I am putting together a stroker 440 using a mech cam and ductile iron rockers and am trying to find the correct pushrod length. The valve pattern is much wider with the crane rockers than you typically see with roller rockers. Anyone have a pic of how the pattern should look with these type rockers? Thanks

Straub industries has a good utube vid on this. several sources say it is the gold std on this, that at half cam lift you want the rocker to be 90 deg to the valve tip/retainer THEN (at that point) you measure the pushrod length needed for however much preload you want. EDIT & Scott on the vid uses chebby stud mounted rockers & lowers them to get the 90 deg at half lift. & the chebby rocker choice for this needs to be right (for the correct wipe pattern) & you have yours already but FYI Mike at B3 racing is top notch for this. MORE EDIT I had a Q on the vid & the guy says to then lengthen the pushrod till you have zero clearance & I am wondering if it needs to be lengthened further for a certain amt of preload or shortened a bit for the cold or hot clearance for solids ???

Get yourself a adjustable push rod to do the
job right.. they are cheap
EDIT
also Crane rockers seem to have some issues..
you might need to shim the shaft up to get it
right or even lower it.. that takes a bit of
work.. try another rocker(you might end up
sending those Cranes back)

I have an adjustable pushrod. The question I have is with roller rockers you typically get a barrow pattern. With these ductile iron rockers I am getting a wide pattern where it is heavy at the start and at the far end. It is very light in the middle. I can't seem to post a pic. Is this normal for this type of rocker?

I cant say with a iron rocker.. I have never
owned any

Go to b3racingengines.com and read his tech pages.

I'm 99.999% sure you need to correct the geometry. I'm that confident.

Make sure you check with him, take your measurements and buy his correction kit BEFORE you measure for pushrods.


This is a shaft system. Pushrod length only affects geometry in that easing or lowering the adjuster will slightly alter rocker ratio.

The adjuster should be out 9/32 of an inch. Correct the geometry and THEN measure for pushrods.

Unless it is a really big cam with a lot of spring pressure you're probably just fine running what you have. Those nodular iron rocker arms have been driven millions of miles over the years. That is a fairly robust setup. All you need to do is to get them centered over the valves and use a pushrod that fits properly.

Sorry, the issue is more complicated than that. The 50% method simply transfers the error to the pushrod side.

The factory Mopar drag race team use to recommend that you set the ductile iron rockers up so the pad would start at the inner third of the valve tip closed and be on the outer third of the tip at max lift, that has worked well for me on many motors
I have had RAS blueprint, bush and change the ratio on a lot of sets to get them the do that

Exactly. That's why I suggested to the OP to call Mike at B3 and let Mike help him. This stuff about its good enough just isn't.

You can fix these things now without machining the stands off an using blocks. It works. It's cost effective. And it should be done with virtually every rocker arm out there.

Absolutely !!! Mike set up my T&D rockers, had to raise them quite abit & move them away from the valves.

That's a bit of correction but think how many guys out there running the same stuff (or even of lesser quality) that have NO correction on their stuff?

You can bet their valve train is pissed off to no end.

I love Mikes system. Simple, cost effective and it flat works.

& Mike was the one that pointed me to the straub vid for the 50% deal being ideal. It would be way harder to find the right angle with OE type rockers as opposed to the chebby types that you just raise & lower the polylock especially if you have to mill the stands to lower the shafts and he wanted me to call back for further edumacation.

Did you see the picture csk posted? That's what a correction looks like.

You just can't move the shafts up and down. If they go up, they have to move away from the valve. If they go down, they have to move closer to the valve too.

The diff is that the stand motion is vertical (unless you make new offset stands), while the valve stem height moves at the stem angle (15, 18 etc.).

The shaft holes have been slotted,makes it offset, so it also helps the pushrod side.

Now I do

mad that 9/32 distance you quoted was measured how?
thanks
many adjusters today are much longer from the ball to the thread so the old "3 thread" setup no longer works and results in too short pushrods
I like the adjusters up as close to the rocker as possible leaving some room for adjustment


while roller tip rockers do not get the side thrust that iron or stock rockers do they need the fix shown in the pic above

Iron rockers need a fix if off because they can give side thrust

From the bottom of the rocker to the end of the ball. And that's as long as the oil feed hole to the adjuster is drilled right under the part where the adjuster goes through.

I had one set of Crane W-2 rockers that had the oil hole about .090 lower than directly under where the adjuster comes through so you has to run the adjuster a bit lower or you'd smoke the adjuster.

That was the only set of rockers I've ever seen drilled like that.

Side thrust (sliding contact between the pallet radius and the stem tip) is present in all non-roller rocker arms BY DESIGN. It's not a mistake, it's needed to produce an oil wedge between the two surfaces.