Pushrod length and Rocker Adjustment

Ping254 · Dec 5, 2007

Hello all,

I just bolted on my new AFR 165 heads and I'm trying to match up the correct pushrod length for my 289. I purchased a purshrod length checker from jegs, but it was too wide to fit in the pushrod hole. So I purchased some rods at 6.805 and then a set of 6.700". The 6.7's fit better but I'm not sure if it is close enough or if it has to be dead on center of the valve. See picture below. The rocker rolls just a little bit further to the exhaust side. Is this good enough to keep me our of trouble? Also, I am udjusting the roller rockers by hand tightening them down until I feel a little drag on the pushrod, then I tighten the nut on the rocker down another half of a turn. Is this the correct procedure? Finally, Comp Cam said that they recommend removing the inner springs from the valve train during initial cam break-in. Is this required? I would hate to rip everything apart again.

BTW it is a 289 w a 268h Comp Cam (Hydrolic flat tappet), AFR 165 58cc heads, and Harland Sharp 1.6 full roller rockers.

Thanks,
Jim

10secgoal · Dec 5, 2007

I've broken in cams with those springs. It would be less of a risk taking them out. But we also run an oil addative with new break ins no matter what.
The pattern looks perfect, but it's hard to tell where is leans more towards. It should lean a little more towards the intake and carb. So when the rocker opens it's a little to the side, and when it reaches the max lift of the cam, it is then centered.
The adjusting method sound right.0 lash and then half to 3/4 turn. the only thing I would try to make a habit of is lifting the back of the rocker as you hand tighten them. Then you can tell exactly when you hit zero lash because the rocker stops moving. Turing can some time be a little more difficult to tell.

Ping254 · Dec 5, 2007

Thanks. It is not perfectly centered on the valve stem. It is a little bit towards the exhaust side, not the intake side. Do you thing I should go with a pushrod .100 or .050 shorter to be safe?

Thanks,
Jim

68EFIvert · Dec 5, 2007

10secgoal said:
I've broken in cams with those springs. It would be less of a risk taking them out. But we also run an oil addative with new break ins no matter what.
The pattern looks perfect, but it's hard to tell where is leans more towards. It should lean a little more towards the intake and carb. So when the rocker opens it's a little to the side, and when it reaches the max lift of the cam, it is then centered.
The adjusting method sound right.0 lash and then half to 3/4 turn. the only thing I would try to make a habit of is lifting the back of the rocker as you hand tighten them. Then you can tell exactly when you hit zero lash because the rocker stops moving. Turing can some time be a little more difficult to tell.

I just put on my AFR 165's this weekend and it looked exactly like what you have except mine is toward the intake side. I glad to hear it doesn't have to be exactly in the middle. I almost ordered slightly shorter push rods and came to the conclusion it was fine, or at least good enough (if there is such a thing when building engines).

68keyblr · Dec 5, 2007

Having just gone through this very same thing, I'd recommend getting it dead on perfect. In my case I think my pushrods are a little on the short side. The valve train makes a fair amount of noise, kinda like a sewing machine or diesel engine. Runs really good though!

Comp cams makes a really nice adjustable pushrod with the measurement marks right on it. I'm going to pick one up and get the perfect length and see if it quiets down at all.

10secgoal · Dec 6, 2007

If the mark is right, it will still make the sewing machine noise. That's just roller locker for ya. If they are real far off, they clack like they aren't adjusted properly.
If it's far off, it can also wear the stem of the valve and wear out the guide prematurely.

68keyblr · Dec 6, 2007

10secgoal said:
If the mark is right, it will still make the sewing machine noise. That's just roller locker for ya. If they are real far off, they clack like they aren't adjusted properly.
If it's far off, it can also wear the stem of the valve and wear out the guide prematurely.

LOL, I guess I'm just too picky

Ping254 · Dec 6, 2007

I had 6.700" overnighted and they are dead on perfect. Thanks for your help.

68keyblr · Dec 6, 2007

Ping254 said:
I had 6.700" overnighted and they are dead on perfect. Thanks for your help.

Jim, I thought that's what you started with?

Stanger007 · Dec 6, 2007

A question for the pros -- is lifter pump up an issue when setting this up? Seems like if your lifters were bled down the pushrod would be "shorter" than it really is once they are pumped up. I spoke with a local engine builder and he said that the lifters need to be pumped up for the most accurate measurement.

Am I making any sense or is this utter hogwash?

I'm setting up the rockers on my Trickflow Track Heat heads and with a 6.500 pushrod I get this sweep with the lifters bled down. I went a little to the intake side of the valve to account for the lifter pumpup.

68keyblr · Dec 6, 2007

I've heard you need to modify an old lifter so that it can't collapse and remains in the fully pumped up position when testing for pushrod length. There's an article somewhere around here on how to use some washers to accomplish that.

Stanger007 · Dec 6, 2007

I've seen solid lifters made just for this purpose, or like you say, a normal lifter can be modified to work.

Wes

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