Poundz9oh9 Posted January 13, 2005 Share Posted January 13, 2005 OK, heres the deal I have a rebuilt 86 up block bored .030 over with rebuilt Vortech heads. The heads or block were not surfaced. The builder used 1.6 ratio roller rockers. Now there has been some concern with why the 1.6's were used. I have heard that I may run into problems with the valve clearance. The pushrods were left with 9 thousandths clearance at the rockers. Now the concern is, if I tighten them down to where they're supposed to be will I have any problems with the valve clearance? Is there anyway to check without pulling the intake and heads off? Quote Link to comment Share on other sites More sharing options...
Guest 77vegasz Posted January 13, 2005 Share Posted January 13, 2005 Make sure that the cam used has hydraulic lifters. If it is a solid lifter cam, some lash clearance is necessary to accommodate thermal expansion as parts war up. The manufacturer will have the correct lash setting for the cam. Also, stock Vortec heads have a lift limitof around .500 or .550, I am not sure, but any GM parts dealer can verify. You need to know the cam lift at the lobe, times the rocker ratio, 1.6 to get the actual valve movement. If this is within the lift capability of the Vortec heads, valve to piston interferance can be checked by cranking the motor over by hand. If it cranks over fine with no binding, there is no interferance, and the motor should operate fine. To determine actual clearance, you have to take a head off, place some putty in the valve relief, reinstall the head, crank over by hand, remove the head, and measure the height of the compressed putty, crude but effective. Jon Quote Link to comment Share on other sites More sharing options...
Tim240z Posted January 13, 2005 Share Posted January 13, 2005 Stock Vortecs are limited to about .410-.420. With the upgraded valve springs you can push them to about.510 Unless your cam is very very timid, there is no reason to band aid the valvetrain by using 1.6 ratio rockers....also, make sure that they are self-aligning rockers. Quote Link to comment Share on other sites More sharing options...
Poundz9oh9 Posted January 13, 2005 Author Share Posted January 13, 2005 Ok, more specs. They are self aligning and this was an excerpt from one of my email questions to the guy. "The factory specs for Hydraulic Roller,is a 0.474"/0.510" lift with a 1.5 rocker arm, with the addition of our 1.6 rocker arms corrected lift #'s are 0.506/0.544. 208/221 degrees is factory specs, and with the 1.6's there would be a slight duration increase also" The valve springs are "new Z28 springs set at 100 lbs of seat pressure" And was told it's a "ZZ4 roller cam kit" Oh, and looking through the old emails I found this little tidbit too when I asked about how much was taken of of the block. "the deck was just cleaned off on it, probably approx .010, and the the gaskets are .039. the .039 is 9cc's. Thanks" Quote Link to comment Share on other sites More sharing options...
dr_hunt Posted January 14, 2005 Share Posted January 14, 2005 The z-28 springs had a limit of .510 lift or so depending upon installed height. From the sounds of it, 100 lb on the seat the builder may have increased the installed height as they usually have 110lb on the seat. So, with 1.5's you should be alright, 1.6's I don't think so IMHO. Quote Link to comment Share on other sites More sharing options...
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