Adjustable Pushrods

Tom Perso · Post by **Tom Perso** » Sat Sep 15, 2001 9:02 pm

Hey all...

I am working on the valvetrain geometry on my 2270. Here are the valvetrain related specs.

Webcam 163/86b reduced basecircle cam
Webcam dual wound valvesprings
48x38mm valves on 1.8 carbed Bus heads
.180 cylinder shims
Webcam solid lifters

So, here's the problem. I had 16 old pushrods sitting around, so I made my own adjustable one. I cut it in half and drilled out the center in one side and tapped the other for a 1/4-20 rod. I put a couple of jam nuts on it and tried it out. Once the cam came on and compressed the springs just a bit, it bent the 1/4-20 rod about halfway thru the cam duration.

I had a friend that was ordering a SVDA dizzy from aircooled.net, so I had him order me an adjustable pushrod from them, thinking that my handy work was not up to par with this engine.

Well, much to my surprise, it bent that pushrod in no time, even at a lower lift point. Am I doing something wrong? Is there something wrong with my valve springs? I had RIMCO do the heads.

The rockers are in good shape, I just disassembled and cleaned them, and re-assembled with FAT performance solid spacers.

Any ideas?

Thanks in advance...
Tom http://www.qtm.net/~persoj

tuna · Post by **tuna** » Sun Sep 16, 2001 12:27 am

Anyone correct me if I'm wrong, but an adjustable pushrod, whether purchased from a vendor or homemade, is not designed to withhold the spring pressure of dual springs. Try removing one the valve springs on the valve you are working on (or using a light spring for measuring purposes) and setting the geometry right. Once the length is set, reinstall the spring(s).

Tuna

MASSIVE TYPE IV · Post by **MASSIVE TYPE IV** » Sun Sep 16, 2001 12:27 am

Tom,
It is VERY important that your adjustable pushrod is of the exact same ball end diameter as the pushrods you plan to use,if not, all those measurements will be nil, as the pushrod will sit more shallow or deeper than the ones you actually use..

Getting to the source...Remove the valve springs, and use just the outers...I leave the inner springs out during camshaft break in,(The cam will thank you later) and atleast during geometry set up..It makes life alot easier...I did 3 sets of rocker geometry today,what a pain..

I will almost bet that you will need to do the folllowing..

Deck the face of the rockers .060
use a .030 rocker pad under the assemblies
end up with a 27.2-27.8 CM pushrod on both intake an exhaust..The intakes are usually 3mm shorter than the exhaust on the 163/86 B

You MUST check both intake and exhaust on a split duration cam..You will soon see just how much 1mm of pushrod adjustment will do to a rocker geometry set up..Good luck, and be careful..This is the toughest part of the build process..AND I HATE IT..

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Jake Raby
Raby's Aircooled Technology
www.aircooledtechnology.com

Tom Perso · Post by **Tom Perso** » Sun Sep 16, 2001 3:01 pm

Tuna, Jake,

Thanks SO much for the replies... I did not even think about removing the inner spring for the geometry settings and for cam break-in.

The adjustable pushrod I have from aircooled.net is very similar to the Bugpack chro-moly rods that I have for the motor. I will get a new chunk of rod and remake the adjuster.

Jake, thanks for the numbers, I will use them as ballpark figures and report to the forum once I get things figured out. I already have taken the face of the rockers down to allow for the 911 adjusters, I have removed at least "0.060 to allow for the adjuster ball. I also have the rocker shim pack from FAT Performance along with the chro-moly rocker studs to help withstand the dual valve springs.

It will be a while, I am back at school and the motor is 75 miles away...

Thanks again!
God Bless everyone...
Tom Perso http://www.qtm.net/~persoj

[This message has been edited by Tom Perso (edited 09-16-2001).]

danielzink · Post by **danielzink** » Mon Sep 17, 2001 7:14 am

<<use a .030 rocker pad under the assemblies>>

<<ll. I also have the rocker shim pack from FAT Performanc>>

Is FAT the only company that makes the shims for type4 ? the type1 rocker shims won't work ?

Dan

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[email protected]

http://users.aol.com/my65notch/index.htm

Steve Arndt · Post by **Steve Arndt** » Mon Sep 17, 2001 11:56 pm

I use just the inner springs when setting up pushrod length. Any light spring will work. Jegs sells valve geo checking springs just for this.
Stevie