[HammerDown]

If it isn't a trade secret, what's a good method of determining proper pushrod length?
As always, your suggestions are greatly appreciated-Ray

 

[Shaun]

oh man... have phun with this one.....

Search my forum in my sig for pushrod there was a ton of info on this from back on hotboat when i was doing this the first time. There are a few methods, in the end i used the marker method.

You take a marker, mark the top of the valve stem, install the pushrod and rocker and roll the motor over a few times. Then remove and look at the tip, you should see a area that was worn, it should be in the center of the valve and should be skinny, meaning most of the valve stem tip should still have marker on it. I used a adjustible pushrod, it worked well.

I tried steel's method, i tried fiats method. With there methods i keept getting different values. I think my problem with using there methods was that i had the real valve springs on and not weak test springs so it was making things difficult for me.

 

[Shaun]

here's thread i was talking about

http://riverracer.net/forums/viewtopic.php?f=3&t=45386&hilit=pushrod

 

[Jetaholic]

Use an adjustable pushrod and a set of lightweight checking springs.

On roller rockers, picture an imaginary straight line between the center of the roller and the center of the roller tip's axle. When the pushrod is the correct length, that line should be perpendicular (90*) to the valve stem with the valve open at half its max lift.

 

[SuperSoaker]

I use the Marker method as well worked great

But I look for the smallest pattern, my not be dead center.

On the Hyd. set up I just put the drill on the prime shaft and locked it on so I would have oil press for the lifters when I turned the motor over 2/3 times.

 

[gn7]

If it isn't a trade secret, what's a good method of determining proper pushrod length?
As always, your suggestions are greatly appreciated-Ray

Here ya go, knock yourself out. Do yourself a big favor and read the entire site, not just the page I linked. If you use any other method, it kind of like useing a breaker bar to torque your heads, your just guessing. Steelcomp did a real nice thread on this awhile back. If I find it I will post it. http://www.mid-lift.com/TECH/TECH-Installed-G1.htm

 

[sleekcrafter]

Yes get some checker springs, and some adjustable push rods, then measure the pivot at 50% valve lift. mine had to be .050" longer than the last go round, to be 90* at mid lift.

 

[Outlaw]

anybody have any idea what length adjustable pushrod
I need for a 9.8 deck BBC? I already have some lightweight checking springs and don't want to buy the complete kit.

here is a link to Steel's method starting on post 22
http://www.performanceboats.com//showthread.php?t=17545

 

[bennyb]

I don't remember the number but the ones I bought for tha big block we built I thought were way to short So I bought all thread so I could make more adjustment, didn't need them. I got them from summit.

 

[HammerDown]

Thanks for the abuve suggestion...just preparing for that day hammers

 

[cstraub]

Ray,
I bought the complete pushrod checking kit from Comp and send it to customers to use for figuring length. If you need it let me know, I will have the last customer forward it to you.

 

[cfm]

Very important question to those who measure their own pushrod - do you realize that not all pushrod companies measure the pushrod length the same way ? Because of differences of ball, oil hole size, oil hole chamfer, and etc ?

Whom every you go to for pushrods, find out how they measure it and do it exactly their way, or better yet, send your 'adjusted' pushrod in so that they can measure it their way.

Edit in:
Smith Bros info: http://www.pushrods.net/terminology.html

Trend's Info: http://www.trendperform.com/measuring.html

Comp Cams info:

3. Measure the resulting pushrod
Measuring the length of a pushrod is really rather simple, but it can be confusing at times. The most important thing to remember is that different manufacturers measure pushrods differently. So not all pushrods of a stated length will measure exactly the same. The three most common pushrod measurements are shown in Diagram B on the next page.

Theoretical Length: This assumes that the pushrod has no oil hole in the end of it. Therefore, the radius at either end is complete, which lengthens the pushrod approximately .017" in the case of a 5/16" pushrod with .100" diameter oil holes, minimally chamfered.

Actual Length: This is what you would measure if you had a set of calipers large enough to measure over the oil holes at each end of the pushrod. This is the measurement that most people can relate to. Unfortunately, this measurement is affected not only by the diameter of the oil holes, but also by the entrance chamfer for each oil hole.

Gauge Length: Although the most difficult to measure (it requires a special length checking gauge part #4997), this measurement is the most reliable. This is because the oil holes and their chamfers are eliminated from the measurement. The only problem is that not all companies use the same gauge diameter. COMP Cams® uses a .140" gauge diameter. All of the Magnum and Hi-Tech custom length pushrods listed on pages 270-275 of this catalog are measured using this technique. See Diagram B on the following page.

 

[gn7]

This is a very valid point. Comp and Trend both use "gauge" length. Others use "actual". I have had very good luck with Manton using the "actual" method, I have adjustable PRs that have exactly the flat on the end that matches up with there chamfered hole size, and they hold a very tight tolerance on their hole diameter.

 

[Outlaw]

very good infodevil

 

[gn7]

If it isn't a trade secret, what's a good method of determining proper pushrod length?
As always, your suggestions are greatly appreciated-Ray

Thanks for the abuve suggestion...just preparing for that day hammers

Here is post Steelcomp but up awhile back. Good luck.
http://www.performanceboats.com//showthread.php?t=17545&highlight=pushrod+length

 

[Outlaw]

Here is post Steelcomp but up awhile back. Good luck.
http://www.performanceboats.com//showthread.php?t=17545&highlight=pushrod+length

caution!!! his nails are DIRTYhand