I have a 4.060 bore motor with 5.7 stage 2 heads. The valves are 2.02/1.60 and heads have been ported. I keep reading on sponsors sites about heads "fitting" up to a 3.90 bore or 4.030 and so on without really defining what this means. What does Fitting a specific bore refer to and I know my heads are set up for a 3.90 bore and not a 4.060 what happens?

I know this maybe a simpleton question but I just dont know enough about heads.

Thanks in advance

 

it basically means that the combustion chamber has been opened up to match a larger bore. if you measured across stock heads you would find that the 5.3, 5.7 and 6.0's all measure a little different across due to the different bore sizes they fit on. when going from a 3.900 to a 4.060 it is usually recommended to open up the combustion chambers to match the bore.

 

because when ever you open up the bore size of the chamber you unshroud the valves and the heads flow better.

 

We currently do custom chambers on our LS6 style heads for 3.905", 4.00", 4.030", 4.060", 4.100", and 4.125" bores. These chambers are available at no extra charge.

 

Thank you all. That makes more sense. I really appreciate the info and will be buying heads from one of our LSTech sponsors. As soon as the warden clears the funds...LOL