im gonna assume thats what happened here, judging by the looks of this thing. would annealing it allow me to use it again? im kinda in a hurry and would rather not wait the week it would take to get a new one. and could this have warped the heads gasket surface? thanks, cheers, barefoot ed
Yes, and yes. Or rather, this could be a symptom of non-flat surfaces. I would check the head and cylinder block for erosion and flatness. This assumes that you have the dimensioning tools to do this. If not, run them down to your local machine shop and have them do it. Don't make any assumptions... measure. When you have it sorted, be sure to repeatedly re-torque properly during the heat cycles of break-in.
thanks don. here is the head gasket surface. ill measure this and see what i get. i may just take the brand new top end off my other project and have something to ride while i finish the other project.
Whether you can re-use the head gasket depends upon the shape the gasket is in. Obviously, annealing does not replace metal that's been burned away!
A blown head gasket is a symptom of a larger issue, and since you'll have to determine the root cause or you'll be doing this job again next week, I suggest you do some thorough research before replacing the head. Did you check the head and cylinder for flatness prior to assembly? Did you get the PRT gasket squish set just right, prior to assembly? Did you toque the head bolts at assembly? These things happen for a reason, you know. Someone once said, "The definition of insanity is doing the same thing over and over, and expecting a different outcome."
I will admit to being anal... which means despite being a proficient mechaninc, I am slow and plodding. I could never make a living at it. Which also means, if'n I were you, I would be following professor Whatley's advice to the letter.
Don't jump to the other head without checking all parts for erosion, including the gasket as RF notes. Be sure that you are certain that the cylinder block surface is flat and with the correct surface finish, not just the old (or new) head. You will need to carefully check the push rod tube gasket squish as if the bike had never been assembled before. These weren't fully interchangeable parts in their day and nothing has changed. Things aren't simply replaced, they require "fitment". Failure to do so results in a "symptom" or as Mr. Whatley opines, "insanity".
Which gets me back to the anal part. If you do all these things, you may have to wait for a new gasket or new PRT gaskets to get it all right, anyway. Bummer, I know. But... what's one week in the life of these bikes?
Duke I put that great photo you posted on my desktop and then expanded it. The photo does look like you have lost gasket material on the right side (of the photo), AND it looks as if there is some kind of warpage, or indentation in the center area. This is not a case of Permatex Copper seal to the rescue. I honestly think you need to have the head and top of your barrel checked. PLUS, this is the perfect time of year to do it and the head is already off!
thanks guys. i knew the answer to this question,i was just hopin. the top end on the other bike is 100% rebuilt correctly,from the pistons on. i know what i have to do. the motor came in a running project i bought, but it was blowin smoke pretty bad. i took the top end off almost hopin to find a set of busted rings. i should have known better. cant be that easy. ill post the results, but im sure the damage is fixable. watch those "killer deals"
The timing side of the head has good witness marks from the head gasket but the drive side shows sweet f.a. The bloke who screwed that head down had other things on his mind. I wondered if the centre bolt was tightened properly?
1950 Speed Twin outfit 1951 Thunderbird outfit (76 degree racebike, or is it 90 deg now?) 1955 BSA D3 minibike outfit Triumph solo's
TT's warning is important. Be careful that your local machinist is not anxious to start removing material to "correct" the problem. Do a search, as TT suggests, on John Healy's advice. Worth more than you can imagine.
thanks all. on closer inspection, the little slot that is machined into the gasket surface around the "bore holes" is completely obliterated on the right side (as in the photo). i just got this bike, and tho it ran when i got it, my morbid curiosity got the better of me, as usual, and i stripped the top end. torque values between the head bolts was nonexistent, and the center bolt was too tight. and i discovered that the pistons are way too loose, tho they are recently new, as is (was) the bore. am i correct that the head leak would have caused the combustion to be on the rich side? i am thinking that rather than cause the piston to suck more air into the mixture thru the leak, it is instead enriched by the piston pushing the mixture out thru the leak before ignition. in any case, there was a nice thick coat of fluffy carbon residue in the combustion chamber and on the piston crown. time to pull the cylinders. ill post the results. thanks again guys, looks like this is gonna turn out to be the "something new" that one is meant to learn every day
and i'd ask, what is the procedure for checking for lost material/warpage on the head? i have access to a surface plate,dial indicators, calipers, etc, and can use them properly. if i can do this myself, i would prefer to acquire the experience. here is the heads gasket surface lightly skimmed on plate glass covered with 600 grit stickyback paper. the depressed part of the surface seems to extend from the combustion chamber to the outside of the gasket surface on both cylinders. this would seem to suggest a bow to the surface from side to side, yet with the center bolt being too tight,i would tend to think iit would warp the opposite way. ill try to get better pics up
That's the way they normally bend.I just blame excessive PRT o-ring crush (more than 0.040") and incorrect tightening/untighening sequence from previous owners. Put a straight-edge across,and measure the dip with feeler gauges.If its less than 0.005",just level it with the surface plate and abrasive paper.Use 240 grit or coarser,if you don't want to spend all day.Do the same with the barrel surface.
I usually lap the barrel and head together afterward (and clean it off well).That way it will seal even without a head gasket.
here is a better pic. and of all the years ive ridden triumphs, ive never known that the thickness of the prt(?) and o rings were that important. ignorane IS bliss, i guess, as long as luck is on your side. never had a pushrod tube leak on me before, and did not know that this could cause a head gasket to quit doing its job. may explain a few blown head gaskets in the past....... and the ".040" measurement is taken with the head sitting loosely on the o rings?
reply: I was getting "poofs" of exhaust smoke in the front and the rear where the head met the cylinders when kick starting my '70 TR6R - (750 Morgo kit).
After removing the head, my gasket and head looked exactly like yours. I took the head to work and checked it on a granite surface plate and found the center was warped .005, so I put a couple of adhesive strips of 180 grit on the surface plate and carefully lapped it flat. I then flipped it over and did the rocker box surface. It was only a few thousands out, but I figured while it was off, I better get it done. Now I will take the rocker boxes themselves in this week and do them next.
I will use new gaskets all over (being safe) instead of trying to reuse the ones on there now, even the copper one. I think I will have a much smoother running engine when it all goes together for this Spring.
im at the point where it has become a number of contributing factors. there were 3 o-rings at the tube/tappet block junction and an o ring, but no square section vtr(?) seal at the tube/head joint. no torque continuity, and broken seals thruout. were these vrt seals correct for pre 72 engines? i dont remember them on my late 60s machines. and my factory manual has no exploded drawings of the assembly. and the m.a.p. online parts book link is broken. anniehooooo....... here is a pic of the gasket surface after removing about .005". there are some remaing scratches that are deep enough to preclude skimming the entire surface down far enough to remove them. is this head shot? and that big gouge on the outer edge of the right side bore? syptom or cause? i just love the gremlins that come with "good deals" and john healy, if you read this, do you remember the heading of your head skimming thoughts? i cannot find it using the search function.
You missed the point. It is not about skimming if head is warped, but about straightening. I suppose that there are tolerances for skimming. But what I think John, meant, and I am not sure, in his post to Ken, is that by skimming the head .005 he adding that much crush to the PRT's.
So one of the major causes, as I understand it, is that people get the PRT crush wrong in the first place. For example I know an old bear of a mechanic, who thinks that the bike that had a warped head, after he re-built it, was do to his workers removing it and not evenly undoing the head bolts. But I have heard that same old bear exclaim that what difference could a little amount of rubber make when torqueing the head. I just bit my tongue.
See? a lot of guys, even with a lot of experience, just do not get it.
Anyway, that is the point. Bad crush leads to head warp, which leads to skimming which leads to bad crush, and on and on to other problems.
There are places where you can take the head and they heat it and control the temperature on the cool, whilst it is bolted to a straight surface, and thus, unwarp it.
Sorry to tell you this after all the skimming is done. I hope it will be OK. Just Pay attention to the crush.
Bob, Lifetime bike: '71 T120R, bought in '71 at Ken Heanes, England.
As Btoour said: This model uses two round section "O" rings and one square section ring.
--The square section goes between the bottom of the push rod tube and the top of the tappet guide block. --One round section goes into a groove in the bottom of the push rod tube and is accessed from the inside of the tube. --The other round section tube sits on top of the push rod tube and is located by a small shoulder on the tube. I use Viton (71-1283) "O" rings in both places even though Triumph only used Viton on the top of the tube.
All three must be lubricated prior to assembly. I use a rubber lube called P-80, but some engine oil or light grease will work just fine. The rings must be offered in a manner that will not cut them.
Once the tubes are in place and the head offered you should have approx. 0.040" between the top of the head gasket surface and the head's gasket surface. You can use as much as 0.060", but 0.040" is enough. More than 0.060", and you will warp the head as you torque in place. It would be no different than laying the middle of a head gasket across a pencil a pushing down on either end. It will bend in the middle!
Cutting any material from the head's head gasket surface increases the crush on the "O" rings leading to "O" ring failure an d the head bending. I orefer to have the head straightened.
There is another fault with these models. The inner 4 head stud washers are too small to spread the bolt's clamping force over a large enough area of the head. In practice the pressure from tightening the head bolts just displaces the aluminum underneath the washer instead of clamping. Thus no matter how many times you or how much you tighten the inner four 3/8" head bolts they are always loose.
This can be cured by using 4 of the same washers (82-2184) used under the four outer head bolts. The gaskets made today are all ready sized for the larger washers. Typically a small amount of aluminum has to be removed from rocker box in the area adjacent to the washer.
Be sure to check that your head gasket was annealed (even if it is new) and dead soft. If the cylinder has been bored oversize make sure that the head gasket doesn't stick into the bore! If it does it must be sized to the bore. Wash all gasket surfaces with alcohol. A light smear of Copper Coat, or similar can be used on the head gasket. John Healy
retro rod: the groove i spoke of was a non issue. it appears to be a groove on the gasket, but turned out to be an impression put onto the gasket by the groove machined into the cylinder block.and the "missing" meat on the gasket seems to be blowby on the gasket itself. anniehooooo..... i have found a new problem. on the late 60s machines i have owned over the years, i dont remember ever using the white silicon seals on any of them. were the "vtr" seals a 71 on thing? i ask because when i assembled the top end with just two o rings, 1 on top, 1 at the bottom of the tube, i found just a few thousanths of clearance at the bottom of the pushrod tube. a little bit more than that between the head and the top of the copper gasket. what im trying to say is the gasket kit i purchased came with 4 different thicknesses of the "vtr" seals, NONE OF WHICH COME WITHIN ABOUT .125" OF FITTING BETWEEN THE PUSHROD TUBE AND THE TAPPET BLOCK. all this seems to suggest no "vtr" is needed. i have heard of mix matching late top ends onto early cylinders, and am sure i have done it many times without realizing it. could this be a case of non matching parts sets? and john to address some of your concerns, i see the "depressed" material under the inner headbolt washer. to correctly use the outer bolt washers, i would think the rocker box gasket surface on the head would need to be shaved, at least counterboring the "depression" to the outer head bolt washer diameter. (was that your suggestion)? i dont see any issues with that line of thinking..... im still tryin to wrap my brain around the clearance issue without the "vtr" seals. and about the head gasket being too small. my brother builds old harley davidson hummers. i know they are two strokes, but they use "stuffer plates" on the flywheel (just a stamped metal plate attached to the flywheel sides that decrease the available volume of the crankcase) to up the compression ratio. the point im gatting at is, what negative effect would a head gasket that is a few thou shy of the bore size have on the engines function? pardon the silly questions, but at 50 years old, im starting to realize how lucky ive been over the years to have had bikes that just ran, and were almost always an "easy" fix, despite my not having a real clue as to how or why. the internet , if nothing else, has served to educate me beyond a greasy manual, solving problems the manual never covered.
So Ken are you going to address the reason the head warped in the first place? Especially since you have added an additional 0.005" or so more crush on the push rod tube seals. John Healy
I understand where you are coming from....but on a 40 year old head, I was surprised it wasn't worse. Who knows how the head was treated all these years. I've only had it 5 years. When I reinstall everything, I'll be extra cautious. Maybe I wasn't too careful the first time (duh).
I have been following this thread with great interest. Indeed I have copied your posts above into an MS Word document for later reference! However, may I seek further advice.
In my ongoing project, I am using Triumph 9-stud 650 heads, bespoke alloy barrels and Nourish alloy tappet blocks. My heads are nice and flat but the orifices where the top of the PRTs go have had to be machined to correct PO bodges. So I do not have a complete handle on PRT crush dimensions.
When I have previously worked on my 1960 T120, I have always measured the clearance of the PRTs without rings, added 50% and chosen ring thicknesses to suit (so that the crush was about 33% of total o-ring thickness).
For my project I had intended to use the same philosophy, except that I have later model PRTs, ie. those with an o-ring located in a groove inside the bottom of the PRT.
The very bottom of the PRT must surely have a square section ring but I can see that there is the potential for failure as there is no retaining feature for this ring which looks as if it will easily squeeze out. Enter the so-called "wedding ring". I have no experience of these at all. I have a selection of them from various suppliers and most of them are slightly different sizes (and none right!). All too loose or tight by some degree. My instinct is to take the tubes and smaller ID rings to a good exhaust fabricator who might be able to expand them to fit properly.
Would you be prepared to comment on my way ahead and do you have any tips wrt "wedding rings".
Regards and thanks.
mike Member #: 147 1960 T120 Bonneville 1999 H*%^a VFR 800 FI V4 Triton Project (still keeping me sane (Ha-Ha!))