I have a 4.8 RC Silverado with a head job port and polish milled .025 heads 2 angles valve job,because no more money for bigger valves, patriot dual gold springs 7.4 hardened pushrods 225/229 581/591 cam 3.73 rear end,Nelson tune.I race already with 5.7 hemis, a friend with a 2004 ss even a guy with a stock 93 camaro Lt all of them got with my little 293.

 

I'm sort of new to the engine building side of having a fast truck. I'm learning everything as I do it with the help of a friend who is a GM mechanic. I have a 05 ext cab z71 with a 4.8 and I just installed a cheatr v3 cam, 317 heads milled .05, a GM performance throttle body 82 mm. Tomorrow I'm putting on the pacesetter LTs. Then I have to get it custom tuned. I didn't know much about the heads except they would flow better, but now it seems even with them milled my combustion chamber is still going to be slightly larger thus I will loose compression.. is there any way to compensate that? My thoughts were to get larger injectors Since I'm getting more air I need to add fuel maybe spark to but I have heard that the ac delco plugs are great. I would like to also get a stall converter but I just rebuilt my trans with a HD converter intercooler and a valve kit. I'm starting to think that after all this money in to it I am not going to be that impressed just because my dumb *** listened to a friend about these heads and how well they will flow. I'd appreciate all the info that anyone wants to share. Thanks. Oh and I have a 3.73 rear.

 

loose those 317s, that 4.8 needs higher compression, not lower. i have a set of ported 706 heads(4.8/5.3) that ill let go for cheap. those 317s are gna hurt ur performance. get the circle-d 278mm stall, get a 3k, i think Chris sells them for $375. and i highly highly suggest a wheatley tune. he is local in houston. tell hin Kasey sent u. any questions, pm me.

 

good advice right here

 

thx bud

 

Look for those heads706 or 862 if you want compression, they are the smallest chambers more copression. if you milled at least .25 with 0.51 head gasket compressed like .41 the compression will be 10.49:1 (+-). Tune the truck, will be other truck. dump those 317 heads! I'm not shure if the intake valves on 317 heads are 2" but if not like 1.89" 706-862 heads 3 angle job will help.:

Small chambers= more compression.