Sep 22, 2015 the cylinder block is the foundation the rest of the engine is built upon. From fbody to corvette, sierra to silverado, g8 to gto, we carry everything for making power with your ls or gen v ride. Just to let you guys know to keep a close eye on it. Time and moneysaving tips from technicians auto service. Read on to see what attention your silverado may need and how you can protect it from damage. Comp cams gm sportsman tool steel camshafts offer strength, flexible. Sep 21, 2015 the ls market has embraced this technology by providing programs for virtually every factory or aftermarket casting. Pushing the horsepower envelope even further is an array of. This is commonly called the castech head failure on the internet. General motors produced seven versions of the ls engine, most of them with different heads. Some vehicles may experience a gradual coolant loss over time. Pressurizing the cooling system at this time may reveal coolant, air, or a combination, weeping in the described area.
This can be seen as a clean or shiny area, on an otherwise stained surface 1. Or is that why you have to look inside to see the castech marking. You can identify which head you have by looking at the threedigit stamping next to the valve cover. For a primer on the entire ls engine universe, read ls engines 101. You need to pull the valve covers and look for the battery looking symbol. Nonproduction blocks, such as gm performance parts lsx block and the c5r, offer the same headbolt pattern as production blocks. Ls cylinder blocks guide for highperformance ls engine diy. Cooling a mighty bigblock chevy is easier than you think.
September 28, 2015 the late model ls engine family has been around now for almost 19 years and has replaced the old first gen small block and big block as the engine of choice when doing a engine swap. While the 706 heads are a spm semi permanentmold and considerd to be a more consistant head casting then the 862 wich are sand cast, once ported there is no difference. I did locate some pictures that showed different font for the 706 number, but those posters never indicated if they found the castech. I was given a bunch of receipts for work that had been done to the car and there was one where some valves had to be replaced in one cylinder and the intake was a 2. Please discard corporate bulletin number 060601019a section 06 enginepropulsion system. This tech tip is from the full book, highperformance gm lsseries cylinder head guide.
If incredibly high horsepower, torque, and rpm are the goal, the needs may surpass the capabilities of even the best factory offerings. Gm issued a tsb on this failure to help service techs identify the problem. Ls6 cam, 706 heads, 317 heads, junk yard dog, and lies. There is a casting company that was producing heads for gm a few years back i beleive they were called castec. Aug 07, 2014 the range of original equipment gm ls cylinder heads offers decent performance out of the box, the mostly notable of which is probably the l92 head. Cnc port ls1truck 862, 706 cylinder heads pair katech. Some of the propaganda from chevy states that the heads on the l33 are ls6 units with bigger valves and bigger ports. Theres been stories going around that some of the gm ls castings have porosity problems and leak water in the oil around the top of the heads head bolt area. We find out which factory ls head works best under boost in this backtoback test of the 706 heads vs.
Rhs pro action 21065cc ls1 bare cylinder head 54240 rhs has introduced their new pro action cathedral port aluminum cylinder heads as a premium ls1 replacement head, ensuring great power on any performance or stock engine build. That was cast techs mark the name of the foundry was something like cast tech my 02 has over 200,000 miles on it with cast tech heads with no issue. Chevy cylinder head identification small block casting. So i just found out i have the 706 casting code on my engines cylinder heads. Supposedly, the 243 mold was done at gm research, the 799 mold furnished to other vendors. Chevrolet car and truck cylinder heads and parts for sale.
In terms of peak flow, the 241 heads offered 242 cfm at 0. Gm casting defect with ls heads don terrills speedtalk. Small block chevy ls cylinder heads by casting number. I am wondering in terms of flow,compression,ect i will be using them on a 5. West coast cylinder heads is among several companies that even port ls7 and ls9 heads, which come cncported from gm. I understand that the 706 castings have the same intakeexhaust port volume as ls1 heads and flow the same once the intake valve is replaced. This tech tip is from the full book, highperformance.
This started about six months ago w only 45000 miles on the truck. I know i have the 706 cause i can see it clearly on the outside of the head passenger side. The range of original equipment gm ls cylinder heads offers decent performance out of the box, the mostly notable of which is probably the l92 head. Coolant leaking into cylinders 706 casting gm truck. The crack location can be found in any of the five cylinder head s oil drains. The issue and i think its 20032007 engines gm in their inifiinite. Surprising hp numbers from our stock ls cylinder head test. This is the case with the ls, as even the wimpy, stock 706 heads used on our 5. Can i run the casting numbers anywhere to find out if they ar. Before i get into the the meat of the bookthe spec chartsthere are a few things you need to know.
For a street car, this design means excellent throttle response, torque and average power. The ls based smallblock engine is the primary v8 used in general motors line of rearwheeldrive cars and trucks. Lq4, ls6 cam, 706 heads, 317 heads, junk yard dog, and lies. Unfortunately i ported and polished the 706 cast heads before i learned of their suseptability for cracking.
Plan a, get the heads pressure tested to see if they leak coolant, decide based on my results. Information on gradual coolant loss over time with no evidence of leak found jun 12, 2007 this bulletin is being revised to include engine rpo l59. Information on gradual coolant loss over time with no evidence of leak found models. New ls2 heads are about half the price of new ls6 heads check. Gm performance parts for the lowest prices on the web. Be careful taking the exhaust manifold bolts out of the head if you diy, i snapped one on a 706 head. Whether you race pro stock, super comp, or just want to rebuild your old chevy 350 small block, there are cylinder heads just for you. All ls heads will bolt up to them, but care must be taken to select the most compatible heads based on the appropriate bore size. Cnc port ls2ls6truck 243, 799, 317, 035 cylinder heads. Sloppy mechanics wiki lsx head cast numbers flow swap info.
Chevy truck forum silverado sierra gmc truck forums. Just wondering if anyone has played around with this before. This article will discuss cracked cylinder heads, weak valve lifters, worn valve seals, and positive crankcase ventilation pcv fouling. However, their thin cross section allows for a highvelocity and smallervolume runner design with excellent flow. The exhaust port is a unique dshape that improves flow. Generation iii internal engine 862706 vs 243 i know stock vs stock the. Lq4, ls6 cam, 706 heads, 317 heads, junk yard dog, and. Meet the hidden gem that helped start the ls swap craze. Ls6 heads are the best choice only when allout power is needed.
May 06, 20 the other choice is to take a pair of 706 heads down to the machine shop and install a larger intake valve. Gm fast burn 62 cc 210 cc intake runner angle plug vortec. This is a relatively common problem you may discover on gm. I traded it in w 50000 and it was starting to get worse. Is anyone having problems with water leaking into the oil with these heads.
So far i know they will raise my compression, from some reading it will be good low end tq but not quiet up top. We find out which factory ls head performs best under boost. This is a discussion on 706 heads on 01 ls1 within the internal engine forums, part of the lsx technical help section category. So far i know they will raise my compression, from some reading it will be good low end tq but. The head casting which can be viewed from the passenger side of the vehicle just in front of the valve cover was 706. Be prepared for a big price tag at the dealer or steep core charge from your head porter. Arp 43610 cylinder head bolt kit chevy ls hex head free 2day fedex shipping. Sep 24, 2015 cathedral port cylinder heads have been mistakenly dismissed by many in lsseries circles for being oldtech. I found a couple cracks in between a couple of my valve seats.
I hate that i have had my truck for 14 years and am only just now hearing about this. When servicing or rebuilding a gm ls engine which includes the lq series. This specific guide is for the chevy lm7 ls truck engine. The reason is that the 706 heads are spm semipermanent mold made, while the 862 heads are sand cast. New and used automotive parts and accessories on sale.
The smaller chamber increases the static compression, which in turns improves power. We have some of the lowest prices on chevrolet performance parts, chevrolet performance engines, and chevrolet performance transmissions. Is there any way to tell if i have castech heads other than removing the rockers and the rail they are sitting on. There are a wide variety of oe, original equipment gm ls cylinder heads that flow excellent numbers and perform right from the production line. And because less timing allows more efficient combustion, the ls6 heads allow the engine to produce more torque. An introductory overview of the gen iiiiv ls engine family. The most obvious answer for the superiority of the 706 heads over the 317s is the smaller combustion chamber. Casting 862 heads i picked up my car that was advertised as 6. The spm method is considered to be a more consistent process, but once you port the 862 head. In this video i show an example of cylinder head on a 5. Visit our whats new page to get all the latest chevrolet performance news, announcements, and specials. They include information on converting from a cathedral port to a rectangular port, some thoughts on the merits of cathedral versus rectangular ports, and a bit.
The past three or four years, i have noticed my coolant level keeps dropping but have never seen any signs of a leak. It had castech heads and was going through a quart of antifreeze a month. History of the ls engine and cylinder head casting number. I do have another question that may be easier to answertalk about. Ls ls1 ls2 ls3 ls6 ls7 lsx 706 cylinder heads set 4. I seen some heads online that are 862 but dont have no logo on them. The tbss intake manifold will support even more, so we had the induction system covered. Jan 26, 2010 there is a casting company that was producing heads for gm a few years back i beleive they were called castec. These heads produce surprisingly good flow and performance and are suitable for power builds. In addition to its regular line of cncported ls heads, tea also offers custom porting options including factory castings such as the l92ls3 and various cathedral port heads. Heres more reading than you ever cared to do on ls heads. The stock aluminum heads can provide a high amount of airflow, which previously.
Coolant leaking into cylinders 706 casting gm truck club. Allied motor parts has over 150 years of experience of remanufacturing automotive and light truck cylinder heads. Oh, if you have the 799 castings the only thing corvette about them is the valve springsretainers. Some of the cast aluminum cylinder heads installed on chrysler pt cruisers. Feb 16, 2019 2004 silverado head gasket replacement gm 4. The ls based smallblock engine is the primary v8 used in general motors line of. This lm7 engine upgrade guide is part of a series of ls engine upgrade guides assembled by a team of ls experts at summit racing that we are sharing at onallcylinders. Should i nip it in the bud and go ahead and replace the heads now. Get the best deals on chevrolet car and truck cylinder heads and parts when you shop the largest online selection at. If they are cracked somehow youll see it when they come off to do the gaskets. The benefit to the 317 over a standard ls1 casting or the 706 5. Hey guys, i just joined this forum because i am looking to buy a silveradosierra soon but still have a couple questions. Im planning on changing my heads with some non castech heads because i currently have the castech 706 and are cracked.
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