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Fitability of different years top end, problem?
#714337 11/09/17 1:50 am
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Hey guys, trying to put together a bitsa 650 engine for a bike... 72 cases, 67 barrels... What would be the best head? I was under the impression that any 9 bolt head would work, now I am being told that this is wrong... Any suggestion??

Thanks guys!!


Jack
1967 MGB Roadster..
1959 Bonnie
1967 Bonnie in disguise as a Trophy
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Re: Fitability of different years top end, problem?
T120C #714347 11/09/17 6:51 am
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Which frame are you using? The OIF will require the later head and rocker box arrangement. The earlier frame will take any unit 650 top end.
Personally, I'm more comfortable with the 63-70 top end. I'm more familiar with them.
I can sort out the lifter blocks push rod tubes etc without too much trouble..

There's some talk of the early TR6 heads flowing better than the later ones. Whatever you do, don't get a ported head. That only ruins them unless the person doing really knows his stuff and it can mean making the ports actually smaller in diameter to make them work. I wouldn't even go there unless you have a machinist who has actually flowed a Triumph head before.

When I build up an engine from scratch like this, using all the same parts from one year solves all sorts of problems as far as the top end is concerned.

Cheers,
Bill



Bikes
1974 Commando
1985 Honda Nighthawk 650
1957 Thunderbird/T110 "Black Tiger"
Antique Fans: Loads of Emersons (Two six wingers) plus gyros and orbiters.
Re: Fitability of different years top end, problem?
T120C #714355 11/09/17 8:22 am
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What Bill said, but remember that if you use a 71-on head and rocker boxes, the latter aren't designed to take the force of the head bolts going through them. It may well work for all I know, but the 1972 studs and long Insex nuts is a safer bet. If you don't know what I mean, a look in the parts books or shop manuals will clue you in. www.classicbike.biz
The 71 bolts and set up is a pain, you have to remove the rocker boxes to re-torque. From 72 and on you can torque them from the outside. T140 studs won't fit, different threads.
I'm currently doing something similar, an engine with a 72 head to be used in a 70 frame. I've opted for earlier rocker boxes and through-bolts, they fit. The other way around, later R/B on earlier heads may not work.

TriCor England/ Andy Gregory used to carry Push Rod Tubes for any mix of tappet guide blocks and heads, if that's required.

Last edited by Stein Roger; 11/09/17 8:23 am.
Re: Fitability of different years top end, problem?
T120C #714370 11/09/17 1:00 pm
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http://transgarp.dyndns.org/motorcycle/2000/20170914/12.JPG

67 cases
67 rocker box
69 gearbox
72 head
72 crankshaft
Morgo 750 barrel
Carrillo conn-rod
AMAL 932

Re: Fitability of different years top end, problem?
T120C #714388 11/09/17 4:22 pm
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Hey Bill, 67 frame...

Good to know, but this is going to be what it will be... So just some adjusting on push tubes is the main problem?

thanks y'all


Jack
1967 MGB Roadster..
1959 Bonnie
1967 Bonnie in disguise as a Trophy
Re: Fitability of different years top end, problem?
T120C #714390 11/09/17 4:37 pm
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...hello HT, why do you say that a 71 72 top end would not work? (OIF)

Re: Fitability of different years top end, problem?
T120C #714396 11/09/17 5:21 pm
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Basically you can use any 9 bolt 650 head on any 650 crankcase/cylinder. The caveat is the tappet guide block, push rod tubes (and related sealing bits) and head have to be used as a set. Some heads have to be used with their rocker boxes.

For example to get a small port to make your bike more tractable (more torque) you can use the 1963 head, push rod tubes and tappet guide blocks on any 650 from 1963 to 1972.

Re: Fitability of different years top end, problem?
reverb #714404 11/09/17 6:53 pm
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Originally Posted by reverb
...hello HT, why do you say that a 71 72 top end would not work? (OIF)


I didn't intend to suggest that. That's an option for any frame, but a must for the OIF.

Cheers,
Bill


Bikes
1974 Commando
1985 Honda Nighthawk 650
1957 Thunderbird/T110 "Black Tiger"
Antique Fans: Loads of Emersons (Two six wingers) plus gyros and orbiters.
Re: Fitability of different years top end, problem?
Stein Roger #714443 11/10/17 1:54 am
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Originally Posted by Stein Roger
What Bill said, but remember that if you use a 71-on head and rocker boxes, the latter aren't designed to take the force of the head bolts going through them. It may well work for all I know, but the 1972 studs and long Insex nuts is a safer bet. If you don't know what I mean, a look in the parts books or shop manuals will clue you in. www.classicbike.biz
The 71 bolts and set up is a pain, you have to remove the rocker boxes to re-torque. From 72 and on you can torque them from the outside. T140 studs won't fit, different threads.
I'm currently doing something similar, an engine with a 72 head to be used in a 70 frame. I've opted for earlier rocker boxes and through-bolts, they fit. The other way around, later R/B on earlier heads may not work.

TriCor England/ Andy Gregory used to carry Push Rod Tubes for any mix of tappet guide blocks and heads, if that's required.


I have a '72 head on my '68 bonnie. Tried to use the '72 rocker boxes but could not fit them over the tall head bolts for interference with the '68 frame. Like I would have had to pull the motor or lean it over to get them on. I know it can be done, and I would love to know what I was doing wrong, but for the life of me I couldn't finesse them into place.

As I felt like R&R on those boxes was going to be next to impossible, I opted to put early rocker boxes on. NOW the problem was that the head had pretty good indentions around the bolt holes under the rocker boxes, and since the clamping force of the head bolts now depend on contact of the inner stud boss of the rocker box to the cylinder head, I felt that (about 60 thou) clearance would have to be taken up by flex (compression) in the box, or it would not clamp completely, and/or it would leak. I ended up making brass washers to shim the difference and glueing them on the head indentions with 3 bond.

Which brings me to today, where I never started the bike like this for fear of oil all over a nice restoration, bought two more heads in effort to get one to work etc...
So, check for indentions on a 71> head if you plan on using early boxes and long head bolts.


'68 Bonnie, '70 TR6r
'74 CL360
trail 70's and minitrails
Re: Fitability of different years top end, problem?
T120C #714463 11/10/17 7:02 am
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Provided that you milled the indentations flat, your solution is sound I think, and besides I believe the earlier box with its "inner stud boss" is sturdy enough to spread the clamping force over the gasket face without distorting too much. This is why I believe the earlier box without these bosses may prove too weak to use with through bolts. I say "may" because I don't really know, it "may" work for all I know. A later box on an earlier head may prove have too little gasket face overlap, that's another potential issue.
I would either use a Covseal or a copper gasket, or perhaps no gasket at all in your application. Loctite 515 or 518 works really well, on copper or by itself.
I hear that our local jeweler is taking up Loctite as it fits their business model and price range, so I've starting exploring cheap "house" branded gasket sealers and thread lock products. So far they seem to work equally well...
Personally I don't like 3 Bond, too thick and too hard.

Re: Fitability of different years top end, problem?
T120C #714666 11/11/17 9:24 pm
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Thanks all for the info, really helps!!!


Jack
1967 MGB Roadster..
1959 Bonnie
1967 Bonnie in disguise as a Trophy
Re: Fitability of different years top end, problem?
John Healy #714766 11/12/17 3:34 pm
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Originally Posted by John Healy


For example to get a small port to make your bike more tractable (more torque) you can use the 1963 head, push rod tubes and tappet guide blocks on any 650 from 1963 to 1972.

Not intending to high jack but I'm intrigued by this. Does this 1963 head have smaller ports with better flow? Does smaller ports mean smaller valves? If I found one of these small port heads will my 69 TR6 valves drop straight in and my rocker boxes bolt up with no mods?

Re: Fitability of different years top end, problem?
T120C #714796 11/12/17 7:10 pm
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One 650 Triumph model was once known as the T110. It bore that moniker because it was able to reach 110mph down the mile long straight out of the Coventry village. In the late 1970's dealers were getting complaints from owners that their new Bonneville's would barely reach 90mph. Triumph had been in a competition with BSA from the day they announced the Big Valve Super Rocket. In an effort to address this Triumph Baltimore kept changing things trying to get back the 20 odd mph lost. Thinking back to the T110 they went back to the 1963 9 bolt head to see if there was any improvement. To their surprise the bike once again became a 110mph motorcycle. On this head both the valves and ports are smaller.

Setting up an engine is not intuitive! On one end you have trials bikes and on the other land speed record machines On one end you have wide ration gearboxes and on the other close ratio gearboxes. You also have to remember when you open up your ports that you will be killing low speed torque to gain high rpm horse power. You don't want to build an Triumph engine that will have a very narrow power band and need to be turned 10,000 rpm to see any benefit and then complain that with your standard ratio gearbox that the bike is a dog around town or will not pull past 90mph.

Re: Fitability of different years top end, problem?
T120C #714801 11/12/17 7:26 pm
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Norton sleeved the inlets on some twins.

Wonder if that would help on a Triumph.


Amateur Loctite enthusiast.
Re: Fitability of different years top end, problem?
triton thrasher #714806 11/12/17 7:56 pm
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That sounds like an interesting idea that could be tried non-destructively. Lathe work for tubing, some hand work at the guide end to blend and occupy maybe dead zones above valves? I haven't the need or facilities, but if you're suffering with a 90mph Triumph and you've got a lathe?

Re: Fitability of different years top end, problem?
T120C #714811 11/12/17 8:38 pm
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Amateur Loctite enthusiast.
Re: Fitability of different years top end, problem?
T120C #714813 11/12/17 8:48 pm
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Wonderfully crude, but if it worked? I have often heard that Norton chamber design was superior to Triumph, but I don't know the fact of that and what made the difference. Do you mate?

Re: Fitability of different years top end, problem?
koan58 #714817 11/12/17 8:55 pm
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Originally Posted by koan58
Wonderfully crude, but if it worked? I have often heard that Norton chamber design was superior to Triumph, but I don't know the fact of that and what made the difference. Do you mate?


I'd be the last to know, but their SS twins had a good power output.


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Re: Fitability of different years top end, problem?
triton thrasher #714821 11/12/17 9:23 pm
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Quite so, I've only used their wideline with all Triumph inside it. I had an ordinary 99 in between my tritons, but I found it drab.
I think Norton had to tune too hard to keep with moderately tuned Triumphs, we surely know that by the early 60's Triumph engines were preferred in whatever frame.
For all their leaky, noisy faults, I still think they were leagues ahead of the oppo, as they should have been with 10 years more experience.

Re: Fitability of different years top end, problem?
T120C #714822 11/12/17 9:27 pm
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In another life, I might have really enjoyed flow porting heads. Re-visit Bernouli, Venturi and Boyle.....

I've seen some folks making some serious changes to inlet ports, initially with pool putty or JB weld, narrowing the ports gradually only to open up tulip shaped right at the valve seat, and with flat floors on the port. The idea is to accelerate the flow going in(flow-rate increases as does inertia) storing some gas mixture right in front of the valve for the next opening.

Really interesting stuff that the makers of our old bikes new nothing about.

For years, all folks did was too open ports and install larger diameter exhausts. This is great on a blown fuelly, but disastrous on a old bike like ours.

In my profession as a Respiratory tech, we got pretty deeply involved in gas flow via our ventilators, the ultimate goal to improve patient comfort and decrease work of breathing.
There was a lot of info going around about laminar flow and proximal airway pressures vs. machine pressures. This science is directly comparable to what goes on in an inlet tract of an internal combustion engine, hence my interest in the subject.

Cheers,
Bill


Last edited by HawaiianTiger; 11/12/17 9:28 pm.

Bikes
1974 Commando
1985 Honda Nighthawk 650
1957 Thunderbird/T110 "Black Tiger"
Antique Fans: Loads of Emersons (Two six wingers) plus gyros and orbiters.
Re: Fitability of different years top end, problem?
HawaiianTiger #714827 11/12/17 9:56 pm
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I find it hard to imagine that for better performance you would advise COPD narrowing of tubes!

Whereas we, as air breathing creatures, need free passage for that air, engines have to mix fuel with the air as best as possible.

I don't think you'd ever convince someone that their breathing should be restricted for their own good, except if you belong to one of the perv parties!

Re: Fitability of different years top end, problem?
koan58 #714829 11/12/17 10:19 pm
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Originally Posted by koan58
I find it hard to imagine that for better performance you would advise COPD narrowing of tubes!

Whereas we, as air breathing creatures, need free passage for that air, engines have to mix fuel with the air as best as possible.

I don't think you'd ever convince someone that their breathing should be restricted for their own good, except if you belong to one of the perv parties!


So, should inlet ports be infinitely wide?



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Re: Fitability of different years top end, problem?
T120C #714830 11/12/17 10:35 pm
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In fact, I'd suggest cutting the entire inlet side of the head off, to make it as free breathing as possible!

I was merely responding to HT's professional comment about human airways (as a respiratory technician), and that I don't think there is a good parallel.

Re: Fitability of different years top end, problem?
T120C #714836 11/12/17 11:40 pm
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Well, I was talking specifically about the ventilator, the connecting tubing, the adapter and the endotracheal tube, not the patient's airways. All this is mechanical and a direct comparison of the relevant parts is possible.

A minor imperfection in the walls of the inlet tract can and will cause turbulence, and this turbulence can build pressure in the tract and severely restrict air flow.

You're looking for laminar flow which proceeds down the tract without turbulence. Cleverly done, the inlet tract can be rather narrow and continuously decreasing in cross section and still flow more than straight sided walls. This is fascinating stuff to me.

Pure physics.

Cheers,
Bill





Bikes
1974 Commando
1985 Honda Nighthawk 650
1957 Thunderbird/T110 "Black Tiger"
Antique Fans: Loads of Emersons (Two six wingers) plus gyros and orbiters.
Re: Fitability of different years top end, problem?
John Healy #714837 11/12/17 11:43 pm
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Originally Posted by John Healy
Setting up an engine is not intuitive! On one end you have trials bikes and on the other land speed record machines On one end you have wide ration gearboxes and on the other close ratio gearboxes. You also have to remember when you open up your ports that you will be killing low speed torque to gain high rpm horse power. You don't want to build an Triumph engine that will have a very narrow power band and need to be turned 10,000 rpm to see any benefit and then complain that with your standard ratio gearbox that the bike is a dog around town or will not pull past 90mph.


Understood. When I read the term "small port head" my thoughts immediately went to a friends (Adam M) A65 Lightening with a small port head. His bike had some crazy get up and go. Thinking perhaps the same could be applied to the Triumph if one could get their hands on a Triumph small port head.


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