If our gov't would just get rid of corn and heptane, we could also elliminate the word "detonation" from out fraternal vernacular!!!!!!!
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If our gov't would just get rid of corn and heptane, we could also elliminate the word "detonation" from out fraternal vernacular!!!!!!!
So the cam works nice. Runs real hard and clean with the little bit of race gas that we had left over. After we burned through that we filled up with the best pump gas available in our area, 91 octane :( The base timing and fuel is set up for 93 octane. We are experiencing some knock at WOT after running hard for a few pulls. Started pulling timing back out of it so we are at about 28* with 4" vaccum from 2000-5000RPM. How far can you retard the timing before you experience drastic power loss?
The first opinion is that the cam seemed to fix the knock problem. The weather this weekend was about as hot as it ever gets around here and I'm sure the little bit of knock we experienced is a result of the low quality gas available and my lack of tuning experience. Thanks for everyone's help.
Any advice on tuning for low quality gas? does anyone make an octane booster that is actually worth a shiite?
Does your fuel injection system back off timing when it senses knock? What water temperature are you running?
The injection doesnt have a knock sensor. I can hear it very faintly tho. The water temp cruises at 175. After running it pretty hard for a few minutes it will get up to 185-193.
If it didn't ping on the race gas, I would say you need to take a little more timing out. This gas in Iowa is crap. One tank seems ok and the next is crap. Also if your at WOT, shouldn't the vaccum be closer to 0. Not enough air flow? Leaning out could be causing the ping. Just some thoughts.
A thought . . . Are you running a new harmonic balancer? Is it stock or an aftermarket unit? The reason I ask--stock harmonic balancers have been known to slip over time and throw the timing marks off. 28 * total is in supercharger territory, so I am wondering if the balancer is giving you an accurate read.
The lowest I saw the vaccum get was 2".
The balancer was checked recently and it has not slipped. The computer was reading 28* after i had taken 6* out of it to tone down the ping. Is 28* too advanced for WOT or too retarded?
We just found a place that sells 93 Octane so we'll be plugging that into our equation now. Hopefully its enough.
Most street engines like 32-36 degrees of total advance while supercharged engines often have a boost retard that retards the timing for each pound of boost. My 383 likes 32 degrees best, common for AFR heads. When it was on the dyno, the technician started out with 36, then 34, and finally 32 degrees which produced the most hp and torque. Older style combustion chambers often like more advance. Retarding an engine to 28 degrees may be what your particular engine likes. They are all a little different. But I would not go any less than that based on what I know about your set up. Once you get 93 octane in it, you can try bumping it up to 30 or so and see what happens.
I re-read all of these posts, and I came up with a question. Since you have the distributor locked down at 10*, does that add 10* onto your total timing read from the computer? If so, that would put you at 38* total advance which is too much. It might be a good idea to call Edelbrock and see what their tech staff has to say. You should not be getting any pinging with this combination.
The computer ASSUMES 10* lockdown. The readout has that factored in. The computer had 34* to begin with. I retarded it 6* to get the 28* advance I've got now. Hopefully the 93 octane gas will be the answer. I am thinking it will because we aren't that far off with the 91.