Question guys, I am completely redoing my heads. I am doing a cam swap as well, Crane 210/218 .551/.551 116 LSA +2 Advance, PAC-1218 Beehive Springs, PAC-R511 Ti-17 Titanium Retainers, PAC Machined Valve Locks, Comp Trunion Kit, Comp Hardened 7.425 Pushrods. I currently have ARH 1-3/4"x3" Headers with highflow cats with Corsa Sport 3" Catback, Airaid Jr kit and Blackbear In-Person 91 Tune.

I was looking into to, if its worth it, going larger valves. First question is I use this truck for towing and playing around here and there, will larger valves with a 5 angle valve job and a slight porting/Polish help in lowend at all?

I was looking into Ferrea 2.040" Intake Valves (Stock is 2.000") and Ferrea 1.575" Exhaust Valves (Stock is 1.500"), which I was told are the largest valves that will work with the stock seats on these heads.

 

I would just get a nice valve job done on the stock ones! That's all I'm doing... If anything I'm just gonna upgrade my exhaust valves to inconel. The stock valves are pretty stout!

 

Im sorry, I meant 2.020" intake/1.575" exhaust.

I am also looking at TSP PRC stage 2.5 head porting, which they well port to my specs and install said valve sizes.

I have been told it can be beneficial while doing a cam to increase valve size slightly ,depending on the head and engine size, which can gain 10-15 WHP. I do not know how true that is. TSP wants $750 if I provide the valves ($300 for Ferrea) of they can use REV or Manley valves and do it for $950.

 

With a cam that small and your use for the truck, i would just run a valve job and mill the heads for more compression. Bigger is not always better

 

I am at 9.6:1 or 9.9:1 Stock Compression ratio, I cant seen to find the correct answer on that. Should I go higher?

 

2.00 and smaller intake valves on the smaller bore of the 5.3 are the ideal setup.

The 6.0 and 5.7 are able to swallow a larger valve without creating a washout on the cylinder walls as happens on the 5.3

West Coast Cylinder Head believes in this practice as well.

**Edited, not sure what auto correct did on my phone. Either way I wrote it to make a bit more sense.

 

Im not sure what youre trying to say???

Larger valves on smaller bores can create shrouding issues where the larger valve comes close to the cylinder wall at peak lift and actually slows down the flow of air.

 

X2!

And for the Original guy is trying to do you won't see a huge difference.

Most put a 2.02/1.57 combo in a ported head.

Why? Because they can set the valve highet after a custom valve job. The slight over size allows them to do this.

If you're doing this on a 5.3L, I wouldn't go past a 2 inch valve for what you're trying to do.

 

Ok ill stick with the 2/1.55 valves. I will have a very slight port and polish done and install Manley valves since those seem to be the lighter than whats in there now.