TC Upper Pushrod Tubes

[FSG]

I had a set of Stock Upper PR Tubes in the old parts bin, thought I'd take a few pix and measurements which lead me to punch the tops out with a 5/8" Drill Bit to a depth of 2", the depth being overkill but a convenient measurement.

You can see the deformity created by compression during the manufacturing process.  Me thinks as a PM measure I'll now punch the tops out of stock tubes as I come across them.

[mike jesse]

Shouldn't the drill open them up to at least .625 in.?

[FSG]

Yes it should have been, I've corrected the mistake. Thanks.

[truck]

Why the need to increase the inside diameter? Is this where some push-rods hit the tube?

[N-gin]

 

[FSG]

Why the need to increase the inside diameter? Is this where some push-rods hit the tube?

Yes, but not usually a problem with stock or mild cams, but now that I've become aware of how reduced the top tube is I'm going to drill all top tubes that come across my lift as a preventative maintenance measure.

[No Cents]

 
TR (Tman) turned me on to that trick 4-5 years ago...it works!

[FSG]

Ha!!  I need to edit the first pic and include the ID of the tube in the area where the OD is .690"   

[Billy]

I'll drill'em all the way through, not necessary, but they're in the lathe, so why not.

[FSG]

so why not

    I only drilled them 2" as the bit I have is a short 3/8" reduced shank fella

[FBobPilot]

Do the pr tubes that come with the S&S adjustable prs have the same issue?

[Billy]

I only drilled them 2" as the bit I have is a short 3/8" reduced shank fella

Gotta have a long tool   

[FSG]

Do the pr tubes that come with the S&S adjustable prs have the same issue?

Good question. I don't know and while I've used S&S PRs I've not used any of their kits that have include the upper tube.

[OzyMax]

I'll bring over a set with the lifters

[FSG]

 

[dynoharley]

Do the pr tubes that come with the S&S adjustable prs have the same issue?

Good question. I don't know and while I've used S&S PRs I've not used any of their kits that have include the upper tube.

some push rods are parallel  11 mm diameter and some of the screamin eagle have premium tapered push rods that start at about 9.5 mm at top, I use them and drill entry to tube on high lift cams

[djl]

I only drilled them 2" as the bit I have is a short 3/8" reduced shank fella

FSG, please elaborate on your drilling procedure.  I have visions of trying this, drill bit being just the slightest bit askew of center and snagging the pushrod which would be secured somehow and breaking my wrist when the bit bites and hangs.

Great post BTW, the last time I took a Dremel tool to the inside of a pushrod tube, I was thinking about drilling as you have done but was too timid to give it a shot.

Is that Twist Gear kit still collecting dust?

[FSG]

I drilled them in my garage lathe, I'd not try it in a hand or drill press, certainly not the press I have due to spindle wobble. 

The Twist Gear, sadly yes.   

[FSG]

Max just dropped off his S&S Tubes. A quick visual confirms they suffer from the same problem.



His 124" Engine is taller than a stock TC so longer upper tubes are required.



The bottom of the S&S tube



The top of the S&S tube   



Tube OD in the bottom section



Tube OD at the top   




The Top and Bottom were drilled out to a depth of 2"






and there is a fair chance that these beefy S&S Quickee PRs were touching the bottom of the upper pushrod tube.

[gordonr]

 

I only drilled them 2" as the bit I have is a short 3/8" reduced shank fella

Gotta have a long tool   

[Azgunner]

FSG, what am I missing here? The top of the tube O.D is .63 & the drilled top of the tube I.D. is .625, surely you're not drilling these out leaving only a .0025 wall thickness are you?

[kd]

    Top OD .6630 / .625 ID = .038 wall remaining 

[Admiral Akbar]

    Top OD .6630 / .625 ID = .038 wall remaining

Don't you mean 0.019 wall?

It's thicker on the tube itself,, (0.697-0.625) / 2 = 0.036

Max

[kd]

 
Quote from: kd on Today at 09:02:47 AM
    Top OD .6630 / .625 ID = .038 wall remaining

Don't you mean 0.019 wall?

It's thicker on the tube itself,, (0.697-0.625) / 2 = 0.036

Max


  double  too much of a hurry I guess. Thanks Max 

I'll stick my neck out further by saying the .019 wall thickness really only holds the position in the rocker box seat and as has been shown to be substantial enough to do the job. 

[Azgunner]

    Top OD .6630 / .625 ID = .038 wall remaining

Duh, you're right I misread the digital readout.  Thanks.
Actually .019 wall thickness.