The bottom line is.......How Deep Is Your Wallet?
The Butler rotating assembly is the best bang for your buck - all new lower end parts and beefier.
Changes I would want is the 3/4 grooved main bearings if these can be substituted.
Add ARP main cap studs, but this may mean the block will have to be align honed in using them. Much stronger however.
You can use the iron
#62 heads if you want, but keep compression around 9.0 ish for pump gas. Aluminum heads can go a point higher or so.
A.) You will have to order custom dished Ross pistons to drop compression with the
#62 heads. But, you don't want to order anything until you have rebuilt the iron heads (if you use them) so you can get an actual cc number for the combustion chamber. This is needed to get the correct dish cc's to get you where you want on compression.
B.) If you use the 1.6 rockers, several things may need changing. First, stock Pontiac heads flow good to about .470" lift and then fall off. Aluminum heads will flow more right out of the box.
C.) Using 1.6 rockers will give you a valve lift of about .534". May not do a thing for you unless you do some porting/bowl work - but you can always try them.
* The springs you currently have may not work - not enough open pressure at maximum lift or not enough pressure could cause a valve to bounce on the seat.
* Next, you could experience valve spring bind. So everything needs to be carefully checked for clearances.
* You may need to use the RAIV valves which are longer than the stock valves so you can use a taller spring that will not bind at higher lifts.
* With 1.6 rockers you will want to slot the pushrod holes so the pushrod does not bind/bend against the intake side of the hole.
* Install bronze valve guides - no cheap knurling of the guides.
* Get a 3-angle valve job.
* Install a new heater hose nipple at this time.
* Some like to install a hardened seat in the head for the exhaust valves. I don't, but my opinion & choice on this one. Aluminum heads will have seat inserts.
* You could save money keeping your lift where it is and using those parts already known to work.
D.) An important and overlooked item is "squish" or "quench." Included a diagram. Squish is the area between the top of the piston and bottom of the head. It is that flat area adjacent to the combustion chamber and is positioned over the piston. You want to get this area to "squish" the air/fuel mixture into the combustion chamber to aid in preventing detonation and providing a better burn. Too large a space here allows the air/fuel mixture to have enough area to ignite as the flame travels across the combustion chamber and that's where you can get detonation.
* Best distance for that space between the top of the piston & head is generally .045" - which is also about the same thickness of a compressed Felpro head gasket. BUT, Pontiac pistons can be .010" to .020" below the deck down in the cylinder. So a .045" head gasket plus the distance the piston is down in the cylinder, let's use .020" like my engine, makes the total squish distance .065". Will it work? Sure, its what the factory used. HOWEVER, this was the day of leaded gasoline where the GTO's used premium and the higher octane had a lot of detonation qualities so it was not so much a concern. Ethanol blends and lower octanes can be problematic and you want to eliminate all the variables you can so you don't get engine destroying detonation or have to retard your timing and give up power.
* So why am I telling you this? If you order custom pistons, you can order them with the piston pin hole moved to give you a "zero" deck height. This puts the top of the piston even with the top of the block (deck) and then using the Felpro .045" compressed gasket, you have a perfect squish area. If using a stock pin location, the procedure would be to mill the deck .020" which will then have the tops of the pistons even with the deck and then you use the .045" head gasket. I am not a fan of milling the block UNLESS you need to - it needs to be cleaned up due to warpage or pitting, or squaring up the block for race purposes. Milling the block can change geometry on other parts like the intake side of the head, or intake, or pushrod lengths. Mill the heads and this is amplified to include fit problems with the valley pan.
* The option I have posted many times here is what I did. My pistons are .020" down in the bore. I used a Cometic .027" head gasket ($100 each) for a total squish area of .047" which should be good and will tighten up slightly when the engine heats up. So it is right were I want it.
* This is my suggestion/opinion and option, and should be discussed with your machinist. Once he knows where down in the cylinder the piston will be (piston height), he could change the piston pin location on the custom Ross pistons you are going to need to have dished.
*So before you order a custom dished piston, you want to know what the head chamber cc's are and the piston height IF you want to move the piston pin at all.
E.) As already mentioned, you will want to check clearances between the larger throw crank and the pan rail.
F.) Other stuff:
* aftermarket hardened oil pump rod if you haven't alread got one - that factory pump rod should not be trusted.
* 1972 and later baffled oil pan. Butler sells them inexpensively. He notes some holes may need to be slotted. Worse comes to worse, I would remove the baffle from the aftermarket pan and install it in your pan as long as your pan is good. You can buy a baffled pan on Ebay, but they seem to be pricey.
* get the rear pan oil reinforcements if you don't have these. Butler sells them. They require a little longer bolt and you may have to go to the local hardware store and get some grade 8 bolts and trim to fit.
* I like a double roller timing chain and gears.
* I am using the Butler blueprinted 60 psi pump. A little pricey. If you don't want to spend the money, get the Mellings 60 psi pump and add Tin Indian's Super Duty Oil Pump Plates
Tin Indian Performance - New High Performance Pontiac Products I got this initially before Butler offered their pro oil pump in 60psi.
* see if you need the new stainless steel water pump plates and rubber inserts. Clearance the water pump impeller to plates as outlined here on the forum.
I think that should be good for starters. :thumbsup: