sierra ss Posted March 2, 2009 Report Share Posted March 2, 2009 Im going to do a P&P / valvetrain upgrade and was wondering which heads would be better to go with, 5.3 or 6.0 heads. I am not new to working on heads or valves(grinding) taught by my cousin in law who has built racing engines for years. I can get a set of either one for 200-300 $. If i went with the 6.0 heads i was going to have them milled as much as possible or go with 5.3's and polish the chamber to lower the CR some and be able to run stock length push rods. Would the CR be too high running the 5.3's. Im trying to go the cheapest route with this, reason for doing this myself instead of going with new or aftermarket heads. Quote Link to comment Share on other sites More sharing options...
02orangepeel Posted March 2, 2009 Report Share Posted March 2, 2009 (edited) id go with the 5.3 heads smaller chambers equal more cr youll be right around 11.1 with the 5.3 heads and that is still driveable on 93 pump gas as long as your tune is set up right thats if you go na if you want to put a blower on sometime down the road id go with the 6.0 heads and just get the ported thats my input. btw if you want some good input on putting 5.3 heads on a 6.0 id ask zippy he did it on his wifes tahoe results were pretty good. Edited March 2, 2009 by kurt (see edit history) Quote Link to comment Share on other sites More sharing options...
2003_SuperSport Posted March 2, 2009 Report Share Posted March 2, 2009 Im going to do a P&P / valvetrain upgrade and was wondering which heads would be better to go with, 5.3 or 6.0 heads. I am not new to working on heads or valves(grinding) taught by my cousin in law who has built racing engines for years. I can get a set of either one for 200-300 $. If i went with the 6.0 heads i was going to have them milled as much as possible or go with 5.3's and polish the chamber to lower the CR some and be able to run stock length push rods. Would the CR be too high running the 5.3's. Im trying to go the cheapest route with this, reason for doing this myself instead of going with new or aftermarket heads. Use the stock 6.0 heads from the sss. Thats what I am running. I took the heads and ported and polished the ports. I also milled them a little more than 10 thousands. You won't be disappointed trust me. Don't forget to resurface the valve seats. With my cam and comp springs. I am running in the upper 11's for compression and when she starts up you will really here how tight she is. My truck came alive and you can almost hear every cylinder popping. The only thing that sucks a little is when I start her up cold. The SSS has a hard time idling on 92 octane and I have to keep here goin a little with the gas pedal like a old muscle car. Once she's warm she runs top notch. Or if you want to spend $4.50 a gallon on some av fuel or racing fuel like I do she will pop and run like a raped ape and idle nice and hyper like. With the AV fuel though make sure to put in some gaskets that wont deteriate and cut your cats out. Good luck bud with it but but if its done right you'll love it. Quote Link to comment Share on other sites More sharing options...
sierra ss Posted March 2, 2009 Author Report Share Posted March 2, 2009 So whats the most you can mill the 317 heads? Thought about going 30 to 40 thousandths and running a ls6, hot cam or asa cam. Quote Link to comment Share on other sites More sharing options...
2003_SuperSport Posted March 2, 2009 Report Share Posted March 2, 2009 So whats the most you can mill the 317 heads? Thought about going 30 to 40 thousandths and running a ls6, hot cam or asa cam. Mill out and port your chambers to whatever your looking for. Just be careful on how much you cut the flat surface area of the heads. 5-10-15-20 thousandths it starts to cut alot away. I'll double check with my machinist on my cut of the head face cause i am not all that sure on what he cut mine. All he said was this should make her bark. LOL I have some before and after pics of my heads on here somewhere I'll find them and show you the link. Quote Link to comment Share on other sites More sharing options...
2003_SuperSport Posted March 2, 2009 Report Share Posted March 2, 2009 Go to waiting room look on first page under engine build and the second page half way down are two pics before and after heads that i had done. Quote Link to comment Share on other sites More sharing options...
2003_SuperSport Posted March 2, 2009 Report Share Posted March 2, 2009 (edited) Here is the pics bud. Edited March 2, 2009 by 2003_SuperSport (see edit history) Quote Link to comment Share on other sites More sharing options...
shadowsniper3006 Posted March 2, 2009 Report Share Posted March 2, 2009 Use the stock 6.0 heads from the sss. Thats what I am running. I took the heads and ported and polished the ports. I also milled them a little more than 10 thousands. You won't be disappointed trust me. Don't forget to resurface the valve seats. With my cam and comp springs. I am running in the upper 11's for compression and when she starts up you will really here how tight she is. My truck came alive and you can almost hear every cylinder popping. The only thing that sucks a little is when I start her up cold. The SSS has a hard time idling on 92 octane and I have to keep here goin a little with the gas pedal like a old muscle car. Once she's warm she runs top notch. Or if you want to spend $4.50 a gallon on some av fuel or racing fuel like I do she will pop and run like a raped ape and idle nice and hyper like. With the AV fuel though make sure to put in some gaskets that wont deteriate and cut your cats out. Good luck bud with it but but if its done right you'll love it. how did you figure your compression ratio is in the upper 11's. if i remember right 1cc is around .005 of decking so your running around a 70cc head, and i assume .051 head gasket. Quote Link to comment Share on other sites More sharing options...
Krambo Posted March 2, 2009 Report Share Posted March 2, 2009 (edited) The only thing that sucks a little is when I start her up cold. The SSS has a hard time idling on 92 octane and I have to keep here goin a little with the gas pedal like a old muscle car. Once she's warm she runs top notch. Or if you want to spend $4.50 a gallon on some av fuel or racing fuel like I do she will pop and run like a raped ape and idle nice and hyper like. Your idle tuning is off if this is the case. My 11.5:1 CR, big cammed heavily ported 243 headed 408 will start instantly and idle nicely hot or cold. With a computer controled EFI motor, its all about control of the motor through tables and numbers in the PCM. If you need to flutter the throttle to keep her chugging, more attention to the tune is in order. Mail order tuning a cam and heads motor is difficult to blindly hit spot on. Scanning and tweaking is really the only way to get runing like a top. Tell your tuner the symptoms you are having and I am sure you will be idling great after another flash. Edited March 2, 2009 by Krambo (see edit history) Quote Link to comment Share on other sites More sharing options...
shadowsniper3006 Posted March 2, 2009 Report Share Posted March 2, 2009 (edited) based on what TEA told me, they don't like to take 317's past 67-68cc due to possible intake bolt problems. So based on that around .020-.025 max cut. My heads are decked .015 and i used a .011 thinner head gasket and i had no problems....yet As far as what heads to use, i like compression so i would lean towards the 5.3 heads but i would check flow rates and runner sizes before i made that call. Edited March 2, 2009 by shadowsniper3006 (see edit history) Quote Link to comment Share on other sites More sharing options...
sierra ss Posted March 2, 2009 Author Report Share Posted March 2, 2009 (edited) based on what TEA told me, they don't like to take 317's past 67-68cc due to possible intake bolt problems. So based on that around .020-.025 max cut. My heads are decked .015 and i used a .011 thinner head gasket and i had no problems....yet As far as what heads to use, i like compression so i would lean towards the 5.3 heads but i would check flow rates and runner sizes before i made that call. Tough desision, flow or compression? What would that bump the CR up to on a LQ4 milling the heads to get to 67 CC and running a thinner gasket? Edited March 2, 2009 by sierra ss (see edit history) Quote Link to comment Share on other sites More sharing options...
shadowsniper3006 Posted March 2, 2009 Report Share Posted March 2, 2009 there are to many specs i don't know for sure to give you the absolute CR. If i did it right around 10.9:1. No piston reliefs, zero deck hieght, aftermarket .040 compressed gasket, 67cc head, 4.0 bore, 3.622 stroke. i thought the denali had the lq9 in it? http://www.rbracing-rsr.com/compstaticcalc.html Quote Link to comment Share on other sites More sharing options...
sierra ss Posted March 3, 2009 Author Report Share Posted March 3, 2009 i thought the denali had the lq9 in it? No the 2001 C3 and 02-04 Denali's had the LQ4. For 05 or 06 cant remember which the Sierra Denali was only avalible in a crew cab but then they had the LQ9. Aint that a b*^ch, better engine but bigger truck. Quote Link to comment Share on other sites More sharing options...
sierra ss Posted March 3, 2009 Author Report Share Posted March 3, 2009 Found this site and its pretty cool. Been playing around on it trying out different combos to get the desired CR that i want. http://www.race-cars.net/calculators/compr...calculator.html Quote Link to comment Share on other sites More sharing options...
sierra ss Posted March 4, 2009 Author Report Share Posted March 4, 2009 So i can get the CR im after by using headgaskets 0.041 thick and having 5.3 heads milled 0.20. But is the loss of CFM's worth the increased CR? Quote Link to comment Share on other sites More sharing options...
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