Lotus Elan

Crankshaft limits ?

PostPost by: elandoc » Wed Apr 15, 2009 11:48 am

Hi Gary,

6015 is a Ford part No. meaning "Engine Block". I'm not sure about the 701L blocks, but on the 711M, on the exhaust side above the engine mount, there are some that have X's cast itno them, the more X's, the more Chromium. Anyway, it's the 1600 cross flow (tall), not the 1500. Mine was bored out +.040, with a 5mm stroked crank giving 1700cc, the upper limit in my class for Targa Rallies. No sleeves. It's not in front of me now, so I don't have the date code. I'm told the 831C AX block is the ducks nuts, although I was told this one was too...

Cheers

Patrick
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PostPost by: garyeanderson » Wed Apr 15, 2009 12:42 pm

Hi Patrick

Was the block decked to achieve the final piston height? Some folk use full height 1600 blocks and use longer rods with a shorter piston pin height and just a light skim off the deck to clean it up. Other engines are constrcted by using the 1600 crank, 1600 length rods, and stock twin cam pistons and mill off .215 inch (nearly 5.5 mm). If you take the top off the block and then bore the block +.060 to get to the twin cam stock bore and remove another .040 things may have been a little weakened around the top of the bores if the deck has been cut significantly too.

Gary

elandoc wrote:Hi Gary,

6015 is a Ford part No. meaning "Engine Block". I'm not sure about the 701L blocks, but on the 711M, on the exhaust side above the engine mount, there are some that have X's cast itno them, the more X's, the more Chromium. Anyway, it's the 1600 cross flow (tall), not the 1500. Mine was bored out +.040, with a 5mm stroked crank giving 1700cc, the upper limit in my class for Targa Rallies. No sleeves. It's not in front of me now, so I don't have the date code. I'm told the 831C AX block is the ducks nuts, although I was told this one was too...

Cheers

Patrick
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PostPost by: RotoFlexible » Wed Apr 15, 2009 4:47 pm

cabc26b wrote:down to two options ( have thrown out billet and stock iron) .

Leading candidate - Scat 77mm crank
Second place en40 forged crank 72.5 -

Was thinking about using stock 125E rods but preped. also thought about cosworth steel rods but have come up short need one ( 1) to make a set - in the past I have use the cosworth steel , farndon steel and Carillo's but this is not a racecar and engine is suppose to be done making power at 7200 or so not sure i need to spend the money on trick rods.

any experience out there with SCAT cranks ? opinions on running the stock rods in combo with ?


The 1700cc (original TC block) motor in my car has a SCAT crank, purchased through Jay Ivey Engines in Portland. Jay does race prep on the crank before shipping it. My engine builder gave it a thorough going over (including crack testing and balance check) and grudgingly admitted that he could find nothing wrong with it - high praise from this individual. The rods are FF-spec NOS Ford rods, longer than stock but a bit shorter than Cosworth. (Bill turned up his nose at the used 125E rods I got on ebay.) Custom pistons, of course. I can't speak to the durability in extreme situations, but Bill felt the bottom end was good for 8,000 rpm although the peak is under 7,000.
Andrew Bodge
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PostPost by: elandoc » Thu Apr 16, 2009 4:41 am

Hi Gary,

Yes the top was machined, but the failure was at the bottom of the bore. Rods are (were) std length, I believe. I still have my old block with the crack in the water jacket - I didn't repair it, because I wanted reliability - more fool me. I might just repair it now, as it gave 7 years of good service and the bores are OK. I'm still trying to figure out what to do next.

Cheers

Patrick
67 S3 DHC - The world's most expensive Elan
64 Morris Cooper S (now sold)
85 Ferrari 308 GTSi QV
79 Ferrari 400i
68 Lotus Europa S2 (in boxes - wanna buy it?)
50 Riley 21/2 Litre (now sold)
65 Lotus Elan S2 (in boxes, soon to be a lightweight)
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PostPost by: rgh0 » Thu Apr 16, 2009 8:26 am

Hi Patrick

Sounds like you were unlucky to get the piston to sieze when the cylinder wall split - I have had 2 failures in this way when I was running 85mm bore engines and both times the worst I got was a slow water leak.

I would be interested to know the wall thickness in the area where the bore failed. Generally above 2.5mm / 0.10 inch is OK, thicknesses down to around 2.2mm / 0.090 probably Ok, much below that and failure will probably occur sooner rather than later.

Getting 2.5mm or more wall thickness in an 83.5 mm bore is generally doable in about 30% of normal 1500 or 1600 blocks provided the block does not have to much corrossion on the bore externals and the bores have not be wrongly bored in the past to use up all the available wall thickness in one direction so even with maximum possible offset boring you still end up with one side to thin.

cheers
Rohan
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PostPost by: rgh0 » Thu Apr 23, 2009 12:08 pm

Hi Patrick

http://www.race-cars.com/partbd/messages/19065.htm

link to new AX block in NZ - not cheap at $3500NZ

cheers
Rohan
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PostPost by: elandoc » Fri Apr 24, 2009 12:48 pm

Thanks Rohan,
I couldn't get the link to work, but I think it's the same one that was up on Trade Me. Brand new, if I recall, and cheaper than a $10,000 rebuild. I have advice coming at me from all sides, right now, but the AX block is at least legal, even thought a BDG is tempting.

Cheers

Patrick
67 S3 DHC - The world's most expensive Elan
64 Morris Cooper S (now sold)
85 Ferrari 308 GTSi QV
79 Ferrari 400i
68 Lotus Europa S2 (in boxes - wanna buy it?)
50 Riley 21/2 Litre (now sold)
65 Lotus Elan S2 (in boxes, soon to be a lightweight)
elandoc
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