pushrods

[bugnut68]

Here's my situation, I initially used steel Bugpack 3/8" pushrods in my 1776 that has an Engle 100 cam, single HD springs and VW 1.25 ratio rockers for its valve train. My question is would HD Aluminum pushrods work just as well? This engine has one hell of a lot of what sounds like pushrod noise. At the very least it's definitely coming from the valvetrain and I've heard that steel 'rods are much louder than aluminum due to the differing expansion rates and what not.

Second question: how can you tell by sound if the pushrods are knocking around on the inside of the pushrod tubes? When teh engine is cold I can hear a sound that makes me think of just that, but I haven't yet inspected the insides of the tubes to see what's up yet.

Any thoughts would be great!

[1955ccbug]

The aluminums will work fine, the chromoly's are needed when you run more spring pressure, like dual springs. I agree with you on the noise, I run the chromoly's in mine and they are really loud.

[turboblue]

CM pushrods can be run at nearly zero lash. If one uses normal lash settings that are designed for the aluminum pushrods, that setting will grow with the steel versions and become quite loud. Too much side lash on the rocker arms sounds like excessive valve lash too.
_________________
Gary

Turbo VW Sand Drag Buggy

"If you don't run into the Devil every once in awhile, you must be going in the same direction!"

[bugnut68]

Might be the side play, but I wrestled that for what seemed like forever and a day and thought I had everything all decent...it does get better once the car is warmed up...and on top of that my package tray is rusted out so I hear nothing but engine noise anyway...lol

[VWDOCTOR]

Its possible the pushrods hitting tubes due to running 1.25 vw rockers without offset rocker shafts.
Tom

[GhiaManiac]

I'd check and readjust with the chromoly ones. They're adjusted at a 'loose zero' as turboblue mentioned.
I like that because there's no need for a feeler gauge. I use the spin method. Tighten the adjustment screw
until you can just spin it with your fingers. Once the engine heats up, you'll end up with a few thousanths of clearance,
and not much noisier than stock aluminum.

[JC Saunders]

could be to much backlash in the cam gear! take the spark plugs out and turn the crankshaft pulley back and forth. also take the valve covers
off and get a look while turning the engine over by hand. just a thought.

[bugnut68]

It definitely isn't the cam gears...I'm running magnum straight cuts and checked all that during assembly. My end play on the cam was right around .002" closer to .003" and the backlash was spot on, when I checked it while turning the crank in the case. I'll change out the pushrods and see how things turn out.