317 Heads

[Tonyrodz]

Just bought my 6.0 and I checked the heads. They're stamped 317. I read somewhere that the 317 heads we're garbage, but I don't remember why. Would you guys agree with that? If so, yay or nay, why? I haven't checked the heads on my 4.8 yet, but if they're better would it be better or even worth it to swap them? Any opinions or info is greatly appreciated.

 

[iamdub]

317s aren't garbage at all. They're basically 243s but with larger combustion chambers. 243s are one of the best-performing stock Gen3 heads and there's still a decently strong market for them.

 

[Tonyrodz]

So would you say the 317's are better than the 243's? I still have to look and see what my 4.8 has on it. I'm thinking of having some work done to the 6.0 by a local garage. They do pushrods, can I think beehive springs and something else, can't remember, for around $2000, along with a dyno tune.

 

[iamdub]

Better? It's not as cut-and-dry as that. They flow the same as 243s (which is great), but have larger combustion chambers. It depends on what you want. If you want higher compression, you can swap on the 243s (or 799s- same exact head, often cheaper because it's not stamped with "243"). All will be the same, you'll just have higher compression. You can't really mill the 317s down to get the same combustion chamber volume as the 243s because the valves will be too close. If you want to run a huge cam or boost, you may want to stick with the 317s. Personally, I like the snappy response of a higher-compression engine and it's better when getting a heavy pig of an SUV moving. If your 6.0 is an LQ4 (lower compression) and you're not boosting, go with 243s/799s. The LQ9 (high compression 6.0) I built for my S10 had 243s on it AND a mild-moderate cam. This put the compression about as high as one would want on a street engine. The LQ9 in stock form requires 93 octane, so my build would've needed that as well as spot-on tuning. These LS engines need stronger pushrods in stock form. You didn't say what type of work the local garage proposed other than pushrods and valve springs. I'm sure that "something else" is a cam. That total package, complete with a dyno tune isn't a bad deal if it's parts, labor, etc. About the only thing that 243s or 799s themselves need at this level is maybe some mild smoothing. I'd strongly recommend a trunnion upgrade kit on the stock rockers if getting a performance cam and the accompanying stiffer valve springs.


Cliff notes:

243/799 or 317 heads- doesn't matter any further than what you want for compression

Performance cam- need stronger pushrods, appropriate valve springs, trunnion upgrade, custom tune

 

[Tonyrodz]

I talked to the shop earlier, although I didn't get the exact specs, he's talking about a mild streetable cam, pushrods, springs, valve seals, not sure about trunnions tho, circle D torque converter, bigger trans cooler to replace the stock one, high volume oil pump, heavy duty timing chain and dyno tune. All parts with labor, $2971. Down time is 3-4 days. And I'm also working on a shift kit and electric fans from someone else. Told him I was looking for something in the low to mid range, don't really need something crazy. Maybe this'll keep up with my GN! Lol

 

[iamdub]

All good stuff. An often-overlooked and underrated timing set is a GM OEM LS2 HD timing set. It's cheaper than fancy aftermarket timing sets, too. The trunnions can be easily added later since they're right under the valve covers. The stock rockers are plenty strong enough for a street cam. But if the bearings in them have some age, it's relatively cheap insurance to have them upgraded. You'd be knocking those rockers around more with a bigger cam while pushing back against all that extra knocking with stiffer valve springs.

Keep up with your GN? Maybe. But it won't have that beautiful turbo whine!

 

[Tonyrodz]

Lol, thx for all your helpful input. I'm gonna ask the guy about which timing set or chain they're going to use. BTW, the 6.0 came out of a 2wd Silverado. I know it was a 2wd because he showed me the trans it came with and he said it was a 2wd trans. So that motor would be a LQ4?

 

[Tonyrodz]

Do you know what the factory stall speed on the convertor is?

 

[iamdub]

Lol, thx for all your helpful input. I'm gonna ask the guy about which timing set or chain they're going to use. BTW, the 6.0 came out of a 2wd Silverado. I know it was a 2wd because he showed me the trans it came with and he said it was a 2wd trans. So that motor would be a LQ4?

2WD or 4WD doesn't determine which 6.0 the truck had. I'm not totally sure this is accurate, but I believe the HD trucks got the 6.0 and the optional "Vortec MAX" package gave it the LQ9. You could get a 2WD HD just the same as a 4WD. It's most likely an LQ4.

Do you know what the factory stall speed on the convertor is?

For your Tahoe or the Silverado with the 6.0? You could probably Google the year and configuration to find out. I know stock converters are generally mid- to upper-1,000s. A common and cheap converter for mild cams is a stock converter from a Trailblazer.

 

[Tonyrodz]

I was talking to a trans guy about the convert or the engine builder is going to use, think he said something like 2600-2800 stall circle d 9 1/2 inch, and the trans guy said it wouldn't need it. So I think it's best to go to the shop and talk to the builder directly. About what I'm looking for, performance wise, and we can go from there.