96s-10ss

iTrader: (16)

what is the largest intake and exhaust valves you can put in a 862 head? I want to go bigger on both intake and exhaust but dont want to change out seats. any input is welcome!

96s-10ss

iTrader: (16)

these are going on a 3.905 bore ls1

KCS

iTrader: (20)

The seats themselves are 2.02" on the intake, so that's about the biggest there. Not sure about the exhaust though

96s-10ss

iTrader: (16)

hmmm. looks like ill just run a set of 241s

wildcamaro

iTrader: (15)

I would run ls6 heads because you won't those that much compression and you will get bigger ports as well as bigger valves, especially on an ls1 bore...the heads are like 350....compared to the prob the same price for new valves and valve job...that's how I look at it anyways

odarabla

iTrader: (1)

I was always told not to touch the exhaust valves. I have a 402ci LS2 in my car with some TFS215cnc heads opened up to 4" bore. We also did a valve job on the heads and installed bigger intake valves. My TFS heads came with 2.040 intake valves and we installed 2.055 intake valves but kept the exhaust valves the stock size.

Remember you can always lean on the cam to get the air in the motor to rather than installing bigger valves which is why I have a 246/255-607-632@113+2LSA cam. Car runs like a top and has gone 10.39@129mph full weight first pass right off the trailer. 3540lbs race weight.

There is still more left in my setup once my motor loosens up some and I get the anti sway on the back..

96s-10ss

iTrader: (16)

yeah. the ls6 heads are a lil pricey for what im doing. this motor is going in my nitrous gto. 241s are cheap and I plan on having them ported and completely rebuilt. imo ls6s arent worth the extra cash right now. next year I will be building a 4xx ci motor and ill go all out on the heads for that motor.

does anybody know the intake and exhaust runner cc difference between the 241 and 862 heads? I know the intake cc on a 241 is 200cc but im not sure the 862 is that big...

wildcamaro

iTrader: (15)

All ls1 heads have the same size intake and exhaust ports and valve sizes, the only difference is the 241 have a better casting procedure making the ports cleaner

2002silverz28matt

If you are planning on porting and rebuilding a 241 head, or any head for that matter, it is NOT going to be cheap. I would look into maybe an as cast TFS 220 head or a Stage 1 PRC LS6 head, you would have about the same money in it and it would be new, ported, and come with upgraded springs

96s-10ss

iTrader: (16)

this is a 5.3 head. thats why im wanting to know if there is a difference.

ive had 3 sets of ls1 heads rebuilt. my bill including parts and machining is always right around $550.

EricYJ-TA

iTrader: (10)

If you put bigger valves in the head would you have to have the valve seat machined for the new valve?

wildcamaro

iTrader: (15)

Yea they have to be grinded in

chrisfrost

iTrader: (8)

The LS heads are not all the same ,,,,,,,,,,,,,but the 862's and the 706's are 200cc intake runners also with 70cc exhaust runners ,,,,,,,,,,,if You look at the stickies up top of this forum alot of the heads and runner sizes and combustion chamber sizes are listed . Think about the valve seat for a second ,,,,,,say You put a 4" valve with same seat how would it flow,,,,,,,,,,,the same as with the smaller valve with more shrouding ,,,,,,,,the inner diameter of the valve seat is the restricting force .