ls1runsthis

Currently have a 03 gmc ext cab5.3 with a 224/230 114 lsa cam longtubes full exhaust 373s and 3200 stall 125 shot . Was thinking about swapping my heads for some 243s worth it ? Thanks in advance

53bowtie

iTrader: (6)

If you already have them then yes I think it would be worth it as long as you have them milled to retain your compression or even bump it up a little.

ls1runsthis

At the moment I do not have them but I need to swap my lifters and might aswell change my heads how much should I get them milled ?

GM_Devil

iTrader: (2)

Mine I just put on couple days ago are milled .040 and I'm using a .040 thick gasket so my C/R is around 10.2:1 also used 7.350 push rods

53bowtie

iTrader: (6)

Do this ^^^ Your nitrous will love the extra compression.....

batboy

iTrader: (6)

Milling 243 heads .020" will put you about at the same CR as the 5.3 heads. Not sure I'd go more than .030" which would be about 59cc chambers.

ls1runsthis

Are you running any nitrous on it ?

ls1runsthis

Just keep hearing that putting stock 243 will actually make less power than my stock heads now .

batboy

iTrader: (6)

The 243 heads flow a little better and have bigger intake valves, but unless you mill them, it'll lower the compression ratio compared to the 5.3 heads. So, not much advantage unless you mill the 243 heads (assuming you're N/A). The 243 heads really come alive when ported though.

GM_Devil

iTrader: (2)

No sir

dunno why you say no more then .030, out of the hours of research i did, people have gone more then what mine are milled to and have been fine, i bought the heads premilled, i wanted .045 but i just didnt feel like sending them in for another .005 so i settled with .040.