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Old 03-09-2010, 09:51 PM   #1
scottto93
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Default triumph head edu-muh-cay-shun

EDITED MY POST TO BE MORE TO THE POINT....would like to run 63 head on 68 bottom end and barrel (actually barrel is 750)....according to a reliable source..i will need to run different tappet blocks and seals.....i will also need different intake spigots, as the threaded part is smaller when compared to the later heads (65+, right?)....exhaust valves seem to be same size as later years, intakes look to require smaller size valves...intake valves on 68 measured 1.59....what size are run on 64-?





is there anything that stands out i will need to run this head on my 68 that i may have overlooked.....?

a buddy that is aiding in the engine build said it looks like a piston hit the chamber on the right in the above pics...it does look as if "something" made contact with it...but it looks like it could be smoothed out.....

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Old 03-11-2010, 07:52 PM   #2
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Default Re: triumph head edu-muh-cay-shun

anyone?
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Old 03-11-2010, 09:08 PM   #3
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Default Re: triumph head edu-muh-cay-shun

Gently draw file those dings out of the the edges of the combustion chambers, for a start. As far as tappet block, et al, basically you need to make sure the entire pushrod equation is matched to your head. This means from the tappet guide blocks, pushrod tubes, all appropriate seals and gaskets therefore, all need to be based on what seals to your head. It is not difficult to do, but may require searching out the correct parts. This is all in order to add up to the proper amount of head gasket "squish", which simply translated means that your head torque figures will accurately reflect how tight that sucker is attached. I hope this is helpful. Keep the faith!
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Old 03-12-2010, 04:11 PM   #4
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Default Re: triumph head edu-muh-cay-shun

Trial and error......
Something that I've heard-
Sometime in the early 60's, Triumph marketing decided that increasing the size of the valves would help sell more bikes. In reality, customers complained how their bikes wouldn't hit 100mph (or thereabouts) anymore. Folks in the know say that the later heads are overvalved for a 650 and prefer the early heads.
Maybe worth a try as is before going to all the trouble of modifying it to later specs. I would, but I'm just cheap.
Mike
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Old 03-12-2010, 08:49 PM   #5
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Default Re: triumph head edu-muh-cay-shun

If you flip both heads over, you can see how the recess for the pushrod tube is machined differently. I believe the later head took a taller tube. Also, those intake spigots are tough to find. They are the same diameter as the ones on the 500 and 650 pre-unit dual carb heads, but the unit bikes had a balance tube. If I remember right, Baxter Cycle had them for $65 each and another $20 for each lock nut. Might be cheaper to get any other year unit head.
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Old 03-12-2010, 09:22 PM   #6
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Default Re: triumph head edu-muh-cay-shun

Quote:
Originally Posted by mblab View Post
Trial and error......
Something that I've heard-
Sometime in the early 60's, Triumph marketing decided that increasing the size of the valves would help sell more bikes. In reality, customers complained how their bikes wouldn't hit 100mph (or thereabouts) anymore. Folks in the know say that the later heads are overvalved for a 650 and prefer the early heads.
Maybe worth a try as is before going to all the trouble of modifying it to later specs. I would, but I'm just cheap.
Mike
amen. The factory thought that BSA had all the power numbers for the era, and they had advertised large ports as the cause. The combo just didn't work for the Triumph, it took quite a few more years to get it balanced again.
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Old 03-12-2010, 10:44 PM   #7
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Default Re: triumph head edu-muh-cay-shun

now this thread is shaping up.... thanks for the history lessons...keep em coming....

lurkinclass ~ any idea what year 500s the spigots may be common? did the 500s go to a course thread spigot too in 68.5?... my buddy has a small arsenal of 500 containers i may ask to rifle thru to see if he's got something that'll work.... kind of off topic, but he has a set of 500 engine cases with no serial # stamped on them.... anything special about them or were they available as replacements from triumph way back when...

6T ~ any idea how many different styles of push rod tubes came on these motors? i will have to look but i know i have 2 different styles with the 2 motors i have..65 & 68 according to serial #s.. the head on my 65 motor has an unledgable casting number so i will have to inspect it further to find out what it is exactly....the 65 motor seems to be a mix and match special...

it's really interesting why they went to larger valves, i noticed on the later year heads the ports were so large they broke through to the head bolt holes....which then had to be sleeved.....the ports on this earlier head look so much smoother and more open around the valve guides.......

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Old 03-12-2010, 11:32 PM   #8
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Default Re: triumph head edu-muh-cay-shun

Actually, the unit 500 dual carb heads had alloy manifolds that bolted on. The 500 spigots I was refering to are pre-unit and probably more rare than any of the others, but I borrowed some from a local guy that races AHRMA, and the chamfer on the end was different, but the threads and diameter were the same. The spigots you need should be 1 1/4" 20tpi. The later ones were 1 3/8" and the threads changed in the late 60's.

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Old 03-12-2010, 11:54 PM   #9
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Default Re: triumph head edu-muh-cay-shun

Mblab is correct, John Healy told of this fact, the T110 did 110MPH, not the T120 due to bigger valves, I think the TR6 heads had smaller valves to 67, the bonny in 63.
When the 750 motor came the valve size was suited so if it was me I'd stay 650 with 63 head or save it for another build.
It came from advertising at the time, Triumph wanted to compete with BSA announcing the bigger valve new bike blurt blah....
Tappet block 63, E1477. 68, E4676
Tappets 63, E3059. 68, E3059r and 70.8801.
Tubes63, E3646. 68, E6000
Pushrods are the same.
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Old 03-13-2010, 08:24 PM   #10
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Default Re: triumph head edu-muh-cay-shun

What we think we know today...
With a 2 valve hemi style chamber(your triumph) the intake valve size should be 53.5% of the bore size. If you ran a Std bore 650cc (2.795"bore) it should have a intake valve size of 1.495". BUT Scotto93 is running a big bore kit with a bore size of 2.991" (I know because Scotts block is in my garage). With that bore size a intake valve should be 1.600"(1.590"would be ok) Since the intake port is round it should be 82% of (ideal) valve diameter or about 1.310". Exhaust valve should be 80% of intake diameter. These values offer the best compromise of high air flow and high gas velocity.I wonder if we could fit those bigger intake valves in older head then port out ports to 1.3". How wide is the intake seat? Exhaust valve diamter? Exhaust pipe/port length/diameter?Length/diameter of intake track from carb to valve? all of these will change torque rpm range of engine. engine does have larger than stock cams also, make it all match or you wont be happy with engine, lots of hard work wasted...

Last edited by engineguy; 03-13-2010 at 09:16 PM.
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Old 03-21-2010, 03:58 AM   #11
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Default Re: triumph head edu-muh-cay-shun

[quote=Daddy Boy;590953]Mblab is correct, John Healy told of this fact, the T110 did 110MPH, not the T120 due to bigger valves, I think the TR6 heads had smaller valves to 67, the bonny in 63.
quote]

thank you for the info!

i do have a tr6 head that is stamped 66 (model year 67), and it does have the larger intake valves....1.6"

anyone have info about using a 500 head on a 650....and machining out the chambers for piston clearance? is this folklore?

or to elaborate on this thread, how about more info on head modifications and other performance techniques.....

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Old 04-24-2010, 09:34 AM   #12
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Default Re: triumph head edu-muh-cay-shun

another question....is it true that there were improvements in the t120 heads that increased performance in 68 (for 69 models?)....better flow design?....if so, were there significant gains to make it more desirable to seek out and run one of these heads? and what makes a head a TT head???????
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Old 04-24-2010, 03:36 PM   #13
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Default Re: triumph head edu-muh-cay-shun

68 casting date / 69 heads have a "bowl" immediately behind the valve seat that is lacking in other heads. Helps the air make the turn. Look at the port from the valve side on a '69 and the difference is obvious.

500 head on a 650? Never heard of that one. Bore sizes definitely different, centerline likely different, head bolt pattern definitely different. Time and money would be better spent porting/flowing the 650 head.
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Old 04-24-2010, 07:26 PM   #14
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Default Re: triumph head edu-muh-cay-shun

Scott
To the best of my knowledge, TT motors had the same head as a regular Bonneville. Main differences were a compression increase and (11 - 1, I believe) and 18 t sprocket.
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Old 04-24-2010, 08:19 PM   #15
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Default Re: triumph head edu-muh-cay-shun

i recall hearing bout a 5oo head being modified for a 65o....searched and found this cool blog....ended up being for a preunit..
http://showandgo.blogspot.com/2009_06_01_archive.html

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