fun_on_the_sand Posted March 27, 2008 Report Share Posted March 27, 2008 I got my 370 Long Rod since last year built by a local shop, but I never really understood what the "Long Rod" implies. Obviously I understand that the Rods are longer (2 or 4mm I gess) but how do you compensate for that so the piston doesn't hit the head? is that a special piston with shorter distance (2 or 4 mm) between the wrist pin to the top of the piston? What is the advantage of this? more torque overall? Thank you guys Quote Link to comment Share on other sites More sharing options...
dajogejr Posted March 27, 2008 Report Share Posted March 27, 2008 More reliable motor. The longer rod (5mm longer, 115mm vs. stock 110) will cut down on the angle of the rod pushing the piston, and in turn will not try to push the piston through the cylinder wall. You might notice a little more HP or torque due to it spinning easier, but...not much to talk about. A piston with a pin height 5mm further towards the crown is used, called a "racer's choice" piston by wiseco, or a 795 series...or long rod piston. Blaster Pistons also use the 5mm offset pin, and if I'm not mistaken, it's .5 or 1mm offset towards the front of the piston as well. Not sure on that one... 1 Quote Link to comment Share on other sites More sharing options...
fun_on_the_sand Posted March 27, 2008 Author Report Share Posted March 27, 2008 More reliable motor.The longer rod (5mm longer, 115mm vs. stock 110) will cut down on the angle of the rod pushing the piston, and in turn will not try to push the piston through the cylinder wall. You might notice a little more HP or torque due to it spinning easier, but...not much to talk about. A piston with a pin height 5mm further towards the crown is used, called a "racer's choice" piston by wiseco, or a 795 series...or long rod piston. Blaster Pistons also use the 5mm offset pin, and if I'm not mistaken, it's .5 or 1mm offset towards the front of the piston as well. Not sure on that one... Nice, that's why I love this site, a lot of experienced guys willing to explain the basics and the not so basics, THank's dude Now, what if I want to add a 4mm stroker crackshaft (to go to 400cc)? What other mods I need? do I keep same rods and pistons? do I need to modify the case? Is it less reliable than the 370 long rod? what would be the difference in performace? Quote Link to comment Share on other sites More sharing options...
dajogejr Posted March 27, 2008 Report Share Posted March 27, 2008 You have several choices. Same pistons will be used. You have a choice of running a spacer plate under the cylinders so the pistons don't smack the head, or...you can get domes or your stock head cut/machined deeper so the pistons don't hit the head. Domes/head cut is the better method in my opinion. Now..that being said. Because you are changing the stroke of the engine, the porting and port timing must be changed to match that. So...figure porting to match the added stroke. If all that is done is matched porting and dropping a 4 mil crank in, figure a 7% rough increase in power...give or take, and more torque, too. 1 Quote Link to comment Share on other sites More sharing options...
fun_on_the_sand Posted March 27, 2008 Author Report Share Posted March 27, 2008 that sounds like a lot of headaches... looks like it would have been a good idea to have the porting and 4mm cranckshaft done at the same time so they can match the timming in the port to the stroker cranck. I visited the Hot Rod website and they have a kit that includes the Crankshaft, Rods and pistons, to avoid the spacer problem, but still, I would have to deal with the timming problem in the port job, which I rather stay away from. I really like the port job I have. Quote Link to comment Share on other sites More sharing options...
dajogejr Posted March 27, 2008 Report Share Posted March 27, 2008 In the right hands, the port job will only be enhanced and improved... Whether or not that's worth the $$ for you is totally up to you. Quote Link to comment Share on other sites More sharing options...
fun_on_the_sand Posted March 27, 2008 Author Report Share Posted March 27, 2008 In the right hands, the port job will only be enhanced and improved...Whether or not that's worth the $$ for you is totally up to you. I'll think about it and I'll talk to D&M who did the port job and see what they can do. Thank you dude, I apreciate your help Quote Link to comment Share on other sites More sharing options...
dajogejr Posted March 27, 2008 Report Share Posted March 27, 2008 D&M built a bike they shipped out here a month or two ago to race on the ice, it was a bike for Donny to ride, they make some nice stuff for sure. They'll hook you up, whichever way you choose. Quote Link to comment Share on other sites More sharing options...
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