What did 243 heads come on

According to the internet, some of the best cathedral port LS heads available have a 243 casting code, and would have originally come on 2001 or newer LS2 and LS6 engines. They have larger intake and exhaust runners and a smaller chamber, meaning more compression and better airflow.

243 heads are 243 heads (different hardware for different short blocks though, i.e. LS6, LS2). 806, 853 and 241 all share the same ports. They are cast in different manners so the surface finishes are different which may slightly influence turbulence at certain lifts. The 853 and 241 heads have the same chamber size.799 LS Engine Cylinder Heads are some of the most recent cylinder heads on the automotive parts market. The cylinder cast architecture is with a semi-permanent mold method. The 799 cylinder heads are in the similitude to the 2004 LS2 cylinder heads due to the triangle casting marks similarity. However, unlike the 243 heads, they do not require ...I am beginning to find and spec all the parts I need to start the 6.0L LS swap for my 2002 Silverado. A significant key to the success of this build is the c...LS engine junkyard performance parts ! NNBS TBSS intake manifold and 243cylinder heads from a 2007 - 2008 Chevy Avalanche LC9 aluminum 5.3 gen4 LS engine. R...Getting the right head for your needs requires you to know a little bit more so you can ask the right questions and get the right answer. Component Breakdown Cylinder Head. LS1 engines come with aluminum heads. Parts and features on the head are the intake and exhaust ports, combustion chambers, seats, valves, springs, retainers, keys, and guides.

Sep 28, 2011 · I would think a 243 head is a 243 head, I think I read that the 243 was used on the LS6 Z and all LS2 motors had the 243 heads. Mr.Bill Reply Like 09-27-2011, 08:43 ...26791 posts · Joined 2006. #7 · Apr 13, 2010. 243's for cath ports and l92s for sqaure ports.. i would say are the best lower budget heads from what i understand that came on stock motors..a 6.0l comes with 317s which are the same as 243s just with a larger combustion chamber..if you want to use boost use them..the 243s are an ls6 head and ...Trucks with 243 had heavier valves. I heard people trying to claim they have zo6 heads but come off a truck. ... 2005 Pontiac GTO,NaturallyAspirated 418", 243 heads,stock water pump,3.73 gears, NW 102mm TB,matchported FAST 102,DuSpeed OTR, Bullet Racing 242*/249* .650"/.650"cam, Tick Performance tunedCompatible Engine Type. Anyone who is considering getting either the 799 or 243-cylinder head needs to know about their engine compatibility to make sure they …I know 243's are good but didn't know if 862's are any good when they're right in front of me. They won't flow as good as 243 but you'll have better compression vs 243. You can have them ported for a reasonable price and have a good valve job done on them to make them perform. They'll never be rock stars but they'll do fine with that cam.

IMO, a 243 CNC head and LS6 intake (or spend the chese for a FAST 92) will definately make a great street motor. i made peak power at 6000 rpms and shift at 6600 rpms. its a mule and could last forever if i didnt decide to spray it all the time ... Come join the discussion about racing, builds, pro mods, hot rods, events, turbos, nitrous ...The 799 and 243 casting Cathedral-port cylinder heads can be CNC ported to flow close to the aftermarket heads. With a bigger cam you can mill the heads for up to 10.8 compression which runs on pump gas. ... If you're gonna do a L33 swap into anything you may may as well leave the 799/243 heads that come one it. Yes I have seen L33s with a ...The 2015 F-150 Ford truck standard dimensions are 243.7 by 96.8 by 75.7 inches in length, width and height respectively. The width measurement includes the length of the truck’s si...Milling 243 heads for LQ9. as many of you have heard my lq9 6.0 destroyed the main bearing a little over 2 weeks ago and now that i have it torn apart i want to beef it up some. one thing i was looking to do was mill the stage 3 243 heads that i currently have. question is i dont know how much they need to go. we only have 91 octane gas here in ...243 is the Z06 casting, 241 is the last and best LS1 casting. The 243 has D-shaped exhaust ports and some other minor differences. Reply Like. 05-16-2007, 01:48 PM. # 3. 94legaleagle. Melting Slicks. Thread Starter. Member Since: Mar 2005.

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May 15, 2024 · The 799 cylinder heads come with a 64 cc combustion chamber, whereas the 243 comes with a 65 cc combustion chamber. While the difference seems ignorable, it is a known fact that a smaller combustion chamber will create more compression and improve vehicle performance.Apr 26, 2018 · If you’re gonna do a L33 swap into anything you may may as well leave the 799/243 heads that come one it. Yes I have seen L33s with a 799 on one side and a ls6’s 243 casting on the other from the factory. There is no reason to put the weaker 862 head on an L33 when the engine comes with the best flowing cathedral port heads GM made.Jan 18, 2014 · It's a 2004 A4 LS1. Lots of good info here. I can't seem to find much on these 843 heads except they're older than what comes with my car. A friend of a friend is looking to sell them to me for $1000. He said they're used off an older corvette, cnc'd on intake exhaust and combustion chambers, new stock valves with 3 angle valve job, ls6 yellow ...The FAST 102 seems to really like the 243 heads...a lot of people say it isnt worth it, but lately we have seen a lot of guys in the tuning/dyno results section put up big numbers with cam and fast 102 on stock 243 heads. ... Come discuss mods, horsepower, engine specs and more! Show Less . Full Forum Listing. Explore Our Forums. Appearance ...

Usually, conventional small-block heads did not flow nearly as much air as the best factory cathedral port heads. The 243, 799, and 317 castings of these cathedral port heads could flow up to 250 cfm which was a major improvement over what preceded them. But the LS3 heads took this concept even further and were capable of an …243 heads, 05/06 FRC~ Jump to Latest Follow ... Come discuss mods, horsepower, engine specs and more! Show Less . Full Forum Listing. Explore Our Forums. Appearance/Detailing LS1/LS2 Engine Tech Texas Drivetrain Wheels/Tires. Top Contributors this Month View AllThe 806 heads are literally 1st gen heads, have a perimeter bolt pattern for the valve cover. Which means you need that cover and IIRC the coil packs bolt directly on the cover vs a bracket that holds the packs together. Flow is meh even when ported. You should look for 317 or 243/799 heads with the emphasis on the later for NA builds, if going ...Changing the ls6 243 valve springs to tick .660 lift dual valve springs, also changing the valve seals.Every year for a few weeks in February, the city comes alive for Montréal en Lumière. Every year for a few weeks in February, the city comes alive for Montréal en Lumière, a festiv...Mar 15, 2018 · Last updated on 05/06/2024. The LS4 engine is a Gen. 4, 5.3L, aluminum small block engine used in GM cars between 2005 and 2009. It is unique because it was the only LS engine used in front-wheel drive vehicles. The FWD LS4 had cathedral port cylinder heads and used Active Fuel Management (AFM). The engine was not Flex Fuel (E85) …799 05 and up 4.8-5.3Truck heads ***reportedly came on a few corvette's too*** These are basically 243 Heads. 873 99-00 LQ4 6.0 Iron center bolt heads. 317 01 and up LQ4 and LQ9 6.0 aluminum center bolt heads. 035 01 - 04 LQ9 6.0 aluminum center bolt heads. Even more detailed info: Casting Numbers 241, 806, 853.124 posts · Joined 2010. #6 · Dec 20, 2012. 243 heads are a great midway step for an LS1. Most people say they're worth about 20 hp. I did them before my cam and the car pulled noticeably harder up top, which is what you'd expect. I'd stay away from those heads at any price. They look like they're in rough shape.Sep 6, 2023 · Also, the finishing is good as it is PCD milled to make sure it is very smooth. Also, all the heads have a new valve stem and can be replaced with new ones to ensure high-quality performance. All the 799 heads have a 3-year unlimited warranty. However, it is essential to ensure installation is done as per the manufacturer’s instructions.The LS2 is a 6.0L, Gen. 4, aluminum small block engine that came in both cars and trucks. The engine specs and information we're sharing here are for the LS 2 that was used in GM trucks and SUVs between 2005 and 2009. The information listed here is for a stock LS2 truck engine. Mechanically similar, General Motors' LS and LS-based Vortec ...This program works on the following head casting numbers: 243. 799. 317. 035. Now you can get this porting service on your cylinder heads at an incredibly low cost! Simply follow this procedure: Remove the cylinder heads from your car. Disassemble cylinder heads to completely bare condition.I am beginning to find and spec all the parts I need to start the 6.0L LS swap for my 2002 Silverado. A significant key to the success of this build is the c...

243 heads are 243 heads (different hardware for different short blocks though, i.e. LS6, LS2). 806, 853 and 241 all share the same ports. They are cast in different manners so the surface finishes are different which may slightly influence turbulence at certain lifts. The 853 and 241 heads have the same chamber size.

The 5.7L LS6 is the most powerful Gen. 3 small block engine as it came from the factory. It is an improved version of the LS1 produced for the 2001 Z06 Corvette. The LS6 powered the 2001-04 Corvette Z06 and the 2004-05 Cadillac CTS-V. Mechanically similar, General Motors’ LS and LS-based Vortec engines wound up on almost every branch of the ...The LQ4 (4.8 liter, 293ci) is the smallest LS ever produced. It shares its iron block with the 5.3-liter engine and even has the same 3.78-inch bore size. The drop in displacement comes from a ...When it comes to fastening two objects together, cap head bolts and cap head screws are two popular options. They both have a similar appearance, but they differ in their applicati...Keep in mind these numbers are going from crappy 853 heads to CNC ported 243 heads. Not stock 243's to cnc'ed 243's. And this was a dynojet. But the type of dyno means nothing really considering both pulls were on the same exact dyno. At this point the dyno is just a tool to see the difference between heads.These heads came on low-performance 6.0-liter truck engines in two variations: “873” cast iron (1999–2000) and “317” aluminum (2001+). The early design …Quote: Originally Posted by lil john. True Tuskyz, also the 821's have less meat, *Some porters don't like to go over 270'cc while the the 823's are good to around 280'cc. Phil @ Advanced Inductions gave me a quote on the 280cc version on my #821 heads. Reply Like. 08-12-2016, 09:11 AM.The LS4 engine is a Gen. 4, 5.3L, aluminum small block engine used in GM cars between 2005 and 2009. It is unique because it was the only LS engine used in front-wheel drive vehicles. The FWD LS4 had cathedral port cylinder heads and used Active Fuel Management (AFM). The engine was not Flex Fuel (E85) capable and did not use Variable Valve ...Sep 21, 2015 · These large-runner heads have a 12-degree valve angle, like stock, and are compatible with factory LS7 rocker arms and stands. The heads can accommodate 1.625-inch-diameter springs, and several are available. A 4.125-inch-or-larger bore is required. Base price is $1,130 each, fully assembled, through Summit Racing.CI 6-7-8-9-10 Veteran. St. Jude Donor '03. Yes, the 243 and 799 heads are now being used on later model (05+) 4.8 and 5.3 truck engines. Reason being is they changed from dished to (now) flat top pistons in those engines, which required the larger head chamber to keep compression ratio about the same.The two types of heads, 241s and 243s are found in many vehicles. The combustion chambers for each of these types differ slightly: 243 heads have an internal volume of 65cc while 241s have a 67cc size. Due to this difference in size, the compression ratio for 243 heads is higher than that of 241s, meaning that more power can be generated from ...

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2623 posts · Joined 2002. #5 · Jun 7, 2004. The 993 heads were used in 72-73 Chevy 350s, many of them were the 250 horsepower version. These heads are very similar to the 441 and 493 400 small block head. They are more preferred over the 882 head due to their heavier casting.GM LS6 CYLINDER HEADS CASTING #243 ONLY REBUILT STOCK HEADS. THIS SALE IS FOR CASTING NUMBER ENDING IN 243 ONLY CATHEDRAL INTAKE PORTS VALVE SIZES intake 2.000 ex 1.552 ... I'll give ya threefiddy, a jar of Vegemite and a box of boomerangs that may or may not come back. -- Olly.The 243 vs. The 799 Cylinder Head. As you have most likely caught on by now, these two cylinder heads are practically the same. The main difference between the 243 and 799 cylinder heads is that the 243 was used on older engines from GM Research, while the 799 has been used on newer engines from multiple manufacturers.You can find 243 heads on a Vette or on a Chevy Tahoe, or even a Silverado. Same for 799 heads. It depends on the year your Chevy was manufactured – be it a sports car, a truck, or an SUV. Back in the …799 LS Engine Cylinder Heads are some of the most recent cylinder heads on the automotive parts market. The cylinder cast architecture is with a semi-permanent mold method. The 799 cylinder heads are in the similitude to the 2004 LS2 cylinder heads due to the triangle casting marks similarity. However, unlike the 243 heads, they do not require ...This listing is for a rebuilt GM 5.3 5.7 or 6.0 liter V-8 cylinder head casting 243 only you must have an exchange with the exact same casting number. These heads come on GMC and Chevrolet trucks and SUV's. For other models see our store listings. This head is completely rebuilt. It has been pressure checked for cracks and resurfaced.Definitely to maintain low end response and torque,stick with cathedrals. LS3 heads and hears why, ls2 l92 heads makes 460rwhp 446rwtq. Over 450Hp, and a fairly broad and flat torque curve with a mid sized cam, and a set of heads that you can assemble with good springs for about $1000. Originally Posted by Rtzracer.The 243 heads do flow better but that can be overcome with larger valves in the 5.3 heads. A set of CNC'd 243 heads will still set you back about the same $$ or a little more than the equal 5.3 heads. ... Racing gas will come into play any higher than that, though. I would definitely recommend a cam with a lot of overlap to help bleed off a bit ...The 243 head came on the more powerful LS6 engine from 2001 to 2006, and was used in C5 Corvettes. Later engines like the truck-spec LQ9 and LQ4 used the exact same port design as the LS6's 243 heads, but had 6 cc larger combustion chambers. ….

So, casting 862 heads would do favors for your car with a perfect set up. Last Words. In a nutshell, the LS 862 heads are the best-performing, affordable, and ported 5.3 heads that will best suit your car. If you are looking for a high-performing cylinder head at an economical price, then the 862 LS heads are definitely a great choice.3012 posts · Joined 2008. #1 · Apr 14, 2012. I have a 2004 Aluminum 5.3 with 70k miles that has 862 heads on it. I also have a set of 243 heads off of a 2009 Aluminum 5.3. Which heads should I use? I've been told the 243's flow better and the 862's supposedly raise compression .5 a point.GM LS6 (243 casting). Information needed…LSX3rdGen. The 241 head is a stock ls1 head it was on the f bodys and also on the ls1 vettes. They were produced between 2000 and 2003. they are the same as the 853, the 853 was made from 1997 to 2000. ls6 heads are 243's.What 350 engine did 041 heads come on originally? It's been rebuilt, the big reman decal is still stuck onto it, as well as the "when first starting engine, to prevent bearing damage..." decal, but with all the dates and casting numbers it looks to be some type of replacement/reman from about early 1970. Heads have L 15 9 dates on them.Colleges and new high school graduates have what I think is a strange idea. They think every freshman is an ad Colleges and new high school graduates have what I think is a strange...The 243 heads come with 1.7-ratio rockers responsible for opening and closing the intake and exhaust valves. The configuration is different from the 1.8 ratios found on most other LS heads. ... Ported 243 heads can still be used today due to their many highlighting features. Cylinder Block. 243 heads. The cylinder block is the foundation of the ...243 heads are a nice upgrade on the LS1. If you want a cam that is dead stock idle, get the LPE GT2-3 (207/220) Great little cam that picks up nicely. I went 12.3 with that cam and GMPP LS6 heads back in '06. If you want to step it up a bit, an EdC 220/224 baby cam will really wake up those heads.The LS2 heads wich is the same as the LS6 head has a casting number of 243. Problem is that some of the LS2 have heads with a casting number "799" truck heads, wrong head!!!:weird: I have checked mine and it has the 243 castings.:thumbsup: A vette owner dynoed his vette with some mods and only pulled 345!!! So far 5 07 vettes have … What did 243 heads come on, Head and face reconstruction is surgery to repair or reshape deformities of the head and face (craniofacial). Head and face reconstruction is surgery to repair or reshape deformiti..., Dec 22, 2010 · 821/823 castings. im going to order ls3 heads but i would like to know the difference between 821/823 castings,i thought i read somewhere they were cast using a different process or something to that effect ,so which is better ls3 or l92 or is there no difference besides the map sensor. IBM 04/A4, #243 heads, Mild Blower cam by Comp …, The LH6 engine is a 5.3L Gen. IV aluminum engine that replaced the LM4 in 2005. It was the first Gen. IV LS truck engine and offered Active Fuel Management (AFM). The LH6 was available in mid-size SUVs until 2009, and in GM pickups from 2007-09. For marketing purposes, it was also known as the Vortec 5300., NEW GM LS 243 HEAD - 4.8L, 5.3L & 6.0L. $349.99. Generation III V8 cathedral intake port cylinder head. Casting 12564243. For truck, van, SUV and perfomance applications. Used on LS6, L33, L20, LH6, LY5, LMG, LC9,LS4, LH8, LS2, LFA, LZ1 engines. Add to Wishlist. Skip to the end of the images gallery. Skip to the beginning of the images gallery., The LS2 is a Gen. 4, 6.0L, aluminum small block engine. The engine specs and information listed here is for the stock LS2 used in GM passenger cars from 2005-2007. Mechanically similar, General Motors' LS and LS-based Vortec engines wound up on almost every branch of the GM family tree: Chevy, Pontiac, GMC, Cadillac, Buick—heck, even Saab ..., CBN milled to ensure a super smooth finish. (CBN stands for Cubic Boron Nitride and is best for cast-iron heads). All necessary parts are cleaned and inspected before final assembly to meet AERA specifications. JJ Original Equipment offers buyers a 90-days (Unlimited Miles) warranty for Remanufactured Cylinder Heads beginning on the ship date., ddawson. 15570 posts · Joined 2004. #4 · Sep 29, 2008. The 317 is a 243 but with a larger CC. I have the 317 on my car with 70CC. 1969 Corvette, 427 Convertible. 496CI Edelbrock Heads, Quickfuel Carb, LS6 Intake. Straub Technologies 229/235 .590/.559 107, Hedman Headers, Magnaflow Exhaust. Speed Direct Rack and Pinion, …, GM Engine & Exhaust Performance - lm7 with 243 heads - hey, I am new here and have been looking at some of the posts. I am going to be pulling the heads on my 03 sierra 5.3 lm7 and was considering putting on some 243 heads with a .040 cometic gasket to bring the compression to 9.8. my concern was with torque, I use..., Newly reworked 243 heads versus AFR heads. Hi guys, I have a 2006 C6 A6 with 145,000 miles on it. Mods include K&N breather, LG Long Tube Headers, and a Circle D stall converter. I recently swapped my LG G5XB cam for a new LG G5X3 114 cam. I have factory 243 heads that have just had a competition valve job including new guides, valves, Comp 921 ..., Some General Motors vehicles, specifically those built between 2001 and 2006, come with the LS6 engine that comes equipped with 243 heads. This includes the 5.3 and 4.8 models, which are generally outfitted with these factory-designed 243 heads now. To check if the 5.3 is equipped with 243 heads, look for a three-digit stamping near …, C5 Tech - 243 Heads question - hey guys i have a question. there is a sale on ebay for 243 heads & the post says they are interchangable. i was under the impression that these heads here not. could someone please clear this up for me. here is the link to the post...., 243 is the Z06 casting, 241 is the last and best LS1 casting. The 243 has D-shaped exhaust ports and some other minor differences. Reply Like. 05-16-2007, 01:48 PM. # 3. 94legaleagle. Melting Slicks. Thread Starter. Member Since: Mar 2005., Mar 26, 2012 · From how I understand it to work...and I'm no expert... 317 heads are designed for a 4.000" bore motor. Your LS1 is a 3.900" bore motor. Therefore, you'll need a thicker gasket on your heads. Stock heads are 67cc and you are going to a 72cc. This is going to drop your stock 10.5:1 compression down some., I've also decided to go with the Flowtech Induction ported 243 heads with stock valves. The cam will customized around those heads and my goals/usage. Won't end up having Ed do the port work till November or December, but can't wait to get the cam and see what he's come up with., get those projects done! should you run 706 heads on your 6.0l for more torque? what about the change in compression and detonation? what if i have to retard..., Phoenix Discussion starter. 6208 posts · Joined 2004. #1 · Sep 14, 2007. My dad just got a brand new Silverado with a 4.8l as a rental. I popped the hood to see what engine it had, and I noticed that the head were 243 castings. Are these the same that are used on the LS2?, The 243 heads made about 20 RWTQ everywhere compared to the 317 heads, the chamber in the LS6 head is far superior to the 6.0 chamber. Bear in mind ECS had these same Stg 3 make over 600 RWHP on a N/A, hyd roller cam, pump gas engine that same year. ... Come join the discussion about racing, builds, pro mods, hot rods, events, turbos, nitrous ..., If the heads are 243's and are stock on a 6.0L engine, you are looking at an LS2. The 243's also came on LS6 engines, but are 5.7L engines. If you are actually wondering which engine came out of the Avalanche and it has 243 heads, you are looking at a 5.3L with some other than stock heads. They didn't install the 243 heads on the truck engines., Jun 22, 2023 · The 243 head came on the more powerful LS6 engine from 2001 to 2006, and was used in C5 Corvettes. Later engines like the truck-spec LQ9 and LQ4 used the exact same port design as the LS6's 243 heads, but had 6 cc larger combustion chambers., the LS6 243 heads have the hollow Intake and Sodium filled exhaust valves for higher RPM use. 7000 rpm Reply Like. 05-01-2012, 11:59 AM #4 chassed. Melting Slicks . Member Since: May 2009. Location: Rio Rancho New Mexico. Posts: 3,123 Likes: 343 Received 281 Likes on ..., CI 6-7-8-9-10 Veteran. St. Jude Donor '03. Yes, the 243 and 799 heads are now being used on later model (05+) 4.8 and 5.3 truck engines. Reason being is they changed from dished to (now) flat top pistons in those engines, which required the larger head chamber to keep compression ratio about the same., The 243 Heads are cast iron cylinder heads that have been CNC-machined to create larger intake and exhaust ports. The combustion chambers have also been machined to be smaller, which increases the compression ratio. While the 243 heads are not the newest or best option out there, they offer a great value for the price., yes the TR224 is a great cam for the 241 and stock 243 heads bc they are just matched about perfectly. the texas speed 244r and 228r are also really nice cams for these cars bc like you said, they have good bottom end. LS1 QSM/M6/17. LS6 heads, 232/234 592/595 111+4. Kooks 1 7/8, Super 40s cat back, K&N FIPK., Why not come to your next water fight properly equipped? An off-the-shelf squirt gun is too light weight and you can't drag a hose everywhere. Build a head mounted water-cannon and..., Texas Speed has ported 5.3 heads for a reasonable price if you want more flow. If the heads are 706 castings, chances are that they are cracked. You can improve performance with 243 heads, but you will need to mill them to maintain compression. Your best bet is to just get some 862s and have some work done to them., 5475 posts · Joined 2005. #4 · Jan 19, 2015. Put in stock 4.8 pistons, they're already flat tops and its what the L33 5.3 is with 243 heads. Stock compression on them is 9.9:1, it'll be a little higher with stock 5.3 heads but if it were me I'd go ahead and do some milled 243's with some bowl work. 2001 GMC Sierra RCSB., I had a close friend of mine hand port my 243 heads. After a re tune I ended up with about 25whp and 30wtq out of them. Im really happy with the results! Save Share. Like. ... I’ll give ya threefiddy, a jar of Vegemite and a box of boomerangs that may or may not come back. -- Olly., Jun 10, 2008 · I did 3 mods at once: 1. 243 Livernois Stage 2 heads 2. Kook's LTs 3. Mild cam (TR 224/224 112) The gain from those 3 mods was 102 rwhp over factory. I debated the 5.3 heads vs. the 243s, was never able to come to a definite conclusion, so for the slight bump in compression I used the .040 Cometic gaskets., Aug 15, 2006 · I know the cam is .525 on both sides, but how much lift can the stock valve springs take on stock 243 heads? I think you're limited to around .550 with the LS6 springs. A lot of guys go to 918 springs with mild camshafts like the GT2-3. Doing the math on a 1.8 rocker makes it .554 lift., Factory has the 862 heads. I’ve been offered a 5.3 block with 243 heads on it for $300. Would the stock 243 heads work better on it than the 862 heads? Obviously they need to go to the machine shop to be looked over but without any alterations to the stock form, which is the better head? Engine is stock other than cold air intake., Nov 24, 2021 · Chevy 706 Heads come with all new stainless steel swirl polished 2.00 and 1.57 valves, new springs for up to .650 lift, new retainers, spring seats, and valve seals. The heads are washed, disassembled, pressure tested, and all valve stems have been replaced as per requirements. Scroll down to learn more about 706 heads. Chevy 706 Heads- …, The casting numbers and heads you want for the Z28 are the 186 numbers you mentioned. They will also have a julian date code below the casting numbers (under valve covers) and should be matched to your motor if thats what you are trying to do. 3927186 (DZ 302 Heads)The other 041 numbers you entered are for other small block applications and and ..., The intake ports on 862 heads flow slightly less than the stock 243 heads that come on most 5.3L LM7 engines from the factory. However, the 862 heads have a smaller chamber size, which raises the static compression ratio by approximately 0.5 point on otherwise stock 5.3L engines. This can improve the power output and durability of the engine.