280zwitha383 Posted August 13, 2006 Share Posted August 13, 2006 I have an all iron 383 with 10:1 compression. My cam is an slp 51010 with 280* duration (@ 0.050" 224/230) and .502/.510 lift. Any thoughts? Quote Link to comment Share on other sites More sharing options...
DspecDJ Posted August 14, 2006 Share Posted August 14, 2006 Should work, I'm pretty sure modern performance cars with computer controlled ignitions just retard spark timing if it detects lower octane fuel, detonation, or knocking. So you should be able to do it manually on your engine to save some money at the pump. Quote Link to comment Share on other sites More sharing options...
grumpyvette Posted August 14, 2006 Share Posted August 14, 2006 if the question, is will it opperate or drive with the lower octane and retarded ignition timing to avoid detonation,? the answer is YEAH! it will run, but youll be very noticably down in power if the engine is set up to run correctly on the higher octane fuel and more ignition advance Quote Link to comment Share on other sites More sharing options...
Pyro Posted August 14, 2006 Share Posted August 14, 2006 What pistons are you using, flat, dished,? What heads are you using? How much advance in the distributor? How much initial timing are you running now? Quote Link to comment Share on other sites More sharing options...
280zwitha383 Posted August 15, 2006 Author Share Posted August 15, 2006 I'm running flat top forged pistons with 64cc Dart Iron Eagle Heads. I have it set to 12 (I think) degrees initial and 36 full (I'm sure) without vacuum. With vacuum total is something rediculous like 50 degrees but I've never heard it ping. I've never had it above 36 degrees without vacuum. What would be a good setting for it? 32* at like 8* initial. Should I leave the vacuum off? Quote Link to comment Share on other sites More sharing options...
Brad-ManQ45 Posted August 15, 2006 Share Posted August 15, 2006 You definitely want to leave the vacuum advance working or part throttle mileage and power will be the pits.... Quote Link to comment Share on other sites More sharing options...
280zwitha383 Posted August 15, 2006 Author Share Posted August 15, 2006 Well that's what I've always thought and done but 50 something degrees total makes me kind of squeamish. Quote Link to comment Share on other sites More sharing options...
Pyro Posted August 15, 2006 Share Posted August 15, 2006 Yes, use the vacuum advance. Don't worry about the advance being too much. At low engine vacuum (open throttle and under a load), the vacuum advance will be zero. Reving up the engine in neutral doesn't reproduce a driving condition. With those heads and flat top pistons you should be able to get by with 32 degrees of total timing. However, you will need to run 15 to 20 degree initial timing for that cam. So you will need to limit the amount of advance in the distributor by welding up one of the advance slots just a little. Quote Link to comment Share on other sites More sharing options...
280zwitha383 Posted August 16, 2006 Author Share Posted August 16, 2006 Yes, use the vacuum advance. Don't worry about the advance being too much. At low engine vacuum (open throttle and under a load), the vacuum advance will be zero. Reving up the engine in neutral doesn't reproduce a driving condition. Yeah, I've know that at wide open there isn't any vacuum but it still bothered me. I have had the cam at 8 degrees before and couldn't really tell the difference. I haven't been able to tell much difference in performance by changing anything because seat of the pants just tells me that it's pretty fast. I have noticed changes in traction because I'm on the verge of never having any so when I do something right I get loose a little sooner. Which probably slows me down... haha. Quote Link to comment Share on other sites More sharing options...
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