Orange Peel

iTrader: (20)

I'm planning to add some PRC heads, with the bigger valves, etc. I run the LG G5X4 right now, I will need to call them to figure out how much I need to flycut the pistons, etc.

I want to get around a 10.8:1 compression ratio, not sure if I can go higher due to only having junk 91 octane here in AZ, plus it's HOT!! What do you guys think?

As far as milling, should I mill them, how much, etc? What gaskets do you guys recommend, I read a lot about people using Cometics, what makes them better than the GM gaskets?

I will be going with Comp R lifters (part #875-16) to replace the stock lifters, are they the right ones to go with?

I will most likely just go with the ARP head bolts, not studs, not sure if I want to try to fit the heads in there with studs, not to mention they are more expensive than the bolts.

I have hardened pushrods already and will have the PRC titanium spring kit on the new heads. So the top end should be VERY nice, I will be looking into the Katech rod bolts, as my motor has 95k miles on it now, but runs VERY strong, and I take care of it very well, full synthetic since startup from the factory.

What else should I be looking at? Thanks for any help!!

Orange Peel

iTrader: (20)

someone please

jrp

iTrader: (16)

well what casting are you planning on getting? i used an .045 cometic to set my quench where i wanted it. skip the Comp R's unless you plan on an adj. rocker. go with the 850's (an oem replacement).

Orange Peel

iTrader: (20)

They are the 5.3l heads from PRC, I may just skip my custom set from him and go with the stage 2.5 to save some money. Why use the Cometic gaskets over the GM ones, are they thicker? What does quench do for you, I have been reading and seeing this term a lot. I'm not sure how much I need to flycut with these heads, how will I know that?

Thanks for the advice on the lifters, that's what I was wondering, what was the right one to get for our cars.

What would it take on the milling to get a 10.8 compression ratio? Doesn't the 5.3l heads already bump compression over the stock 853 castings I have?

Thanks dude!

Beast96Z

iTrader: (21)

The 5.3 heads have about a 63cc combustion chamber stock. I would not mill them at all, and run a .045 cometic gasket. Most people go with the cometics to get your quench right. No one else makes custom gaskets for our cars, so were stuck with there high price. Quench is the area between the top of the piston and the deck of the head. Setting it up correctlly provides optimal burn in the combustion chamber. Anytime you get the best burn, you make the most power. There isn't much reason to go with the cometics other than the quench issue. Not milling the heads and running the .045 gasket will get you close to 10:8:1. If you gunna be flycutting, I'd go ahead and take some extra incase you ever want to run a bigger cam. I'd prolly do .080 deep.

jrp

iTrader: (16)

depending on the final chamber volume of thee 5.3's i woudnt mill them at all, should be able to hit 10.8 unmilled with a stock gasket.

the .040 and .045 cometics are thinner then the stock MLS gaskets, hence why they raise your CR and reduce quench.

as far as fly cuts i'd hit up Louis and see what type clearances they've found with the X4 and milled heads and i'd also measure ptv clearance as well.


http://www.popularhotrodding.com/tec...power_squeeze/

Orange Peel

iTrader: (20)

I would like NOT to have to flycut, but with the G5X4 cam that's inevitable now with heads, so I don't care what I need to do, as long as it works and is optimal. So no milling, and those Cometic gaskets would be the best setup then? What would a stock GM gasket and not milling get me for compression? I tried to call LG yesterday and it was too late, they were closed, I plan to call them tomorrow and see what they say about the PRC heads and the X4, what I need to do, etc. I plan to measure anyways, but if I'm not milling the heads, and the gaskets are the only thing bring the head down and closer to the pistons, I would only need to flycut as much as the difference the Cometics take away from the stock setup right?

Thanks for the info, I NEED this