Panko 2,482 Posted April 26, 2015 Hi guys, i have 3 sets of con rods, all still attached to pistons. one set has TRW on them, another set Ford (both these have 250 cast into them) then the 3rd set, have 3.9 cast into them. they look identical, but would i be right in thinking the 3.9 casting means they are from a 3.9L OHC engine? sorry i have no pics on this one if they are indeed OHC 3.9L rods, is there benefits of running them over a normal 250 cross flow rod? the ones cast as 3.9 are also attached to cross flow pistons. cheers guys Share this post Link to post Share on other sites
gerg 10,871 Posted April 26, 2015 Yes 3.9 is a pretty good clue. I don't think there would be much difference between the two without seeing them side by side except for the rod bolts (perhaps) being metric. Share this post Link to post Share on other sites
Panko 2,482 Posted April 26, 2015 Yeah it didnt look like they were much different. Share this post Link to post Share on other sites
slydog 7,873 Posted April 26, 2015 I used 3.9 rods in my 250 before...but my question is when has anyone on here seen a xflow conrod brake ? So with that said a set of ARP Windsor bolts or at least new metric OHC bolts on any rod will be enough. Share this post Link to post Share on other sites
ando76 4,354 Posted April 26, 2015 The later model rods are a bit heavier and therefor stronger I would believe. seem to recall someone on the other site cutting them apart to show the difference. I've seen the difference first hand and yeah later are heavier. In reality like sly said they are not overly weak and can handle a fair bit of abuse - provided the oiling system and the tune are correct. In a boosted application I would use the later stuff as extra insurance. In an aspo engine that you want to turn quickly I would go for the lightest rod. New rod bolts (arp) are good insurance as these engines are getting on a bit now. Having said that the standard bolts only go to 33nm so if the engine was standard bore, I'd happily re-use them. Anything with an oversize bore and they might have been through a few tightening sequences and be getting a bit marginal in a performance/boosted application. 4 Panko, matt_lamb_160, gerg and 1 other reacted to this Share this post Link to post Share on other sites
matt_lamb_160 252 Posted April 27, 2015 TRW ones are later crossflow conrods. There is a forum somewhere which compares cut crossflow and E-series rods. E-series have more meat. Unfortunately, I cannot remember where it was. 2 Panko and gerg reacted to this Share this post Link to post Share on other sites
broken-wheel 659 Posted April 28, 2015 EF has more meat as the crank was bigger/heavier Share this post Link to post Share on other sites
Lord_fahrquhar 2,580 Posted May 12, 2015 EF has more meat as the crank was bigger/heavier You could use this comment to go somewhere. 1 tpak addict reacted to this Share this post Link to post Share on other sites
