hi

i have 799 heads bought it before a month ,

my engine is LM7 2004 iron block , i plan on take the 862 out and put 799(243)
instead , my cam no# 231\239 617\621 113LSA . i put with it a set of PRC dual spring 660 kit and chromo pushrod 7.4 , LS7 lifters milling oil pump C5r timing chain ,

i know i have to mill at least 0.30 to restore stock Cr , i want to rise my cr to 9.9.1 or close to it ,

i am afraid i will face PTV issue or overheating with extra milling (0.40)

what do you suggest i do to get to my goal ? and which gasket to use ?

thanks a lot

 

Cometic stock style gaskets.
I wouldn't go more than .030 with that cam. More important than max lift is going to be valve events being radically different with that much duration and change in the LSA. You should test for PTV either way with that cam and heads combo.

 

I would also check pushrod length when you do get everything back together and not just toss the 7.4s in

 

thanks a lot guys

 

We mill 243s .020" for our Torquer cams which have low 230s duration and .030" for our 228R. I wouldn't go much more than .015"-.017" with a 231/239 to be honest with you.

 

thanks beau , that is valuable info
appreciate it

 

 

those heads will be put on hold for some time ,

yesterday we completed cam tuning after i left for home something happened with check engine light blinking all the time exept when braking or stopping ,

i checked pcm for faults and nothing came up , oil pressur is perfect
there is a sound similar to broken piston and it only appear on low rpm ,

if anyone have or faced similar problem please do tell

 

Flashing CEL is random misfire detected. May want to check plugs, wires, coil pack connectors. I also got the dreadful flashing CEL when I had a bad injector connector that was coming loose.

 

it's a 2 plugs on the passenger side one burning and the other is toost change them and it's all good , thanks now the truck run great random misfire on idle but it's okay with this big cam .