for a na 408 that will maybe sprayed once and awhile what do you guys recomend for heads? i want to keep it oin a budget so i was thinking 317 or ls6 heads but what work would be good to do to those two heads to build alittle more power over stock. and does anyone have info on the dart heads that are spose to be coming out?

 

The reason i'm building the motor is because im going to school for automotive and a take 12 weeks worth of engine building classes and during that time you can work on your own stuff and they encourge you to work on your own motor so I can do all the machine work for free port the heads i choose add bigger valves as long as i supply the parts and they encourage all of this. so i still have to pay for school but i want to do the motor when i'm in those classes so thats why i was talking about on a budget. and instead of a little power over stock i should of put more flow over stock. and for this motor if i see 400-425 rear wheel numbers from this setup i'll be perfectly happy.

 

have you considered using stock heads?

 

TEA has proved to be one of the best sponsors you can go with time and time again. Between their products, price & customer service they are hard to beat. I would say 400-425hp would be a pretty easy chore for a 408 with their heads and any kind of aftermarket cam.

http://www.totalengineairflow.com/pr.../gmhead/gmls1/

Ryan

 

Dart or AFR's 225's IMO.

 

go for the ls6 sounds like your gonna hand port em. I was gonna do that with my 5.3's then I got lazy and tired of having engine parts in the bathtub and kitchen. Im interested to know what they say at the school about hand porting

 

thats the plan use eather 317s or ls6 heads and hand port them then put them on a flow bench to see what it did. and i want about 10:1 compresion with some flat top pistons. and if you want to now what they say about hand porting ask fullthrottledan he went to the same school im going to.

 

i will say i put about 1500 miles or so on a 408 with stock heads and it drove just fine. with the converter stalling at 2400 i pulled off a 13.8 in a 5500lb truck including driver. shift points were only 5800 and 5600 for the 1-2 and 2-3. it's the torque monster you're looking to build.

 

My thoughts:

TEA, DART, AFR, even Patriot - these are not budget heads that you would want to modify yourself. TEA and Patriot will be pre-ported stock heads; DART and AFRs will be a completely new head design.

I suggest you start with stock 6L heads, add some larger valves, do a valve job, unshroud the valves, and give them a mild hand porting to remove the stock casting material. This way you start with an inexpensive good design and make them better while learning in class.

Flat top pistons and achieving 10:1 compression on a 408 will require either a large chamber or a valve relief / dish in the piston. You'll learn the math in school I'm sure.

10:1 compression is going to be a little low I think. I suggest you shoot for something between 10.5 to 11:1, which will run just fine on good pump gas and have no problems of detonation or pinging. The LS6/6L head design really works well with high compression and fighting off detonation.

Budget wise, I suggest you find a complete motor to start with. Look for a GM service pull motor that has some minor issues, since your rebuild will correct any problems. Cost wise, a used complete 6L will be the best deal compared to buying a block, heads, and the misc parts to finish it. Those little parts start adding up if you have to buy them seperately (covers, pan, reuseable bolts, lifter cups, rockers, ...).

 

i would stay with a set of stock heads as big tex said either the ls6 or the 317s.