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  1. #26
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    Since we`re on this topic was wondering what do you guys think of MSD`s Cap-a-dapt design for a billet MSD distributor?

    Thanks
    George



    "If ur going to beat a Hemi you better have a Buick"

  2. #27
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    Quote Originally Posted by Nicholas Sloop
    Attached is an article I wrote for The Build Sheet on making your own advance bushing. One issue I have since discovered is that it is possible to make a bushing that allows 20 degrees of movement, but it could turn out to be 16 degrees of advance and 4 degrees of retard!!!! Found this out after I installed the springs and the bushing was not at the end of its travel. So, if you use this method, throw the springs on as you are measuring your progress while making the bushing!

    This is really the way to go on distributors designed for very low initial advance (like the 0 degree initial spec on a stock 68 400) since they have a huge slot for a ton of mechanical advance.
    Thanks Nick,
    A great addition to the thread
    Larry
    1998 "Fully Optioned" SC3800 Riviera
    70 GS 455 Stage1, TSP 470, 602 HP@ 5900, 589 TQ @ 4900
    TA Hyd Roller Cam, 230*/238*, 112, .544"/.577" lift, 4-7 swap
    MSD Digital 6+, Ignitionman Distributor w/MSD trigger
    THM400 with Ultimate 258mm converter, Gear Vendors OD
    AED 1000 HO Carb, 800 CFM 7042240 Quadrajet
    8.5 10 bolt, 3.73's Race weight 4025lbs.
    Best E.T. 11.54 Best MPH, 116.06
    Larrymta@verizon.net, GSCA #291
    BPG # 1063
    N.E. GS/GN Club Assistant Director

  3. #28
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    I bought the moroso recurve kit for my 350 HEI but I ended up modding the thing myself because the kit was inadequate. It did not come with bushings so I was on my own with the total advance. First I took the dist apart and welded up the plate as an alternative to bushings. The trial and error process was taking too long. I am impatient about things like this so I thought of an alternative to bushings. I made two adjustable stops out of machine screws. I put the nuts on the screws and held them with vise grips and used a bench grinder to make the head into a cam shape. I used nylock nuts on the screws so they didn't losen up. I'm pretty sure I used holes that were factory. I did have to grind off a tiny part of the under part of the rotor to clear the screw heads. Now total advance is easily adjustable with the rotor off.

    The springs did not get my advance in when I wanted it either. If you look closely in the pic the weights are modified as well (the pointy part). The shape and size of the weights as well as the cam the ride on have a lot to do with how fast the advance comes in. The moroso weights and springs did not do the trick. Now the advance is all in by 2000.

    I also made am vacuum advance stop similar to the one larry posted. It works fine.
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    Andy, 1970 Skylark Custom

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  4. #29
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    Vrey creative, Andy. Good work

  5. #30
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    thanks Nicolas, glad you like. now all I need is another 200 or so horses
    Andy, 1970 Skylark Custom

    Support your country
    Support your neighbors
    Support yourself
    Buy American

  6. #31
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    Default Limiting Mechanical and Vacuum Advance ala Factory

    FYI, The way the factory limited the mechanical advance was to use different cams on the distributors. This is the part with the slot for the bushing, and the 8 sided cam for operating the points.
    On the underside of the cam arms, there is a 3 digit number stamped, usually 500s or 700s, (i.e. 728). There are many different numbers. I have found that the smaller the number of the last 2 digits, the less mechanical advance. Is also seems to follow that number closely, that is, a 728 cam seems to have 28 degrees advance, a 518 has 18 degrees, etc. At least this is what I am seeing on my Sun distributor machine.
    The difference in these cams is the length of the slot for the advance limiter pin, which is what the bushing would go on. The longer the slot, the more mechanical advance.

    You should be able to use any 8 cyl GM point cam from a clockwise rotating distributor. I don't know about counterclockwise units.

    That means you can use Buick, Chevy, and Cadillac cams. These range from the teens to about 34 degrees mechanical.

    It seems that the Cadillac distributors have the shortest curves, with the most vacuum advance.
    The distributor specs from any manual should tell you which ones to look for if you want a specific advance. Just look at total mechanical advance for that unit, then find one in the junkyard.

    This would allow you to use the stock bushing.

    The vacuum advances were done in a similar fashion.

    The flat part of a Delco vacuum advance is stamped with 2 numbers. The 3 digit number is the end of the GM part #, and the 2 digit number is the amount of vacuum advance built into the unit.

    Therefore, an advance with 236 and 16 on it would be GM part number 1115236, a 16 degree vacuum advance.

    This also applies to the GM Hei units, but I am not familiar with the numbers.

  7. #32
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    Thank You,
    I mention the slot, and pin in my original post, but that information makes a great addition, and I appreciate it. Most vacuum advance units have entirely too much advance to be used with lighter springs. 8-10* should be the max. That's easy to limit with a stop plate. Thanks again.
    Larry
    1998 "Fully Optioned" SC3800 Riviera
    70 GS 455 Stage1, TSP 470, 602 HP@ 5900, 589 TQ @ 4900
    TA Hyd Roller Cam, 230*/238*, 112, .544"/.577" lift, 4-7 swap
    MSD Digital 6+, Ignitionman Distributor w/MSD trigger
    THM400 with Ultimate 258mm converter, Gear Vendors OD
    AED 1000 HO Carb, 800 CFM 7042240 Quadrajet
    8.5 10 bolt, 3.73's Race weight 4025lbs.
    Best E.T. 11.54 Best MPH, 116.06
    Larrymta@verizon.net, GSCA #291
    BPG # 1063
    N.E. GS/GN Club Assistant Director

  8. #33
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    Quote Originally Posted by LARRY70GS
    Most Buick V8's run best at WOT, with a total timing of 30-36*, all in at 2500 RPM, or less.
    Larry,
    This may be a engine 101 question and Ill go back to reading if it is, but why do most Buick V8's like 30-36*? My initial thought was it would be more Cam related than just engine specific.
    I'll be applying this method shortly... Just worried about the outcome. Minimally modified 72 CA emissions SBB350 (save the components it arrived without installed or connected to vacuum lines when I received it)

    Thanks for the great info.
    Matt
    72 Skylark Custom Convertible
    TSP Level 1 350 "prototype" http://www.v8buick.com/showthread.php?t=153248

  9. #34
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    Quote Originally Posted by mmbs72
    Larry,
    This may be a engine 101 question and Ill go back to reading if it is, but why do most Buick V8's like 30-36*? My initial thought was it would be more Cam related than just engine specific.
    I'll be applying this method shortly... Just worried about the outcome. Minimally modified 72 CA emissions SBB350 (save the components it arrived without installed or connected to vacuum lines when I received it)

    Thanks for the great info.
    Matt,
    Buicks have a fast burn combustion chamber, and as a rule require less advance than other engines. 30-36 is a good figure, but some engines might need as little as 28* And yes it is cam related, as well as combination related. That's why the range. You need to find out what your engine likes. There's no one size fits all. Best way to find out is on a chassis dyno, or the dragstrip if you can test and tune. With a mostly stock engine, I think you'll find 30-32 is best. Getting the advance in fast(at or before 2500 RPM) will always give good results, and you'll be able to feel it in the butt dyno Just remember to modify the vacuum advance also.
    Larry
    1998 "Fully Optioned" SC3800 Riviera
    70 GS 455 Stage1, TSP 470, 602 HP@ 5900, 589 TQ @ 4900
    TA Hyd Roller Cam, 230*/238*, 112, .544"/.577" lift, 4-7 swap
    MSD Digital 6+, Ignitionman Distributor w/MSD trigger
    THM400 with Ultimate 258mm converter, Gear Vendors OD
    AED 1000 HO Carb, 800 CFM 7042240 Quadrajet
    8.5 10 bolt, 3.73's Race weight 4025lbs.
    Best E.T. 11.54 Best MPH, 116.06
    Larrymta@verizon.net, GSCA #291
    BPG # 1063
    N.E. GS/GN Club Assistant Director

  10. #35
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    Quote Originally Posted by Smartin
    Here is the kit at Jegs:

    http://www.jegs.com/cgi-bin/ncommerc...32&prmenbr=361

    720-928G

    Delco Point Type Distributors
    Includes 1-bushing
    3-sets of springs (heavy, medium and light).


    Look correct to you Larry?
    Of these 4, which on edo I need. I have a 455 in my 69 with no smog stuff on it.
    GM
    720-925A Delco Distributors pre-1969, Includes 2-Weights, 1-Bushing and 3-Sets of Springs (heavy, medium and light). $9.99

    720-926G Delco distributors 1969 and later, Includes 2-Weights, 1-Bushing and 1-Set of Springs. | View Product $8.99

    720-928G Delco Point Type Distributors, Includes 1-bushing, 3-sets of springs (heavy, medium and light). | View Product $7.99

    720-929G Fits HEI Distributor, 1974-79 w/o Computer, Includes 2-Weights, Special Center Plate, 3-Sets Springs,and 2-Pairs of Nylon Bushings. | View Product $7.99

    "Sometimes the place to be is right where you are"

    Ken Mild
    Proud member of The Stepchild Nation
    69 GS400; 462ci; 430hp, 530lb.ft.
    12.90 @108.45mph - Open diff. / 3.08 / BFG T/A's
    http://www.youtube.com/watch?v=9JjGIo3V40E

  11. #36
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    Quote Originally Posted by LARRY70GS
    I thought I would try and compose this post to answer timing questions I see all the time on this BB.

    I see alot of questions about what initial timing to run on a modified BBB, without regard to what the timing is as the RPM's increase. Everyone should know exactly what their total advance is, and at what RPM it's all in at. The right timing, at all RPM's can make a huge difference in the way your engine runs, and makes power.

    There are 3 components to total timing. Initial advance, mechanical or centrifugal advance, and vacuum advance. Since vacuum will be at or near 0 at wide open throttle (WOT), initial advance + mechanical advance are most important to how your engine runs under race conditions.

    Initial timing is simply how you have your distributor installed, and adjusted, in the engine. You simply attach a timing light, and with the engine running,(vacuum advance plugged), you turn the distributor until the timing mark lines up with the desired number on the timing tab. As you increase the engine RPM's, you'll notice the timing mark move upwards, and out of sight. This is the mechanical advance in operation. There are weights inside the distributor, that pivot against spring tension, and move the base plate so that the spark occurs earlier(advance).

    The springs determine how quickly the mechanical advance increases with rising RPM. There is a pin that moves in a slot under the weight plate. This is what determines how much mechanical advance is built into the distributor. Aftermarket advance curve kits generally provide a bronze bushing that goes on that pin, and limits the movement of the pin in the slot, thus limiting total mechanical advance.

    The only other way to modify the amount of mechanical advance in the distributor, is to disassemble the distributor, weld the slot, and file it until you have the desired amount of advance you need. This is why you can't simply buy a junkyard HEI or other distributor, and put it in the engine, and run whatever initial timing you like. If there is too much mechanical advance in that distributor(this is typical for all factory spec'ed distributors), you'll overadvance at higher RPM. If you need higher initial timing, you need to reduce the mechanical advance in the distributor to avoid over-advance.

    Most Buick V8's run best at WOT, with a total timing of 30-36*, all in at 2500 RPM, or less. The easiest way to determine your total advance is to use a dialback timing light. You simply connect the light, plug your vacuum advance, and have a second person slowly rev the engine. With the dial back feature, you adjust the light to keep the timing mark in sight as it rises. When the timing mark stops moving, you hold the RPM's steady, adjust the dial until the balancer mark lines up with the 0 on the timing tab, and read your total advance off the dial.

    To do this with a conventional timing light, you need to make a 30* mark on your balancer. The Buick 350, and 455 balancers are 6 3/4" in diameter. Circumference (360*) of a circle is pi(3.14) X diameter. 6.75 X 3.14 = 21.195"/12 = 1.76" (30*). Looking at the engine from the front, measure exactly 1 3/4" clockwise around the balancer, and make a second mark. This is your 30* mark. Connect up your timing light, and watch your 30* mark as you increase the RPM's. At some point, your 30* mark will stop rising, and move no higher. This is the RPM, where all of your mechanical advance is in.

    At this same RPM, with the distributor loose, adjust it so that your 30* mark lines up with the 0 on the timing tab. You now have 30* of total timing. Line it up with the 2, 32* total, ect.

    Keep in mind that a stock distributor usually has stiff springs in it, that don't allow full advance in until 4000 RPM or more. For best performance, you want your advance in at 2500 RPM, or before. The easiest way to do this is to purchase a Crane adjustable vacuum advance kit. It comes with 3 sets of springs to allow your advance in as early as 1600 RPM, or as late as 3200 RPM, or anything in between. For points distributors (Jegs part # 270-99601-1, GM HEI, 270-99600-1). What I did was purchase the kit, and install the lightest springs(2 yellow). I used these springs to adjust my total timing, that way, I didn't have to rev the motor very high to see my total. Afterward, I installed the springs that brought my advance in at 2200 (2 silver)

    One important note is to make sure the timing is returning to the initial setting, when the engine is idling. So when setting your timing, pay attention to when the advance starts, as well as when it is fully in. Having the distributor in the advance curve, at idle speeds, can cause excessive rpm drop with an automatic trans, with some camshaft/converter combinations. Generally, the more agressive a camshaft you use, the more important this will be. Advance curves should generally start at around 1000-1200 rpm, when your idle speed is around 800 in Park.



    Now for vacuum advance. Some people prefer not to run vacuum advance at all. Under race conditions it is totally irrelevant, because it won't function at WOT. BUT, on a street car, it can be used to enhance throttle response, increase gas mileage, and let the engine run cooler at idle and low speed.

    The problem occurs when there is too much vacuum advance coupled with a modified mechanical advance. As mentioned before, stock distributors didn't allow total mechanical advance in until upwards of 4000 RPM. At your typical cruising speed of 3000 RPM, only part of your mechanical advance was in. The vacuum advance would supply an additional 14-18* for a total of around 40* or more. At light loads (cruising), an engine can easily tolerate this much advance. The result is better gas mileage.

    With a modified mechanical advance, all your mechanical advance is in at cruising speeds. Add the 14-18* of vacuum advance, and the engine pings when you punch the throttle, and the advance from the vaccum cannister doesn't/can't go away quick enough. The answer is to modify the vaccum cannister to allow only 8-10*of additional vacuum advance. With 30-34* timing + your vacuum advance, you'll be at 38-44* which should be optimal.

    As far as running your vaccum advance off manifold or ported vacuum, everyone has a different opinion. In most cases, OEM used ported. I use manifold vacuum. With a wild cam, you can use manifold vacuum advance to give extra advance for a smoother idle, and better low end response. Everyone's engine will be different, so you need to experiment with your combination. With the Crane adjustable advance cannister, there is a better way to limit the degrees, than what Crane suggests. I'll post some pictures to detail this. With the stock cannister, you'll need to fashion a block off plate. You basically restrict the pull pin travel to .086" for 8*, or .104" for 10*. Again, I'll post some pictures. Photos, courtesy of Dave Ray(The Ignitionman) Hope this post helps to answer alot of questions.
    Ok, now I'm confused. All the Buick books I look at say the timing should be set at anywhere from 0 to 2 to 4 degrees BTDC. Where is everyone getting these 30 degree things from?

    Most of what I've read here makes sense, but in the books it says for instance for a 69, 0 degrees BTDC, for the 455, like 2 degrees BTDC. What does this equate to in the overall scheme of things? Sorry I'm so dence, but I don't have a dial back light and can't afford to spend another dime. I have a dwell meter and a regular timing light though.

    Edit: Ok, by the way, this is great info you've posted Larry. And others as well. I didn't mean to put my confusion before that. It sounded greedy. Sorry.
    "Sometimes the place to be is right where you are"

    Ken Mild
    Proud member of The Stepchild Nation
    69 GS400; 462ci; 430hp, 530lb.ft.
    12.90 @108.45mph - Open diff. / 3.08 / BFG T/A's
    http://www.youtube.com/watch?v=9JjGIo3V40E

  12. #37
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    Quote Originally Posted by Ken Mild
    Of these 4, which on edo I need. I have a 455 in my 69 with no smog stuff on it.
    GM
    720-925A Delco Distributors pre-1969, Includes 2-Weights, 1-Bushing and 3-Sets of Springs (heavy, medium and light). $9.99

    720-926G Delco distributors 1969 and later, Includes 2-Weights, 1-Bushing and 1-Set of Springs. | View Product $8.99

    720-928G Delco Point Type Distributors, Includes 1-bushing, 3-sets of springs (heavy, medium and light). | View Product $7.99

    720-929G Fits HEI Distributor, 1974-79 w/o Computer, Includes 2-Weights, Special Center Plate, 3-Sets Springs,and 2-Pairs of Nylon Bushings. | View Product $7.99

    Ken,
    Of all the kits listed, the 720-928G looks to be the best one. The 929G is for an HEI. You have a points distributor, correct? You do not need the weights, or center piece in the other kits. You can use your current weights. The advance limit bushing is nice to have. The kit states, it allows full advance between 2000, and 2800 RPM.

    The reason I like the Crane adjustable vacuum advance kit is that it comes with better, more versatile springs (IMHO). It is more expensive because of the adjustable vacuum cannister. It does not come with an advance limit bushing though.
    Larry
    1998 "Fully Optioned" SC3800 Riviera
    70 GS 455 Stage1, TSP 470, 602 HP@ 5900, 589 TQ @ 4900
    TA Hyd Roller Cam, 230*/238*, 112, .544"/.577" lift, 4-7 swap
    MSD Digital 6+, Ignitionman Distributor w/MSD trigger
    THM400 with Ultimate 258mm converter, Gear Vendors OD
    AED 1000 HO Carb, 800 CFM 7042240 Quadrajet
    8.5 10 bolt, 3.73's Race weight 4025lbs.
    Best E.T. 11.54 Best MPH, 116.06
    Larrymta@verizon.net, GSCA #291
    BPG # 1063
    N.E. GS/GN Club Assistant Director

  13. #38
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    Quote Originally Posted by Ken Mild
    Ok, now I'm confused. All the Buick books I look at say the timing should be set at anywhere from 0 to 2 to 4 degrees BTDC. Where is everyone getting these 30 degree things from?
    Initial timing will vary according to which distributor you are using. Distributors are different for different engines, and different years. The initial timing specified depends on the total amount of mechanical advance in the distributor.

    An engine requires more advance(earlier spark) the faster it spins. The distributor has a mechanical advance system inside that advances the spark with rising engine RPM. If you remove the distributor cap, and rotor, you will see 2 weights and springs. The weights are forced outward by centrifugal force, as the distributor turns faster. The springs restrict the outward movement, and determine at what RPM the weights reach their full travel. When the weights reach full travel, we say all the mechanical advance is in. In a stock distributor, with stock springs, this occurs at about 4600 RPM.

    Quote Originally Posted by Ken Mild
    Most of what I've read here makes sense, but in the books it says for instance for a 69, 0 degrees BTDC, for the 455, like 2 degrees BTDC. What does this equate to in the overall scheme of things? Sorry I'm so dence, but I don't have a dial back light and can't afford to spend another dime. I have a dwell meter and a regular timing light though.
    The actual amount of mechanical advance in a distributor varies, and is built into that particular distributor. It is not easily changed. To do so requires disassembly of the distributor, however, you can restrict the mechanical advance with the bushing in the Mr. Gasket kits. You must determine how much mechanical advance is in the distributor you have. You can do this with your regular timing light, and a set of light springs(like the ones in the Crane kit) Just follow the directions in my original post.

    Edit: Ok, by the way, this is great info you've posted Larry. And others as well. I didn't mean to put my confusion before that. It sounded greedy. Sorry.
    No problem Ken I'm not sure you really understand how the advance systems work in a distributor. We might be speaking 2 different languages. A chassis manual explains the basics very well. I think if you read up on distributor basics, what I have written will make more sense.
    Larry
    1998 "Fully Optioned" SC3800 Riviera
    70 GS 455 Stage1, TSP 470, 602 HP@ 5900, 589 TQ @ 4900
    TA Hyd Roller Cam, 230*/238*, 112, .544"/.577" lift, 4-7 swap
    MSD Digital 6+, Ignitionman Distributor w/MSD trigger
    THM400 with Ultimate 258mm converter, Gear Vendors OD
    AED 1000 HO Carb, 800 CFM 7042240 Quadrajet
    8.5 10 bolt, 3.73's Race weight 4025lbs.
    Best E.T. 11.54 Best MPH, 116.06
    Larrymta@verizon.net, GSCA #291
    BPG # 1063
    N.E. GS/GN Club Assistant Director

  14. #39
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    Ok, I've read it, and read it again, and then printed it out, and highlighted the important bits, and it's slowly sinking in... I'm a little bit confused abut the bronze bushing that is supposed to limit some of the built in advance by going on a pin in a slot under the weight plate. Is this something that is only for points distributors, or only HEI's or both? I got the crane kit, with the vacuum canister, and then I also ordered kit 929G from mr gasket to get the bushing I thought, but it doesn't seem to be any bronze bushing included, just four nylon ones. This is the correct kit for a 74-79 GM HEI according to mr gasket's site, am I missing something here?

    I sent them an e-mail to mr gasket's tech support:

    "I am in the process of re-curving the HEI distributor I have installed. I have heard that every distributor has a built in amount of mechanical advance in them. You can limit this advance by adding a bushing on a pin that moves in a slot under the weight plate. I am looking for this bushing, I've been told it comes in certain re-curving kits. I purchased kit #929G and I am not sure if the nylon bushings supplied are the bushings I am looking for, or if they are meant to go on the weights? The bushing that goes on the pin underneath the weight plate has been mentioned as being made of bronze, do you have any idea about this? According to your site, this 929G kit was the correct kit for my 1975 GM HEI distributor. I have not taken the HEI apart to see this slot and pin myself, this is just what has been described to me, and it is possible that the HEI does not have this feature, but it is described like it would, so if you could please help me out with this question, that would be great."

    What's the situation here, anyone knows?

    many thanks
    Kimson
    1966 Wildcat


    - 1972 Centurion (R.I.P.)
    - 1973 Riviera (sold)



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    Kimson
    Yes, your HEI uses the same pin and slot arrangement as described here; you just ended up with a kit without an advance bushing. The bushings you did get are for the weights. (And, by the way, not all HEIs use those, so you may not need them)
    Personally, for an HEI I would go with Andy's method at the top of this page.

    Added in edit--
    I think maybe HEIs might have two pins and two slots, and two of the nylon bushings could be for weights and two for the advance pins...
    Need to go out to the garage and find an HEI to look at...

  16. #41
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    Kimson,
    The HEI is a little different than the points distributors. The kits come with bushings that are meant for the weights. They fit inside the pivot holes on the weights. Like Nick said, there are 2 slots and pins on the HEI. To see them, you must remove the weights, springs, and center piece. Here's a picture of the slots and pins on an HEI. Notice how big they are. Remember, the distributor turns at half the speed of the crank, so 1* of distributor rotation = 2* of crank rotation. If you can fashion some bushings to fit on these pins(difficult), you may be able to limit the advance. I think you may end up binding up the distributor, and it may not work correctly. Remember, everything must be smooth. When the weights move out against the spring tension, they must be free to return, as engine speed returns to idle. The right way to do this is to disassemble the distributor, weld the slots to reduce their size, and file them to the correct size for the amount of advance you want. You may be able to do this with some JB Weld, I've never tried it, and I'm not sure what dimensions = what amount of degrees. Guess it will have to be trial and error. I'd start by reducing the slot size by half, and go from there.
    Larry
    1998 "Fully Optioned" SC3800 Riviera
    70 GS 455 Stage1, TSP 470, 602 HP@ 5900, 589 TQ @ 4900
    TA Hyd Roller Cam, 230*/238*, 112, .544"/.577" lift, 4-7 swap
    MSD Digital 6+, Ignitionman Distributor w/MSD trigger
    THM400 with Ultimate 258mm converter, Gear Vendors OD
    AED 1000 HO Carb, 800 CFM 7042240 Quadrajet
    8.5 10 bolt, 3.73's Race weight 4025lbs.
    Best E.T. 11.54 Best MPH, 116.06
    Larrymta@verizon.net, GSCA #291
    BPG # 1063
    N.E. GS/GN Club Assistant Director

  17. #42
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    This is getting to be more then I would know how to fix, but it's been like that for a while now so why not. How imprtant is the balance of this thing when it spins? you'd think that if you start messing with it, it could easily lose it's balance and wear out quite quickly, or break?

    Is this kind of what is needed to be done?
    Attached Images Attached Images
    Kimson
    1966 Wildcat


    - 1972 Centurion (R.I.P.)
    - 1973 Riviera (sold)



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    Could you maybe try something like this?
    Attached Images Attached Images
    Kimson
    1966 Wildcat


    - 1972 Centurion (R.I.P.)
    - 1973 Riviera (sold)



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    Is there any other way I could compensate for the built in advance without fiddling with this pin?

    I don't know what is underneath this thing, but maybe just drill a smalll hole and stick a little screw down next to the pin? If it doesn't work, I'll just take it out and make sure the hole is smooth.
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    Kimson
    1966 Wildcat


    - 1972 Centurion (R.I.P.)
    - 1973 Riviera (sold)



  20. #45
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    Balance shouldn't be a big deal I would think. Whatever you try, just make sure nothing binds up the advance mechanism, or interferes with moving parts. Your trying to reduce the mechanical advance dso you can run more initial timing.
    Larry
    1998 "Fully Optioned" SC3800 Riviera
    70 GS 455 Stage1, TSP 470, 602 HP@ 5900, 589 TQ @ 4900
    TA Hyd Roller Cam, 230*/238*, 112, .544"/.577" lift, 4-7 swap
    MSD Digital 6+, Ignitionman Distributor w/MSD trigger
    THM400 with Ultimate 258mm converter, Gear Vendors OD
    AED 1000 HO Carb, 800 CFM 7042240 Quadrajet
    8.5 10 bolt, 3.73's Race weight 4025lbs.
    Best E.T. 11.54 Best MPH, 116.06
    Larrymta@verizon.net, GSCA #291
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    N.E. GS/GN Club Assistant Director

  21. #46
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    Kimson
    Yes, your photos all show viable ways to do it. However, I don't think I would try JB Weld; I would be woried about it breaking off and being loose inside the distributor.
    I still vote for doing it the way Andy did it in Post #28 at the top of this page. I did it that way, but I only used one screw. I don't think that is a problem.

  22. #47
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    Quote Originally Posted by 70aqua_custom
    First I took the dist apart and welded up the plate as an alternative to bushings. The trial and error process was taking too long. I am impatient about things like this so I thought of an alternative to bushings. I made two adjustable stops out of machine screws. I put the nuts on the screws and held them with vise grips and used a bench grinder to make the head into a cam shape. I used nylock nuts on the screws so they didn't losen up. I'm pretty sure I used holes that were factory. I did have to grind off a tiny part of the under part of the rotor to clear the screw heads. Now total advance is easily adjustable with the rotor off.
    I'm not sure I get it 100%.

    First the plate was welded up to limit the available space for the pins to move in, when that didn't work out because of too much trial to get it right he made two adjustable stops out of machine screws?

    - - -

    Machine screws?

    Was the plate still welded, or was it made back into it's original state first, and then the screws came into play?

    How was the two holes made that became adjustable?


    - - -

    "I put the nuts on the screws and held them with vise grips and used a bench grinder to make the head into a cam shape. I used nylock nuts on the screws so they didn't losen up. I'm pretty sure I used holes that were factory. I did have to grind off a tiny part of the under part of the rotor to clear the screw heads. Now total advance is easily adjustable with the rotor off."

    - - -

    Made the head of the screw into a cam shape?

    Used holes that were factory?


    - - -


    I'm sorry, I just can't picture it what it looks like? Hope someone can fill in here..

    Many thanks for your help.
    Kimson
    1966 Wildcat


    - 1972 Centurion (R.I.P.)
    - 1973 Riviera (sold)



  23. #48
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    Kimson,
    Very simple really. look at the rotor mounting screw holes. Inboard of each hole is a factory hole not being used. He simply used a screw and nut(nylon locking). Then he ground the screw head so that it would stop the rotor from advancing past a certain point. It should work. Again, some trial and error involved.
    Larry
    1998 "Fully Optioned" SC3800 Riviera
    70 GS 455 Stage1, TSP 470, 602 HP@ 5900, 589 TQ @ 4900
    TA Hyd Roller Cam, 230*/238*, 112, .544"/.577" lift, 4-7 swap
    MSD Digital 6+, Ignitionman Distributor w/MSD trigger
    THM400 with Ultimate 258mm converter, Gear Vendors OD
    AED 1000 HO Carb, 800 CFM 7042240 Quadrajet
    8.5 10 bolt, 3.73's Race weight 4025lbs.
    Best E.T. 11.54 Best MPH, 116.06
    Larrymta@verizon.net, GSCA #291
    BPG # 1063
    N.E. GS/GN Club Assistant Director

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    Looks smart, they might be a bit different though, I'll have to stick my nose in mine to see what the deal is.
    Kimson
    1966 Wildcat


    - 1972 Centurion (R.I.P.)
    - 1973 Riviera (sold)



  25. #50
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    Looks like we're in business on this one. On the second picture where the hole is just about to slide under the plate, you could fit the bolt and nut. The pin is pretty much exactly halfway down its hole then. The head of the bolt would sit just a little outside of the hole like in the pic. Sweeeeeet
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    Kimson
    1966 Wildcat


    - 1972 Centurion (R.I.P.)
    - 1973 Riviera (sold)



 

 
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