Bare or assembled
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Joined: Jul 2003
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From: Marysville, OH
Bare or assembled I did a search and found no answer to my question.
Would it better to buy bare casting heads (ported or unported) vs. assembled? I know that there is a price break associated with bare heads but is it worth it. PP has bare heads and SDPC has LS6 bare heads as well. If you bought bare heads you would have to have valves machined to match the seat correct? Would this cost of valve machining, springs, retainers, seats, seals, and valves overrun the price advantage of bare heads? I am thinking that the answer is "GO assembled" b/c these are the only 2 specific sponsors that I found advertising bare unassembled heads. Anyone go the bare head route?
Would it better to buy bare casting heads (ported or unported) vs. assembled? I know that there is a price break associated with bare heads but is it worth it. PP has bare heads and SDPC has LS6 bare heads as well. If you bought bare heads you would have to have valves machined to match the seat correct? Would this cost of valve machining, springs, retainers, seats, seals, and valves overrun the price advantage of bare heads? I am thinking that the answer is "GO assembled" b/c these are the only 2 specific sponsors that I found advertising bare unassembled heads. Anyone go the bare head route?
I went with the bare SDPC LS6 CNC heads.. They already have a professional valve job. You just need to lap in the stock valves.. I had never lapped in any valves before these heads and it's easy.. Just get the lapper and some compound from Napa for a few bucks.. I don't know what the guy is talking about with setting up the spring heights etc.. I went with the bare heads because I had plenty on stock valves, comp 918s.. I only had to lap the valves and put in new valve seals.. A buddy of mine polished out the CNC grooves and I picked up 40 hp with the SDPC heads.. 
Nope, it won't mess up the valve job at all.. It simply allows the surface of the seat and the valve surface to be mated well. The tool looks like a suction cup on a dowel. The compound you get needs to be fine and not coarse. The compound is an abrasive. You just dab some on your finger and put it around the valve where it seats on the seat in the head. Then place the lapping tool on top of the valve surface in the head and rotate vigorously. Think of starting a fire using friction with a twig by rotating in your palms ala boy scouts. Do it until you have a ring worn (cut by the abrasive compund) on the valve and the seat. You'll then know they will perfectly seal. Good Luck.. 
Do it until you have a ring worn (cut by the abrasive compund) on the valve and the seat. You'll then know they will perfectly seal. Good Luck..
Originally Posted by blk~2000~Z28
Will lapping mess up a valve job? What does lapping do to the "valve" to make it seal better on seat?
What part number SDPC heads are you using? the only one SDPC list is 12564825
this is just a bare ls6 head, no mention of CNC or porting or a valve job.
these heads are 589.50 each bare. this is better than absolute stg 1 (1200.00)
assembled heads? (by a pro no less) i stand by my orginal post..
this is just a bare ls6 head, no mention of CNC or porting or a valve job.
these heads are 589.50 each bare. this is better than absolute stg 1 (1200.00)
assembled heads? (by a pro no less) i stand by my orginal post..
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I don't know what the guy is talking about with setting up the spring heights etc..
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Verdad Gallardo i guess i should mention the reason for spring heights.
as denzss mentioned, valvesprings are set to a specified installed height.
now, valve spring pressures advertized are always given at a specific spring height.
doesn't matter for a lawn mower or a ls1.. fact of life.
this info is important for cams (valve float, cam wear, coil bind) the cam manufacture
will know what will work. given the springs are set up to that spring height.
(see where this is going?)on a stock cam i doubt this is of concern but on anything
else it should be given at least some thought.
as denzss mentioned, valvesprings are set to a specified installed height.
now, valve spring pressures advertized are always given at a specific spring height.
doesn't matter for a lawn mower or a ls1.. fact of life.
this info is important for cams (valve float, cam wear, coil bind) the cam manufacture
will know what will work. given the springs are set up to that spring height.
(see where this is going?)on a stock cam i doubt this is of concern but on anything
else it should be given at least some thought.