Carb and timing on LQ9
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Hey guys. I have an 1985 Oldsmobile cutlass with a '02 lq9. Stock 317's which I have shaved and a good valve job. It has a Texas Speed Tsunami can 235/240, .649/.609 lift, 111 LSA. 10.2 to 1 compression. Th350 with 3500-3800 stall, 1 3/4 LT headers and 4.10 gears. Should be 3400lbs. OK I'm using the MSD 6010 and I wanted to timing suggestions. I also have a Holley 750DP and i wanted some basline Carb tips as in jet sizes and accelerator pump diaphragms? Thanks guys.
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I was just looking at the thread where everyone was talking about their timing and heres what I came up with.
Timing: 15 degrees at 0, 28@ 750, and 34 degrees at 2000 rpm on up. What you think?
For the carb, should I put the 50cc shot in front and 30cc in the back or leave it 30cc front/50cc rear?
Timing: 15 degrees at 0, 28@ 750, and 34 degrees at 2000 rpm on up. What you think?
For the carb, should I put the 50cc shot in front and 30cc in the back or leave it 30cc front/50cc rear?
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#8
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id go with the 30cc pump in front and rear to start, if it hesitates you may need to go up in shooter size. I still run the 30cc front and rear in my 850, but I run a 40 shooter in front and 35 in rear. If it still hesitates with a 40 shooter then you could try the 50cc pump in front.
And i agree with speedtiger - start off on the safe side with timing - 28-30ish, if the plugs are not showing heat then add a bit......
And i agree with speedtiger - start off on the safe side with timing - 28-30ish, if the plugs are not showing heat then add a bit......
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A wide band is a great tool for ball parking until you can track or dyno tune it. Holley factory jetting should not be too far off. Mine ended up needing a lot more jet, but others did not. With all the different potential combinations, there is really no way to know without testing.
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Not sure if it will help you or not, mine is an 02 LS-1 w/ TEA heads and a 230/230 612/591 lift 111+2. My plugs look perfect and I have 78s in the front and 88s in the back, it's a Holley 750 DP also. I went up one squirter size in the primary too.
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Hey Joye, I think it depends on the list # but if I remember correctly, mine had a 27 in the front and a 31 in the rear. I moved the 31 from the rear to the front, and put a 35 in the rear. The plugs look great and throttle response is really good.
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If the carburetor is used and new to this build I would suggest that you return the carb to the factory jetting and calibration listed in the Holley document that I listed above and then tune from there. To tune accurately you will need one of these scenarios:
Even if you go to the track or the dyno for a tune, you should still get an A/F meter to set your cruise A/F ratio. Most of the double pumpers have a cruise A/F ratio of about 12.5:1. It needs to be 14.5:1 for clean plugs and good fuel economy.
- a wide band a/f meter.
- A dyno tune.
- A trip to the drag strip to tune for fastest MPH and/or the ability to read plugs properly.
Even if you go to the track or the dyno for a tune, you should still get an A/F meter to set your cruise A/F ratio. Most of the double pumpers have a cruise A/F ratio of about 12.5:1. It needs to be 14.5:1 for clean plugs and good fuel economy.