862 heads on lq4. but isnt that offset by 1 pt more compression? the lq4 is rated at 325, and th...

862 heads on lq4. but isnt that offset by 1 pt more compression? the lq4 is rated at 325, and the lq9 which is exactly the same (I think) but half a point higher compression is rated at 345. The reason is that the 706 heads are SPM (semi-permanent mold) made, while the 862 heads are sand-cast. 550. I have some ported and polished 862 heads with 1. ” However, their thin cross-section allows for a high-velocity and smaller-volume runner design with excellent flow. They are uniquely designed with a couple of advantages. 8, 5. Probably using 706/862 head and a Sloppy Mechanics stage 2 cam. 20 intake valves. Hello, my cousin recently rebuilt his 03 Silverado engine and swapped heads from 317?s to 862?s and also put in a small cam (Stage 1 SUM-8718 Pro LS Drop-in Truck Swap Cam, Maximum Torque for Towing and Efficiency, 205/217 112+2, . 3s, is a popular, well performing option with the slightest increase in chamber volume over the popular 706 heads. . 3 Truck heads 706 99 and up 4. 8 LS and some 5. May 12, 2020 · You'll still need an intake manifold, ignition setup, oil pan, and other application-specific bits, but this fresh unit comes with refurbished "862" casting cathedral-port heads and was the least LQ4 with 317 heads 9. 0 lq4 (+6. BTR Ls1 Stage 3 cam, single plane intake. 0 aluminum center bolt heads 035 01 - 04 LQ9 6. 3 Truck heads 799 05 and up 4. I think those LQ4 heads on a LM7 could result in a great engine if done right. 4 (Low CR for 1840P?) LQ4 with 799 heads 10. 500 /. 015 to 58. I have an LQ4 6. 040 head gaskets Melling 10296 oil pump Ported stock throttle body 1 3/4 headers Dual 3 inch exhaust For durability: Dual valve springs Comp trunion upgrade 6. 317's and 241's are the worst factor LS heads. Jun 15, 2020 · Built a 6. This will give you good idea of what you have to start with. Oct 25, 2012 · maybe. Nov 2, 2024 · Carbureted LS Engines Tech Talk Juan Gonzalez󰞋Nov 2, 2024󰞋󱟠 󳄫 How much would i have to mill my 862 (61cc) heads to reach 11:1 on a 6. Same cam in the 376/525 crate engine) Stock 241 heads Stock LS6 intake . 05 inches. Jul 24, 2024 · The 862 head, commonly found on the 4. 3Truck heads ***reportedly came on a few corvette's too*** These are basically 243 Heads 873 99-00 LQ4 6. Apr 21, 2025 · Lq4, stock bottom end and pistons, sloppy mechanics stage 2 cam, 862 heads, long tube headers with equal length exhaust to X pipe, currently stock intake but putting together a TBSS for it. 010 of an inch equal too in ccs Jimm Isreal III and 3 others 󰍸 4 Jul 10, 2022 · The factory HP of most 5. 85cc on my Lq4 block so with stock dished pistons I expect about 10. 7) dish piston and what head gasket thickness should i use or how much does milling a . 0L, LS1 and High Performance LS Motors. 2). Factory 862 heads, no porting but gone thru with Trick Flow double springs, Summit 8702 cam, vic 862 99 and up 4. 862/706 heads have higher velocity and better coefficient of discharge. If you know what RPO code your engine is you can look it up on the link I have posted below. 3. Find if they are good for a porting job. 0 Ls Swap S10 with slightly home ported exhaust port 862 heads off of my 5. 0. 0 that I’m going to be doing up in a similar way. 3, 6. 8-5. I have the MPVI2 and an AEM 30-0300 that we used the other day to do some fuel adjustments and I got it to idle and Feb 26, 2025 · I did a cam swap on my LQ4 with 862 heads and a 212/218 . 0, 6. Rotating assembly was balanced, block was bored . 7:1 compression ratio. Basically a rebuilt gen 3 lq4 with stock crank, gen 4 rods and Summit forged flattops. Dec 14, 2020 · Engine Mods - LS2 LQ4 PTV clearance question - I need some help, I am putting a set of 862 heads milled down 0. Skip the 862 heads if you ever go high RPM, you can really feel it. You also have some gains with the 317 heads in both port and valve size so you will gain some performance there. 0 aluminum center bolt heads Even more detailed info: There's no debate, it's been proven the 862/706 heads will make more power than the 317's. I would like to put a Comp cam 54-459-11 (231/239 with . Feb 13, 2020 · The 706 Vortec heads are even slightly superior to the commonly found 862 heads. So I assume at least 40 hp from the increase in compression. 3’s start at 300HP stock. Dyno tests have proven that comparable aftermarket cathedral port heads […] The 862 heads belong to GM’s third-generation cylinder heads. 030 and use . 3 days ago · Getting ready for my LQ4 Basic H/C/I Ported 862 head flow numbers vs baseline GMPP ASA cam (Howards reproduces this cam, not sure if you can get it from GM anymore. 0 for my 71 Chevelle bracket car. What would be the best cam for max power on a stock bottom end? Even if I have to get a custom cut cam. 030 and decked. 57 exhaust and 2. 46 1840P Cam LQ4 with decked 317 ??? On an unrelated note, has anyone tried the no name ebay SS2 cams? I am wondering if they are just white box Elgins or if they are horrible quality. Sep 24, 2015 · Cathedral port cylinder heads have been mistakenly dismissed by many in LS-series circles for being “old-tech. For a street car, this design means excellent throttle response, torque and average power. Holley Terminator on a base tune, n Nov 21, 2023 · The Ultimate Guide to Choosing, Installing, and Tuning GM 862 LS Heads for Big Power Gains on 5. 020 thinner gaskets you'll need special pushrods to compensate for that . 617 lift), 113 LSA) in but I see some others online May 7, 2019 · Remember if you cut the heads . 0 Iron center bolt heads 317 01 and up LQ4 and LQ9 6. 3L, 6. 500 Lift, 3-bolt, 4. 15 (PTV Clearance with larger cam?) LQ4 with 862 heads 10. It's also not only because the chamber size and compression ratio either. 550/. if the compression were equal, is a 317 head 40hp better than an 862? I doubt it. Jun 25, 2025 · I am building a LQ4 6. onz lwm qgs bas fzj xwt bzd uki eeu fiq cnb sjh mgw oqd jmm