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Replacing the Stock Distributor with a MSD Pro-Billet Unit

Joined
Aug 29, 2001
Messages
3,239
Location
Norcross, Georgia, United Stat
Corvette
2017 Arctic White Grand Sport
For Father's Day I got a nice MSD Pro-Billet distributor. The actual installation seems fairly simple. Take the cap off the old, mark somewhere on the car where the rotor is pointing, mark which cylinder, pull the old and replace the new lining up the marks you made and pointing the rotor at the correct cylinder.

Setting it up is the confusing part. I have read previously that you want to get 36 degrees of mechanical advance at about 3000 rpms measured with the vacuum advance disconnected though Lars' paper has indicated that 2,500 to 2,800 is acceptable.

The graph MSD provides has two advance curves that appear relevant, though I suspect that one is too aggressive. The fastest advance has the mechanical kicking in about 6-700 rpm and hitting top advance at about 2,400 rpm. I suspect that this is too agressive.

I have been leaning toward the second most aggressive advance curve which kicks in at about 1,300 rpm and has top advance kicked in at 3,200 rpm. Anybody have any thoughts about this.

The second question relates to total mechanical advance. It appears that I want 36 degrees at 3000 rpm but the smallest red bushings limits mechanical advance to 28 degrees, 8 degrees shy of where I want to be.

Any help would be appreciated.
 
my opinion. go with the springs that top at 3200 unless you want to run race gas. get your additional total timeing by raising your initial static timeing. so if your mechanical gives you 28 you need static set at 8 to get total of 36. be sure to check static timing with vacuum disconnected.
 
Thanks Curtis. I want to run what I have always run and that is good old regular.

I figured out the additional 8 degrees and was coming to revise my post. The car recommends timing of 8 degrees BTDC for a total of 36.
 
I replaced the springs tonight with the springs (light silver and light blue) that will start the advance at 1,300 rpm and have full advance in at 3,200 rpm.

I also changed the advance stop to the red, smallest bushing. This will allow 28 degrees of advance. Add in the 8 degrees that it is supposed to be timed at at idle and I should have the ideal 36 degrees of advance.

The springs weren't too hard to replace. The bushing is on the under side of the plate and was a bugger to get to. Of course it took a 9mm wrench, the only wrench I did not have so I had to make a trip to the store.

How do you hook up the timing light to a power source? The cables on the timing light are not long enough to reach the battery back in the car.
 
I normally use the post on the alternator as the plus and any metal as the ground, just be careful not to short it out. Congrats on the dizzy.


Cheers

Richard
 
Pulled the old distributor out, put the new one in after struggling to get the oil pump lined up for about an hour and it started right up. Timing was a little off, about 14 degrees, adjusted it and am now waiting for the engine to cool off so I can get my hand under the distributor to tighten the distributor retaining bolt.

I checked the old distributor before pulling it out and I was getting about 20 degrees of advance at 3000. The new one has 36 degrees by 3,000 rpm.

Any idea why a dwell/tach would show the proper RPM until it got above about 2,000 rpm and then it would just go to zero? It worked fine with the old distributor but is doing this with the MSD.
 
my 2 cents says maybe has something to do with the MSD drops the double spark after about 2000 rpm. no clue how to cure the problem, Ihave propped up the wife's big mirror in the seat to reflect the dash tachometer toward me when I'm at the front of the car. Sounds dumb, but without hand held tach it worked great.
 
i just plug in a auto tach mounted to a board for adjusting
 
Were you able to get the distributor to set up like you wanted it? How does it perform? Can you tell a difference? Inquiring minds want to know.
 
I'll post something later this week. All 36 degrees of advance are in at about 3,000 rpm, which is pretty much what I wanted. I need to put it all back together and take it out for a drive. Being 4th of July weekend I have not been given a lot of time to work on the car. We are just about to go out to the river.

One thing I did notice is that even if I had not replaced the distributor, I suspect that the stock one would have needed rebuilding. There was a lot of end play in it. The new one is significantly less.
 
The new distributor seems to give it more get up and go with the power coming in under 3,000 rpm rather than spread out up to to red line.

I jumped on it pretty hard today and no pinging with regular gas. Remember I have a smog car with 8.5:1 compression ratio.

Every little bit helps.
 
Put about 150 miles on the car today. Seemed to have more bottom end power, got a little better gas mileage and ran cooler.

All in all I'm quite happy with it.
 
Good to hear the distributor works so well. Just curious, is yours a tach drive model?
 
Interesting thread. I'm just about to go thru this exercise myself as I think I previously set up my tach drive to be a little too aggressive. Did the new billet distributor come w/ a vacuum advance as well? Many of the drop replacements that have tach drives seem to skip the vacuum can which I don't think is a good idea for a regular street driven application.

FYI the HEI and the tach drive distributors that preceded them can be modified to have same/similar curve w/ different springs/weights and adjustable vacuum cans can also be added.
 
Came with the vacuum can attached.

I had toyed with the idea of rebuilding my distributor and re-curving it. This one was just so pretty and easy to set up as well.
 
Yep - It's darn good looking! I want to say the HEI needs to be modded to get the same amount of centrifugal advance compared to earlier or aftermarket units - by the time you spend the $ and time on new parts, upgrade the guts for high RPM spark and such - not sure it's worth it.
 

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