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S rods on A crank

Posted: Wed Jul 28, 2010 12:57 pm
by Vegard
I've just had an A crank reground to fit S-rods. However, as we all know, S rods are too wide to fit the bearing journal.

I've measured that I need to remove approx 0.35mm from each side.

The question is: Should I remove the same amount from each side??

Re: S rods on A crank

Posted: Fri Jul 30, 2010 12:55 am
by eightport
Yes, cut the same amount from both sides.You should try to keep the offset the same.

Re: S rods on A crank

Posted: Fri Jul 30, 2010 10:00 pm
by littler
keep the crank strong and make the rods light :P

Re: S rods on A crank

Posted: Sat Jul 31, 2010 9:23 am
by Vegard
I calculated that I needed to remove 0.40mm from each side. Now done. Let's see if it fits the crank now ;)

I know some engine builders in the UK uses LOTS of sideways thrust clearance on rods. Is there a clearance one should aim for?

Re: S rods on A crank

Posted: Mon Aug 02, 2010 9:56 pm
by Vegard
After removing the said amount, it was time to try the entire thing in the block. The pistons popped out 2,25mm. It was obvious that the block had been skimmed, so OK I though.
After measuring the rods I've found that I've just modified a set of 970 rods to fit a 1293 A crank.

Bollox!

I guess I have to fit these in a long stroke engine to get a better stroke/rod ratio.

Do you guys know if MED for instance widen the journals or narrow the rods in their long stroke engines?

Oh BTW. Those of you who think that 1071 and 970 rods are from the same forging with a differently drilled small end, you're wrong. The 970 rod is definitely from a "longer" forging.

Re: S rods on A crank

Posted: Mon Aug 02, 2010 11:35 pm
by sandman
Veggy;

"Everyone" knows that 1071 and 1275 share the same rods - unlike the 970, that uses longer rods... :twisted: :lol:


(Sry - just could'nt resist adding some salt :)

Re: S rods on A crank

Posted: Tue Aug 03, 2010 8:30 am
by Vegard
Ed you misunderstood. Some say that the 970 and 1071 are from the same forging, only drilled differently. This is surely not true.

Re: S rods on A crank

Posted: Tue Aug 03, 2010 8:57 am
by guru_1071
whats that saying verg?

'measure twice, cut once......



:lol: :lol: :lol:

Re: S rods on A crank

Posted: Tue Aug 03, 2010 9:04 am
by Vegard
I never even knew I had a set of 970 rods. I think someone on Ebay has fooled me ;)

Re: S rods on A crank

Posted: Tue Aug 03, 2010 9:29 am
by guru_1071
Vegard wrote:I never even knew I had a set of 970 rods. I think someone on Ebay has fooled me ;)

they are more likley long stroke 1275 rods......... :lol: :lol:

Re: S rods on A crank

Posted: Thu Aug 05, 2010 4:31 pm
by Minimania

Re: S rods on A crank

Posted: Thu Aug 05, 2010 11:37 pm
by Vegard
Minimania wrote:Your opinions are welcome;

http://www.minimania.com/web/DisplayID/ ... ticleV.cfm
Long rods are god on an Asmathic engine, no doubt, so get us some longer rods and shorter pistons ;)

Mmmmmmmmmmmmmm http://www.7ent.com/detail.cfm?pageid=2964

Re: S rods on A crank

Posted: Sat Aug 14, 2010 8:35 am
by Vegard
It's not like I had few to choose from....

All S rods:
Image

Three sets of modified A ones in addition waiting for balancing.

Image

For those of you who have tried balancing rods, knows that it's one of the most shitty jobs ever... Luckily I didn't have so many to do...

Image

Re: S rods on A crank

Posted: Wed Aug 18, 2010 9:50 pm
by Vegard
Damn Rich, you're disappointing me. How could you not be commenting on my rod?