All 9-bolt heads will work. While there are very minor differences, they can easily be overcome.

I understand some folks have even bolted up 8 and 10 bolt heads to 9 bolt jugs, but I haven't personally tried it.

One of the biggest buggers is getting the pushrod tubes to seal up properly; but, then again, that's still the case even with the correct head!

You cannot tell the difference between 9-bolt heads looking from the outside EXCEPT for the tiny rockerbox alignment pins on the late model heads, and the matching rockerbox contours.

 

All 9-bolt heads will work. While there are very minor differences, they can easily be overcome.

Okay, great. Thanks for the info!

Whats the problem with the one on your bike?

There isn't one... totally MIA.

You could use a '69 or '70.

'71- early '72 heads might not seal so well around the rocker box

Okay, great to know. Thanks! I will look earlier, rather than later!

 

..there should be LOADS of 1968 heads your side of the pond so just have a squint on fleabay & you should find one.Whats the problem with the one on your bike?I have the official data changes per year for Triumphs,but maybe have a look at yearly part numbers for 'heads'.. get back if you need more help?Cheers!

 

You could use a '69 or '70.The threads are different :1/4" x20 UNC bolts to hold the rocker covers;you'd need 4 new bolts.1/4" UNF nuts on the intake flanges.Otherwise they're the same.
If you use an earlier head ('63-'67),you still have 1/4" x 26 tpi threads.Valve sizes are smaller before mid-'67,but there's enough metal to cut the seats to the larger size (if it hasn't been done already).Some like the small-valve heads better.I like the idea of a smaller exhaust valve.
Valve springs are different on the earlier heads,but you just need to use the right lower spring collars with the right springs.
If you use an earlier head,it would be a good idea to change the intake flanges for the later ones with shouldered bolts and rubber washers.

Most heads had a manufacture date cast in an oval between the intake valves. "66" would mean a '67 model. They stopped doing that ;some later heads have the oval mark with no numbers.They still have a casting number,like "E 3663" to identify them.

'71- early '72 heads might not seal so well around the rocker box,even if you remove the roll-pins.I'm not sure if there's enough metal to suit the earlier rocker box.Late '72-'74 9-bolt heads would have the same problem (if it is a problem),but they also use different exhaust pipes (push-in,instead of spigot mounted),and they have a different intake flange arrangement.You could fit exhaust spigots,but the intake flanges would be obviously later than '68.

 

Most heads had a manufacture date cast in an oval between the intake valves. "66" would mean a '67 model.

Hmm. My '69 T120R head has a '69' cast between the intake valves. Did someone put a '70 head on there at some point, or was there some overlap? My bike was made in June '69, so maybe they were already using the newer heads late in the model year?

Ken

 

...I'm ALWAYS impressed by your knowledge Mr Pete,thanks...They say the earlier heads(small valves)produce more power...

 

Avoid the '63 head unless you want to pay a machine shop to bore and rethread the intake ports. They were smaller than the 64 and later ones. Lesson learned!

 

Listed as a 68 head'''
cant beat that price.

http://cgi.ebay.com/ebaymotors/Vint...orcycle-Head-/150629255380?pt=Motorcycles_Parts_Accessories&hash=item23123408d4


m

 

All the 1968's cylinder heads that I've seen are built in 1966. Also notice that around the 66 number are radial lines that represent months.
I hope this info helps. Good luck with your search!

 

The cylinder head on my 68 Bonneville (DU83038) has a 68 stamped in it. How can I decipher the radial lines?

 

I'm faced with a head on my '69 that has a severely stripped exhaust spigot. So I went to my spare engine and checked the head. It has clean exhaust threads, but was cast in '64. It was made for the shorter, older style pushrod tubes. I cannot find any combination of parts that will allow use of this early head on the later engine. The tappet blocks also must be different to accomodate the different pushrod tubes, maybe if they were swapped it would work. But '69-up have the extra oil feed to the exhaust tappet block, I wouldn't want to give that up.

Both my heads have the exact same casting number, E3663 HDA. The '69 head has no date, just the oval. Unless you measure from the head surface to the pocket for the pushrod tubes, you couldn't tell them apart.

This explains why the spare engine (which came with a different bike) leaked like a seive -- it is also a '69, this head wouldn't seal on it either.

 

They had oil feed to exhaust cam followers in '66.Early follower blocks didn't have the O-ring seal.That was soon changed.

 

My crankcase is '67 T120R
My rocker box is '68 T120R
My cylinder head is '72 T120R

http://transgarp.dyndns.org/motorcycle/2000/20110728/01.jpg

 

What year was the first for 9-bolt? I've forgotten...

I think the tic marks are the month. 2 tics = February.

 

on cars 60's + earlier valves required leaded fuel, not sure about bikes but something to think about. hardened valve seats were installed in the 70's + could be fitted to earlier models, additives are available, but costly if you ride a lot

 

Our bikes do not require leaded fuel or hardened valve seats!

What year was the first for 9-bolt? I've forgotten...

1963

 

that don't sound very reassuring!! a little search showed the issues early BMW airheads had until hardened valve seats appeared in the 80's. surely early triumphs did not use a hardened valve seat + if driven a lot could quickly recede the valves into the head. it was noted that only 4 oz of leaded AV gas per gallon could protect the older softer seats. had a 70 bonnie i thoroughly enjoyed, the extreme vibes mattered little at 20 YO now in my 60's i enjoy a smooth 2012 bonnie!!

 

that don't sound very reassuring!!

\\Take heart rodhotter, these hard old seats will take anything that combustion can throw at them.

I've heard of an odd owner having the valve seats replaced to accommodate unleaded fuel (a scam by workshops or ignorance, or both. God knows how they replaced the seats anyway!!)

Take "god's" word for it. "Our bikes do not require leaded fuel or hardened valve seats!" RR

 

Agreed although scam is a bit harsh

The received wisdom is that there will not be an issue in the average owner's lifetime and that even if it was necessary, the valve seat recession would be very slow so best allow recess ion and fix it if/when it breaks ( IMHO never)

 

Agreed although scam is a bit harsh

Perhaps. There are plenty of unscrupulous workshops out there Dave.

Taking money from an unsuspecting person for work that is not required (repair/repaint the roof) would be called a scam in different circumstances. RR

 

surely early triumphs did not use a hardened valve seat + if driven a lot could quickly recede the valves into the head.

With Triumph's, valve seat recession has not been a problem with unleaded gasoline. It was common for Triumph riders "in the day" to use Amoco "white" gas, which was unleaded, with absolutely no valve seat recession! No-lead gasoline might be something new to you, but it isn't something new to Triumph valve seats!!!

Vincents use bronze valve seats without any problems with valve seat recession and many of them are high mileage.

There are several things that will cause valve seat recession: Too much guide clearance; fuel mixture too lean; and a ham fisted mechanic working on your cylinder head.

The real problem with unleaded, and seat recession, comes when the valve seat is cut directly from the cast iron cylinder block. This is where there is no separate valve seat and the valve is seated on the iron casting itself.