Nastyc4

iTrader: (13)

Bought used Crane 1.8s. the Crane kit comes with 7.250. I have someone local selling a sealed box with 7.3 for super cheap. Is .050 THAT critical on a hyd.roller? Could I just give it a 1/4 turn extra when adjusting to try and keep position the same as called for??

69LT1Bird

iTrader: (1)

No, there is no adjustment.

Just put the right ones in the first time.

jkkaz

I don't think anybody could tell you for sure. Mabe it is and maybe it isn't. This question comes up everyday. The only way you can tell for sure is to measure it. Worst case scenario is you already have to long a pushrod and a big cam that puts you into coil bind.

An adjustable pushrod is about $20 (US). The next question is how much preload do you want to run. You see varying opinions from about .06 to .1.

It's important you understand zero lash and preload. While it does not have to be perfect, an understanding will keep you from breaking stuff.

masterz28

iTrader: (8)

jkkaz, can you point me in the right direction to become more enlightened on zero lash and preload, i am doing heads cam in a couple weeks and my only weakness is this p.rod stuff.Or can you explain it to me, pretty much everything, on PM, sorry to highjack...

jkkaz

The lifter is a sort of a mechanical damper or you can call it a type of shock absorber. It has a spring inside to keep it expanded and it is filled with oil to slow the spring compression by bleeding off the oil at a controlled rate. Zero lash is the point just before the spring starts to compress, so if there is no oil in the lifter it compresses quite easily. Everybody seems to have their own way of setting up zero lash. Some wiggle the lifter, some compress the spring and let it snap back. If it snaps back after compressing the spring inside the lifter (you can hear a light click). At this point there is no mechanical slop and the spring is not compressed. Obviously there is room for error here, but it is small enough for valvetrain work. It may be easier you find a cross section of a hydraulic lifter to look at.

From this zero lash you can adjust Preload. This is the amount of lifter compression past zero lash. With a non-adjustable rocker this is determind by where the bolt bottoms out. I've tried measuring it before to get an exact measurement, but it's extremely difficult. On a 1.72 rocker, one turn is appoximately .1". I'm not sure if it's different with a different ratio rocker. It maybe, but I'm not positve.

If you are running adjustable rockers you have a lot more flexibility and should be okay (sorry I just realized this after writing all this junk), but you may want to check you wipe pattern. Vettenuts did a big write up on it on this forum or corvette forum. The wrong length pushrod can shift the centering of the rocker tip on the valve, which will make the valve tend to want to tilt and give you excessive wear on the valve guide, but I couldn't give you an exact number on what is bad. I just like to see it centered when I put and engine together.

Nastyc4

iTrader: (13)

Cam is stock and motor is completely stock. Crane used to include 7.250 with their kit. Saves me about $150 if I go with the 7.3 that's why i was considering it. I guess I'll just order the correct ones.

jkkaz

You may want to check it. For all you know the wipe pattern may be spot on. Every rocker is a little different. As the cam opens the valve, the roller tip will move across the valve tip. Ideally the pattern should be centered across the valve tip. If I remember right mines moved towards the intake side as it swiped. The total width of my wipe pattern was about a sixteenth of an inch. I just used antiseize compound with a bright halogen light to see it.

Jon@Texas-Speed

iTrader: (18)

At the point you are doing all this, spend the money and get the correct parts. If you don't have the money for pushrods you definitely won't have the money for lifters if one were to collapse and kill the cam much less a block. Stuff breaks on factory motors that are set up properly. It is more critical with the use of aftermarket parts. Put the stock rockers back on until you have $100 for pushrods would be my suggestion.

Jon

Nastyc4

iTrader: (13)

Appreciate the input. Money really isn't a concern i just wanted to know if .050 was enough to possibly throw geometry off with a hydraulic roller. I haven't installed the rockers yet and having to wait for pushrods from the u.s. is just a little tedious with duty , tax and brokerage blah blah blah... I'm sure Crane did their homework by including 7.250s with the kit so I'll go with it.

thanks for the input all.

vettenuts

iTrader: (4)

With the Cranes, the pushrod sets both the wipe and the preload. The key is to get the correct wipe and preload. I found that there is a pretty good variation of rocker height that doesn't affect the wipe too much. There is a way to figure it out, but you need check springs and a way to measure depth. Other option would be to put a Sharpie on two of the valve stems and simply install and run the motor for a while, take those two out and check the pattern.

One other note, the Crane instructions have you set the lifter pretty deep with the 7.250" pushrod, so if you follow them you will likely bottom the plunger with the longer pushrods. If you contact Trend pushrods, you can get a new set hardened for guide plate use four around $80 or so.

Not sure how cheap these are, but the Yella Terra is a much better setup (I have had both).