Rebuilding The Dirtiest Junkyard Ls 706 Heads Ever! Will They Work?  

0.051" is standard thickness, so if the heads and block aren't milled the pushrods should be just fine. What engine are you using them on? I would probably use 706/862 on anything from a 4.8, 5.3, 5.7 or dished piston 6.0. Especially if it's a car you're going to use on the street or if you are going to add boost. Those heads provide a sizeable tq advantage from 2000-5000rpms and only lose 5-9hp over 500rpms at the peak on a 6.0.vs 799/243 heads. On the street you'll appreciate the TQ and with boost you'll spool much quicker and have better throttle response and I would guess better fuel economy cruising. If you have a heavier vehicle with taller gears it's definitely going to be better. I would probably massage the ports on 5.7-6.2L, on any engine I would consider using thinner head gaskets, flat tops or have the heads milled for purely n/a work where you don't mind using 91-93 and especially if you have E85 access. 0.027" gaskets add 0.7:1 compression, on a 5.3 or 6.0 with wished pistons flat tops also add 0.7:1 compression. It might be wise if you are starting with n/a and might want boost later to get compression with thinner gaskets and then when you want boost use 0.060" LS9 head gaskets to drop compression 0.8-1:1 for boost. I have a set of grimey 706s that I am planning to use on an old LQ4 in my '04 6spd GTO, it's a big heavy car, kinda tall 3.46 axle, definitely street use, with cam+spring, headers, just bolt ons and tune. Should be a great runner, I'm using 0.027" cosmetics on it, should go from 9.4:1 as an LQ4 with 317s to 10.6:1 with 706s and 11.2-11.3:1 with 0.027s, if I mill the heads or switch to flat tops if the bores look too rough with a dial bore indicator and I have them honed. I'd like to see 11.2-11.6:1 and use an adjustable timing set to get the dynamic compression where I want it to run on 93 and be able to pop the timing cover and advance it a little on E85. Enjoyed you video.

OH YEA!!!!!

Oven cleaner will get rid of all the nasty

I can guarantee those valves have never been done before It was a lawn truck and they didn’t even change the oil

You cant be serious ....omg you are.....

I have a set of 823’s off of a L96 that i need to do this to….you did a awesome job considering the methods used….my heads arent as grimey but i just took them to a pressure washer to blast away the initial grime and sludge on one of them….then winter came…..so im not even half way done…i think im gonna go with some .660 lift dual springs when i put it back together though……the blue gm .560 beehive springs dont really give you much room to grow with your cam grinds if you plan on going wilder in the future…i have a LSA supercharged 370” LQ9 with 64cc LS3 heads in my nova with a hair over 11.15:1 compression in my nova and it runs great if i have close to 100 octane in it…..91 premium doesnt cut it so im on the fence about putting the factory 68cc style rectangle ls3/l92 heads on there …..but at the same time i have a vortech centrifugal supercharged cammed 4.8 in my ‘73 c/10 short bed fleetside and that was the same motor i had in my nova before i pulled out in less than a year and put the LSA 370” into …..i have a feeling the c/10 will be getting an upgrade once i get the itch again….i have a spare 6.0 (l96) that i did i fresh rebuild on with new ls2 flat tops and the same 64cc ls3 style heads on sitting in the garage covered in the corner…. Im debating stroking it to a 408 and 24x so i can put it in my c/10 and be able to run my terminator x system on it without having to hack the harness ….and putting the l96 crank and rods with LS1 pistons into the 4.8 to make an iron 5.7 (LS1)……then it will sit in the garage as a backup spare engine for either my nova or c/10 if one of them shall give up the ghost….love to get another car to LS swap but the wife isnt on board condidering we already have 6 cars😂…….but my son is 15 and he has been eyeballing them dirt cheap 4.6 mustangs….i told him if his mom is ok with it he might have a chance…but when that 4.6 shits the bed….were definitely LS swapping it…….so many decisions!!!!…..maybe ill just leave it a 4.8 untill the kid graduates and earns his cubic displacement😂

Nice build. I had very good luck with a long sanding block it works very good but I like to leave the finish in 180 grip 80 it’s too rough. What’s your compression ratio with the 706 heads?

.51 headgasket? Am I the only one who caught that? I know you meant .051"

You need to understand that when you are filming and moving the screen we are experiencing every little move so you start to experience movement sickness/distraction. It makes it hard to enjoy what you are sharing. Need to steady the camera more so we are moving so much.

Chump