Pi engine

[Alex]

I took the head off my engine today theres a slight scratch in one bore not very deep but you can feel it with your nail(I can feel it with mine ;D).Just wondered what people consider acceptable?Otherwise theres just a bit of glazing nothing much though.
Cleaned the top of one piston and its got +20 pistons.
I need to borrow an engine stand so I can drop the sump but is there anything else I can check?

[Richard B]

There's an engine shop in Chobham that 'might' be able to hone it out, new set of rings and you would be sorted. Well...  and new seals, bearings, thrust washers.....

[Alex]

How much do you think a full set of rings would be?

[Jason]

Alex - I've got some NOS rings in the garage, don't buy any until I've had a looksee. New set would be circa £35?

[Alex]

Jason that'd be great thanks.
However.....it would appear that all is not as it seemed.The cranks not cross drilled so not original which leads me to suspect that spitbang was correct all along and its a 2000 in a 2500 block :'(
How can I be sure?

[Tim Bancroft]

Is the Mk2 Pi crank cross drilled??

[Jason]

No good to you either way sorry - they are Chords  standard bore, marked "853 Triumph STD 74.7mm" I'll bang 'em on eBay now I've dug them out!

Not all PI cranks were cross drilled so that's not a reliable check for engine size.

[Alex]

Thanks all the same Jason!

[Deleted User]

You could always check the stroke length of the bore ...2000 about 74 and 2500 about 76 i think

[Alex]

Dont know if this may help ?

[Alex]

A picture of the crank but I think you could guess that?
Also whats peoples opinion on the head?

[Alex]

How do I check the stroke I assume its a crank out job or at least one piston?

[mikeyb]

unless my eyes deceive me there are 3 rings on the nose of that cam - that means 311399 - TR6 CR engine 125hp and Mk2 PI.

I've never seen a cross drilled crank!  Only Mk1 PI and TR5 were to my knowledge.  Dont know about early TR6.

Are the pistons flat topped or domed?

[Alex]

Yes definately 3 rings and flat pistons.
I thought the cross drilling would be obvious?
Kd said they sort of go --->   <---- across the fat bit if you see what I mean.But I could have misunderstood I guess?

[Royboy66]

Didnt all 2.5's have a duplex timing chain??

Roy

[Alex]

Its got that but do 2000's?

[mikeyb]

oh yeh I forgot about the chain - think all 2.5 (certainly PI's anyway) were duplex, think all 2000s were single.  Flat topped pistons are correct by the way!

[Alex]

Oh so perhaps it is a 2.5 maybe its an old engine of Jasons and needed a new crank?You know what he's like with them ;D ;) :P

[Deleted User]

Alex ,leave crank and pistons in and just turn crank till one piston is at it's lowest and then measure down the bore

[Alex]

Thanks Doug just did it if I'm doing it right its 95mm so what would that mean?

[Alex]

Just answered my own question Doug,it a 2.5 thanks.


So on that note anybody got any views on the head/valves?

[Deleted User]

just found where i got the figures from...i remembered them wrong 2000 stroke length is 76  2500 is 95   so it's def a 2500

[mikeyb]

too dark to go out and look at mine now - but the head should have a 6 figure number stamped (not cast) in it on the inlet manifold side between head studs, near the front I think.

[Alex]

Sorry I meant the colour of the valves,its a 2.5 pi head as its got the double springs.
Just wondered wether the colour would indicate what was wrong to make this engine get pulled out or is it acceptable colouring?

[andy thompson]

X- Drilled cranks look like this....

Some very early Mk2 (short back) cranks were also cross drilled... 1969/70 PIs and some Tr6's... but they had the anchor flywheel