[Ponteach]

First post, so a little background. I am doing a frame off restoration of a 67 Lemans convertible, which my brother and I have had since 1983. With that we are putting in a 455. I have read many post and learned a lot since I signed up here and have had good luck with the assembly of the 455 so far. I am at the point of determining pushrod length. I initially followed the info in Jim Hand's book and had the roller tip right in the middle of the valve. The push rod length was 9.1125. When I called (well known Pontiac shop) about ordering an new set, I explained how I came to the measurement and was told the travel of the roller was to wide, it was about an 1/8 of an inch (3rd picture, a little hard to see). He said I need to use the 90 degree method. So I have done that and now the travel is much smaller but as you can see from the 1st picture it is way down toward the exhaust side. It results in lift of .540 intake and exhaust of .558 and a pushrod length of 9.3375. Does this seem okay? I have tried shorter lengths in .050 increments which results in the witness mark widening and moving back to the center.

All thoughts are appreciated.

Basics of the motor are as follows

Bored 30 over
Eagle stroker crank
RPM 6.8 rods
RaceTec pistons
Zero decked
6x-4 heads, measured at 95cc, bowl blended, not ported
HS 1.65 rockers (they will help down the road, when I put in a roller cam and new heads)
Cam - Crane 288-2h (Yes its old but in great shape) Dur @.050 - Int 218, Exh 230 - Lift - Int 300, Exh 310 - LSA 114

[BierManVA]

It honestly looks to me like your 90 degree photo is not right. I'd say the rocker needs to be backed off a little thus raising it higher at the pushrod side. Are you using a small square piece of stock? I use an allen wrench that is just the right thickness so that I can see the marker line just above it.

[Ponteach]

I agree its not quite at 90. I just did it again and got it closer to 90 but all it did was move me down closer the edge of the valve. I am concerned that being that close to the edge is a bad thing, but I don't know for sure.

[Squidward]

I went through this several months ago. I started out measuring via some info on the web that wanted a centered pattern. And then I was coached into measuring for narrowest pattern with the 90* method. It made sense to me eventually. My narrowest pattern with the 90 method put me off-center from the valve tip.
http://forums.maxperformanceinc.com/...d.php?t=784145

[dataway]

Shouldn't the 90 degree measurement be based on the contact point at the valve tip and not the center line of the tip roller? The object is to achieve 90 degrees between the center of the rocker pivot and the tip of the valve. To demonstrate .... imagine a tip roller 1" in diameter .... if you base your 90 degrees of the center of that, the actual relationship between the rocker pivot and the valve tip will be no where close to 90 degrees.

In the picture it appears the valve is not at 1/2 travel either ... so hard to determine angle from the photo.

[BierManVA]

I used this video when I did my measurements. It was the best I had found and really brought things into focus for me.

https://www.youtube.com/watch?v=o5is9BsH5OU&app=desktop

[Ponteach]

Thanks for the replies. I watched that video and thats how I tried to set up my 90 degree line. It sounds like Dataway is suggesting that line might be wrong. I am going to have a run at it using Dataway's thoughts just to see what that does.

Squidward, I read that post some time ago but it was good to look at it again. Your sweep line is close to what I am getting. It looks like it was on the exhaust side of center. Did you run it that way? Was the actual valve lift above what the expectations for your cam and rocker was?

In the end I just want to know if its ok to be so far off center and that close to the exhaust side of the valve tip

Thanks again.

[johnta1]

Why does the rocker arm look like it is offset toward the valve at the stud bearing?
(2nd pic I think)

Illusion from pic?

[Willshire]

That video is how i set my geometry. worked awesome

[Ponteach]

Johnta1 - I think its just the angle of the picture. They are Harland Sharp rockers and ARP studs so it lines up pretty well.

The current witness mark is a result of following the video the best I could. Its just that it results in the contact near the outer edge of the valve and the lift is way higher than I expected.

[Blued and Painted]

I watched the 90 degree vid.

The teck holds the rocker at 90, then screws the nut in 1/2 gross lift.
Since he's moving the push rod side of the rocker, and the valve does not move. Why not use 1/2 the lobe lift.

[Willshire]

Because the 90* has to be to the valve measured on the valve side of the rocker fulcrum. so the ocker multiplier must be taken into consideration.

[Blued and Painted]

Here is a little diddly on why total lift changes with push rod length.

http://www.eatonbalancing.com/blog/2...-the-pushrods/

[Willshire]

Did not know that about shaft mounted rockers. Interesting

[dataway]

Here's a photo of my rocker sweep/position on the valve tip. Stock length rods, 068 cam, 1.5 CC roller tip rockers, decked .012".

When I set this up I used the 90 degree method at 1/2 lift (at the valve), and used a line from rocker pivot center to the contact point on the valve tip.

[Squidward]

I also did the center pivot point to roller tip surface. It made more sense to me to do the roller tip contact surface.

[gtofreek]

Are the valves in your 6X heads longer than stock? If so, it will position the valve tip closer to the rocker stud, making the rocker arm have contact further out towards the exhaust. You may need to go to a SB Ford rocker arm to shorten the arm length up a little to get the rollout pattern centered. The narrow pattern is much better than the wide pattern, but you really should get it a little closer to center. If you used 5.100" long valves or RAIV valves to get spring installed height higher, that would explain your problem.

Also, Did you make one of your lifters solid? Or is it bottoming out when you are running through the lift cycle? If it is not solid[except for leaving the pushrod seat about .040"-.050" below the clip for lifter adjustment], you will not get accurate results. That looks like you are using the inner spring to do your testing, but it is still way too stiff itself to use on a hydraulic lifter that has not been made solid.

[Ponteach]

Thanks for the replies. I think Paul hit the nail on the head. I used Ferrea 5000 series valves which are a bit longer. 5.095 on the intake and 5.11 on the exhaust. I did take one of the lifters and removed the internals and used washers to get it back to the exact height.

So the feeling is that the current location is to close to the valve edge? Are there any alternatives short of buying a new set of rockers?

Thanks again for the help.

[gtofreek]

I suppose it's not the end of the world being that the narrower the pattern is, the straighter it's pushing on the valve[less valve rock, and yes, valves will still rock with roller rockers]. That centered pattern will be rocking the valve, and wearing the guide a whole lot more. Or you could compromise and shorten the pushrod to 9.250"[since pushrods come in lengths every .050"], and see how that looks.