LQ9, 317 or 799 heads?
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Teching In
Joined: Dec 2019
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From: Zephyrhills, Fl
LQ9, 317 or 799 heads? I'm building an 02 LQ9 to go in my 99 2 door 2 wheel drive Tahoe. With the LQ9 flat top pistons on pump gas, should I stick with my 317's, or go with 799's? I've found some reasonably priced 799's and may have a line on a LH6 with bad lifters to get geads off of(and put the parts I take off my LQ9 to good use). This will be a daily driver on pump gas that needs to idle fairly smooth and have good street manners.
The current build plan is the LQ9 bottom end, some mild port work on the heads(port and cylinder matching), tbss intake, 92mm dbc throttle body, long tube 1 3/4" headers, 1.7:1 roller rockers, 4l80e trans, stock high stall converter, 3.73 gears, 9.5" 14 bolt, 29" tall tire, and I'm looking hard at the Vinci "butt kicker HL" camshaft.
The current build plan is the LQ9 bottom end, some mild port work on the heads(port and cylinder matching), tbss intake, 92mm dbc throttle body, long tube 1 3/4" headers, 1.7:1 roller rockers, 4l80e trans, stock high stall converter, 3.73 gears, 9.5" 14 bolt, 29" tall tire, and I'm looking hard at the Vinci "butt kicker HL" camshaft.
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From: South Carolina
I have a similar build LQ9 TBSS, 92mm, with PRC heads. Don't make the mistake (like I did then later buying the 1 7/8") and buy 1 3/4" headers. 1 7/8" will give you more power everywhere. You want the compression with the 799 heads. No need for roller rockers with the .595" lift. Stock rockers with the trunion upgrade is actually better and saves some money. What octane can you get in your neck of the woods?
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Joined: Dec 2011
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With the 799 heads, you will have an iron block LS2. Unless you have concerns about working it hard (heavy towing, etc), I see no benefits to the 317s. They will be down on power everywhere compared to stock 799s.
Agreed on the advice above. Headers: get 1-7/8 if you have the option. 2.5" dual exhaust will be fine. Stock rockers with upgraded trunnions are just fine. That cam should be fine. Stock 4L80e converters are giant heavy beasts.
Agreed on the advice above. Headers: get 1-7/8 if you have the option. 2.5" dual exhaust will be fine. Stock rockers with upgraded trunnions are just fine. That cam should be fine. Stock 4L80e converters are giant heavy beasts.
Thread Starter
Teching In
Joined: Dec 2019
Posts: 26
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From: Zephyrhills, Fl
There's not many options for stainless headers that will fit an obs, and most say it takes hammering the bejesus out of the headers AND cutting the upper control arm mounts. I will be towing some, but nothing heavy. I've seen the vids where roller rockers made 14hp on a stock 4.8l, figure with higher lift they will be worth more, and I always put roller rockers in my sbc builds, so why not in my 1st ls build. I have 93 octane available locally and E85 isn't that far away. I already have the 317's and after all those Richard Holdner vids, people around here want stupid money for 706's, and Ludacris money for 799/243's(but 317's are now boat anchors).
I actually ended up picking up an 06 LH6 today with a bad lifter/cam out of an Envoy for less than what most want for a set of 799's, so the 799 heads off it will be going on my LQ9 build. I'm going to take the parts I pull off the lq9, put into the lh6, put some 706 heads on it, and I'll have 2 LS's.
And I'm used to working on allison's with triple disc converters, so the 4l80e converter doesn't seem that big to me in comparison.
I actually ended up picking up an 06 LH6 today with a bad lifter/cam out of an Envoy for less than what most want for a set of 799's, so the 799 heads off it will be going on my LQ9 build. I'm going to take the parts I pull off the lq9, put into the lh6, put some 706 heads on it, and I'll have 2 LS's.
And I'm used to working on allison's with triple disc converters, so the 4l80e converter doesn't seem that big to me in comparison.
Last edited by THEFERMANATOR; May 11, 2021 at 10:39 PM.
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From: South Carolina
Joined: Jul 2007
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From: ELSA, South TEXAS (956) 802-7700
You got 317s and are not going with a big cam where ptv issues could be a concern. Save money and just mill the 317s .030 and use factory trunion upgraded rocker arms over the heavier roller rocker arms.
TECH Fanatic
Joined: Dec 2019
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Don't waste your time/money on roller rockers. Guys have been 6s in the quarter mile on stock LS rocker arms.
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Teching In
Joined: Dec 2019
Posts: 26
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From: Zephyrhills, Fl
I got a complete LH6 with the 799's on it, so I'm going to go ahead with them. I'm also looking into a bigger cam. Was hoping to get started building it this summer, but my Dr's appt on Wednesday may have just put this project on the back burner. So now I have 2 builds that will be waiting things out.