TR2/3/3A Blown head gasket TR3 what to do next?

The head gasket is leaking on the back driver side corner so I plan to remove the head and renew the gasket. Any suggestions for an up grade while it is out. The obvious is harden exhaust seats and new bronze valve guides. What about valve stem seals? Also what is that bolt on the back side of the head? Is it like my Tr250 and 6's where an auxiliary oil line can be added?

What is the mileage on the engine?
I'm not real familiar with the TR3 motor, but if it did not come with valve stem seals (and I don't think it did) then I wouldn't go putting them on, you might find it wearing out the valve guides quicker, better to burn just a little bit more oil than that.
Your other ideas on hardened exhaust seats and new guides sound like the right plan.
Are the valves and springs in decent shape?
Probably should inspect the rocker gear while in there and don't forget to pull the tappets (lifters) out of their bores and inspect the bottom of them for breakup against the cam.

Seems like the bronze guides aren't such a big upgrade after all ... even though in theory they wear slower than the cast iron ones, they also need to be reamed larger after installation (or risk sticking valves).

And I'd stay away from the external oil feed and the stem seals needed with it. The factory actually hit a pretty good compromise with the amount of oil that the guides see; you're not likely to improve on it. Both too much and too little are problematic.

Things I would do (not necessarily in any order) :

. Send the rocker shaft off to Rocker Arm Specialists
. Replace the valve springs (be sure to find out if the set you buy needs the pedestals or not)
. Convert to the smaller exhaust valve stems.
. Modify the combustion chambers per the Comp Prep manual
. Take the compression ratio up to about 9.5:1 (if you aren't there already)
. If there is any doubt about it, remove the cast aluminum core plug near the center, and replace it with a screwed in pipe plug.

If you pull the lifters to inspect them make sure you replace them in the same spot. They become matched to the cam lobe.

So I take it the plug on the back of the head is a auxiliary oil line. I was concerned about flooding the rockers with oil if I went in that direction. i may have a cure for that though.

What is Rocker Arm Specialities and what do they do? I have replaced many rocker arms over the years since 1983. I'm sure they are under oiled. Does it pick up the oil from the rear cam bearing like the 6 cylinders do?

What is this aluminum plug about. I probably put this motor together in 1980 so my memory does not recall this plug.

Also what is the thickness of the head to achieve this 9.5:1 compression ratio? I did put TR4 pistons in back then. I believe they were 87mm. So that works into the equation too.

It's worthwhile replacing that core, or welch plug, at the back of the head, as it has a nasty habit of failing just after you put the motor together again. It needs expert fitting though, as I've seen home installed ones come out as soon as the coolant heated up.

Keep coolant in the block if you can, up to water pump level, as the pump seal can fail if allowed to dry out for any length of time.

Viv

Rocker Arm Specialist
19841 Hirsch Court
Anderson, CA 96007
Tel (530) 378-1075
fax (530) 378-1177
mailto:rocker@c-zone.net
https://www.rockerarms.com/

They will take your oid rocker shaft assembly and rebuild it like new. In fact I'm not absolutely certain what I got back from them wasn't new! Certainly they replaced the shaft itself, all the bushings, springs, adjusters and nuts. Rockers were refaced and apparently plated with something copper colored. And the cost was just barely more than I would have had to pay for the parts alone.

I seem to have no trouble getting 100,000 miles out of a set of rockers, so I'd suggest you have something else going on. Do you check for oil flow occasionally ? I've seen other people's engines with the rocker shaft full of sludge. They are fed from the rear cam bearing, which has an insert that can be installed wrong (blocking the passage). Believe it or not, I bought an engine with the insert turned wrong; and didn't notice the problem until I checked for flow a year later! Of course dirty oil is a problem too.

On top of the head, in the space between #2 and #3 exhaust valves, you should see a round spot roughly 1" in diameter that is a lighter color than the remainder of the head. The head casting has a hole there that was used during the casting process to support the sand "core" that formed the water passages inside the head. After the head was cast, the factory filled the hole with aluminum and machined it flat. However, the plug can suffer dissimilar metal corrosion and start leaking coolant into the oil (friend of mine called with this problem just a few days ago, which is why I was thinking of it).

How much to remove from the head depends on which head you have, how much metal you remove when modifying the combustion chamber (required when raising the CR, IMO), how much it's had skimmed before, etc. I would definitely suggest doing most of the combustion chamber work first, and then checking the volume (also known as "CCing the head") of each chamber. This also lets you equalize them for best performance. Then after milling, go back and round any sharp corners created.

TRF sells reproductions of the original factory "Competition Preparation" manuals (written by Kas Kastner "back when") for just a few dollars. Definitely recommended reading before you start making modifications. They also carry Kas' later Triumph Preparation book, which covers in one book TR3-6, Spitfire and GT6. But it's more money and has pretty much the same information about TR3-4 heads as the earlier books do, so not as essential.

Thanks for that link and all the info. As i recall I'm quite sure the rocker shaft was replaced years ago and the problem of replacing rockers has slowed or quite. I may have had the sludge problem.

Is there a number on the head that will identify the type. It is the original head to the car. 1960 TR3A TS67708. What is the original compression?

It's just known as a "high port" head and the casting didn't change from the small mouth TR3, circa engine TS12606E, right through sidescreen car production. Sorry, I don't have the Stanpart casting number.

TR3A compression was 9.0:1

Viv

If memory serves, original compression ratio with 83mm liners was advertised as 8.5:1. Obviously (I hope) larger liners will raise the compression ratio unless you also enlarge the combustion chambers to match. But the factory was not always careful about getting such things exactly right (appropriate to a relatively low cost car) so there is some variation from head to head. The new exhaust seats may also have some effect on compression, depending on how far they are seated into the head casting

There's a guide to head identification at
https://www.tjwakeman.net/TR/FAQ_heads.htm

Is there water in the oil? Have you lost compression?

Good info on the TI wakman site. Brings up a concern too. I don't remember having the head chambers increased to match the 87mm pistons. What kind of problems could or could have arisen? Compression would go down too if chamfered because of the increased chamber size. That would mean more shaving . Also it looks like the factory chamfer the edges to match the enlarged cylinders. Is that what I'm looking at doing at a machine shop?

sp53
Haven't gotten that far yet. Pulled it in the garage and has been setting while I gather information.

Looks like I have the later head with the diagonal slant on the underside of the thermostate housing. Acording to Teri Ann's site I probably had the 86mm pistons and a possible chanfered chamber. I'll know when I take it off and It will be a while befor that happens.

TR3ATR250 said:

What kind of problems could or could have arisen?

Click to expand...

Leaving the sharp corners exposes increases the chances of detonation (knock). Since you must control detonation (or risk destroying the motor) by increasing fuel octane or retarding the spark (etc), it wastes money and/or produces less power.
<div class="ubbcode-block"><div class="ubbcode-header">Quote:]Is that what I'm looking at doing at a machine shop? [/QUOTE]Generally it's cheaper to buy the tools and do the chamber work yourself. It's not difficult, but it is time-consuming. Paying a shop $100/hour or more gets kind of expensive (plus many of them won't do it).

Any info on procedures? I've ported heads before. My first thought was to use a die grinder and a carbide cutter to trim it off. I can tell you there is no loss of power. I had the carbs professionally rebuilt and installed 5 years ago and the owner of the shop could not believe how fast my car was. In fact I won my class in a autocross race that year at TRF.

No pinging problems ether. This leads me to believe that I "may" have a 86mm head. Won't know until I get it off. May not be until August but I'm getting my ducks in a row first.

Also he did say there was a lot of carbon build up on the pistons. I figured it was from the poor shape the carbs were in.