Carbureted LSX forum - 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.

Oh and a Victor Jr. Forgot to mention that.

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.

You need to look at the sticky thread on the database of builds

Yep. Lot's of data there.

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?

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?

I think ill do that tigger. Just to be safe. Any input on my carb question?

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......

Ok. Ima go look up some shooters.

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.

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.

Tommy, what is the factory squirter size in the front?

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.

Tommy, what is the factory squirter size in the front?

This document link is a real asset:
http://holley.com/data/TechService/Technical/Carb%20Numerical%20Listing.pdf

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.

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.

PS, I didn't have to do anything with accel pumps or cams.

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.

Just checked the carb and I have 71s front and 80s rear. Should I stay there or do 75/85?

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:


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.

Ok. And yes I still have it set to factory specs. I'm about to price a wideband.kit now.

Hey Joye, mine came with 70s in front and 8os in the rear in stock form, ended up 8 sizes larger on both.

Damn. Mine is back factory with 71 front and 80 rear.