Timing on your Race BBB's

Discussion in 'Race 400/430/455' started by GS Kubisch, Oct 21, 2007.

  1. 2 68 Rivs

    2 68 Rivs Gold Level Contributor

    Jim, Gary, thanks for the info on retarding the timing, I think I get the concept. Man, there are a lot of variables working together here. I'd bet the electronic engine controls for new vehicles probably have retard built into their timing curves. Be interesting to see how they compute the ideal timing. Thanks again!
     
  2. gymracer01

    gymracer01 Well-Known Member

    This is a good discussion. I've figured this out mostly on my own with my car. I did try the Jenkins trick several years ago on a 250hp 283 fuel injection engine in a NHRA stocker. I run an ignition system that most have thrown away and determined as "no good". That's the Holley system that came out 8-10 years ago. I can program any timing curve at each 500 rpms.
    It also has a cranking retard and rpm switches and limiters. I guess some people had trouble with them and they stopped making them. I had them in two cars with no problems. I switched to aluminum heads over the winter but have not really worked the timing deal much since going with them. The car was fast as I needed (index) with the old iron head timing. I'm sure I could pickup it up a little if I tried.
    Jim N.
     
  3. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    All I know is that when I used the high speed retard at E-town, it hurt my performance. I had it adjusted for 4* to come out at 4400 RPM. I had 34* retarding back to 30*. My engine would fall back to around 4200 RPM after the 3rd gear shift. As it climbed through 4400, and the retard kicked in, I could hear the engine sort of go flat for half a second then the RPM's climbed all the way through the traps. Listen to the motor in this clip. My best was a 12.56@ 107.30

    http://s172.photobucket.com/albums/w20/SLD1624/?action=view&current=LarryRun1A.flv

    At Cecil County, I eliminated the timing retard and ran 109 + first time down the track. Increased the timing to 36*, ran over 110 MPH. Went to 38-39*, it went just a shade under 112 MPH. This was my 12.20 @110.65 MPH pass

    http://s172.photobucket.com/albums/w20/SLD1624/?action=view&current=Cecil07.flv

    I'd like to try the retard again. Maybe at a higher RPM? The module selector I use allows adjustment from 3000-5200 RPM in 200 RPM increments. I am going through the traps at 5500 RPM. Should I take the timing out at 5200? Would do you guys think?
     
  4. Jim Weise

    Jim Weise 1000+HP

    Larry, just looked at your video for the first time..

    My advice..

    1. set your governor kit up to shift at 6000 1-2.. and 2-3.. The SP-1 wants that. You need to keep the motor up to around 4800 on the shift. If the rods let go from an extra 500 rpm, it was time for a fresh shortblock anyway. :laugh:

    2. Take the air cleaner off, and install a 1" spacer under the carb.. The SP-1 wants that too. Install the air cleaner in the trunk.. Best spacer is the HVM Super Sucker..

    3. pull out timing back to 32-34* after 5000 rpm. It should pick up mph. I know it doesn't want 39* past 5000.. no question, I would never even go there on the dyno, cause it would have fallen on it's face back around 36* I think the timing is helping your MPH because your getting the mass moving faster, before wind resistance takes over, and slows your rate of acceleration-- remember how the speed trap works on the strip.. if you enter at a higher mph, you can actually be not accelerating as fast, yet see a higher mph on the slip.

    How's your 1/8 MPH with the different ignition timings.. and on the same track, the same day.. should be the same diff as it is at the end, I would bet..

    With good air and track, you just might get your 11 second run.

    Your type of car, and the times it's running, is the most likely on to see improvements from timing changes during the run.. as long as you can hook..
     
  5. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    Thanks Jim,
    Yes, 1/8 Mile improvents were the same as at the 1/4. So 38* pulling 4* out at 5000 RPM. I'll have to try that.
     
  6. gymracer01

    gymracer01 Well-Known Member

    Larry, I think Jim is giving you some good advice there. I know back in by SBC days I thought it took a bunch of timing and sometimes it did go a little faster, but I think I had other problems that the added timing was just covering up. I have always been conservative with the timing on my Buicks. Think that has helped me not have bearing problems and kept the pistons out of the pan.
    JIm N.
     
  7. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    Well, the hardest part will be calibrating another governor to shift at 6000 RPM. I don't want to shift it myself, it's so much nicer to leave it in Drive and let the trans do it's thing. It's easy enough to set the retard on my MSD Digital 6.
     
  8. TORQUED455

    TORQUED455 Well-Known Member


    Jim, would using no air cleaner with a sealed Stage 2 scoop cause too much turbulance for the carb to work properly?
     
  9. TORQUED455

    TORQUED455 Well-Known Member

    What else do you have going on going down the track?? :laugh:
     
    1972 Stage 1 likes this.
  10. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    :laugh: :laugh: I try to watch the gauges and the track. It's over before you know it:grin:
     
  11. gusszgs

    gusszgs Well-Known Member

    Come on Wiz, tell the truth....you watching the air freshner:laugh:
     
  12. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    :laugh: :laugh: Not that Tree.
     
  13. Staged70Lark

    Staged70Lark Well-Known Member

    Larry,

    I have never seen any gain in ET when going over 32 degrees of timing. Right now I keep my timing at 31. I am a believer in tuning for MPH. The higher timing might help off the line but it will hurt on the big end. Higher timing also puts the engine closer to detonation which could cause some problems.

    Take Care
     
    1972 Stage 1 likes this.
  14. gusszgs

    gusszgs Well-Known Member

    Just to add here, when I was at the track this past weekend I made one timing change. I had the timing set at 32* and went 11.34@119 then bumped it to 36* and went 11.33@121. So, no et reduction but almost 2mph faster.
    I may have bumped too much and missed the sweet spot. I'll try 34*next time out.
     
  15. 7 skylark 1

    7 skylark 1 Well-Known Member

    seems to be an awful big variation in timing numbers. is it possible the guys that need to run really high timing are too rich or have to much octane in the fuel?(or maybe its the other way around). projected plug nose or not = different timing numbers:Do No: . just thinking out loud, what do you think?
     
  16. Landshark1969

    Landshark1969 1969 GS convertible

    Larry I used all your mods on my distributor from your post invaluable information
    next step for me is programable box. My engine always liked a lot of initial timing and always pinged after 4000 until I modified my distributor's mechical advance to half it's travel all in quick one light spring one medium. I set the timing until it pings then dial it back until pinging goes away. I will put the light on it this week I'm curious to what it is actually! What are the specs on that 118 cam?
     
  17. blown455

    blown455 Pit crew

    now i know why so many of you guys have bearing problems,,,,, unless you run alcohol anything over 34 degrees is stupid, a buick spark plug is not in a location that can tollerate that much timing,they also have large bore, detonation is the #1 killer of bearings , I have made 1400 plus horsepower for over 5 years and have NEVER hurt a bearing
     
  18. Hector

    Hector '79 Buick Limited

    That's what I think of when I say "Fast with Class" to a non believer.That's how I want mine set up also:TU: .
    Lots of good info here:gp: .
     
  19. Guy Parquette

    Guy Parquette Platinum Level Contributor

    I'm a true believer in this, but more so in a hemi style head.
    A while back we dyno'd nothing but different spark plugs for two full days (about 20 hours of dyno time) on our race snowmobile engines...these were our stockers where one to two hp could make a difference in a win or loss.

    When we saw a difference in a plug change either way, we would retune the engine for that plug, which included carburetion and timing changes.

    Basically what we found;
    There were hp and tq differences in the long and short reach plugs, and we tried every thing out there including our own made clipped plugs, indexing, different metals, split fire (no difference) ect.

    Now, what we found like mentioned were differences between long and short reach plugs. But when we retuned the engine for that plug the hp/tq ended up being the same with a slight advantage over the long reach plug, about a half horse. Probably do to a slight comp increase from filling the chamber more.
    Anyways what we found with timing was the short reach plug likes more timing over the long reach.
    The engineers at SkiDoo which we worked closely with had a reason (they always did!:rolleyes:) The long reach plugs advanced the timing bc it put the spark further down the cylinder there by lighting the mixture sooner.

    All that testing did help bc we now could make a timing change with plugs between rounds if the weather (air density) changed. just another tuning tool.
    Sorry for the long post but I thought it was all very interesting...
     
  20. john hixon

    john hixon Well-Known Member

    Will a moderator please post this string as a "sticky".

    I'm one of those "stupid" people that wasted three Buick motors in my track efforts with all combos pushing 625HP or less.

    Pretty sure I ran 36 degrees + of timing. I'll have to go back to my old logs and dyno sheets to verify.

    This information would have been real helpful to me about 4 years ago.

    Thx.

    John
     

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