors carefully, and also that they are clean! Disconnected I would do a continuity test of the switching function. I would have to see how you are wired up (equally connected up for the coil connections etc

Chevrolet themselves felt transistor boxes and dual point dizzies were essential in the higher performance realm! MSD and others bring that same technology to the masses! If you go to the actual race tracks and look under the hoods, plenty of MSD units ran by the professionals, so if you are trash talking them, your pretty ignorant! Know what you are doing or what they do prior to trash talking!

PS I can't see running points, with the existence of magnetic pickups!

4 Speed Dave

End of thread.

Yeah them gosh darn MSD boxes are junk. You old guys that have a hard on for point ignitions crack me the hell up.

kolsen911

I've run dual MSD's in my 3.0L 1972 Porsche 911 for over 15 years. Twin plug heads so one MSD for each set of plugs and a switch to turn one off to make sure the other set of plugs is firing. Of course you have to run a special distributor.

Tcheairs38655

I had a 66 427/425 car for about 20 years. I was never able to get the TI ignition system to work right even after a $1,000 overhaul of the distributor by the (you know who) TI guru. So I dropped in a stock dual points distributor and replaced the points with a Breakerless SE kit from Lectric Limited and the beast would wrap up to 6k before i could get my heavy foot off of the accelerator! Even hid the ballast resistor behind the dash.

wmf62

sounds like an aircraft engine test....

Bill

wmf62

Bill

tubman

Maybe not important, but my stock '67 L79 would always start to break up before the red line, even though the distributor had been completely rebuilt with quality parts. After some research, I replaced the rotor with a specialized one that had a longer tip and the car would go to the red line (and maybe beyond if I kept my foot in it) with no problems. It seems that GM (and most of the aftermarket manufacturers) had gone to a .060" shorter rotor tip in the '70's for emission reasons. In those days, they valued clean air over performance.

TCracingCA

You don't have to run a distributor! We don't as you see on the pictures of one of our cars!!!!! And working on the same on my Corvette race car!












The instrument has 16 k-type thermocouple inputs for various types of sensors
For the left bank of channels 1 - 6 I have cht (cylinder head temp 14mm ) sensors under each lower spark plug on the twin plug heads on the right bank of channels 1 - 6 I have egt ( exhaust gas temp) probes drilled and mounted into each pipe at 1.5 inches from each exhaust valve. Channel 7 left is a p120 k-type sensor mounted into a manifold block connected to my lower transmission drain plug which feeds a check valve posited up at the level of the transmission fill plug and goes to a oil pump, cooler then expands from -6an to -8n to reduce pressure before returning to a 90 degree swivel an fitting drilled and tap threaded into the 901 directly above the ring gear. The check valve and diameter change are critical to keep the oil level at height so when pump is off, the oil cooler doe not over fill the transaxle and the diameter change is so I don't pressurize the case and blow seals when in operation.
Back to the gauge, the right channel 7 is again a p120 temp sensor but this one is mounted to the top extra cap port on my front right wide mouth oil cooler

So you can see that channels 1 thru 6 give me cht and egt for each cylinder and channel 7 is trans oil temp on left window and external oil cooler temp at the right front fender. Channel 8 unused (for now)

Now the gauge can be programmed for upper, lower and differential limits. One can use the center switch to manually step to each channel or place it in scan mode where it constantly scans the user defined limits and flags the red lights if something goes outside limits.

For tuning the PMOs, it comes in handy big time. I can adjust my fuel air mixtures and idle air correctors until all egts are all within about 25 f of each other. Typical idle at 900 to 1000 rpm is around 1100 f. If a cylinder is rich , it lowers, if lean raises and if clogged jet or not spark then of course it's way down near 100 with the others still at 1100. ( please note I have dual mtx-l air fuel sensors gauges and use my carb sync to open and balance the air correctors to match vacuum on each cylinder and open them all equally until I obtain a perfect 12.5 to 1 on each side bank of three. This with the egt helps me idle a 906 cam (early rsr) cam 318 and 292 duration with the 906 1.5 rockers instead of standard 911 1.45 and idle like any new production car. Smooth.

Also the air correctors opened a little give me a better progressive with zero flat spots when transitioning to mains.

I don't have 2.8 liter secrets so the pistons are JE 92mm with 25.5 volume dome and the heads are 74 modified to 42 intake and 38 exhaust ports with standard 46/40 valves and 68 cc chambers giving a CR of 12.0011 hence why I run vp 101 street legal unleaded for good measure (specific gravity of .713 @ 60f)

Head valves and ports match the pmo carbs and Venturi. 46/42. And for exhaust the head ports 38 matches the 1.5 inch headers (38mm)

Back to the gauge

It provides me with a very safe and early warning monitor of engine parameters which can be costly and ring damage etc if not caught instantly.

It helps me tune to a level beyond what a plug read can do

It's just good insurance and it's cool and fun to use and tune with.

The next picture is of the afr gauges






They obviously help me tune for power.

In the earlier picture you can see the bung welded aft of the merge for the left bank exhaust for cylinders 1 2 and 3. Note there is an aluminum heat sink that is finned between the bosch sensor and the bung that must be oriented with the airflow direction and reduces temp at the o2 sensor to prolong life. Same for the right header cylinders 4 5 and 6.

These help me set idle up thru 8k and can be logged via computer link when driving under load to see afr vs rpm

I target 12.5 to 1 because most know that is best power whereas 14.7 to 1 is best emissions.

I run the PMO 46 with 42 Venturi and 160 mains, F 2 emulsions and 180 air correctors to obtain within plus or minus 1 of 12.5 to 1 all the way up.

GTOguy

To answer your question, NO, you DO NOT need an MSD of any kind on your car. They offer no measurable performance gain driving down the road. Personally, I stick to stock points ignition systems on cars that were born with them. Never been towed due to an ignition problem in any of them.

TCracingCA

Most people that have MSD boxes, don't derive any benefit, because all they do is hook it up. Zero engineering done! My opinion is that they are not for plug and play. They only come into play when you are pushing the timing advance, and for efficiency of a complete combustion cycle of the engine. And especially are beneficial if set up right for those things happening during high rpm usage. I have seen a lot of guys have their engines lay down when hitting high rpms. All kinds of things from Lean misfires, to washed out spark during combustion chamber fill!

After38Years

I don't race my car. Mechanical points are fine for street driving.