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Discussion Starter #1
I have a 540 with an F2, A/A ic & Rodneys water / meth set up running 50/50.

I'm still learning the transbrake, start line procedure so the bottom end is a bit raggy but thats me not the car. Launching in 2nd top end is 150mph @ 9.7 seconds so its making power. Engine is at about 6400 at this speed. Engine limit is set at 7200. Prologger shows AF @ 11.5 / 12:1 but to be honest I'm still learning so can't look at & remember every reading 100%.

My question is have I got my timing right?

I'm currently locked out at 30* and have 1* coming out per lb boost & have 16# pulleys on. I am at the moment hitting around 12-13# at the top end. Also have a set of -9 NGK's to go in this week. It feels very strong in the 2nd to third shift and really pulls ass in the final 1/8th but am I leaving 'safe' power on the deck?

At the moment I've set this all up pretty much on guess work. Car is both street and strip driven due to the class I am in. Aiming for mid to high 8's when I get my start line shit sorted & am confident I have the timing right.

NGK-9 plugs what gap should I have these at?
Can I go higher with the initial locked timing say 32-34-higher or is 30* ok?
Should I pull more timing per # boost 2lbs? or less 1/2lb?
What # level should I start to pull timing at?
What boost level should I start the water / meth? (progressive system).

I'd appreciate all input & why you think so too as understanding the reasons behind changes is I feel as important as the change it'self.

Thank you in advance.
 

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When I dynoed my sbc at Steves we were running 32 degrees of timing with 27 pounds of boost on C16 with a A/W intercooler. That being said I believe alot of what is going to dictate how much timing you will be able to run is going to be how high your IAT is. I am running the same heat range plug you are and my timing mark was just above the weld on the strap. We had the plugs gapped at .025 . But really you would be best served to let your plugs tell you how much the engine wants. Start conservative and make some runs and see what the plug is showing. Every engine will be a little different depending on the makeup so what might work for one will not always work on the next.
 

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What RPM and boost are you launching at 2nd gear? What is your gear ratio and tire height? Is that to help with getting out of the hole without spinning? I definately agree with the gap.25 you dont want to blow that candle out, I would start the meth in at different levels seeing what works the best for you. Myself mine is locked in at 29 deg and I start taking out timing 1deg at a time at 3 lbs of boost. Definately read them plugs, that will be the final say on your tune.
 

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I think the biggest piece of the puzzle is the cam. Timing has always been alot easier to find on a dyno for me. Also, is this a blowthru?(thought I saw pics of your car and it was) Blowthrus typically can stand more timing also.
 

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Discussion Starter #5 (Edited)
Ok, first thanks for the responces so far. I'm running pump gas about 100 octane as thats another stipulation of the class. The cam is one of Steve's so spot on as far as blow through is concerned. I'm leaving in 2nd because I'm still getting used to the car and the limitation at the moment is me! I have done about 14 runs so far from an 11 to the current 9.7. Next time out I'm gonna launch off the brake in 1st at around 3,500 rpm. I will add some C16 while I'm getting the tune right then drop to C12 then the 100 octane when I can understand what the engine wants.

I just want to get as close to a safe but decent tune as I can. Keep the advice coming!!
 

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Steve can tell you I will bet really close for each octane, he has dynoed so many. Especially since it's one of his cams.
 

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Discussion Starter #7
Yea, I didn't want to take up his time if I could get the answer on here but your right he would get me bang on the nail eh.
 

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I would try the following 1-set plug gap to .020-.022 that will guarantee that the plugs stay lit , 2 set your timing higher- 40 degrees then pull 1 degree per lb boost you should end up around 25 degrees total under full boost ( still very safe I believe) but adjust the initial to delay 2 lbs , you need to set meth. to start just past your transbrake rpm and set full on at max boost but if it high speed misses or goes rich A/F set max higher by 5lbs.I think your SLR starting line ratio might be off from what you said can you tell us what tire-gearing-trans.-converter you have?
 

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Discussion Starter #9
Sorry forgot that info. 33" tall MT S/Pro's. 4.10:1 gears. Hutch TH400. Chance bolt together converter (Hutch had it made to fit my application).
 

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That answered my question you are not making anywhere near enough H.P. to use a 10 inch converter.You should see if you can borrow a 9 inch from somebody and try it.I have 1560 corrected hp and use a 9 inch from ati 6% slippage shift at 7500 cross finish line 7500 [email protected] mph adjusted altitude 8500 feet. the owner of ATI transmission Jim Beattie (my sponsor) did the math and said a 10 inch would kill my car's acceleration.Assuming your car is very heavy I would guess you are around 1000 h.p. based off the 150mph speed.
 

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Discussion Starter #11
The car should make close to 1400hp with the correct timing etc hence my initial quiery but so far I haven't had the initial launch in 1st so it's taking longer to build up speed before the finish line. The car is set up for mid to high 8's at approx 165mph. Hutch reccomended the 10" after asking everything bar what I have for breakfast!! I don't know exactly what the fin angle is. The car weighs around the 3250 - 3350lb mark with me in it.
 

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That's a really nice car you did a great job on it! I still believe the 10 inch is going to kill your combo.Call bob at ATI monday and see what they think.My car was used by ATI to R&D a converter combination for this very application ,heavy car-bbc-f-2 very similar to yours.We spent a summer altering converters and changing diff gears until we achieved the best performance with the least converter slippage.At one time we were 1% on the converter slippage but I took gear out of the car to lower my engine rpm and slippage went to 6%.Don't be afraid to wack it on the transbrake I launch mine at 5500 rpm no 2 step and drive on the wheelie bars for 50-75 feet,nothing to be afraid of, don't pay any attention to the lights until you are comfortable with the launch and catching the 1-2 shift on time then start working the tree, It took me a while to get used to it also.Also I agree with your H.P. estimate once you put timing to it it should be able to make 1400 with that boost.Still not enough for a 10 inch by a long shot
 

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Discussion Starter #13
I know Hutch altered the pitch of the fins once he had recieved it but being in the UK it's not easy to just get hold of spare converters to try. We did discuss a 9" but he thought I'd be better off with this one, maybe because of the street driving I do & it's very different driving over here to the wide open roads you have. Right or wrong it's what I have to work with so I need to tune around everything with everything if that makes sence.

Thanks for the kiind words on the car, the thinking was if it ain't fast it will look good going slow :). Sleep time for me now, thanks for your input it is appreciated & noted.
 

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Discussion Starter #14
What are others running with their F2 - BBC set up's. Be good to get more ideas & opinions.
 

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I have ran 9.71 at 134MPH car topping out on RPM well short of the 1/4 mile it has a hyd roller at 6 PSI of boost car made 700 HP to the ground on Chassis dyno, I have mine locked of at 29 degrees, Car weights 3600 with me in it, 29 tall slicks 3.73 gears launching at 4400 on trans brake, this motor is a 540 10.1 motor set up to run N/A (Smeding 540 extreme to be exact) that is why I am running so little boost to be safe while I am saving to build a blower purpose motor. Did you say it has an 850 CFM carb? You might want to go with a 1050 with that horsepower you are wanting to achieve.
 

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Discussion Starter #16
Blow thru carbs are rated differently to N/A carbs. An 850 will handle 1,600hp with twin needle assemblies. Sounds like you really have that car hooked up on the start line.
 

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Discussion Starter #17
what different combos are the rest of you running?
 

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Discussion Starter #19
If it stopped raining here long enough to try it out I'd happly answer!! Its just to wet over here to play. I'm going to up it to 34* then take out 1* per lb boost which would put me at 18* @ my full boost of 16lb. I was thinking 36 but I think I'll try 34 then check the plugs before I try anything more.
Thanks for asking I'll report back as soon as the sun come out!!
 

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Get a data logger in that thing. It will make a huge difference in figuring out the converter and recalling what happened in the motor on the pull. It also makes it easy to show people what you're looking at.
 
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