setting advance on msd distributor? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

ocbaud · 03-04-2004, 07:58 PM

okay, i got my pro-billet distributor(8361) today. i need to know what would be the best setup for my engine and truck?

**swervin ervin** · 03-04-2004, 08:15 PM

Use the light silver and a blue spring. This is what I run in my Pro-billet HEI. This should be all you need to do.

ocbaud · 03-05-2004, 12:43 AM

what about the advance stop bushing?
what do i want the total advance to be at? and what does the vaccum advance add to it all?

with the silver/blue setup and the blue stop bushing that is in there, it says i should be running at around 21 degrees full advace at around 3000rpm.

if i ran around 12 degrees initial, it would give me 33 degrees total. is that about what i want? would i still need the vacuum advance then?

**swervin ervin** · 03-05-2004, 01:05 AM

You don't mess with any bushings or the mechanical advance. Leave it at 21 total.

95% of small block Chevy's run best with the total timing between 32-36 degrees. I've found through testing, mine is best at 35 degrees. 21 mechanical and 14 initial. Your's may be different. It all depends on compression, cam, gas quality, etc.

The vacuum advance canister MSD uses provides around 16 degrees. A tad too much for non EGR engines, which work best with around 12-13. Not much you can do about it though. A Crane adjustable canister won't fit the MSD distributors.

Oh, and run it on a full vacuum at idle. Ported is for emissions, not performance.

ocbaud · 03-05-2004, 01:14 AM

so, if i set my initial timing at 13 degrees + 21 degrees of mechanical + 16 degrees of vacuum = 50 degrees?

that sounds like a lot. it would be 34 without the vacuum hooked up correct? but the vacuum is only operating durning part throttle?

so under WOT, i would only be running at about 34 degrees? which is what i want, correct?

**swervin ervin** · 03-05-2004, 01:49 AM

Yes, basically. Thing is, don't worry about the vacuum advance in the equation. You will not have over a max of 34 degrees ever.

The vacuum advance is for economy only. This is the very reason it needs to be hooked to vacuum at idle. Some will swear it is supposed to be hooked to a ported source, or above idle vacuum. This thinking is totally wrong IMO. A properly tuned distributor works best with full vacuum at idle. The reason most will say to use ported vacuum is because they have spark knock if they don't. This is nothing but a crutch for a mistuned distributor. Most stock GM canisters have upwards of 25 degrees advance. This is the reason they have spark knock, not where they have it hooked to.

Edit: I put 44 instead of 34.

DCRANER · 03-05-2004, 10:37 AM

If I can jump in here, I also agree that a smallblock runs best in the 32 - 36 range in total. Now ocbaud has a healthy cam, similar to my ZZ430, and I know from much research that my engine is best at 32 total. I think a hot cam and no EGR setup would be best in the lower range of the 32 - 36 range. That said I think you also want that total timing to come in at the 3,000 - 3,400 rpm range. That said I would suggest ocbaud use two blue springs, since the springs control the rpm at which total timing occurs. Now my paperwork from MSD indicated the stop bushing was at 19. In any event swervin is correct, do not change the stop bushing because you want the highest initial advance possible and the least mech. advance to get to your total timing.

Now I do not use the vac. advance at all, I just disconnect it on the MSD, see the instructions that comes with it. Again, I have a hot cam & no EGR. swervin is correct on full vac. if all is factory type vac. advance use. Ported vac. does nothing in my opinion. But keep in mind my suggestion is for best top end power with still a good idle.

Also, keep in mind with the MSD vs. an HEI to open up your spark plug gap. In the 50 - 60 range. With 10 to 1 comp. like ocbaud I would go with a tighter gap, say 50 - 55. Out to 60 would give a smoother idle, etc. but fall off slightly in power at high rpm's.

Well, those are my thoughts. Good luck ocbaud, that is a killer combination.

Doug

76bonanza · 03-05-2004, 06:49 PM

I am getting an msd hei probillit in a few weeks but I have a 4x4 daily driver all stock but headers intake and exhust. Looking for throttle response low end power and also gas milage. Never sees over 4000 rpms for very long. So do I want my advance to kick in quicker or later? Also would I want ported or full vac?
Any thoughts would help I really do not understand the inner workings of advance in relation to performance.

**swervin ervin** · 03-05-2004, 08:16 PM

From my experiements, a heavy vehicle can't stand advance as quick as a light vehicle without spark knock. With a 4x4, I would try the light silver and blue spring like I use in mine. Run full manifold vacuum and see how it does. I would set the initial at 12-13 degrees to start with. If no spark knock, raise it a tad. If it does pink back it off a couple degrees. Then if it still pinks, trade the light silver spring for a blue one and try it again. If this fixes the spark knock you might have had with the light silver, try raising the timing back up a couple degrees.

I'm not sure on Eric's distributor, but I do know my Pro-billet HEI came setup with 21 degrees. So a basically stock 350 should be able to handle 34 degrees or so. When working with the timing, remember, you have 21 degrees in the distributor, plus the initial so you can add it up from there. The springs will control how fast the mechanical advance comes in.

Nothing is set in stone here. It's a try and see method of tuning. Every vehicle/engine combination is different. There is a close area to start with and you can work from there. What you are shooting for is the most timing you can run without going to the extreme. Like I said, most small blocks seem to run best between 32 and 36 degrees. A lot of things come into play on how much is best or works best.

Good luck with it and don't get frustrated. It's not as hard as most think it is. When you get it right, it can make a night and day difference in performance, as well as economy.

Mike

76bonanza · 03-05-2004, 08:30 PM

Thanks mike very in depth post do you have any step by step instructions on your site for changing the dist?

Thanks

76bonanza · 03-05-2004, 09:24 PM

One more question I was going to run my vacum advance on my stock hei off of full vac insteaded of ported the way it is now. But my tranny runs off my full vac port and it looks like it is the only one on the carb is this right? It is a holey not sure what model. So what can I do?

**swervin ervin** · 03-05-2004, 11:35 PM

Yes, there are articles on 73-87.com but it's not my site anymore. I gave it to Jeff (bigblock73).

Full vacuum is vacuum at idle. It don't matter where you have it hooked. Just remove a vacuum hose and feel if it has vacuum. Of course if it does, you will be able to tell by the way the engine runs with the instant vacuum leak. A ported source will not change anything unless you open the throttle some. If you don't have any places left to hook it, use a plastic tee in an existing line somewhere.

03-04-2004, 07:58 PM	#1
ocbaud Garage Queen Material Join Date: Oct 2002 Location: USA Posts: 4,129	setting advance on msd distributor? okay, i got my pro-billet distributor(8361) today. i need to know what would be the best setup for my engine and truck?

03-04-2004, 08:15 PM	#2
swervin ervin You get what you pay for Join Date: Dec 1999 Location: Cherryville, NC Posts: 4,798	Use the light silver and a blue spring. This is what I run in my Pro-billet HEI. This should be all you need to do. __________________ Mike 1985 Chevy C-10

03-05-2004, 12:43 AM	#3
ocbaud Garage Queen Material Join Date: Oct 2002 Location: USA Posts: 4,129	what about the advance stop bushing? what do i want the total advance to be at? and what does the vaccum advance add to it all? with the silver/blue setup and the blue stop bushing that is in there, it says i should be running at around 21 degrees full advace at around 3000rpm. if i ran around 12 degrees initial, it would give me 33 degrees total. is that about what i want? would i still need the vacuum advance then? Last edited by ocbaud; 03-05-2004 at 12:47 AM.

03-05-2004, 01:05 AM	#4
swervin ervin You get what you pay for Join Date: Dec 1999 Location: Cherryville, NC Posts: 4,798	You don't mess with any bushings or the mechanical advance. Leave it at 21 total. 95% of small block Chevy's run best with the total timing between 32-36 degrees. I've found through testing, mine is best at 35 degrees. 21 mechanical and 14 initial. Your's may be different. It all depends on compression, cam, gas quality, etc. The vacuum advance canister MSD uses provides around 16 degrees. A tad too much for non EGR engines, which work best with around 12-13. Not much you can do about it though. A Crane adjustable canister won't fit the MSD distributors. Oh, and run it on a full vacuum at idle. Ported is for emissions, not performance. __________________ Mike 1985 Chevy C-10

03-05-2004, 10:37 AM	#7
DCRANER Registered User Join Date: Feb 2004 Location: Atlantic Highlands, N.J. Posts: 139	If I can jump in here, I also agree that a smallblock runs best in the 32 - 36 range in total. Now ocbaud has a healthy cam, similar to my ZZ430, and I know from much research that my engine is best at 32 total. I think a hot cam and no EGR setup would be best in the lower range of the 32 - 36 range. That said I think you also want that total timing to come in at the 3,000 - 3,400 rpm range. That said I would suggest ocbaud use two blue springs, since the springs control the rpm at which total timing occurs. Now my paperwork from MSD indicated the stop bushing was at 19. In any event swervin is correct, do not change the stop bushing because you want the highest initial advance possible and the least mech. advance to get to your total timing. Now I do not use the vac. advance at all, I just disconnect it on the MSD, see the instructions that comes with it. Again, I have a hot cam & no EGR. swervin is correct on full vac. if all is factory type vac. advance use. Ported vac. does nothing in my opinion. But keep in mind my suggestion is for best top end power with still a good idle. Also, keep in mind with the MSD vs. an HEI to open up your spark plug gap. In the 50 - 60 range. With 10 to 1 comp. like ocbaud I would go with a tighter gap, say 50 - 55. Out to 60 would give a smoother idle, etc. but fall off slightly in power at high rpm's. Well, those are my thoughts. Good luck ocbaud, that is a killer combination. Doug __________________ 86 GMC SWB, DK. BLUE, ZZ430,TH400, 4.11'S, HEADMAN CERAMIC HEADERS, WELD BILLETS, BFG 275 / 60 / 15, 325 / 50 / 15 DRAG RADIALS, FIBERGLASS COWL HOOD, B&M SHIFTER. MSD, MARCH PULLEYS / ALT. / PWR. STEER PUMP, BECOOL RAD., BILLET GRILL & GRANT WHEEL.

03-05-2004, 01:14 AM	#5
ocbaud Garage Queen Material Join Date: Oct 2002 Location: USA Posts: 4,129	so, if i set my initial timing at 13 degrees + 21 degrees of mechanical + 16 degrees of vacuum = 50 degrees? that sounds like a lot. it would be 34 without the vacuum hooked up correct? but the vacuum is only operating durning part throttle? so under WOT, i would only be running at about 34 degrees? which is what i want, correct?

03-05-2004, 01:49 AM	#6
swervin ervin You get what you pay for Join Date: Dec 1999 Location: Cherryville, NC Posts: 4,798	Yes, basically. Thing is, don't worry about the vacuum advance in the equation. You will not have over a max of 34 degrees ever. The vacuum advance is for economy only. This is the very reason it needs to be hooked to vacuum at idle. Some will swear it is supposed to be hooked to a ported source, or above idle vacuum. This thinking is totally wrong IMO. A properly tuned distributor works best with full vacuum at idle. The reason most will say to use ported vacuum is because they have spark knock if they don't. This is nothing but a crutch for a mistuned distributor. Most stock GM canisters have upwards of 25 degrees advance. This is the reason they have spark knock, not where they have it hooked to. Edit: I put 44 instead of 34.

03-05-2004, 06:49 PM	#8
76bonanza Senior Member Join Date: Mar 2003 Location: St robert Mo Posts: 2,001	I am getting an msd hei probillit in a few weeks but I have a 4x4 daily driver all stock but headers intake and exhust. Looking for throttle response low end power and also gas milage. Never sees over 4000 rpms for very long. So do I want my advance to kick in quicker or later? Also would I want ported or full vac? Any thoughts would help I really do not understand the inner workings of advance in relation to performance. __________________ 1968 c10 lowered 3" 4" 355/Th400 built by Hatfield racing in joplin MO

03-05-2004, 08:16 PM	#9
swervin ervin You get what you pay for Join Date: Dec 1999 Location: Cherryville, NC Posts: 4,798	From my experiements, a heavy vehicle can't stand advance as quick as a light vehicle without spark knock. With a 4x4, I would try the light silver and blue spring like I use in mine. Run full manifold vacuum and see how it does. I would set the initial at 12-13 degrees to start with. If no spark knock, raise it a tad. If it does pink back it off a couple degrees. Then if it still pinks, trade the light silver spring for a blue one and try it again. If this fixes the spark knock you might have had with the light silver, try raising the timing back up a couple degrees. I'm not sure on Eric's distributor, but I do know my Pro-billet HEI came setup with 21 degrees. So a basically stock 350 should be able to handle 34 degrees or so. When working with the timing, remember, you have 21 degrees in the distributor, plus the initial so you can add it up from there. The springs will control how fast the mechanical advance comes in. Nothing is set in stone here. It's a try and see method of tuning. Every vehicle/engine combination is different. There is a close area to start with and you can work from there. What you are shooting for is the most timing you can run without going to the extreme. Like I said, most small blocks seem to run best between 32 and 36 degrees. A lot of things come into play on how much is best or works best. Good luck with it and don't get frustrated. It's not as hard as most think it is. When you get it right, it can make a night and day difference in performance, as well as economy. Mike

03-05-2004, 08:30 PM	#10
76bonanza Senior Member Join Date: Mar 2003 Location: St robert Mo Posts: 2,001	Thanks mike very in depth post do you have any step by step instructions on your site for changing the dist? Thanks __________________ 1968 c10 lowered 3" 4" 355/Th400 built by Hatfield racing in joplin MO

03-05-2004, 09:24 PM	#11
76bonanza Senior Member Join Date: Mar 2003 Location: St robert Mo Posts: 2,001	One more question I was going to run my vacum advance on my stock hei off of full vac insteaded of ported the way it is now. But my tranny runs off my full vac port and it looks like it is the only one on the carb is this right? It is a holey not sure what model. So what can I do? __________________ 1968 c10 lowered 3" 4" 355/Th400 built by Hatfield racing in joplin MO

03-05-2004, 11:35 PM	#12
swervin ervin You get what you pay for Join Date: Dec 1999 Location: Cherryville, NC Posts: 4,798	Yes, there are articles on 73-87.com but it's not my site anymore. I gave it to Jeff (bigblock73). Full vacuum is vacuum at idle. It don't matter where you have it hooked. Just remove a vacuum hose and feel if it has vacuum. Of course if it does, you will be able to tell by the way the engine runs with the instant vacuum leak. A ported source will not change anything unless you open the throttle some. If you don't have any places left to hook it, use a plastic tee in an existing line somewhere.



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