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 deluxe hunter
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 posted on May 18th, 2004 at 07:13 PM |
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Long stroke 94mm Pots & pistons ???????
I've got a set of 94mm pots and pistons (mahle) for 82mm stroke crank. As far as I understand the pots are longer -so spaces are not needed and the
length between the wrist pin and the piston crown is shorter. Unfortunately I don't have a stock set to compare to.
I will be running a 74mm crank.
My question is... can I just machine down the pots to the approriate length and use the pistons (with the shorter crown to pin) -or will I stuff up
some geometry that I have not thought of yet??!!
thanks for your info.
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Menangler
A.k.a.: Dave Becker
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| posted on May 18th, 2004 at 07:38 PM |
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In a Mahle "B" kit, the barrells are the same length as an "A" kit, the only difference is the wrist pin is 5mm higher on the piston to allow for
the longer stroke crank,
FAHRVERGNUGEN;
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Experienced when a car and it's driver are in mutual harmony, A unique driving experience, Pleasure, Satisfaction,
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seagull
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| posted on May 18th, 2004 at 07:51 PM |
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So this does what then dave ? seagull
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Menangler
A.k.a.: Dave Becker
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| posted on May 18th, 2004 at 08:09 PM |
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With the wrist pin 5mm further up the piston, it stops the piston sticking out the end of the barrell, but on an 82mm crank, the piston will still
stick out the end of the barrell with out the use of a big spacer to get the required deck height, this is with stock length rods of cause.
On a 74mm stroke crank with a "B" kit the barrells will need to be shortened as the deck height will be too much.
A 78mm crank works best with a "B" kit with no machining of barrells and only thin spacers to get the desired compression ratio.
The other problem of big strokes and Mahle "B" pistons, is when you have the barrell sitting on a 5mm spacer to get the compression right, the
piston pulls a long way out of the bottom of the barrell on the down stroke, leading to premature piston wear.
Hope this makes sense
FAHRVERGNUGEN;
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Experienced when a car and it's driver are in mutual harmony, A unique driving experience, Pleasure, Satisfaction,
A feeling experienced by Volkswagen Drivers.
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seagull
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| posted on May 18th, 2004 at 08:35 PM |
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Yes thanks Dave ,there is a lot to do when doing these big motors .
I gess as well why the cost so many $$ .
I have got hold of some pistion kits 82.9 mm are these 1398cc dave ??
And sorry to rob your post !
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Keith Haeusler
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| posted on May 18th, 2004 at 11:18 PM |
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Deluxe Hunter,
I have built a 74 stroke engine using `b` pistons before. You just have to machine the barrell base to gain your desired deck
height, which inturn narrows the engine somewhat. Also pushrods need to be narrowed as required, the pushrod tube length becomes an issue ( although
you can use 40hp ones ). I think the tinware fitted up ok, exhaust may become an issue if its not able to be narrowed to fit back on the heads. If
your using twin webers they may interfere with the fanshroud also requiring clearancing. Anyway its certainly do able, just build it and enjoy. Hope
this helps, Keith.
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deluxe hunter
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| posted on May 19th, 2004 at 12:57 PM |
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The box that I've got does not say A or B set. It does say they are for 82mm stroke 2300cc big bore.
I have measured them and the barrel length from cylinder head face to case shoulder is 114mm. The dimension from piston crown to wrist pin centre is
35mm (24mm from outside edge of wrist pin bore to crown).
Do you know whether this means I've got an A or B set?
thanks for the info
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Menangler
A.k.a.: Dave Becker
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| posted on May 19th, 2004 at 04:28 PM |
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The new 1904cc engine I am selling is using "B" pistons, the barrells have been machined to suit, makes a nice narrow engine that fits into an early
body very well.
FAHRVERGNUGEN;
Description of a pleasurable sensation,
Experienced when a car and it's driver are in mutual harmony, A unique driving experience, Pleasure, Satisfaction,
A feeling experienced by Volkswagen Drivers.
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