Roller rocker arms brain teaser...

[Tabcon]

...At least for me.

I'm in the process of installing some roller rocker arms (1.65 ratio) and a new hardened shaft I bought from Good Parts, very nice parts if your looking for something like this, but the new chromealloy hollow pushrods I'm using, which are the stock length, are too long. My rocker clearance against the top of the valve spring is zip and a tight fit at that. I'm also using new set of aluminum pedestals from Baastuck, but I assume the shaft alignment on these is the same as stock also.

In order to get the clearance I need, it seems that I would need to either shorten the push rods, which I cannot do, or use taller pedestals.

Would shimming the pededstals to acheive the correct clearance instead of buying new shorter pushrods have the same effect, or whould it change the rocker arm geometry and screw everything up? At this stage, I do not want my pistons to be eating my valves for lunch.

Inquireing minds want to know.

 

[TR3driver]

Shimming the pedestals will change the rocker arm geometry, tho it's hard to say if it will change it from right to wrong or vice versa. I'd contact Richard and see what he says ... if nothing else, he'll have the proper shorter pushrods.

 

[TR6BILL]

Don't even think of shimming the pedestal. Bite the bullet and get shorter push rods. I love Richard to death but he actually tried to get me to shim the pedestal to remedy that problem. Don't work. Even sent me the shims. Talk to Ted Schumacher for what you need.

 

[Twosheds]

I think Ken Gillanders, British Frame and Engine, sells shortened pushrods, too.

 

[martx-5]

Yes, Ken has shorter pushrods. I got a set from him. He can make them to whatever length is necessary.

Edit: British Frame & Engine...

 

[swift6]

The tubular chromoly rods should be able to be shortened by a machine shop shouldn't they?

 

[Hap Waldrop]

You can shorten the tubualr pushord yourself, then end hust push on, I would take off the top, the cup side. Here's what I do, I put the pushrod in a vice in soft jaws, use vice grip to grab the cup then turn them counter clockwise with a liitle WD40 and they'll come off, then shorten the tube the required amount, I use my valve tip facer on my valve grinder for that, but you file the for that matter, then reinstll the cup. If that intimindate you, then fiquire how much adjustment you would like to have at your adjustment harware, and reduce the pushord lenght that much (pushrod lenght is fiquire by total length minu cup depth) and give Smith Brothers Pushords a call and they will ame you a set any length you want for well under $100.

 

[Tabcon]

When i got them from Darryl at Racestorations, he told me that they were not the type that can be shortened, but I think you're right Hap since the top cups do look like a separate piece, as do the bottom rounded ends. I'll try that and if it doesn't fly I'll just go ahead and try shimming.

BTW...I am not easily intimidated! LOL

Thanks!

 

[70herald]

The problem with shimming is that the valve side of the rocker needs to be at the correct height. That is what shims are meant to correct if needed. Basically you want the rocker to be level when the valves are half way open. In other words you are trying to center the arc created by the rocker around the valve travel. Unless whatever rockers you bought have screwed up geometry this shouldn't be a problem.
The design of American (V-8) rockers is quite different and they need shims to get the geometry to line up perfectly.

 

[Tabcon]

I took the push rods back out, and sure enough I was able to remove one end, shorten the rods and press the ends back on. Piece of cake...thanks Hap!