msd distributor break in

Steve Elias · #1 (**permalink**) 11-28-2002, 12:50 PM

Hi everyone, first post. I just bought an msd 8578 pro billet for my 351 crate that has 2500 miles on it. Just switched to red line 10/30 oil. The distributor has a tag saying no synthetic oil to be used during distributor gear break in. I hate to change oil again. Any thoughts either way and any advice on best advance curve and total timing?

Jack21 · #2 (**permalink**) 11-28-2002, 02:02 PM

Make sure you're using the correct gear for your camshaft. The MSD comes with a cast iron gear with a red warning tag to this effect. If using a hydraulic ROLLER cam, you need to change the gear out for steel gear. It's in the SVO parts catalog.

Take a wire brush in a drill and deburr the gear. Polish it up some.

Put plenty of camshaft moly break in grease on the gear. Put some on the cam gear as well.

I used one medium, and one light spring (if I recall) for 20 degrees centrifugal, all in by 2500 RPM. Static is 14 degrees.

Also using vacuum advance. MSD vacuum advance is not adjustable, provides too much advance, (causes lo load miss at cruise RPM) and has to be replaced with a Crane or Accel adjustable unit. ('57 - '72 Delco). Crank vacuum advance down to 8 - 10 degrees.

Steve Elias · #3 (**permalink**) 11-28-2002, 02:13 PM

Thanks Jack, flat tappet cam, iron gear. no vacuum advance on this one.

Mr.Fixit · #4 (**permalink**) 12-02-2002, 08:21 AM

The argument over what oil to use during break in is here again. MSD tells you to not use synthetic. REDLINE says to not use their oil during break in as well, but use a mineral based (regular) oil instead. More important than which oil, is that the gear is sitting at the right height, and the oil pump shaft is not bottoming out and under preload. Many people have had problems with their MSD distributor gear "going away" even with a non-roller cam. For that reason, some people are changing them out before they ever install the distributor. If it bothers you, than drain the redline out into a clean container and save for the next oil change. Check and recheck the fitment of the distributor before firing up the motor. Liberally cover the gear with the red lube supplied with the MSD distrbutor. I never run vacuum advance on cobra motors, they don't need it. Just give the dist 10-15 initial and have the centrifugal come in by 2500 to a total timing of 28-34 degrees, depending on what's in your motor and how the car is geared.

Steve Elias · #5 (**permalink**) 12-02-2002, 05:14 PM

Thanks for the advice MR.Fixit. I did drain the red line out and will save it. lots of break in lube on the gear. I set the dist up with the blue stop bushing "21 degree" with 11 initial all in by 2500 for total of 32. no vacuum advance. I will go real easy for a few hundred miles and check the gear often, and let you know. Thanks.

Chaplin · #6 (**permalink**) 12-03-2002, 04:51 PM

Mr. Fixit-
Why don't you need a vacuum advance distributor in a Cobra? I have always used vacuum advance distributors and was surprised to find that every engine builder I spoke to also does not use one, but no one could really explain why. Wouldn't mpg improve with a vacuum advance distributor?

Any insight is appreciated.

Thanks,
Mike

Jack21 · #7 (**permalink**) 12-03-2002, 05:29 PM

I use a vacuum advance distributor, and have on every street machine I've ever built.

The additional advance at high vacuum, low load cruise increases fuel economy.

However, when you dial centrifugal advance in sooner, you have to reduce the amount of vacuum advance so the combined centrifugal, and vacuum advance do not over advance the timing.

OEM distributors didn't have all the centrifugal advance in until perhaps 4000 RPM. This is way above cruise RPM, typically passing. When accelerating, the vacuum, and vacuum advance dropped out so the engine did not have full centrifugal, and vacuum advance at the same time.

At cruise (2300 RPM, high vacuum), the engine had full vacuum advance, but not much centrifugal advance. Again, not both at once.

In a warm street engine, when dialing in a distributor that will have all its centrifugal advance in at cruise RPM, the engine needs some, but less vacuum advance to optimize cruise RPM fuel economy.

Think if it this way. Centrifugal advance optimizes power at wide open throttle (low vacuum). Vacuum advance optimizes fuel economy at cruise RPM (high vacuum).

Mr.Fixit · #8 (**permalink**) 12-04-2002, 08:51 AM

Vacuum advance is what we called a "milage master" and it is only there to improve fuel economy. But once you recurve the dist. so all the advance is in by 2500, no more advance is wanted or needed. Besides, who worries about milage in a car that makes 500 hp and has a holley double pumper (or two) on it?

392cobra · #9 (**permalink**) 12-04-2002, 01:54 PM

has it exactly right.

i would follow his advice on this. vacuum advance is not needed in this situation and could easily cause harm.

chopper · #10 (**permalink**) 12-09-2002, 11:03 AM

I agree with Mr Fixit on this one also. In fact, VW used to sell an optional, centrifugal-only distributor refered to as the "009" which was very popular with the modifiers and dune buggy crowd. I used one on a 75 SuperBeetle from which I had removed the unreliable fuel injection system. That car used a "double diaphragm" model which didn't have any centrifugal advance at all. John Muir, who wrote the book "How To Keep Your VW Alive For The Complete Idiot," hated the vacuum advance units and recommended that any VW owner switch just out of general principle. I installed one and it worked like a champ. The MSD unit on my present car is centrifugal advance only and it also works well.