Pistons

[GT6 M]

Whats the thinking on County  Pistons.

A Mr D Cent Chappie ,  sells em at a v v reasonable price compared to some others, for the same thing.

thoughts folks get or avoid

M

[thescrapman]

It used to be that the pistons are good quality (if a touch heavy) but the rings needed to be better quality, so you purchased a separate set of County rings which oddly came from a different source (somewhere in Switzerland?) to the rings fitted to the pistons.

Cheers

[Tim Bancroft]

Read a good article about these within the 'Good Parts' website in the USA a year or two ago.

Just had a look and cannot open the link to the article.

[Hogie]

Hi  Marcus,
             Like Tim I also  read an article  by a  supplier/builder in  the states.
He compared AE, County and  some other  super-duper  piston.

The  overall winner was the  County. Not just  price/economy but  absolute values  like uniform weight/ finish quality/dimensions.

Would you put them in a  serious  race car - why not!! (what could possibly go wrong). I've done 150K miles in my 4A with no problem.

Roger

[dazzer]

Had county +60 in the rally car for 45k now. Hi comp, thrashed to within an inch of their life and no problems whatsoever. They were lighter than originals as well. Individually bored with larger tolerances in the hotter areas.

I'm using them again on my latest rebuild. Cant fault them.

[thescrapman]

Is this it??

http://www.wishboneclassics.com/tech/tr6/engine/triumph-tr6-cast-piston-comparison

[don cook1]

Having just fitted them to my GT6 I hope they are the best available. Don'tcha just hate driving with your fingers crossed.

[Hogie]

Yes,  that's the  one.  Quite  a good article.

Roger

[TedTaylor]

I was trying to decide what t do about pistons for the Mk1 PI estate because the ones in it were a mixed bag of County and 'Stanpart'.

Read the article mentioned above and so checked the ones that I had.  The compression heights and weights of the County pistons more evenly matched than the factory ones so went for a set from CW which proved the point made in the article.  

County were better (more strongly) made, much more evenly balanced but lighter than 'original', and compression heights within a few thou of each other.

MUT

[GT6 M]

GT6_Don wrote:

Having just fitted them to my GT6 I hope they are the best available. Don'tcha just hate driving with your fingers crossed.

So just hoo doo ye hold the wheel then (think)(think)

Well it seems that the County ones are OK,
been d,n a bit of digg,n my self,  and come to same conclusion really.

Noo then only other thing is, go back to a +60 for 2580
or go lower say +20, and then if engines worn oot agen, nee need to go ratch oot another block.!!!

BUTT, when that happens I may be tooo Olde to drive the GT,
BUTTT, a Poster on heres atleast 110 ear older than me, and He still driving the GT, ;) ;)  :)

{ Pistons at mo are Hepolite +60,
but i suspect the ring lands may be worn, coupled with bore wear,
or total lack of any hone, maybe a combination of both that I got alot of CC pressure
So for the prics ive been offered, looks like its a new set }

As ever, a good respondo frae the Ladds thats in the no,
thanks

looks like I be giv,n  Mr D Cent Bloke a Ringo Starr the morrow then

M

[Slimboyfat]

We have been selling/using County pistons for getting on for 20 years.

Never once had any issue's other than we get the odd set with a bit of transport damage, but we check each piston individually before selling them on.

Worth checking as soon as you receive them if ordering from elsewhere.

[Nick Jones]

Used County pistons on the PI rebuild.  They were fine.  Weights within a gram, pin to deck virtually, the same diameters virtually the same.  Guy who bored the block told me it didn't matter which piston went in which hole.  When he did my Vitesse engine (Hepolite) he numbered them!  The Hepolite weights varied 5 grams across the 6 too.

Nick

[James]

Back in 2005 when I was building the engine for my Spitfire I got the County pistons back from the machine shop unmarked — thinking they hadn't weighed and matched them I took them back and they told me they were all identical. They double checked and showed me on the scales.

[Spider]

Got them in the GT6 I bought from Keith Dandridge and it does go well. :)

[GT6 M]

Ok, new one,  before the bloks bored, will a set off BIGG washers and tightend doon
on all studs , be as good as a tourque plate.

seems to be alott of loot for a one off job.
Butt then Ive med tools up, and never used em since the OE job !!

Me think,n here is, that with just bigg washers, the distortion will be just where the studs are.

noo then some may questionee this,  BUTT, when Ive bunged me honing stones doon the bore, the type like a long flat finger, 3 off,
no the ball on a wire type.

then there is definate areas where the cylinder is not  lets say, equal all owa.
this maybe a cause of me blow by, as well as 130+thou miles

thowts frae the resident Boffins please.


Ohhh, and got a good lead on some bronze guides for ex valves too,
like 25£ ish  a set,or no much moer,or maybe less.
bulk order will maybe get em even less !!
oohhhh,ee im hearing some folk say.
any one want some when I bung me order in !!!

ayhh what a gud ladd i am, try,n to gett you lot good stuff for next to nowt,

M

[Nick Jones]

Not sure you'll get the torque plate effect with washers.......

I do think it has an influence though - below pic was the well used bore or my PI engine, which had also been somewhat rusty. You can clearly see that there is a low area that the rings have not been wiping right where the root of the head stud would be putting the block under tension.  This showed up in several cylinders, but this is the best pic I have

Nick

[GT6 M]

yip thts what im seeing Nick
Im thinking  bigg washers will be OK,  as they moer ..localised  
can only give it a go,

M

[Nick Moore]

Is there someone who can lend you a torque plate? Either someone here, or a machine shop? Maybe we should have a register of people with fancy tools - hub pullers, spring compressors, that sort of thing?

Andy Thompson lent me his, but we're a bit far away I fear. It was well worth doing though. My engine builder was very pleased to see it. And grumbled that Andy's was better than his torque plate!

[GT6 M]

Nick, good idea, but ive a feelin they as rare as

owa here, never seen one being used,or heard of one being used.

If I get it med, then its on offer to the Triumph lot on here.
Butt, only in six form, unless the 4 pots bore spacings  an bolt wols are same, then a 6 cyl can stik oot a bit at each end.(think)
any one confirm

M

[don cook1]

What does one look like, how's it used?

[piman]

Hello Don,

a picture for you:-


Before boring or honing a block, the plate is torqued down on the block so that any block distortion due to the pull on the studs is compensated for during machining, i.e. the block is pre stressed which gives a slightly more accurate bore shape.

Alec

[heraldcoupe]

That's not something I've previously encountered. I guess it would be fairly easily made by someone with access to a large mill, and possibly a scrap head?

Cheers,
Bill.

[mikew]

heraldcoupe wrote:

That's not something I've previously encountered. I guess it would be fairly easily made by someone with access to a large mill, and possibly a scrap head?

Cheers,
Bill.

Its best made from a piece of steel plate, not some soft casting - machine the head down too much and it will be somewhat flexible (due to the material, water ways etc) a flat 1" steel plate with holes for the bores and the studs is what is required

[piman]

Hello Mike,

I found this on the BHJ site, they make plates for a large number of engines including Triumphs, unfortunately for us, they are in California.

"1-3/4" thick Meehanite Cast Iron or Aluminum Tooling Plate give maximum rigidity and resistance to permanent distortion and most closely simulate the stresses induced on the cylinder wall by the cylinder head when it is torqued in place. In addition, these materials have essentially the same coefficient of expansion as cylinder heads, important to those honing at operating temperature."

Note the last bit of the paragraph, that is something I'd not heard of before?

Alec

[don cook1]

Would/should there be a similar thing when a crankshaft is machined?