ok, i've been running these valves all day trying to get the valvetrain to stop making noise. The sound is a TAP, not a tick. To me, this means i'm probably getting coil bind correct? The noise seems to get louder as i tighten the rockers more and more, which to me makes sense. I know that when the valve is fully opened there is very little gap between each coil.

the springs are:
1.470 in. Springs
1.470 in. O.D. single with damper
120 lbs. at 1.780 in. installed height
300 lbs. at 1.280 in.
360 lbs. per inch spring rate
.540 in. max valve lift

My cam is an xe274 with 1.6rr, making for .522 lift, which is within the limits of the springs. Comp cams recomends the 981 springs, but they are only good to .490 lift.

I'm running trickflow 23* heads. When i installed them i checked the geometry as per instructions, and it seemed that the recommended 7.850 pushrod was the one to get, so thats what i went with. I'm beginning to think that maybe they are too long.

How much clearance should there be between the coils when the valve is fully opened? Would a shorter rod give more clearance?

Eric

 

check it with a feeler gauge and see if you have coil bind instead of guessing, should check push rod length too. rb just replied yesterday to a thread about push rod length. do a search and it'll pop up.

 

When I changed to 1.6 rockers on my TFS23° heads I had to grind the slot in the guide plates deeper for the pushrods. First, there's quite a bit of slack in the holes under the rockers studs and they tend to **** a bit when you tighten the first rocker stud, second, there just weren't cut deep enough.

I wasn't sure that the problem was and had installed a full set of aluminum 1.6 Comp Cams rockers. Had a lot of noise even though it seemed to run normal. I changed lifters, bought shorter pushrods, installed 7/16 rocker studs and adjusted until I was sure that wouldn't help anymore. I'd adjust one, it would get quite, start on another, and the one I just finished would start ticking again. About went nuts!

Thought maybe it was the rockers so I used a set of 1.5/1.6 Pro Magnums from my buddy. Most of the noise was gone, (the 1.5's eliminated 8 of the potential problems of course) but one 1.6 rocker was persistent. That's when I noticed it wasn't quite oiling properly either and was polishing the pushrod just slightly. I could see this on the new expensive black pushrods but couldn't see it on the standard silver hardened pushrods. I removed the guide plate, cut the slot maybe .125" deeper, put it back on and the problem was solved.

Also, along the way here I noticed that several of the 3/8" rocker studs were not straight! So, along with the expense of changed the springs from single 1.25" to dual 1.46", and all that hardware that goes with it, I installed the 7/16" rocker studs.

Hope this helps

 

Push rods too long will not cause coil bind. When you adjust the rocker, you are setting its heignt to where it produces the correct amount of valve movement.

Comp's 981 spring recommendation for that cam is when used with 1.5 rockers. I had one of those cams for a while, with 1.6 rockers. My friends at Comp recommended 986 springs for that combo, and told me that even those those were getting close to their limits.

I'd suspect that Smasterson is right, that you guide plate slots aren't deep enough, and the push rod is hitting the bottom of the slot. The way rocker ratio works, is that it is the ratio of the distance from the stud to the valve stem, divided by the distance from the stud to the push rod. Since you can't change the distance from the stud to the valve by replacing the rocker, the only way to get a higher ratio, is to move the push rod seat in the rocker inwards toward the stud, thereby increasing the ratio of the 2 distances.

The push rod seat in the end of the rocker does not move in a straight line. Instead, it moves in an arc, whose radius is the distance from the stud to the push rod seat. Obviously if that was a very large distance, the tip of the push rod would almost move in a straight line; but the shorter the distance, the more the push rod moves toward and away from the stud during its travel. So with the higher ratio rockers, not only is the push rod closer on average to the stud than stock, but it also moves more toward the stud during its travel.

You might want to try the heater hose in the ear trick, probe around with the other end of it to find the exact source of the noise. You'll probably find its a push rod getting forced out of its seat by a guide plate.

I've had the same experience of having to lengthen the slots, but it was with a set of "Genuine GM" guide plates.

 

ok, i pulled all the plugs and had a friend turn the motor over by hand while i watched the pushrods. The guideplates did not appear to be hitting the pushrod, but i'm gonna clearance them just a little bit anyway.

What i did find, is that two of the rocker studs seem to be out of line. I put a straightedge along the sides of all the studs, and there was a small gap between the stud and the straightedge on 2 of them. i'd say it was about a Millimeter. I'm assuming this is a bad thing, so i think i'm gonna order a new set of studs and go from there.

Eric

 

Could also be a lifter issue. Not pumping up properly.

 

TTT,

anyone have thoughts on the rocker studs being off a little bit? I'm assuming as little off as it is, it is a problem, but i don't wanna be throwing parts at this thing for no reason.

Eric