• Hi Guest!
    If you appreciate British Car Forum and our 25 years of supporting British car enthusiasts with technical and anicdotal information, collected from our thousands of great members, please support us with a low-cost subscription. You can become a supporting member for less than the dues of most car clubs.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

Triumph TR Pushrods //rockers??

Share this page

H

Hydroglen

Member
Country flag
Offline
Hi Guys,
Some of you may remember I was having lifter and pushrod issues with my car. Somebody else was working on it before I got it so some of it was "creative"!
Some were bent and broken.
Anyway I had the head surfaced and i got new tappets and pushrods and a couple of exhaust valves. This proved interesting as my head is the special one and basically a smaller diamter valve. Anyway got it all together, torqued the head and then %^)()Y(*
The rocker shaft towers will not seat on the head because the pushrods seem too long. The screws are backed out all the way and it does not look good. The one closest to the firewall is the worst but they are all tight and I am still off the head.
There seems to be only one lenghth pushrod so are the rockers wrong?

I suppose I could machine small spacers to go under the tower base.
Now I see why the old ones were broken.
Ideas??
Dorien
 
Do you know (have you measured) how much has been removed from the head?

There may be some geometry involved that requires a solution more complex than spacers.

<span style="font-style: italic">PS: I checked your profile, but you might want to mention this is a TR3.</span>
 
The only "wrong" rockers I've seen were visibly quite different from the stock ones (machined from billet aluminum rather than cast iron as original).

Another possibility is that the lifters have been replaced with different ones.

I think I mentioned before, several "racing" vendors offer shorter pushrods.

I assume your smaller valves are just the ones with the smaller stem (5/16" instead of 3/8"). There are "conversion" guides available to use those valves in the earlier heads. (My point being only that you may still have an earlier head with the later valves.)
 
This may sound dumb but are your lifters in upside down?
 
Re: Triumph TR 3 Pushrods //rockers??

My head is stamped 511695. The valves are the smaller stem 5/16.
Moss only stocks one kind of tappet and pushrod and that is what I have.
The head is now 2.980 so well on spec.
Not sure about my profile and TR3, but that is what I own and have listed.
Why would some people want shorter pushrods? Cam reasons?
Do you have a name of such a shop/store?
Maybe the cam has a lot of extra lift, but did not look that way when I measured.
Any reason you can see against spacers?
No the Tappets are ok not upside down LOL
Dorien
 
Just for the heck of it rotate the crank by hand about 90 degrees so that the cam lobes come to a different position..See if things change for the better as you rotate.
If necessary you can get an adjustable push rod so that you can determine the needed length and have your's either cut to fit or get a new set custom made. Give Ted Schumacher a call for more information if you have to go that route, pretty sure he canhelp.
https://www.tsimportedautomotive.com/
 
Thanks...my dear wife has been slowly hand cranking whilst I check each little bugger!
In turn they all go tight with the screw all the way out and the tower a 1/8" approx off the head.
I took the complete rocker set off a spare engine and it was the same. Getting good at switching them...can do it in the dark!
Dorien
 
As the head is surfaced, the rocker shaft moves closer to the cam...the result is double the surfacing comes out of the clearance. For example.

Say you, the PO and the PPO each took .010" off the surface of the head for a total of .030". Your valve clearances will now have been reduced by .030" times 2, so .060". As you can see, it becomes significant.

The solution is shorter pushrods.

A by-product of the head surfacing is also higher compression. This should give better throttle response, but may require a reduction in timing and/or a higher octane fuel before you get detonation.

John
 
CJD said:
the result is double the surfacing comes out of the clearance.
Click to expand...
I disagree on the "double" part. The surfacing does not change the position of the rocker relative to the top of the head, so the surfacing only moves the rocker by the same amount that is removed from the bottom of the head.

The accepted stock thickness for a high port head is somewhere around 3.330", so it sounds as though yours has been milled by quite a lot. Almost makes me wonder if there isn't some mistake, as I don't think the deck was that thick to begin with. I know Kas Kastner talked about having to reinforce the deck when milling a lot off stock heads, and as I recall, he even had the factory make a run of heads with the cores offset (to give a thicker deck).
 
Thanks all,
Ok I installed 4 washers 2.8mm thick or say 0.110 under the towers..one per tower. Works well and was able to set the valves loosely, just to see if I could get slack and valve compression. Looking good.
My wife did the cranking, but in fairness I provided her with the factory hand crank and there were no plugs in the head LOL. Yes I am lucky.
Sorry again about the head milling. my mistake. I assume 3,325-3.330 and now it is 3.231 so within the .165 spec limit. Too many bits of paper in front of me!!

I can "refine" the washers, can make small aluminum pads, drill an oil hole for the last one and carry on, BUT still no idea as to why?
Now I have a number.... a 2.8 mm loss of height or ??
I thought the block may have been cut but with a liner engine I see that as unlikely.
There are no dumb suggestions.
Dorien
 
Sorry I am late answering this question....
My car has had a lot of material removed to raise the compression and to make up for material removed from the inside of the combustion chamber to unshroud the valves.
This meant that I needed pushrods that were 100 thou (one tenth of an inch) shorter to correct the rocker geometry, I got stronger tubular rods of the correct length from British Frame and Engine in Temple, California. Ken Gillanders is a very nice guy to talk to on the phone, and has all sorts of special parts for modified TR engines.
 
Also if you had a cam reground with higher lift the lobes are not higher. The grind comes off the base circle so your tappets set lower in the block then stock. So you may have had 30 thousandths taken off the head but you won't need to take that full amount off the push rods. I'd pull everything and remeasure the head thickness, cam lobes, pedestals, tappets and push rods. Then get ahold of some noted expert and let them know what you have and get a professional plan to reassemble properly.
Sounds like you got someone's hodgepodge of parts that tried a backyard mechanic rebuild. Your head will make or brake your engine. Done right it will be great. but done wrong it will brake it.
 
Hydroglen said:
I assume 3,325-3.330 and now it is 3.231...

Now I have a number.... a 2.8 mm loss of height or ??
Click to expand...

Looks like .099" has been taken off the head and that is 2.51mm -- so isn't that where your loss of height came from?
 
I belive some engine rebuilders have an adjustable push rod you can borrow and install it in the lifter and it has a screw adjustment at the top, you can then adjust it till you get the right length then you can measure the length and have your pushrods made to that length instead of guessing

I belive Wishbone classics can do that for you. he rebuilt my TR6 engine and told me he had such a device

Hondo
 
An adjustable push rod could be handy at times but in this case I don't think you need it. Basically 0.1" has been milled off the head, so push rods 0.1" less as Simon has used would do the trick.
 
For 15 - 20 dollars you can buy an adjustable pushrod to measure the length you'll need from Jegs, Summit Racing, places like that. If you have a speed shop or NAPA, you can probably get one over the counter.
I think that sometimes we believe that our engines are so unique that we have to rely on a TRiumph specialist for stuff like this, but in reality just about any engine builder has similar projects to deal with..
 
Yep Jegs has them for 11.99

didnt know that!

you could just get push rods that are shorter by how much the head is milled,but you would still be guessing, but for 11.99 more you can find out exactly how long they should be. I was told to get the correct length you put some blueing compound on the top of the valve stem, turn the adjuster all the way out to all the way in and count the turnes and set it half way turn the engine over for one valve cycle on the one you are testing, then look at the contact area, the blueing should rub off where the rocker is hitting the valve stem, and it should be centered on the stem

if not you would either make the pushrod longer or shorter and retest, when correct measure the pushrod and thats what you order

seems simple to me

Hondo
 
hondo402000 said:
you could just get push rods that are shorter by how much the head is milled,but you would still be guessing,
Click to expand...

I give up, in what way would that be guessing?
 
well we are just offering opinions here, but you know how much the head was machined but do you know if the block was surfaced too and if so by how much? I have learned to never assume anything is factory original on these cars

just my opinion, its free

Hondo
 
Back
Top