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Shortening pushrods

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mcoomey Avatar
mcoomey Silver Member Michael Coomey
Paxton, MA, USA   USA
From a previous post I learned that after having the engine head machined and the valves and seats ground it's often necessary to shorten the pushrods to maintain the previous geometry and allow the adjusters to be set to the specified rocker arm gap. I thought it would simply be a case of removing the end cap from the hollow tube pushrod, machining the rod to the new length, and pressing the end cap back on.

I made up the tool shown in the attached photos to pull the end cap and tried it out on an old pushrod. It worked like a charm until I tried pulling the cap off of a new pushrod that was recently purchased from Moss. Despite applying a tremendous amount of force via the 3/4" threaded rod the end cap would not budge. I wondered if perhaps the Moss replacements had the caps threaded on so I tried twisting off, but once again they didn't yield.

Does anyone have any experience or suggestions on removing these caps? If not, any idea of a source for shorter (or custom) length rods?



Michael Coomey
Paxton, MA

'57 TR3

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TR3driver Randall Y
Confusion, Los Angeles, USA   USA
Yes, new pushrods are made differently than originals were.

I got mine at BFE http://www.britishframeandengine.com/parts.html

And BTW, normally it's not necessary to shorten the pushrods if the head was just skimmed to bring it back to flat again. Most likely someone (not necessarily you) has had the head machined to increase compression. No reputable machine shop would pocket valves that badly without specific instructions from the customer.



Randall
56 TR3 TS13571L daily driver
71 Stag LE1473L awaiting engine rebuild
7? Stag awaiting gearbox rebuild

mcoomey Avatar
mcoomey Silver Member Michael Coomey
Paxton, MA, USA   USA
Thanks, Randall. I'll follow up with British Frames and Engines as you suggested. I see from their website that they offer various rod lengths, but they don't seem to have any online ordering???

Regarding why I need shorter rods, I'm not sure. The shop that did the work for me had great online reviews, has been around since 1968 and was currently working on several vintage engines, so I don't think they would have done anything drastic without warning me -- but who knows?!



Michael Coomey
Paxton, MA

'57 TR3

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TR3driver Randall Y
Confusion, Los Angeles, USA   USA
BFE was (and AFAIK still is) a very small, one-man operation. At the time I bought pushrods (and many other items), it was run by Ken Gillanders out of his back room, "as a favor to my racing friends". Ken has unfortunately had a lot of medical problems recently, and was unable to keep running BFE, so it has been taken over by someone else (whose name I unfortunately forget offhand).

I don't know if the new man is keeping the web site up to date or not, but Ken was somewhat "technologically impaired" and didn't update it very often. So the prices were often out of date, and often he would have parts not listed (or not have those that were listed).

So, give BFE a call. If you don't get an answer during reasonable hours, call back later. Again, I don't know about the new guy, but Ken was often out of town if a race was going on and the phone just went unanswered.



Randall
56 TR3 TS13571L daily driver
71 Stag LE1473L awaiting engine rebuild
7? Stag awaiting gearbox rebuild

Britnut Randy DeRuiter
Nacogdoches, Texas, USA   USA
See my note on the other thread - I suggest calling British Parts Northwest - I think their pushrods will fit. I can help with some reference measures if you need them.

Randy

edfmay Avatar
edfmay Edwin May
Loveland, Colorado, USA   USA
Michael, the best place for shorten push rods is, Smith Bros.,
I got a set from them for my TR6 engine that I milled the head on and they were only about $80. Thats about $100 less than Moss.
Plus there a upgraded rod.
They have been around for a very long time and do push rods for all cars.

mcoomey Avatar
mcoomey Silver Member Michael Coomey
Paxton, MA, USA   USA
Edwin, thanks for the source on the custom pushrods. I decided to shim the rocker pedestals instead of going with the shorter rods to try to maintain the proper rocker geometry, but if anyone is interested, Smith Bros' web site is www.pushrods.net.



Michael Coomey
Paxton, MA

'57 TR3

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TR3driver Randall Y
Confusion, Los Angeles, USA   USA
Is there something you're not telling us? Unlike more common engines, shaving the head on a Triumph does not change the valve geometry, so there is very rarely any reason to have to move the rocker shaft up. If the valves are pocketed that bad, you should be looking at new exhaust seats & oversize intakes instead.



Randall
56 TR3 TS13571L daily driver
71 Stag LE1473L awaiting engine rebuild
7? Stag awaiting gearbox rebuild

mcoomey Avatar
mcoomey Silver Member Michael Coomey
Paxton, MA, USA   USA
Hi, Randall. This forum thread was started as a follow-on to my other thread "Unable to achieve rocker arm / valve gap -- now what?" but I now regret splitting the topics as the full story has gotten mixed between them.

Essentially, the story is this. I have an engine with an unknown history that someone even less knowledgable than me did some work on before I took ownership. While attempting to hand re-lap the valves with cutting compound and the suction-cup-on-a-stick method I wasn't making any progress so I brought the head to a local shop for help. They ground the seats and valves and said that they noticed a slight warp in the head so they shaved it flat. After re-assembling and attempting to set the valve/rocker gap with newly installed adjusters, new pushrods and new tappets from Moss I could not achieve the 0.010 spec. I have no idea if this condition was present before I started work because I didn't check the gap prior to disassembly.

Following suggestions on the other thread to shorten the pushrods, I ran into trouble doing so and started this thread. Meanwhile the debate continued on the other thread regarding shorter pushrods vs. shimming the pedestals vs. replacing the valves and seats and the importance of maintaining geometry.

Prior to that I had never considered rocker geometry as a concern, but it seemed logical and if the valves are pocketed deeper (hopefully not too deep -- whatever that would be) then raising the pedestal seemed like it would accommodate that.

So now I've gone ahead and added shims under the pedestals which has enabled me to set the proper gap. I have no idea if this was the appropriate or best thing to do, I was swayed by someone's first-hand experience of doing this very thing. I would prefer not to incur the expense of replacing the seats and valves, but I greatly value your input and if you feel that is the way to go then I will follow your advice.

Thanks again to everyone for helping me figure out my latest dilemma. Does this get easier with the second car? I've got my eye on a nice '73 Spitfire! smiling smiley



Michael Coomey
Paxton, MA

'57 TR3

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CJD john durant
Southlake, Texas, USA   USA
In reply to # 1488031 by TR3driver Is there something you're not telling us? Unlike more common engines, shaving the head on a Triumph does not change the valve geometry, so there is very rarely any reason to have to move the rocker shaft up.

But it does reduce the distance the pushrods have to span. Now we need to discuss the difference between clearance and geometry?!?



John
Southlake, TX

'55 TR2

TR3barton Avatar
TR3barton John Taylor
Greenfield, MA, USA   USA
Hello,

Is the head off the motor at this point? If so you may wish have a careful look at the pushrod tubes on the mating surface side.

Are the tubes flush with the gasket surface or slightly recessed? If your shop only did a skim and the head has never been before the
the tubes will be slightly below surface. If they are flush then the head has been cut and at least 30thou. This amount would NOT require shorter pushrods.

There is a person on the web, http://www.expeditionlandrover.info, and she has a good listing of all the TR heads and the stock thickness.

I would start at that point.

mcoomey Avatar
mcoomey Silver Member Michael Coomey
Paxton, MA, USA   USA
Thanks for the input, John. Unfortunately, the head is back on the engine which has been put back in the car, so any measurement or inspection of the pushrod tubes would be difficult.

As discussed in this thread, I ended up shimming the rocker pedestals a bit to compensate. I have since discovered that the head I've got is actually from a TR4. I'm not sure if that the the root of the issue or not, but I'm hopeful it will all work out.



Michael Coomey
Paxton, MA

'57 TR3

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