In message <79*/S=heyer/OU=imdm/OU=uke/PRMD=uni-hamburg/ADMD=d400/C=de/@MHS>
Daniel Heyer writes:
>
> Well... You probably noticed the naughty bit, as Monty Python's might
> put it: my car hasn't got the original engine! Why didn't I ever wonder
> about the bizarre engine number? Surprise, surprise. Maybe this is the
> reason why I just couldn't get a decent idle, not to speak about the
> high-rev hiccups, as the car is certainly TR4A from the manifold
> upwards with its double ZS carbs and the closed breather circuit...
> Thank you, PO! What an interesting puzzle to solve during those long
> and dark december evenings. Somehow this makes further decisions easy,
> as I will not stick to originality as close as I might have done with
> an original engine, but I will try to get a rebuilt TR4A engine with an
> unleaded head. These cost about DM 3.500 (US 2.150) around here on an
> exchange program with a 1 year warranty. Sigh...
>
Daniel,
Don't worry. The engine blocks of the TR2 through 4A are for practical purposes
identical.
The engines have wet sleves (cylinder walls) The TR3 originally came with 83mm
pistons & sleves. By 1958ish, 86mm pistons & sleves were a factory option. In
the TR4 the 86 mms were standard. All with the same block.
Here is where the major changes were:
Head: there were about 7 different cylinder heads used throughout the Tr2->4A.
The original style head for your car has a flat section behind the first head
nut (front). There is usually a number stamped there. If the area behind the
first head nut looks like the area behind the third head nut, you have an
earlier head that was designed for the 83mm pistons. This means that you do not
have an extra squish area inside the comustion chaimber. The earlier head on
86mm pistons will give you a higher compression ratio, but will otherwise work.
If the flat section is there, you have the correct head for your car. 83mm
pistons have been getting hard to find over the past few years, and everyone has
been upgrading to 86 or 87 mm. Chances are you have 86mm pistons in the car
(86mm was a factory option in '59 TR3s). You have the correct carbs, manifolds
& SMOG stuff, which should work correctly on any engine & head (over carbed for
the original TR2 hed)
The TR3 & TR4 have different front plates that bolt to the front of the block.
The engine mounts fit on this plate. The TR4 one is wider than the TR3 one.
The fact that your engine is bolted to car says you have the correct front
plate.
The carbs & mainfolds change a few times, but everything is interchangable,
except you want to keep the early TR2 carbs, manifold & heads together. I think
the later TR2 Le Mans head can take the 1-3/4 inch SUs & later carbs.
I haven't looked into this, but there may be a different curve built into the
later distributers for SMOG
Other than a few little things the '59 TR3 engine with optional '86mm pistons
and TR4A engine are the same with the TR4 engine having the SMOG related stuff
added and a wider bolt on front plate.
As far as stumbling at high RPMs, I would look at the basic state of the engine
& its tune. A bad distributer advance, timing, points, partially clogged fuel
line/filter, ruptured fuel pump diaphram, worn valves, worn cam lobes, poorly
adjusted carbs (they get blamed for everything), or who knows what else is more
likely to be your problem.
TeriAnn Wakeman Large format photographers look at the world
twakeman@apple.com upside down and backwards
|