Birdracing

Hey i have a 5.3 motor that was given to me it had the 706 heads but i dumped them, seeing that they like to crack. Question is the 319 heads what are they like?. Thinking about going with them plan was to go with a cam, those heads, and a LS6 intake or Fast 92 haven't made up my mind on that yet. The block is cast iron, how much spray do you think a stock bottom end will handle? I always wanted to build a motor, and spray it. I was thinking a 150 to 175 shot, i see videos with guys running turbos on stock 5.3's with no problems. If they can handle turbos spray should be good. What is the best cam to go with? so many choices out there.

redtan

iTrader: (5)

Never heard of 319 heads, but you should pick up some 243s for more compression. 150 shot should be ok for a while given you have the right tune and fueling.

As far as cam, talk to a cam vendor about spec'n you a cam specifically for the setup you are running.

gagliano7

The 317 heads which I assume you are talking about will lower the compression on your 5.3 and make it a dog n/a.

96capricemgr

iTrader: (1)

Some of the specifically Castech manufactured 706s had issues but to blindly pitch them without understanding if they were even made by the company with some failures is pretty stupid.
As said 317s have a big chamber, they flow well but would be a bad choice for a NA 5.3l.

omc8

iTrader: (7)

True dont throw the 706s away have them checked . If you are going to run flat top pistons , deck the block and and are willing mill the 317s alot , but it will take a alot they have 71 cc chambers . Then you may consider them . The fun quick and easy solution, replace with 862s and you maintain the same cr without doing anything to them. Any other casting will have to be milled in order to maintain cr even the 243s are bigger.

Birdracing

Sorry they are the 317's the 706's are already gone and yeah they were cracked. I am thinking about going with a set of AFR's also to be honest, i am taking my time with this build and i want to do it right the first time. Trickflows are another head i am looking at decisions decisions..

RockinWs6

5.3 is a good motor, ran over my 1st wife with 5.3 under the hood............

NoorJ

did you just confess to first degree murder on the internet? lol

96capricemgr

iTrader: (1)

Said he ran her over, didn't say killed........

People are too quick to jump on the aftermarket head bandwagon.
If looking at spray I would save some money by using a ported OEM cathedral head LS6 intake and use the savings to setup the nitrous very well with all the proper safeties.
You get into aftermarket heads you need to look at swapping them to PM guides or going to a heavy harder to control aftermarket rocker, the costs spiral out of control pretty quickly.

Birdracing

Like everybody i am trying to do this on a budget seeing that i have 2 other vehicles. I can get the 317's for a good price i am told they can just bolt up and go, but i will get them checked out. I am planning on going with a LS6 intake i am going to port the heads, get a cam that matches what i want. Like everyone i think i will be looking for a foxbody Mustang, or S10 truck but i am leaning towards the foxbody. At first i was going to convert frm LTX to LSX, but where i live, i would be better and cheaper to buy a LS Camaro. So i think i will purchase the 317's and start off with the build. Another question is Texas Speed a good place to buy a cam or go with Comp Cams, or Eldebrock? Which is the best place to shop?

Mercier

iTrader: (15)

862s should be the same price..$150 or less for a nice set. You already don't have a lot of compression with an early 5.3 like yours. 9.5:1. When you go lower, it wont be fun. Good LSx OEM heads are a dime a dozen so don't buy the wrong thing just because you think someone I giving you a deal. I have a set of LS1 heads that were taken off at 12K miles and they are beautiful and probably only worth a bit over $100.

BTW, 862 is the factory head on a lot of earlier 5.3s. 706 is the same basic head but of course had the problems. 862 did not have these problems and is the actual direct bolt on replacement for a 706. 317 will bolt on but is different. And you can mill the 862 and get compression up in the 10+ range for even more fun.

MuhThugga

862s run between $100-$150. I would go with 862s and, if money allows, have the heads milled a little bit to bump up the compression.

Or you can run 862s and get some flattop pistons and be at around 10.5:1.

Birdracing

I am going to hold off and see if i can score a set of 243's if i can't i will go with the 862's. I was researching the 317's, they are awesome for turbo's or blowers but i am not going that route. I want to build a car the way i want.

MuhThugga

243/799 castings are good heads. They are also the most expensive cathedral port factory casting. They typically run in the $400 range on the used market.

Mercier

iTrader: (15)

Agree on 243 = good heads. Don't they have a slightly larger chamber than the 862? Mill a bit to get compression up? Or is the ~3cc not worth worrying about? What do you guys think? I had this same question when I was building my last 5.3.

Birdracing

I could of got a set of 243's for 300 bucks and let them go, only if i had my time back.

Mercier

iTrader: (15)

Either there was something missing/wrong with those or somebody wanted to make you their girlfriend.

KCS

iTrader: (20)

Some people just need cash. I got my last set for $300 and nothing was wrong. Another $200 for a valve job and surface and they're basically brand new.

I've since jumped on the aftermarket head bandwagon though, but that's for my Mustang.

Mercier

iTrader: (15)

If they don't need a valve job or resurface then the value is normal; about $450 right? Or is that the going price assuming you would still have a valve job etc. done?

KCS

iTrader: (20)

The ones I have didn't need a valve job at all. They could have been run as is, but I wanted a better valve job to go with the bowl work I'm doing. When you buy used, obviously you run the risk of really getting something that's in good shape, or will need some work. Those "like new" heads for $550 could have a broken guide and a bent valve, but you wouldn't know until you take them apart.