excort Posted May 31, 2007 Share Posted May 31, 2007 has anyone attemptd to do this them selfs ive been told it makes the rods stronger but then ive read it allso makes them weaker ? Quote Link to comment Share on other sites More sharing options...
Gaz Posted May 31, 2007 Share Posted May 31, 2007 Removing the casting marks reduces friction...slightly. Not really worth it IMO but then cant really hurt.. doubt very much at all it will decrease stregth as your only removing casting marks. Quote Link to comment Share on other sites More sharing options...
mikuni Posted May 31, 2007 Share Posted May 31, 2007 I wouldn't touch them for the gains that you will get. If you get rid of the casting marks well on a couple and not so well on the other couple then it will put the engine slightly out of ballance wouldn't it? Quote Link to comment Share on other sites More sharing options...
Unclejake Posted May 31, 2007 Share Posted May 31, 2007 I do it sometimes (lighten and polish) but I have the right gear and scales that go to 0.1 gram. To lighten and balance a conrod you really need two scales so you can match the end weights. I have never actually end weighted a conrod - I pay someone else to do it. Old Ford four cylinder conrods can have about 180grams removed from them safely (I think - it has been a while and I would need to refeer to my notes etc.) The best option is to lighten them and then send them away to be balanced and shot peined. That is the strongest option for modified a factory rod. I had a set made in Australia a few months ago (forged) - I don't have them with me to photograph but they are SEX! Quote Link to comment Share on other sites More sharing options...
mikuni Posted May 31, 2007 Share Posted May 31, 2007 The best option is to lighten them and then send them away to be balanced and shot peined. That is the strongest option for modified a factory rod.I had a set made in Australia a few months ago (forged) - I don't have them with me to photograph but they are SEX! Nice info mate. I have been searching for shot peining facilies lately. Where are the best places / any places? Would you suggest just getting some forged lightweight ones made over the above method or does the gain vs price not work out? Quote Link to comment Share on other sites More sharing options...
Unclejake Posted May 31, 2007 Share Posted May 31, 2007 The only reason to have any made would be if you could not find a rod with the dimensions you want. It isn't cheap. IMHO one of the best places to send any balancing work is Collier Motor Engineers in Levin. Colliers will lighten, stress relieve, balance and shot peen a rod for about $100-$125 each. They are also very good for crank balancing as they have a $75,000 balancer EDIT - If you only wanted the shot peening I guess at $45 per rod. Quote Link to comment Share on other sites More sharing options...
sholdowa Posted May 31, 2007 Share Posted May 31, 2007 To lighten and balance a conrod you really need two scales so you can match the end weights. I have never actually end weighted a conrod - I pay someone else to do it. Or decent scales and mark the pivot point. Quote Link to comment Share on other sites More sharing options...
Unclejake Posted May 31, 2007 Share Posted May 31, 2007 True - it scares me though so I don't do it myself. Infact I don't touch my engines at all anymore. Too chicken. Quote Link to comment Share on other sites More sharing options...
mikuni Posted May 31, 2007 Share Posted May 31, 2007 So a forged rod offers no additional strength or any other advantages over a lightened shotpeined one? Quote Link to comment Share on other sites More sharing options...
Unclejake Posted June 1, 2007 Share Posted June 1, 2007 Don't quote me as I only play with 40 year old Fords - but my understanding is that most Japanese rods are forged from factory (and most have steel cranks too). Forged is much stronger than cast (old Cortina shit is cast) so I guess it would depend on what motor you are dealing with. I only build (or more acurately pay others to build) old N/A engines so I really don't know much about the stresses and combustion chamber tempratures involved with turbo motors etc. Quote Link to comment Share on other sites More sharing options...
mikuni Posted June 1, 2007 Share Posted June 1, 2007 I only build (or more acurately pay others to build) old N/A engines so I really don't know much about the stresses and combustion chamber tempratures involved with turbo motors etc. No, but high revving NA engines is your department I don't know about the steel cranked, forged rod engined jappanese motors. I know a few of them do from the factory but certainly not the majority. Quote Link to comment Share on other sites More sharing options...
Unclejake Posted June 1, 2007 Share Posted June 1, 2007 [ I don't know about the steel cranked, forged rod engined jappanese motors. I know a few of them do from the factory but certainly not the majority. You are prolly right mate. It is a bit outside my knowledge area. A few of my fellow racers put Jap conrods in their engines and I am not aware of one ever failing. The old cast Ford rods fail from time to time but it is seldom clear what failed first - the rod or the rod bolt. I have a steel crank in my Mk1 Cortina - it cam out of a Datsun 1600 (L16). Even early Valiant V8s had steel cranks. Quote Link to comment Share on other sites More sharing options...
Gaz Posted June 1, 2007 Share Posted June 1, 2007 Does the engine you are using have problems with weak rods Brad? A decent balance will reduce this problem if it is only a bit.. say they have known problems with rods at 7000RPM with 200hp. Id guess they would be fine if the engine was balanced and the rods stress relieved. However go pushing 8000RPM and 220hp might break em. Not very clear what im trying to get accross but meh. Quote Link to comment Share on other sites More sharing options...
mikuni Posted June 1, 2007 Share Posted June 1, 2007 I think I know what point you are getting at, even if you don't My engine red lines at 7250. With rod bolts it will go to 7750 safely. But I want more and this is all the standard crank, rods and pistons can handle. I'm pretty sure the pistons will be fine above that and cranks can be expensive. I need to look at what type of stuff may fit I think because it uses a 86x86 as far as I'm aware which is the same as a Toyota 3s-ge so perhaps some bits can be shared? Probably not. I don't know too much about internals. Just looking into it at this stage but I think will decent light rods and bolts I should be able to push it up above 8krpm. Quote Link to comment Share on other sites More sharing options...
Unclejake Posted June 1, 2007 Share Posted June 1, 2007 Failed Cortina conrod (and matching camshaft FTL) v This one due to oil surge in corners and Unclejake not being quick enough with the kill switch. Invoice = significant. Quote Link to comment Share on other sites More sharing options...
Gaz Posted June 1, 2007 Share Posted June 1, 2007 ^^ bugger. This was what tempted the move to dry sump I guess? Maybe with the revs you want you should look into Vtec rods Fuck I touch myself. Um yuh. Other rods may be the way to go. Im not sure as too how much shot peening does to rods but Im pretty sure a decent balance will do wonders. There will no doubt be some rods that can be used however even if they slightly change stroke Quote Link to comment Share on other sites More sharing options...
th130 Posted June 1, 2007 Share Posted June 1, 2007 Awesome that is a mess. Quote Link to comment Share on other sites More sharing options...
Mr Revhead Posted June 1, 2007 Share Posted June 1, 2007 polishing removes stress points by eliminating sharp edges worth it depending on the application Quote Link to comment Share on other sites More sharing options...
excort Posted June 1, 2007 Author Share Posted June 1, 2007 sweet guys cheers for all that info i doing a 2ltr ford pinto up 205 block so rods are rather strong only doing a na engine Quote Link to comment Share on other sites More sharing options...
Spencer Posted June 1, 2007 Share Posted June 1, 2007 ^rods take more of a pounding from revving than boosting Quote Link to comment Share on other sites More sharing options...
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