Ignition: Advance Curve

[Kato]

I'm just getting ready to install a new distributor and they provide 3 sets of spring for the mechanical advance. It currently has the silver (medium) springs. What is the best advance curve for a street driven 62 GT 289? (see attached)

Also, I did a cold compression test and 7 of the cylinder were in the 120 to 130 psi range except for #8 was at 105. I squirted some oil in and it rose slightly to 110. Anything to worry about?

[Mike Van Veghten]

Normally for the best all around performance and mileage...the timing should be "all in" by about 1600 to 1800 rpm. That is, both the vacuum and the mechanical... The initial timing (damper) should also be well above the "book" values for the same reason. With the combustion chamber shape of the Stude engine (most early cars), the wedge shape, likes a lot of ignition timing.
People in general, don't seem to understand that both horsepower and gas milage is affected by the ignition timing. Higher timing good, lower timing...not so good. Just keep the engine from going into detionation. If it does, back the initial down 2°, until the detonation stops.

Since your graphs above won't allow 1600 or 1800, then the "gold" springs would be your best choice. And like I said, more initial advance.
Use a timing light and a marked damper ring, (that one's on you to do), the total initial timing should start about 34°. Add 2° until the engine detonates, then back it back down 3° or 4° .

If you have a drag strip near by or a good chassis dyno shop, all this can be proven on the track or quicker on the dyno.

Have fun.

Mike

[Kato]

Normally for the best all around performance and mileage...the timing should be "all in" by about 1600 to 1800 rpm. That is, both the vacuum and the mechanical... The initial timing (damper) should also be well above the "book" values for the same reason. With the combustion chamber shape of the Stude engine (most early cars), the wedge shape, likes a lot of ignition timing.
People in general, don't seem to understand that both horsepower and gas milage is affected by the ignition timing. Higher timing good, lower timing...not so good. Just keep the engine from going into detionation. If it does, back the initial down 2°, until the detonation stops.

Since your graphs above won't allow 1600 or 1800, then the "gold" springs would be your best choice. And like I said, more initial advance.
Use a timing light and a marked damper ring, (that one's on you to do), the total initial timing should start about 34°. Add 2° until the engine detonates, then back it back down 3° or 4° .

If you have a drag strip near by or a good chassis dyno shop, all this can be proven on the track or quicker on the dyno.

Have fun.

Mike

Wow, great info, thank you. I had no idea the timing should be that much more than factory. I already have the balancer marked so I'll switch to the gold springs and start experimenting. Thanks again.

[4NStudy]

Kevin
I used the gold springs and the black bushing combination on my setup. Get the timing as high as your engine can tolerate without detonation as Mike suggests and try to use the best gas you can. Use Ethanol-Free 93 if you can find it (Shell should have it up your way) You will be amazed at the difference.

[Bud]

The distributor specs for a stock 289 are 24 degrees @2400 engine rpm for the centrifugal advance and around 13 degrees@ 13 inches of vacuum for the vacuum advance. You can advance the spark a few degrees, but I don't recommend going much more than that with today's gas as you could get detonation at high speed on a warm day which you can't hear until there is engine damage. I've found that a stock 259-289 doesn't need more than about 32 degrees of advance to run properly. Pushing the advance farther than that may be good for racing but not on the street. You have and engine with an 8.5 to 1 compression ratio that will run on regular gas quite nicely. Over advancing the spark will necessitate the use of premium gas. Bud

[PackardV8]

Also, I did a cold compression test and 7 of the cylinder were in the 120 to 130 psi range except for #8 was at 105. I squirted some oil in and it rose slightly to 110. Anything to worry about?

Yes, the compression is on the low side.
No, nothing to worry about.
Maybe, stay more toward the Shop Manual advance recommendations. A worn engine will have more blow-by when the timing is advanced.

jack vines

[Kato]

Kevin
I used the gold springs and the black bushing combination on my setup. Get the timing as high as your engine can tolerate without detonation as Mike suggests and try to use the best gas you can. Use Ethanol-Free 93 if you can find it (Shell should have it up your way) You will be amazed at the difference.

Thanks Sandro, I re read your PMs and you already told me that..LOL I forgot already! I have been running Shell V Power. I'm really hoping this solves my issues. What sort of timing did you set?

[Kato]

The distributor specs for a stock 289 are 24 degrees @2400 engine rpm for the centrifugal advance and around 13 degrees@ 13 inches of vacuum for the vacuum advance. You can advance the spark a few degrees, but I don't recommend going much more than that with today's gas as you could get detonation at high speed on a warm day which you can't hear until there is engine damage. I've found that a stock 259-289 doesn't need more than about 32 degrees of advance to run properly. Pushing the advance farther than that may be good for racing but not on the street. You have and engine with an 8.5 to 1 compression ratio that will run on regular gas quite nicely. Over advancing the spark will necessitate the use of premium gas. Bud

Thanks Bud.

[Kato]

Yes, the compression is on the low side.
No, nothing to worry about.
Maybe, stay more toward the Shop Manual advance recommendations. A worn engine will have more blow-by when the timing is advanced.

jack vines

Got it... thank you!

[Bud]

It's my theory on ignition timing is the factory engineers did extensive testing on our engines before they were put into production and came up with the ignition timing specs. When I rebuild a Studebaker distributor, I stick with the factory recommendations as far as the centrifugal and vacuum advance settings. The Studebaker engineers specified a fairly quick advance curve compared to Ford, Gm and Chrysler which had full advance on their distributors coming in somewhere above 4,000 rpm where the Studebaker non R V8's have full centrifugal advance at around 2400 rpm which with today's gas can cause detonation problems if the spark is advanced much more than what is recommended which is 4 deg before top dead center on the 259-289 engines. I usually run my engines with maybe 3 or 4 extra degrees of advance, but that is it. Most stock Studebaker V8 engines are seldom run above 3,000 rpm on the street so a bunch of extra advance doesn't do anything, but risk the chance of un noticed detonation which if it continues for any length of time can cause serious internal engine damage especially at high speed on a hot day. Bud

[Kato]

It's my theory on ignition timing is the factory engineers did extensive testing on our engines before they were put into production and came up with the ignition timing specs. When I rebuild a Studebaker distributor, I stick with the factory recommendations as far as the centrifugal and vacuum advance settings. The Studebaker engineers specified a fairly quick advance curve compared to Ford, Gm and Chrysler which had full advance on their distributors coming in somewhere above 4,000 rpm where the Studebaker non R V8's have full centrifugal advance at around 2400 rpm which with today's gas can cause detonation problems if the spark is advanced much more than what is recommended which is 4 deg before top dead center on the 259-289 engines. I usually run my engines with maybe 3 or 4 extra degrees of advance, but that is it. Most stock Studebaker V8 engines are seldom run above 3,000 rpm on the street so a bunch of extra advance doesn't do anything, but risk the chance of un noticed detonation which if it continues for any length of time can cause serious internal engine damage especially at high speed on a hot day. Bud

Thanks Bud, good advice.
Looking at the advance graphs for this distributor, what stop bushings would you recommend for the light springs I have installed? (graph F)
Am I reading this right, using the gold bushing with the gold (light) springs would give quite close to max advance around 2200rpm and assuming I set an extra 4 degrees we would have a total advance of about 25.5 degrees (4+4+17.5)? Is that enough advance or too much for these V8s? Would the silver or black stop bushings be more appropriate?

[Bud]

The gold springs and gold bushings should get you close to the stock specs. You want to check the total advance on the crank shaft with the vacuum advance disconnected and depending on the quality of your gasoline, I would keep the total advance to no more than 32 degrees or less if detonation occurs around 2400 engine rpm. If you can find someone in your area that still has a working distributor machine, that would be the best way to set up your distributor. If you can't get the total advance where you want it, try removing the advance stop. You want somewhere around 24 degrees of centrifugal advance in the distributor and maybe 8 to 10 degrees of base timing to get you to the desired total advance. You do not want to use more than 12 degrees of base timing as that can cause the engine to try to kick back on starting which can cause damage to both the starter drive and the ring gear. Bud

[Kato]

The gold springs and gold bushings should get you close to the stock specs. You want to check the total advance on the crank shaft with the vacuum advance disconnected and depending on the quality of your gasoline, I would keep the total advance to no more than 32 degrees or less if detonation occurs around 2400 engine rpm. If you can find someone in your area that still has a working distributor machine, that would be the best way to set up your distributor. If you can't get the total advance where you want it, try removing the advance stop. You want somewhere around 24 degrees of centrifugal advance in the distributor and maybe 8 to 10 degrees of base timing to get you to the desired total advance. You do not want to use more than 12 degrees of base timing as that can cause the engine to try to kick back on starting which can cause damage to both the starter drive and the ring gear. Bud

Outstanding, thank you!

[bensherb]

My '62 GT 289, came to me with a window type distributor. It ran relitively well. I measured its advance and it's mechanical advance would max at 15 degrees at around 1500 rpm. When the vacuum let the distributor go to total advance it maxed at 45 degrees. this was with the stock initial setting of 4 degrees.

I replaced that distributor with a GM HEI that I made by grafting the top of the GM distributor to the lower portion of a Stude distributor. I set it up so that the mechanical maxed out at 1500 rpm at 15 degrees and adjusted the vacuum diaphragm to give a total advance of 45 degrees at 2500 rpm with an initial advance of 4 degrees. So it was pretty much the same as the window distributor but higher energy. The engine now ran smoother, especially at low rpm. This is something I had noticed in the past with other engines too when swapping to a high energy ignition.

Since changing the distributor, I swapped the manual trans for a GM automatic overdrive trans, and have consequentially added a few more degrees to the initial timing.

As for "Most stock Studebaker V8 engines are seldom run above 3,000 rpm on the street " ; this may be true, but I don't often run below 2500 rpm and very often hit between 3000 and 4000 rpm (unless I'm at a cruse on the freeway) . My 289 is over bored, so its more like 300ci now, and its balanced. It's also mounted quite solidly with five urethane mounts. There is no percievable, engine vibration once off idle. It runs very well, (once it's fully warmed up) and seems to be most happy and pulls best around 3000-3500 rpm, but cruises smooth as glass at just under 2300 rpm @ 75 mph

[Kato]

My '62 GT 289, came to me with a window type distributor. It ran relitively well. I measured its advance and it's mechanical advance would max at 15 degrees at around 1500 rpm. When the vacuum let the distributor go to total advance it maxed at 45 degrees. this was with the stock initial setting of 4 degrees.

I replaced that distributor with a GM HEI that I made by grafting the top of the GM distributor to the lower portion of a Stude distributor. I set it up so that the mechanical maxed out at 1500 rpm at 15 degrees and adjusted the vacuum diaphragm to give a total advance of 45 degrees at 2500 rpm with an initial advance of 4 degrees. So it was pretty much the same as the window distributor but higher energy. The engine now ran smoother, especially at low rpm. This is something I had noticed in the past with other engines too when swapping to a high energy ignition.

Since changing the distributor, I swapped the manual trans for a GM automatic overdrive trans, and have consequentially added a few more degrees to the initial timing.

As for "Most stock Studebaker V8 engines are seldom run above 3,000 rpm on the street " ; this may be true, but I don't often run below 2500 rpm and very often hit between 3000 and 4000 rpm (unless I'm at a cruse on the freeway) . My 289 is over bored, so its more like 300ci now, and its balanced. It's also mounted quite solidly with five urethane mounts. There is no percievable, engine vibration once off idle. It runs very well, (once it's fully warmed up) and seems to be most happy and pulls best around 3000-3500 rpm, but cruises smooth as glass at just under 2300 rpm @ 75 mph

Very interesting! The distributor I have has no way to adjust the vacuum advance, only mechanical. It is supposed to provide 10 degrees of advance although I have not tested that yet. It does run better at lower rpm as it is set up now but still seems a bit sluggish on acceleration. As set up now I should be getting 17 degrees of mechanical and 10 of vacuum at about 2200 rpm on acceleration so a total of about 35 so a bit low by your figures. Unfortunately other than setting initial higher there's not much more I can do with this distributor unless and adjustable vacuum pot is available!