Guest Posted April 24, 2002 Share Posted April 24, 2002 Hi Don, I have a few more questions. I'm looking at Keith Black Silvolite Hyp. pistons and having trouble determining what size and what size push rod. Also the Vortec head specs on GM's site says a max cam lift of .475 and the xe468h comp cam lift is like .490 will this effect push rod length? I'm confused Thanks, Don Link to comment Share on other sites More sharing options...
Guest Posted April 24, 2002 Share Posted April 24, 2002 Donny, you will have to change the valve springs, there are several companies that make a .600 lift drop in spring, look on www.competitionproducts.com. the are about $80 a set and is a good sring. pushrod length has nothing to do with lift directly it's all in the geometry. for a real mild deal like your building a stock 7.8" pushrod should be fine. as for the pistons are you having it bored .030 over? are you reusing the stock rods? if the answer is yes to both then you need .030 over for the 5.7' rods. Don Link to comment Share on other sites More sharing options...
Monte Posted April 25, 2002 Share Posted April 25, 2002 Donny rice is correct on the length size 7.8 should be right. However if you want you can buy a push rod length checker for about 15 bucks and check it. I will copy an old post from a while ago which will give you some direction on a "basic" way to check your geometry. The post may read a little funny as It was an answer to a different question. Monte You can get rocker splash guards from the local auto store which will keep the oil from going everywhere. Not all splash guards work with roller rockers. Take a rocker with you to make sure you can get it on. Mine are super super hard to get on but they do work. Also before you install all of the roller rockers. You need to check your rocker geometry. Many roller rockers depending on design can change your rocker geometry. This also is effected by how much lift your cam has. The tip of the rocker arm should ride close to the center of the valve stem during the lift. If the tip of the rocker rides on the outside or inside edge of the stem you have a geometry problem and this can lead to stress on the value and failure of the valve or the valve guide. You can buy a push rod length checker that is adjustable so you can determine the proper length push rod for your set up. The correct length push rod should allow the tip of the rocker to travel in the center of the valve stem during the opening and closing of the valve. The rocker tip will travel a little toward the outside edge of the stem and a little toward the inside during this process but most of the time should be in the center section of the valve stem . Again if the rocker tip rides from outside of the valve stem to the center or inside of the valve stem to the center you have a geometry problem. You also need to check the clearance between the stud and rocker at full lift. Some roller rockers can bind on the stud at full lift. It is sometimes hard to see as it will usually bind on the bottom side of the rocker toward the tip of the rocker. Monte Link to comment Share on other sites More sharing options...
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