706 chevy heads crack

Time and moneysaving tips from technicians automotive service. Each set of heads is milled and assembled to the owners specifications and utilizes stainlesssteel valves. Ive read a lot about these heads, but my thoughts are inconclusive. Small block chevy ls cylinder heads by casting number. Stock ls heads including the 706 heads on our lm7 5. There are 2 other sets of 706 s that are not affected.

It does not indicate the 706 marking in the document. Fiftyfive years of manufacturing have left us with an endless number of different cylinder heads for the sbc engines. The constant change in temperature causes cracks to form in aluminum heads. Pressurizing the cooling system at this time may reveal coolant, air, or a combination, weeping in the described area. Chevy cylinder head identification small block casting numbers, big block cylinder head, camel back heads, double hump heads. This is a relatively common problem you may discover on gm. Cracking causes the head to lose pressure, resulting in lost power for your vehicle. Pontiacchevy aluminum, 91cc chamber large rectangle port.

Gms 706 vortec heads are the cheapest and most effective heads you can use for your 5. Apparently the castech heads have a tendency to crack, allowing coolant to mix into the oil. The local chevy gmc dealer keeps a supply of replacement heads in stock. Ls ls1 ls2 ls3 ls6 ls7 lsx 706 cylinder heads set 4. Silverado engine cylinder heads best engine cylinder. To enjoy a quick replacement and highstrength components, install an aftermarket chevrolet silverado cylinder head from autozones premium selection. Dec 12, 2014 so i just got back from visiting 3 different dealers. Cathedral port 243799 are the best flowing gm production heads for. Sep 24, 2015 new 862 or 706 casting cores are cncported and machined to specifications dictated by extensive research and testing. Every thing ive read says the 862 on the l33 are the same as 706 heads. Chevy performance sbc cast iron vortec cylinder heads jegs. Does the product blue devil really work for fixing head and. Thanks to the added compression from the 706 heads, torque production improved through the entire rev range.

So far i know they will raise my compression, from some reading it will be good low end tq but. The universal fit called for meant the original sr heads had small valves, but these heads were so well received that they felt justified in producing the sr. No 243s or 799 have the casting defect that ive heard, it was pretty isolated to the castech only 706s on gen iii 4. Product was successfully added to your shopping cart. Does the product blue devil really work for fixing head. The crack location can be found in any of the five cylinder heads oil drains. After adding coolant the second time i knew something was wrong. Apr 04, 2019 the real problem with these heads has to do with the cracks by the oil drain holes.

But he was going to check his 2006 silverado to see if he has the 706 heads. The real problem with these heads has to do with the cracks by the oil drain holes. Jul 04, 2006 vortec heads were designed based on the 1996 caprice 9c1impala ss lt1 castiron head castings. Discussion in the hokey ass message board started by 1946chrysler, jan, 2009. It takes a fully ported fuelie head to eclipse those flow numbers. I have been searching for a few days and it seem as if no one has the answer to the question about only castech making the 706 head. Does the product blue devil really work for fixing head andor head gasket issue. I am wondering in terms of flow,compression,ect i will be using them on a 5. When performing your own check for cracks, you need a method of testing that does not use expensive equipment and works with a nonmagnetic metal. Nov 27, 2017 what we had planned to test was a set of stock 4.

Cylinder head cracking overheating is the most common cause. I found a couple cracks in between a couple of my valve seats. Chevy cylinder head identification small block casting. When servicing or rebuilding a gm ls engine which includes the lq series, cast iron or aluminum blocks. Coolant leaking into cylinders 706 casting gm truck. How to check aluminum heads for cracks it still runs. A guide to vortec vs oe small block chevy heads by bobby kimbrough march 03, 2010 small block chevy heads have been manufactured since 1955, and have been used in high performance applications as soon as the first one rolled off the assembly line. Ok i was reading everyones blaming the 706 castech heads there saying they go out at 80,000 miles mine has 174,000 mile no coolant leaks. Typical 346cid output with daily drivable hrs is 440480rwhp sae.

Americas favorite highperformance cast iron small block cylinder heads offer big power and bigger value. The first service writer was no help at all as he hadnt heard of the issue. I seen some heads online that are 862 but dont have no logo on them. Hopefully its a head gasket and not a cracked head but the signs dont. If the cylinder head fails, it will lead to the engine and by extension the vehicle breaking down. L33 engine in sons turbo truck has a cracked block. This is a discussion on 706 heads on 01 ls1 within the internal engine forums, part of the lsx technical help section category. So, when replacing either the cylinder head or the head gasket. Chevrolet silverado 1500 engine cylinder head getting the job done is easy in your hefty chevy silverado, but even that ample torque doesnt go far with a worn cylinder head. Cylinder heads that are identified with the number 706 are potentially plagued with porosity and cracking problems. In this video i show an example of cylinder head on a 5. Customer requsted repair by the way, they had bought this stuff and wanted me to do the work.

There are 2 other sets of 706s that are not affected. Allied motor parts has over 150 years of experience of remanufacturing. Some of the propaganda from chevy states that the heads on the l33 are ls6 units with bigger valves and bigger ports. So i just got back from visiting 3 different dealers. Hey guys, i just joined this forum because i am looking to buy a silveradosierra soon but still have a couple questions. New 862 or 706 casting cores are cncported and machined to specifications dictated by extensive research and testing. Lq4, ls6 cam, 706 heads, 317 heads, junk yard dog, and. Gm has issued a tsb for the issue, but provides no help funding the millions of necessary repairs. To test our daily driver head and cam package, we selected a 6. I recently found out i have the dreaded cracked heads by castech. Use these casting numbers to identify the heads you have. We dont try to fix the heads at all as its quicker to get replacement heads and get the vehicle back in service either the same day or overnight.

So far i know they will raise my compression, from some reading it will be good low end tq but not quiet up top. General motors estimated that through 2005, more than 90. While i have the heads off though im thinking of throwing in a 220r cam and z06 timing chain might as well since i dont have the service records. The complete cylinder head guide for chevy small block engines. Im trying to narrow down my solution to my problem and wanted some opinions before i throw more money at this thing. Just wondering if anyone has played around with this before. The only difference is the water jacket revision so these heads could be used on conventionallycooled small blocks. Vortec heads were designed based on the 1996 caprice 9c1impala ss lt1 castiron head castings. Read on to see what attention your silverado may need and how you can protect it from damage. Gm casting defect with ls heads don terrills speedtalk. Well, i bought a used pair of vortec heads and theres a tiny crack at the edge of the combustion chamber, its just big enough that i can barely hook my finger nail in it.

Surprising hp numbers from our stock ls cylinder head test. This article will discuss cracked cylinder heads, weak valve lifters, worn valve seals, and positive crankcase ventilation pcv fouling. No 243s or 799 have the casting defect that ive heard, it was pretty isolated to the castech only 706 s on gen iii 4. Iv decided to trade it and and im trying to avoid having the same problem again with my new truck. Equipped with the 706 head upgrade and mild comp 265 cam, the 6.

Chevy truck forum silverado sierra gmc truck forums. Nearly half of the 706 and 862 castings are cracked around the three head bolt bosses in the middle of the head. Our compression lessons chart illustrates how the compression. Allied motor parts sells cnc ported lm4lm7 706862 cyl heads. This can be seen as a clean or shiny area, on an otherwise stained surface 1. So far i have a buddy with some 862 heads hes gonna let me have for 80 bucks, not bad. These heads outflowed the corvettefbody aluminum lt1 heads. Gm has issued a tsb for the issue, but provides no. The only problem is this one has the castech heads too. The most common reason for cylinder head failure is overheating caused by coolant. The 1996 lt1 castiron head was the highestflowing lt1 head used by gm. Chevrolet vortec cylinder heads fast burn combustion chamber and highvelocity ports combine to produce big horsepower. Plan a, get the heads pressure tested to see if they leak coolant, decide based. This specific guide is for the chevy lm7 ls truck engine.

You need to pull the valve covers and look for the battery looking symbol. I wouldnt even bother with it just pull the heads off and check the head for cracks or a head gasket. The sr heads were originally intended to satisfy a market for heads to replace the later lightweight and thin highly crack prone castings gm was producing from the mid to late 1980s on. The cylinder head included in this listing will fit the vehicles listed below. 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. Major cracks can cause severe damage to the cylinders of the engine. Oct 24, 2011 stock ls heads including the 706 heads on our lm7 5. Small block chevy heads have been manufactured since 1955, and have been used in high performance applications as soon as the first one rolled off the assembly line. Im planning on changing my heads with some non castech heads because i currently have the castech 706 and are cracked. In terms of peak flow, the 241 heads offered 242 cfm at 0. Stay away from 706 heads, some of the early ones have a bad casting that cause them to crack and leak coolant. Vortec heads can be mildly ported for additional performance and milled up to. So, even a brand new car can experience cylinder head cracking. Also, there looks like something hit the top of the chamber between the intakeexhaust valves, like theres a little piece of it missing, though it doesnt go as far as to.