Triumph 68-71 Cylinder Head Compatibility

[Jay Everyday]

Hi All, Ive searched the JJ and www but have had a few contradicting answers ect so thought id put the question out to my exact years.

Ive got my 1st build im working on, a 68 T120R engine (stamped T120RDU66849) in a TR6 stamped frame, with an absolutely rooted '68 TR6 cylinder head (Stamped E3925 & 67). I had it costed to be repaired but was looking to be way to much for now, and picked up cheap a TR6 cylinder head (with new guides & cut seats) stamped 71-2358 (thats a 71/early 72 head???).

what im wanting to know is will this head be able to go straight on (with my original rocker boxes & new 68 bolt kit) with no problems/ alterations?

if there are alterations needed, what are they? (so i can get an engineer to do it with as much info as i can give)

Thanks,
Jay

[deluxe72]

I believe the greatest factor is number of head bolts/studs. If you are replacing a 9 bolt head with a 9 bolt head then most or all of everything else is completely compatible.

[Tony the torch]

I think your 68 push rod tubes are shorter ones than the 69 and up tubes, look inside the 68 head and compare the depth of the hole where the push rod tubes go in to the 71 head,
So all you should need is the later style push rod tubes and then just pull the rocker box locator pins out of the 71 head.

[Drew71]

The rocker boxes are different, the rocker box bolts are different & as Tony mentioned the push rod tubes are different.

You will need the later rocker box bolts and push rod tubes, and maybe remove the roll pins from the rocker box gasket area.

[Englishman]

Speaking from experience, using a mix of 71 head and earlier rockerboxes will produce leaks. The 71 head will accept rockerboxes from 71 up, including the T140 style. The pins really help with the gasket spitting out the back problem.
I'd recommend finding all the 71 parts and using them for the 71 head. The advantage being you can torque the head properly and still remove the rockerboxes for installation n shit without having to redo it all. Plus of course the center bolt for the head steady is easier to deal with.

[Tony the torch]

We are stocking and using the better grade rocker box gaskets out there that are metal based with gasket covering, we stopped using those cheap paper gaskets and have put several bikes together with the early boxes on the later head, The 72/73 style boxes have that little round access cover on the side that has a tendency to leak and looks like shit, as for the head bolts they I think changed in about 1974 to the easy re-torque style.
all it takes is an 1/8" of sealing surface to work on the rocker boxes and the metal based gaskets don't blow out when tightening the head bolts.

[Englishman]

I kinda like the little round access cover. Mine have never leaked and I replaced the originals with the polished stainless versions.
The 72/73 style were the four screw oval covers, yes?

[Drew71]

68 head. rocker box gasket area (showing rocker box bolts)



71/72 head . rocker box gasket area



68 rocker box on a 71 head



Your original 68 T120 head probably had small head, cycle thread bolts on the rocker box , I just tried a couple of bolts in a few heads 69 on are all seem to be the same right up till T140 (part number TR6 S1875 Rocker Box Bolt 2 5/32in, UH)
I measured a 69 and 72 head and they both have the same depth cut out for the push rod tubes

[Jay Everyday]

Great! So it doesnt look like its going to be too much of a sweat then? with the thicker gaskets, new bolts? Also, my original head is a TR6 had i think. single carb.

Tony, how would i go about purchasing a set of those thicker metal gaskets from you? Posted to Melbourne, Australia??? paypal? CC? send me a message with any info ect. Also, just looked through the TR6 build, that bike is next level! really dig the paint, especially the 2 colored front end. very nice.

[Tony the torch]

here is pic of the 71/72 rocker box, they leaked, then it changed to the 4 bolt tappet cover in 73/74, they leaked, then it changed again to the 6 bolt tappet cover the leaks finally slowed down....

[Scorcher]

Please sell your stuff on PM's.


-Jason