I have a 3800 SC series II that I have rebuilt with primarily ZZP parts. I hit a snag when I was installing the pushrods. So, here is what I have in the engine: XP cam, triple layer head gaskets, Std stainless valves, steel retainers, 136# springs, LS7 lifters, 1.65 rockers and 7" 3/8 pushrods. I got a adjustable pushrod from ZZP and did the steps to obtain the needed length of pushrod. I came up with 6 27/32" ? I ordered in 7" pushrods instead of the 6.95". ZZP statement spoke of the limited tolerance with LS7 lifters and 1/2 turn limit. My setup when tightening is over 3/4 turn. I have contacted customer support at ZZP for three days and nothing. The information on PFF has never let me down. I may be over reacting but, maybe someone can shed a little info on me. I am disappointed with ZZP. We spent a large sum of money with them and no, zero support.
I finally got a call from ZZP. The fellow said that they had conferred and they "Thought it would work." Their engineer was suppose to give me a technical reply in 2-3 days. Never heard from anyone. Not being a computer whiz, I will try typing the instructions here as they appear on the ZZP site: "How to determine proper rod length by measuring "Lifter preload"." To check for lifter preload or lifter squish you need to first get to zero lash. Turn the engine over so that one valved on a cylinder is open. Because one is open, you know the other is closed, meaning the lifter is sitting on the base circle. With that lifter on the base circle loosen the rocker bolt and then re-tighten with one hand while spinning the pushrod with the other. This way you can tell when everything first makes contact (the valve is touching the rocker tip, the pushrod is touching the rocker and lifter and the lifter is touching the cam). At this point of first contact you are at zero lash. Everything past this point is lifter preload. Continue to tighten the rocker tolt until this bolt hits its snug point. This is how much lifter preload you have. Each 1/2 turn of the rocker bolt is - .050 of lifter preload. Your goal is generally to have between 1/2 turn and 1.5 turns if you have stock lifters or 3/8 turn to 1/2 turn if you have Comp or LS7 lifters. As you can see the stock have more room to play. If you have too much preload and you have exhausted the adjustment of the lifter, the valves will stay open and the car will not start due to lack of compression. If you have too little preload, the valve train will bed noisy and you risk exploding a lifter and having a very costly repair." This is the instructions for determining pushrod length. Does this help explain my situation?
Originally posted by Bubblhd90: This is the instructions for determining pushrod length. Does this help explain my situation?
Well, no...
In your first post, you mentioned that you received an adjustable pushrod from ZZP. Normally, the adjustable pushrod's length is adjusted (by trial and error) so that the rocker opens the valve just right. You then order custom-length pushrods based on (but perhaps not exactly equal to) the final length of the adjustable pushrod.
The instructions you typed up make zero mention of an adjustable pushrod. So I don't see how you go from fiddling with lifter preload to pushrod length.
[This message has been edited by pmbrunelle (edited 05-07-2018).]
You are totally correct. I read the instruction to mean that I rolled the cam into the base circle for the closed valve that I would measure. I then placed the adjustable pushrod into position on the lifter and screwed on the rocker arm until the rocker arm bolt was finger tight. I then unscrewed the adjustable pushrod until it came in contact with both the lifter and rocker arm. I removed the rocker arm and measured the length of the pushrod. The measurement I get is 6 27/32" . In order to determine if a 7" pushrod is acceptable, I then adjusted the adjustable pushrod out to exactly 7". I followed the ZZP instructions and tightened the rocker arm down tight. I loosened the rocker arm and retightened the rocker bolt to finger tight. at this point I tightened the bolt and it is here where I got a 3/4 turn of the bolt which according to the instructions, should be no more than 1/2 turn to tight with the LS7 lifters. I think if the ZZP engineer would respond, this whole issue could probably be settled. I am definitely NOT inventing the wheel here.
Update on my dilemma. I translated ZZP's 6.95 measured pushrod into inches and went through the instructions and the tightening swing is just under 1/2 swing to tight. I am returning the 7" pushrods and have ordered the 6.95" pushrod set. This has been a "Simple/Stupid" moment for me and my apologies to the braintrust on PFF. I still haven't received a response from ZZP. They are probably still trying to diplomatically give me a response to a stupid question. Thanks again to everyone.
