I remember reading somewhere that I can install 2.0" intake valves from the LS1 in my stock 5.3 heads. The motor is from a 04 Suburban and its going in my 86 Regal project along with a T-56 and a 70-75mm turbo. I have already built the shortblock and Im using a 02 Z06 cam. I just wanted to do some inexpensive work to the heads while there off the motor. I figured I'd clean up the ports and bowls and get rid of any obvious restrictions but not change the shape of the ports. It seems (from what I've read) that the 5.3 intake valves are the major restriction in the heads so I thought if it was cost effective I would change them out. Could I just lap them in or do the seats need to be cut? I know I can get 243's for around $450 but its just not in my budget. Plus if I frag a piston and it damages the head I wont be ruining my nice heads that I just spent $450 on. Any input or suggestions appreciated.

 

Take the heads to a machine shop near you and they will clean up you head for around $130 and also make you intake valves bigger. I tried to port my own intake valves on an extra set of heads didnt work out that great...(f**ked them up)

 

Proper cylinder head work requires some experience and the proper equipment to do a precision valve job. There's more than just grinding seats and lapping valves. The valve seat angles are most important and are arrived at using a flow bench, dyno and track testing. On the porting side, in the case with the 5.3l heads the intake ports need only minor work to help elevate power across the band. The same thing can be said about the exhaust ports too.
Remember, you get what you pay for. Cheap has it's price.

Good luck,

Richard

 

So am I better off just leaving the valves alone and cleaning up the ports and bowls with some cartridge rolls? I do understand the importance of a correct valve job I was just trying to find out if the statement about the larger valves was true or not. Id like to at least clean up the heads some before I just throw them on the motor. I know if I was porting them and changing the geometry of the runners and bowls I would need to use a flow bench to see if Im helping or hurting but that is not my intention. I just want to increase the efficiency of an already decent part while I have the oppourtunity. I would appreciate any suggestions. At the same time, I dont want to near or exceed the cost of purchasing a better set of heads. Since I am an Auto Tech my tools and skill are availible as well as my time so Id like to use those if possible instead of my money.

 

Get a good reputible cylinder head shop to put them in for you. they will flow better.

 

I do have access to a good machine shop that we use at the dealership.

Here is my planned course of action
1) polish chambers with emory cloth and scotchbrite (to prevent detonation and carbon buildup)
2) polish exhaust port and bowl (to promote less turbulence and prevent carbon buildup)
3) clean up intake runner and bowl with a moderate abrasive (to leave a slightly abraded surface not a polished finish because I have read that that is the desired finish for an intake port)

Advice please!

 

You can fit the larger valves. We use stainless steel intake valves that measure 1.940" instead of the overly large 2.00" valves. We find it makes a nicer fit to reduce shrouding by the cylinder bore.

Richard

 

That is a good idea given the small chamber of the 5.3 head. Is this valve an off the shelf GM part or is it aftermarket?

 

I'm sure it is aftermarket. PM richard@WCCH I'm sure he will help you put.

 

The valves we use are aftermarket made for us.

Richard