? for the Fuel Head Guys

We're running a KB stage 10, standard deck (i think, 10.850"), raised cam block, BAE Fuel heads, Dechellis stands, Stage V intake arms (1.6), Kluff exhaust. We're having a problem w/ the intake pushrods rubbing the head. The exhaust side is fine, in fact the holes for the exhaust pushrods are bigger than the intake pushrod holes. If the intake holes were bigger, we'd probably be fine. Or maybe a smaller pushrod? Pushrods are 7/16". If we went to a lower ratio rocker arm, does it move just the pushrod side of the arm out? Just curious what other experiences you guys have had.

Josh

 

Okay so after doing a little research, I didn't know crane made .120" taller lifters. That will probably fix our problem.

 

Nevermind...we lifted the lifters .125" and it's actually worse. Back to square one...

 

is it just touching at the top or the bottom of the travel or binding hard?

 

It actually looks to be touching all the way through...as if it's exactly parallel to the pushrod hole in the head.

 

Some say just touching is good works like a guied prevents flex. I wont some clearence and stopping the pushrod from spining is not good. Could you just run a paper roll down it a couple times.

 

Well we've noticed some of our pushrods are cracked where the cup meets the pushrod shaft...like it was loading it sideways too hard...and you can definately tell by looking at the rub marks in the middle of the pushrods it's been rubbing. Not sure if you can tell in the pic's, but the exhaust pushrod hole is around .125" larger than the intake pushrod hole. I've noticed it seems most people have had problems w/ the exhuast rubbing, it's looks like someone fixed this on the exhaust but not the intake side.

 

i had a friend had that problem kept messing up the push rods he ended up raising up the rocker stands .100

 

Yeah you'd think that would help Jim. We called BAE and they said lowering the rocker stand helps our situation.

 

i had the same problem, but with Dart heads. We actually made a run with no lash caps to try and let the push rod delfect a bit. We shipped them to Sanches to see if the hole can be made bigger.

Jay

 

have the same setup as you, and we have the identical problem as we speak. we just sent our heads to our machinist to get the holes drilled out, and the same diameter sleeves pushed in that are in the exhaust holes....... it may not be the easiest solution, but we found that playing with the stands heights make the the rocker ride on the lash cap a little too off for our tastes............... im sure there is gonna be a better way of doin it, but that seemed to us at least the best way to handle it.

 

I too had the same problem with Dart heads. It didn't rub that bad so we just ran it with no problems. Are the Dechellis stands you have the plus ones? Those were designed for .100 long valves and move the rocker shaft for beter geometry with the longer valves. Can you try a 1.75 ratio rocker?

 

Well I think increasing the rocker ratio (ie-1.7-1.75) should shorten the pushrod side of the rocker, and we're needing that side to be longer. 1.5's would probably work, but we'd like to stick w/ what we got.

 

I agree....making the hole bigger would probably fix our problems.

 

Pushrod Clearance

If you raise the rocker shaft until the rocker geometry is correct you will not be able to put a 3/8 push rod through the head.
The correct way to fix this problem is to use a rocker arm that is longer on both sides of the fulcrum.
The valve side fulcrum length of a Stage V rocker arm is 1.600". We manufacture a rocker arm that has a valve side length of 1.675". This rocker moves the push rod away from the head by .030"-.050" depending on the ratio that you use. The roller is also placed in a more correct position on the valve.
These rocker arms are listed in our 2009 Catalog.

Noel Manton
www.mantonrockerarms.com

 

Thats good to know

 

just thinking can you take 100 off the stands? but remember once it off it's off....measure twice cut 1 time..Dave
www.myspace.com/daveloweswr
www.myspace.com/lowesk8way

 

Coming from a Comp Eliminator, high rpm engine background, I consider valve geometry very important. Any changes that I would consider in stand height, pushrod length and valve length will need to be coordinated for proper geometry and rocker arm sweep on the valve tip. The changes in geometry will also change valve lift and events.

There are inherent harmonics within valve motion which become increasingly critical with increase in RPM. Pushrods and valve springs produce harmonic frequencies. In our Comp Engines near 10,000 if the pushrod ever touched the head, the change in harmonic frequency could have enough energy change that it caused the valve train to go crazy and sometimes the mating between the pushrod and rocker arm would jump naked. The major Pro-Stock and camshaft companies study these phenomenum on Spintron fixtures where they spin the engines up while studying the valvetrain action with stroboscopes.

These thoughts are not near as critical in something like an A/FD that only turns 6500 but none the less IMO the basic geometry and clearance guidelines should be seriously considered for optimum performance. With this said, I would first set the geometry as correct as possible then clearance evrything else as needed. We always look for those shiny spots on the heads and pushrods after runs and try to alleviate the collisions.

I hope this helps. I like what Noel Manton relates above.

Steven Smith
Smith-Fair Racing
Atlanta, TX

 

push-rods

Noel is the man. When in doubt. call as many manuf. as possible and listen to what they say. Try and grab all the answers that are the same or close. Then sit and think about it.. Good luck Just something else to think about. Don