TR2/3/3A shaved heads

[sp53]

Well I purchased some tr3 parts on Crag’s list that are probably worthless. When I looked closer at the cylinder head, I noticed it had about 3/16 shaved off the bottom. I have no experience with shaved heads, but the stuff was cheap and my cheapness got the best of me. Is a head like this a problem to run? This guy was a racer, so I imagine the shaved head makes tighter combustion, but I like things stock, and I think he unloaded the stuff on me. In addition, I got these connecting rods that are not cast iron, but something else, perhaps some high carbon steel. Any input on this is much appreciated. The old saying that we pay for our education is true again.

 

[TR3driver]

3/16" sounds like a huge shave; even if there has been a lot of other work done to enlarge the chamber. My guess is that the resulting CR will be way too high to run on pump gas. And those "octane improver" additives at FLAPS border on worthless if you need any real bump in octane. If you can even find one that specifies how much actual increase you'll see, it will give it in "points". where it takes 10 "points" to increase the octane number by 1 (eg 89 to 90 octane). And generally, to get even that much, you have to use multiple cans of additive per tankful of fuel _every time_. Way too much hassle, IMO.

Only way to know for certain though is to measure the combustion volume. Not that hard to do if you can scrounge up a suitable piece of acrylic and a medical syringe graduated in ml (1ml is also 1cc). Or any number of sources will sell you a "CC kit" with a burette that is a little easier to use. Google for "CC cylinder head" for instructions.

Are you sure the rods aren't just ground and polished? If they are really aftermarket steel alloy rods, and there is nothing wrong with them, they may be worth some money. ISTR Carrillo rods go for around $1000-$1200/set new. A waste of money on a stock engine IMO, but the racers building engines to turn 7k+ really like them (along with a couple grand for a Moldex crank and so on).

 

[sp53]

Thanks for your input Randall you are always helpful, and yes I am sure the amount taken off is 3/16 plus; at least that is what I get with a tape measure compared to my heads. I took a picture of the rods, but my camera is not that precise. So you figure the head is not something someone would want on a driver. I also got an oil pan with some baffles in it with a place to hook an oil cooler on the side and the oil cooler. I basically was looking for an extra head because they are getting hard to find, and the guy wanted to get rid of the other stuff, and gave me the how about this for everything deal. I hope the rods or worth something.

 

[TR3driver]

I'm no expert, but those do kind of look like Carrillo rods. Are there any markings on them?
https://www.cnc-motorsports.com/car...onnecting-rods-triumph-tr4-tr3-tr2-6-250.html

 

[2long]

You may want to check the precise thickness of the head with a caliper gauge and compare to original the thickness of 3.330 inches. Thicker, custom solid copper head gaskets can be used to get the compression ratio back to normal and restore the rocker geometry, but obviously there is a point where too much of the head has been shaved and the thing is compromised.

Dan

 

[JerryVV]

3/16 is .187. I doubt very much that there is enough material on a TR wet liner head to cut .187 and if it is cut that much my guess is that it's too thin to use. Any chance to see a photo of the combustion chamber. Also what's the rough thickness of the flange on the push rod side of the head (drivers side).

 

[Simon TR4a]

I also doubt the head has been shaved 187 thou. I suppose it may be possible if using the steel shim gasket as an extra, if a large amount of work had been done on unshrouding the valves, but even then you would need very short pushrods to correct the geometry of the rocker gear.
Best way to tell is to use the burette with oil, obviously with valves on the seats, and measure combustion chamber volume, which should be around 58cc., depending on what compression ratio you want.
Nice looking connecting rods, they look expensive!

 

[CJD]

"H" beam rods....cool!

It looks like you got decent performance parts. Won't help if your a stock kinda guy, though.

 

[sp53]

There is no writing on the rods, but they are identical to the ones in the picture Randal. This guy was a fast talker, so I do not if they are any good. The more I look at the head the more incorrect it looks. I have 2 heads but they are bolted on. I took some pictures, but I am not sure of what I am doing with the details

 

[BobbyO]

Note in Moss catalog says "Original cylinder head thickness is 3.325 - 3.330. Never mill below 3.170." That gives you a maximum of 0.160 that could be milled, starting with a head thickness of 3.330. 187 thous is way up there. I have a head that I got with a bunch of spares when I purchased my car. It has been milled quite a bit (don't remember how much right now) but the standard push rods won't work with it. Had a burnt valve and was planning to use the spare head. Didn't realize it had been shaved and found out about the push rods when I installed the it and found I couldn't adjust the valves. I guess the steel shim gasket is an option but they are expensive IMO.

 

[Bob Claffie]

If you could get hold of an original Kastner competition prep manual it might tell you how much was allowable to shave.
Back in the day he suggested a huge cut on 1300CC Spitfire engines, which I did with no bad after effects (strictly track use)

 

[TR3driver]

If you could get hold of an original Kastner competition prep manual it might tell you how much was allowable to shave.
Back in the day he suggested a huge cut on 1300CC Spitfire engines, which I did with no bad after effects (strictly track use)

Good thought! The TR4 version says that .150" will result in about 11.7:1, using 87mm liners and the "shim steel" head gasket. It also talks about the different head castings, and notes that you probably cannot go that far on the stock TR3 casting. He's talked in other books about adding pins to the quench area to support it after extreme milling. But what he didn't mention (AFAIK) is how much octane it took to run with that much compression. Back then, you could find 100+ octane at any Sunoco station, but today there are only a very few places that sell racing fuel and the prices tend to be on the high side (like $10/gallon or more).

 

[CJD]

I've had more than one car I had to run on avgas...

 

[sp53]

Here is an update on the parts I bought. I took them out to a machine shop and they were kinda impressed mostly because it is an old Triumph. The pistons are Venolia out of S. California and are in good shape. I think they are 89mm, but I need to measure them and do not have an mm ruler or gauge. Does anyone know what 89mm is in thous? I called Venolia and they said they make all their foreign stuff up special and only stock Chev and Chrysler. The head is something I doubt I will ever use, but there were lifters with a holes drilled at the bottom and some push rods that are about 3/16 too short when I compared them to the stock ones. I might use the rods and pistons someday. At Venolia, they wanted me to measure the rings for new ones because they have to order them. I wonder if I could find them cheaper myself.

 

[poolboy]

https://www.convertunits.com/from/mm/to/inches

 

[TR3driver]

An inch is exactly 25.4 mm. 89/25.4 is ~3.504"

The shortened pushrods will be necessary with the shaved head.

Venolia will almost certainly want to take a markup on the rings, since they will be backing the sale, sourcing the rings and so on. Odds are that you can buy them cheaper elsewhere, but of course then it's your responsibility to order the right ones.

From what I've heard, drilling the lifters only weakens them and doesn't provide any real advantage. The theory is that the hole lets the oil drain out to reduce overall lifter mass; but the oil gets splashed out pretty effectively when the engine is running even without the hole.

 

[martx-5]

A millimeter is exactly 25.4 inches. 89/2.54 is ~3.504"

Tough night Randall, You got it backwards...25.4 mm to the inch! And 89/2.54 is well...enough said.

 

[sp53]

Venolia wanted me to measure the rings and give them the numbers and they would order for me. Does anyone know a manufacture that is user friendly and would kinda walk me through the numbers they need?

 

[CJD]

They likely need the width of each ring, it's position (ie. top, second), the diameter of the groove in the piston, and finally the finished diameter of the cylinder bore. Since everything is high performance, I'd ask for them to be "fit to bore". They are too large and you then grind the edges to get the perfect gap when installed in your engine.

Personally, im very impressed! If you got them for a decent price, I think you got some very decent performance parts. Normally the cam lobes get oiled by splash from the crank. I would think the lifter holes help with lubricating the lobes by allowing more oil to reach them.

Those rods are much stronger than the stock. You would need a trick crank to get the extra RPM, though. If I were building it, I'd regrind a stock crank for larger radius filets on the crank pins. Then grind imperfections smooth, and finally shot peen it to mil-spec standards. Add decent springs to the valves, and you could spin it north of 7k rpm! Fun project...

 

[TR3driver]

Tough night Randall, You got it backwards...25.4 mm to the inch! And 89/2.54 is well...enough said.

D'oh!

But at least the final answer was right