Brian'sCharlotte(TA)

iTrader: (2)

Okay so I'm doing the l92 head swap on my lq9 and have everything together but i'm having a bit of trouble with the pushrod measurements. The cam is the TSP 233/239 with a stock rocker set up in the l92's. .650'' dual PRC springs and stock valves. GM mls 4.085'' .051'' thick. Heads are also unported. I measured and measured on the intake valve for cylinder one until I found zero lash at about 10.5 turns on on the comp cam pushrod length checker. (which is about 7.325'' without figuring in lifter preload) This measurement was consistant with cylinders 3 and 5 on the intake valve. However, when I measure for the exhaust valve approximately 11 turns gets me to zero lash. (length of 7.35'' without preload) 10.5 is definitely too short for these as there is a lot of room for the 'tick' noise. Am I trying to be too precise here or does something sound off or is there anything i'm doing incorrectly?

vettenuts

iTrader: (4)

Couple of ways to play this. If exhaust is consistently a different length, order 8 pushrods of each length. Second option is to strike a balance between the measurements since off the shelf pushrods only come in 0.050" increments although they do stock in 0.025" increments near 7.400".

The measurements will vary due to tolerances, etc.

badazz81z28

iTrader: (6)

I had the same issue when I measured for my PRs. I choose the middle ground in terms of whats available off the shelf.

I ended getting 7.375" PR. Which put some of the lifters at .075 pre-load and others at like .060. I stayed within the spec of .050-.080 for stock lifters.

PRs are actually sold in .025 increments. 7.350" and 7.400" would have put me out of the tolerance zone.

Brian'sCharlotte(TA)

iTrader: (2)

Well, now that I have had a sec to sit and crunch a few numbers... If I take the smaller measurement from the intake of 7.325'' and add the smallest amount of preload for the stock lifters (.050) I come to 7.375''. So If I do the same for the length I measured on the exhaust valve (7.350) I come to 7.400'' after I add the preload. So I guess the 3.375'' would be best? I'm trying to shoot for a preload of around .050 to .060. I'm about to go back and double check as well as put the other head on and try the other bank

Brian'sCharlotte(TA)

iTrader: (2)

Okay I must be doing something wrong. I verified those measurements on cylinders 1,3,5, and 7. However, the exhaust on cylinders 2,4,6, and 8 measured 11.5 turns that's .050'' larger than the 4 exhaust valves on the other bank The intakes were also .050'' larger on this side, measuring zero lash at 11 turns rather than the 10.5 on the other side. All measurements were consistant across the cylinders so I must have messed up somewhere. I have a few bolts in but they aren't torqued to spec but they're muscled in there pretty good. Also have the head gaskets on. Could the heads not being completely torqued down be the problem?