The intent here is not to do an all out port job for high horse power but to correct casting errors to optimize stock flow and to clean up other areas to make the engine less sensitive to gas octane requirements. One of the areas is port core shift during casting. Notice the intake port under the machined part of the throat where it is under the throat opening on the left but it shows a ledge at the right side of the throat. The sand core should have been better centered. Similar deal in the opposite direction for the exhaust. The job here would be to blend the machined area below the seat into the bowl area of the port for both intake and exhaust. Derek hit on some of these details in the last part of post #35 After doing sixteen of those if you feel more comfortable you may want to try some massaging around the valve guides. The reason for working the combustion chambers first is to give you time with the grinder, to get a good feel for it before attempting any work in the ports. You don't need to polish the chambers to mirror finish, just simply knock down some of the "Orange Peel" surface. This will help with carbon retention and detonation. Then please remove the boss next to the spark plug hole. It will give you practice doing heavier grinding. Details on technique later.
This is what I do. Clean up around valve, not really trying to change shape. Grind down valve guide some and smooth it into wall. Runner is just clean up. No opening larger. This is light to mild port. About 1/2 hour per valve with sharp cutters/grinders. I actually use a stone depending on where I'm working. Just my choice. But you really don't need to port if you don't want. There are cams that do work fine on stock heads. I personally have a used Crower level 3 I'm considering putting in my convertible 350, but then I would want to change out my 3.73 for 3.42 or 3.23 gears and pull my 2800 convertor for a 2000. And I don't think the sp3 is right for that cam either
Andys got the bowl shape correct. nice job. I've never removed the chamber lump. Your just lowering the compression.
If you are going for 9.5:1 compression ratio it simply means the pistons don't have to sit as far in the hole. If the heads happens to need milling then you recover the volume the lump displaced. That's why you do the heads first before completing the short block. You know the sequence as well as anybody. Do the head, pick the cam then build the shortblock to match. Paul
Well I got the motor pulled today and disassembled it down to the short block. Cylinders looked pretty glazed but I think they will clean up good. And holy crap that iron intake manifold is a hoss! The heads were pretty grimey also. I'd upload a few pics but I'm on mobile and they won't upload.
When you pull pan. You will see the oil pickup screen. I suggest you replace it . the new one is 5/8 tube so that should help get oil to pump. Also drill out the pickup passage in block to pump to 1/2 or if shop does it 9/16. That should help suction side of oil pump. Do not use the long gear hi volume pump . stock gears with booster plate should be fine. But change oil relief spring to 60 psi.
Ok guys I'm going to start on the heads here soon. Shooting for 9.5:1 cr and using the crower level 3 cam. Will I need different valve Springs for that cam or no? I'm having the machine shop do pretty much all the work on the heads and wanted to know if I needed to get new valve Springs for them to install.
You have a choice of using either the Crower 68405 spring or the TA 1130 spring They are real close to the same spec. If you set the installed height at 1.700" you will have 110 lbs on the seat and around 290 lbs open. Paul
Ok thanks! Another question, is it doable to do a valve job at home? Reading up on it it seems everything can be done except decking the head and refacing the valves. I would disassemble the head and take it to the machine shop to get it magna fluted and decked. And take the valves to get them refaced. But I could do the valve seals and grind the valve seats at home. Then of course lap the valves and so on. Sorry for all the questions, I want to do as much of this myself, but at the same time I want it done right.
Yes get springs. Important to control valve float . if your specs are average like mine,with 340p pistons, stock 58 cc heads,.043 felpro head gaskets and .010 off block deck and squared you will have about 9.5. Mine has .020 off which puts mine closer to 9.7 . check post from Steve who recommends this cam. Gives some idea of his experience with the Crower. http://www.v8buick.com/showthread.php?292865-Next-step-for-my-350
Andy, have you done the math on your combo? I doubt your anywhere near 9.5. How far down are the 340 pistons and how many cc is the dish? If you were at zero deck and a 10 cc dish you might be close.
I thought for sure orielly had the kit on thier loner tool list but they dont. Bummer, I'll just have the machine shop do the heads.
I'm at .039 down hole( feeler gauge and straight edge) . estimated cc on dish from Gary farmers info. 58 cc according to shop after having valves done. I used both summit racing calculator and Wallace. Wallace was around .04 lower that summit racing
58cc chamber 10cc piston dish .043" head gasket 3.830" bore .039 deck 3.850" stroke I'm showing 9.68 compression ratio.
Most shops will not take as much time and care as you will to get the valve job done right especially the valve stem height. It is easier for them to cut the top and bottom angles then the 45 till the width is correct without regard to the valve height than to cut the 45 so all the valves are the same height then work the bottom and top angles so the seat is positioned correctly on the valve head and the correct width.
So what's a good game plan for the heads then? I was going to use the 68405 springs and take them and the heads to the machine shop and have them do the valve job, ect. And have them deck the heads just enough to get them straight. Then once my heads are all straight I can begin to take all my measurements to determine what I need to do to the block to get to my 9.5:1 cr
