Help me tune my dizzy?

Electrical and Ignition

  1. AJ/FormS

    AJ/FormS 68 B'cuda fb, Form S clone ... 367/A833/3.55s

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    So then if you set the total all-in to 34*, then the idle-timing will be 34 less 17 = 17 idle-timing. That's a pretty good start.
     
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    • seabee

      seabee FABO Gold Member FABO Gold Member

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      That is where it is currently at.
      17' initial
      34' Total at 2500rpm
      50' Total at 2500rpm with Vac Advance hooked up.
       
    • vntned

      vntned Well-Known Member

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      So I spent some time yesterday tuning on the engine. I set the initial at 16deg, and it looks like my total is 35deg. The motor pulls very strong, considering how mild it is.

      However, after driving it around awhile and it gets hot, it doesn't wanna restart easily. It's very hard to turn over and it sometimes trips the 100amp breaker I have in line with the positive cable.

      Also, it doesn't wanna idle below 1k rpm as is either. My brother in law thinks the timing is too high, but it pulls great and doesn't ping up to 5800rpm, which is as high as I've turned it.

      Suggestions?
       
    • AJ/FormS

      AJ/FormS 68 B'cuda fb, Form S clone ... 367/A833/3.55s

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      Your timing is good, don't mess with it anymore.

      Fresh engines always seem to run warmer than usual. Try to stay above 30 mph for the first 100 miles, and no extended idle time, unless your cooling system is up to speed which yours doesn't seem to be.
      As to the starting issue, what starter are you using; the Dakota mini-starter should whack that little bugger over like nothing. If it doesn't I would look to a high resistance connection in the starter circuit, or a problem battery.

      The high idle during break-in is a good thing;Make sure there are no vacuum leaks and then just let her be for the first 50 to 100 miles.Stay away from full-load-WOT during this time, but don't be afraid to exercise her either..
      Then after the rings are relaxing, we can have a look at the T-Port sync. Your 16 and 34 are good numbers, especially if the all-in occurs at 3000 to 3400 as manual trannys do not like it all-in early, like the automatics get away with.
       
      Last edited: May 26, 2017
    • crackedback

      crackedback FABO Gold Member FABO Gold Member

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      Keep your BIL away from your car! :)

      Vacuum leak?

      Do you have control of the idle with your idle speed screw? If not, there is something wrong. At 1K rpm you may be bleeding mechanical timing into the idle. When it drops in gear, that timing drops out and you are no longer at 16*. Just something to check with a timing light.

      Engine should idle easily at 750-850 with minimal drop when placed in gear, maybe 100rpm drop.

      100 amp breaker in the starter main wire is a BAD idea! Try an additional jumper cable ground from battery neg to block and see if it turns over easier when hot. 16 initial with that set up is pretty decent and should start easily.
       
    • Lustle

      Lustle Well-Known Member

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      Why do you have a 100 amp breaker in line on the positive cable?

      The engine when hot WILL be hard to turn over. It will create a large draw on the battery/electrical system. So you will need to make sure all of that is up to the task.

      As for the high RPM idle. That could be two things.
      1 - You're into the mechanical advance. As I mentioned before. Some distributors start the advance at 800-1000rpm. If you are "into" the advance. It can be difficult to tune it down. As AJ mentioned. Check to see when your advance comes in.
      2 - Carb tuning problem. This is why I mentioned that it is VERY important to make sure the carb is set properly, and the idle reset, every time you make an adjustment. Carb's are essentially a controlled gas leak. If the carb is not set properly, it could be dumping more fuel in there than you want at idle, causing it to stay so high. Even with the butterflys closed. As AJ mentioned, the T-port sync is very important at idle.

      Or maybe even a vacuum leak? But I would think that would be noticeable by now.

      As for your timing numbers. They look good. 16 really shouldn't be that hard to start. Especially with manifolds instead of headers. As the head pipe should give the mini-starter plenty of clearance. I would check your electrical system. I would not be surprised if you could get 18 or even 20 degrees of initial timing and still be able to hot start, as long as your electrical system is up to it.
       
    • vntned

      vntned Well-Known Member

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      So I played with the timing some today as well as the basic carb adjustments. First off, I found out that my timing light was FUBAR, so I borrowed a good one and ended up putting the initial timing at a true 16deg. Idle air screws on the carb ended up 1.5 turns out. Idle is about 900rpm right now, I wanna get it a little lower to 800rpm.

      Took it out for a 30mile test drive. It runs really strong, and cruises fine, however it runs warmer than I'd like. At a steady 50mph/2000rpm the SW mech temp gauge shows around 200-205deg. At idle it'll creep up to nearly 220deg. I'm not sure if that's ok or normal, considering it is a 0.060" over 360. I'm running a 180deg Tstat, an aluminum 22" radiator from Northern Rads, and an electric fan.

      I also found out that if I roll into the throttle in 1st gear, it's fine. However if I snap the throttle off idle it develops a traction issue even at part throttle. Weird, right?!
       
    • Lustle

      Lustle Well-Known Member

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      Idle screws out 1.5 turns sounds pretty good. Do you do the t-port sync yet? That may help with any slightly higher idle problems.

      As for overheating. 200 isn't bad. The hotter the engine runs is actually better for cylinder wear and mileage. You ideally wanna be around 190. That's usually where small blocks do best. That said. MORE initial timing actually runs COOLER. So your car may still want another 2-4 degrees of timing. Assuming you can still hot start it. What kind of fan setup are you running? And more importantly, do you have a shroud?
       
    • vntned

      vntned Well-Known Member

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      The fan is some no name 16" puller that claims 3000cfm. I'd bet it's more like 2000cfm.
       
    • Lustle

      Lustle Well-Known Member

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      Electric? Mechanical? Clutch? And do you have a shroud? You'd be amazed the difference they make.
       
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