I'm working on a prototype set of stainless pushrod tubes.
Advantages:
Precision machined heavy duty ends for greatly improved o-ring retention
Stop using paste sealants to keep oil from leaking at pr tube seals
Lower heat transfer than mild steel
Slightly smaller (3/4" od) tubes for better stub pipe clearance without need to dimple the pr tubes
Available in custom lengths, longer or shorter
Never rust out - never need replacement
I'm also considering using separate oil return hoses from both rocker boxes so that the pr tubes no longer have to handle that function.
That would allow the smallest possible tubes without the p-rods rubbing.
Machining the ends would be simplified, thereby lowering the cost of production.
Your thoughts?
Edit 09/12/14: These are in Production. Go to Post #26 for add'l information.
I wish you would have come out with these back when I still had my -4.....
I love the idea though. When I get another 914 with a -4, I'll buy a set.
God yes!
I would be interested; especially if you could eliminate those wire thingies that are a PITA whenever I adjust the valves. I can't get my finger past them to feel is the stainless pushrod will spin (zero lash cold but the pushrod should spin is what I'm told to aim for).
I'd be interested in that!
Any estimate of cost? I'm interested.
Sound like a go for me. Appx production time ?
I would be up for at least two sets if priced fair.
Interesting
i would go for two sets, depending on price of coarse.
Sounds good!
Add something to ease PR tube removal. Grabbing them with pliers is effective, but damaging.
I've always thought something welded to the valve cover would do the trick. I hate setting my valve lash and spinning the pushrods (for a loose "0") with the wired bales...
Then again, a simple clamp device at the head side of the pushrod tube would also keep it from sliding out.
Here's the first crude prototype.
Installed in our exhaust assembly fixture.
The flange is there for easier removal.
I'm not sure the flange is necessary. This thing is a lot sturdier than the stock pieces.
With just a little motor oil on the o-rings the tube presses in without much difficulty, and the shoulder on the large end may be exposed enough to push against for removal.
There's plenty of compression on the o-ring but the correctly shaped groove does an excellent job of supporting it.
I've pushed this tube in and out many times already, without being all that careful, and no sign of damage to the o-rings.
I was thinking a snap ring on the back side of the head might be suitable for retention, but there are too many engine variations possible. A small change in engine dimension might make that feature unusable.
Another idea was safety wire from the flange to the case but there's no good place on the crankcase for all the wires.
I also considered some kind of bar screwed to the case which overlaps the edge of all 4 holes at the small end of the tubes.
The wire bales will still work with these tubes.
Not sure what's best yet. Trying to keep it simple.
We're building a 2.5L track engine right now and the customer doesn't want any oil leaks,
so I've ordered material to make a pilot run.
Rather than make them all 3/4" od, part of each set will be 7/8" od.
The smaller tubes clear the exhaust stubs better and the larger tubes flow more oil.
My materials cost is within $0.05 per tube assembly between the two sizes so this doesn't have any effect on final price.
They will be initially priced at $240 per set of 8.
Custom lengths will be available for $20 more.
Great work! Those look really nice and will be a great upgrade for anyone.
Good evening Chris,
Is that $20 additional for the set, or each? BTW they look very nice.
Thanks
David
I think the section where the seal rides would certainly be considered an upgrade. The stamped and formed tubes seem very inconsistent in the old tubes.
Nice job Chris
I would buy a set.....
i like the idea, and can see the benefit. unfortunately i just put in brand new ones, and i installed them per advice from the crusty one, just use a bit of motor oil on the viton seals to give some lube when installing them. installation seemed to go good, but if i have leaking issues i might consider it. and when i do my rebuild, this will be on the short list of things to do.
These are now available.
For details see my Whats New at Tangerine Racing Products thread in the Member Vendors section
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