Carbureted LSX forum - What size carb for stock LM7?

Just as the title states, what would be a good size carb for a stock LM7? Maybe a light cam, but stock otherwise? It's going in a cruiser, so drivability and mileage are most important. I'm thinking an edelbrock 600 or 650?

I don't think its gonna make much difference between those 2. Not really a edelbrock fan but hey they don't leak!

I went with a 770 CFM ULTRA STREET AVENGER just because I have a cam close to the Zo6 but it also gave me room to grow if i did heads and other things down the road.

http://www.youtube.com/watch?v=i5UaTQuFzk8

I suggest the 670 Holley Street Avenger like they used in this video, especially if you don't plan to spin it past 5000 rpm.

I personally hate Edelburp carbs.

I run a plain Jane Holley 750 vacuum secondary on my stock 4.8 in my gmc and my 5.3 with a cam in the Trans am. 4.8 spins 6000, drives perfect....driving it right now.

Put a stock 5.3 in the 85 TA that I gave the little brother, it is set at 6000 and pulls to that no problem with a stock vac sec 750 as well.

A 650 would do great, but the 750 for me is allot easier to find used in good shape.

The reason I'm looking at an Edelbrock over a Holley is because I'd like to get the best mileage I can. This isn't a performance build by any stretch of the imagination, in fact it rarely sees over 2500 rpm alone. It idles at 500 rpm, drives at around 1200 or so, and has a 700r4 backed by 2.xx gears.

Actually, I probably wouldn't even need secondary's at all. World's first 2BBL LSx? :lol:

I have a edelbrock 600 on my stock lm7. and it runs perfekt.
makes good power, and goes long on the juice.
just tride a edelbrock 750 on it but sems to use more gas. so will go back to the 600.
have you lookt at the street Demon 625. sems to be a cadidat.

The reason I'm looking at an Edelbrock over a Holley is because I'd like to get the best mileage I can. This isn't a performance build by any stretch of the imagination, in fact it rarely sees over 2500 rpm alone. It idles at 500 rpm, drives at around 1200 or so, and has a 700r4 backed by 2.xx gears.

Actually, I probably wouldn't even need secondary's at all. World's first 2BBL LSx? :lol:

My LS2 with a 750 Holley double pumper does that. Manual trans with3.5 gears though. Pulls down better than 25 mpg. Tune it with a wideband and you will get either carb to do just about whatever you want.

http://www.youtube.com/watch?v=i5UaTQuFzk8

I suggest the 670 Holley Street Avenger like they used in this video, especially if you don't plan to spin it past 5000 rpm.

I personally hate Edelburp carbs.

That was a pretty interesting video. Probably should be required watching for anyone with a 5.3

One thing I don't understand is if you are buying a crate motor to begin with why not go with a larger displacement? For JY pull outs the smaller displacement makes sense cause they are so much cheaper. But damn, all the upgrades they looked at are nothing compared to what 6.0L starts with.

For me, a 400$ 5.3 is perfect, have not had a junkyard Ls motor give me issues yet, and if it broke, well, guess I drop another 400$ and do it again. Not to mention...warranty? I would void it instantly I'm sure.

Edelbrock is suppose to be a better street carb and I think you are on the right track with a 650.

That was a pretty interesting video. Probably should be required watching for anyone with a 5.3

One thing I don't understand is if you are buying a crate motor to begin with why not go with a larger displacement? For JY pull outs the smaller displacement makes sense cause they are so much cheaper. But damn, all the upgrades they looked at are nothing compared to what 6.0L starts with.

Well like he said at the beginning, the reason they went with a 5.3L is because GM has seen alot of movement with them lately and they wanted to see what they can do with them without voiding the warranty.

That was a pretty interesting video. Probably should be required watching for anyone with a 5.3.
As well as the power difference in a single or dual plane intake. The bottom line...for a mostly street driven car that won't see regular trips to the track or over 6500 get a dual plane.

I've got a Holley 700 Double Pumper/Mechanical Secondaries carb sitting on the shelf, it's newly rebuilt but I don't know what jets are in it. Could I just disable the secondaries and run this one?

go to ebay. get a edelbrock 600cfm part 1406 of some sort.
by a rebuildkit and put it on.
i think you will spend under 100$ on it and it will work like a new car and get good mpg

I've got a Holley 700 Double Pumper/Mechanical Secondaries carb sitting on the shelf, it's newly rebuilt but I don't know what jets are in it. Could I just disable the secondaries and run this one?

What size vehicle is it going in and with what trans?

I get excellent drivability out of a 750 DP but it did take a little while for me to learn enough to get it that way. My car is light with a manual trans so mechanical secondaries were the right call.

That 700 will probably work fine without having to disconnect the secondaries.

What size vehicle is it going in and with what trans?

I get excellent drivability out of a 750 DP but it did take a little while for me to learn enough to get it that way. My car is light with a manual trans so mechanical secondaries were the right call.

That 700 will probably work fine without having to disconnect the secondaries.

It's going in a 1986 Chevy C10 2WD long bed, 700r4 transmission. I'm half tempted to just throw it on once I get everything together and see how it runs as is.

go to ebay. get a edelbrock 600cfm part 1406 of some sort.
by a rebuildkit and put it on.
i think you will spend under 100$ on it and it will work like a new car and get good mpg



Was tempted try a eddyjunk on my 4.8.

try it
it is a good DD carb. not a race carb at all but it does the job

Need to find one at a reasonable price or find one that will be a loaner.

Bump. I'll try my 600 cfm Edelbrock on my planned 5.3, or a 670 cfm Holley Street Avenger. This 600 cfm carb drives nice with my cammed SBC.