Lt1 heads

[rccola01]

I watched it on the speed channel and One of my bodies already did a self home job of ported and cleaning his own LT1 heads. Is it possible to do this? And at what degree wider than the stock opening?
Or would the Lt4 heads work better.
Also was looking to change my rocker arms on my 94 lt1 with a 1.6 rr arms which would you recommend and the price at which would be fair.

[Craig 94 TA GT]

As far as rocker arms, I recommend the Comp Cams Pro Mag rockers. The 3/8" ones are for stock studs, but why not go for 7/16" since the threads inside the head are already for a 7/16" stud. You would need to buy new 7/16s studs if you go that route. If you get the non-selfaligning, you will need hardened pushrods (CC Hi-Tech Chromemoly) and GM guideplates installed between the stud and the head. Personally, I'd recommend the options mentioned...haven't had a problem with them and installation wasn't too bad.
Also, you will need better springs due to potential coil bind. A decent, cheap set is the LT4 springs...good up to .540 lift, if I recall correctly. Lastly, if you don't plan on changing your valve covers, you will need to flatten out the supports inside. The Pro Mag rockers are a bit too fat, so the supports get in the way.

[Joe 1320]

Porting is a skill that you better practice on a set of junk heads first. The problem is that the ports must end up flowing a uniform amount or you will have unbalanced airflow. What you want to clean up is the bowl area directly under the valve, the runners and the physical port. The combustion chambers should be smoothed to eliminate any rough edges. The problem is those last couple of sentances could be expanded to fill a book. Let's start with the combustion chamber.....

Smooth the area but do not remove much material or you end up changing the volume and that means a lower compression. Your goal is to remove any rough edges that will contribute to hot spots and the cause of pre-ignition. This is what perople refer to as polishing the combustion chamber. It's not critical, but while you're there you may as well do it.

The bowl area under the valve can be opened up and any casting flash or high spots are removed. Typically the circumference can be enlarged a certain amount that ends up being much closer to the valve seat. All intake bowl openings must be uniform in size (use a caliper to measure) and all exhaust bowl openings must be uniform. The interior contours are smoothed and the area around the valve guides are cut down to more of a cone shape and a smaller dimension, aiding flow.

The intake and exhaust runners are smoothed and any rough edges removed. Here's where things get tough.... you can't start removing materiel without knowing how much to remove or airflow will not be uniform. Professional shops have a flow bench so that they can constantly check their work. At home, I would stick to polishing the runners. You can port match the intake and the heads by bolting down the intake and exhaust gaskets, scribing lines or using machinist's die and grinding the port size to match. Don't go wild or again, you can mess up the flow. What your goal for the home port job is to merely clean up the flow by eliminating any flow disturbances due to casting flash and production variances.

this is not a game for the faint of heart. Trashing a head is pretty easy, but I hope this helps somewhat.