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Carb and timing on LQ9

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Old 01-28-2012, 02:48 PM
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Default Carb and timing on LQ9

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.
Old 01-28-2012, 02:49 PM
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Oh and a Victor Jr. Forgot to mention that.
Old 01-28-2012, 04:54 PM
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You need to look at the sticky thread on the database of builds, you will probably see 34 or so timing, and jettig will be around a low 70 primary and 8 to 10 size larger onthe secondaries. Ect.
Old 01-28-2012, 07:23 PM
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Originally Posted by ZONES89RS
You need to look at the sticky thread on the database of builds
Yep. Lot's of data there.
Old 01-28-2012, 09:00 PM
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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?
Old 01-28-2012, 09:05 PM
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Just listen carefully for any sign of detonation. Always better to error on the side of caution. Maybe 30 degrees total until you can track or dyno test?
Old 01-28-2012, 09:33 PM
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I think ill do that tigger. Just to be safe. Any input on my carb question?
Old 01-28-2012, 10:41 PM
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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......
Old 01-28-2012, 11:05 PM
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Ok. Ima go look up some shooters.
Old 01-29-2012, 07:39 AM
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Originally Posted by Joye227
Any input on my carb question?
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.
Old 01-29-2012, 11:31 PM
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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.
Old 01-30-2012, 03:49 PM
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Tommy, what is the factory squirter size in the front?
Old 01-30-2012, 07:41 PM
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Think squirters are usually 28s allot of times, but a wide band as mentioned and a trip tothe track will help to dial that dude in.
Old 01-30-2012, 07:45 PM
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Originally Posted by Joye227
Tommy, what is the factory squirter size in the front?
This document link is a real asset:
http://holley.com/data/TechService/T...%20Listing.pdf
Old 01-30-2012, 08:05 PM
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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.
Old 01-30-2012, 08:07 PM
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I work out of town every week, but when I get back home I can look and let you know exactly what sizes I have in there.
Old 01-30-2012, 08:10 PM
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PS, I didn't have to do anything with accel pumps or cams.
Old 01-30-2012, 10:24 PM
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Ok. Thanx tommy and zones89rs. I'm going to see what jets and whatever is in my carb tonight. My carbed list number is 4779-9.
Old 01-31-2012, 09:48 AM
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Just checked the carb and I have 71s front and 80s rear. Should I stay there or do 75/85?
Old 01-31-2012, 10:01 AM
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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:
  1. a wide band a/f meter.
  2. A dyno tune.
  3. 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.


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