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I understand the deficiencies of the stock springs over time and if I was to rebuild this head for the purpose of producing more power I would buy some aftermarket springs. But I just want to get this thing back together and running with the possibility of building a better prepared engine to be swapped in later. I miss driving it and don't have the funds to do it the right way at this time.
My thought was to shim the stock springs to increase the valve seat pressure and offset some of the loss in tension from their life so far. But I obviously don't want to shim them to the point of binding. Hence my question.
I just squashed one in my vice and got a bind height of 1.102. Does this sound right? Have I measured this correctly? Is there another method?
THANKS FOR THE ADVICE RYAN!!!!!
And tectic I have read as many post as I can find from BogusSVO here and on DSMTuners. He's a good man and provides great info, I would welcome him to chime in on this post.
I get that the stock springs lose tension over time. I also understand that shimming valve springs is one of the most common and preferred methods for achieving adequate seat pressure and installed height at machine shops. So saying that it is "very bad" without qualifying it doesn't mean much.
I have measured my valve springs and get a free height of 1.878, with the FSM listing 1.866 as the service limit and 1.906 as the factory spec.
Based on my installed height of 1.575, the stock cam lift of .252 and the coil bind that I measured of 1.115 this leaves .208 of free spring travel at full lift. I could use a .030 shim and still have .178 of free spring travel before coil bind. adding .030 on my 1.878 free height would put me at 1.908 free height which is bang on spec and should equate to better seat pressure without the risk of coil bind.
Not sure if you care but thought I would let you know. I've decided to go with the BC1100 valve springs. This choice came about after putting in many hours of porting and polishing work on the head, it would be a shame to increase boost and lose that benefit due to soft springs.
There was also a key calculation I left out of my previous post which is the rocker arm ratio (1.7?) which actually leaves very little room for shimming the stock spring before hitting coil bind.