On the 3.8's (GN)with a roller cam. #3 big end rod will make contact alot of the time with a stroker crank. Usually needs to be clearanced . Im used to watching for it.
4 rods hit on mine. I clearanced all rod corners on the inside only, to keep rotating & reciprocating weights the same. Each rod ended up at 515 grams.
This guy is going to surprise everyone when this thing gets to the track. 12.42@107 A 120 shot of nitrous should put it at 10.99 Will that special crank floating around be used to put that 10.99 up or will it be that turbo guy that never gets to the track. The saga continues...
No, 4". Offset the full .150 Virgin crank. Cleaned up with just a fuzz off stock jrnl . 350's have slim & none for cam to crank room. Small base circle would help some, but not enough. There's a lot of crap whipping around in there... I'm pretty sure Demko had to cut corners on his Molnars, and he has stock stroke.
Rod bearings are limited. -.001, std, & +.001 is all that's available. I went -.001 so a polish or .001-.002 fuzz job if needed could be done down the road. No std, .010, .020 & .030 choices....
Readings some comments above about clearance. What hits? The rods or the counterweights? I don’t have a 350 dissected in front of me to look at,just 455’s. Turning down the counterweights isn’t bad. I’ve done that for some other custom builds,but if the rods are hitting,then that’s something else entirely. As much as I like to add stroke to everything,the Buick 350 actually has some decent stroke that I can work with,but if I had a crank made,I would want the added counterweight. I’ve had all of my other ones made like that. Make the rod journal 2.00” or 1.88 Honda. I can run a nice long rod in a 350 with a short,light piston. 7” rod is no problem.
Yes I did have to grind a bit on the shoulder (I think that’s what it’s called) on IIRC 4 rods. Not a lot but enough to gain around .050 clearance as best I could measure, it IS tight between the rod big ends and cam in the 350
Yes, cam lobe to rod corner hits. Will 7" rods add to to interference? Guess you will have to mock one up...
Yes the longer rods will also contribute towards less clearance. The main issue with stroking the crank is trying to maintain the rod strength while grinding the rods to add clearance to clear the cam lobes. The other issue is the lack of bearing options for refreshing the engine later. If NA I can see why people want to get the 368 cube setup but under boost I don’t see much gain over the 355 cubes with a 30 over bore. My billet crank is setup fir standard sized bearings so it could easily be freshened 2 or 3 times using off the shelf bearings. I also don’t see the point in trying to bore over 40 over, keep the block as thick as possible.
I have 7" rods in my 340 and they interfered with the cam. That was a 1/2" lift flat tappet cam. I'm going to a roller, it might get tight. I had to trim the shoulders a bit and bevel the ends of the capscrews. The ring package was a bit tight. I used the 1mm rings and 3/4" wrist pins. There was Maybe 1/8" from the pin to the oil ring, maybe a little less. Jim
That was stock stroke Jim? The 340 and 350 have the same deck height so that is useful information. Imagine a huge roller cam and how that would effect the clearance.
I run a few different engines that have .043,.043.3mm ring stacks,so I’m good there. The reason I would reduce the rod journal size is to help with clearance. I know I won’t get a GRP aluminum in there,but I can work with a steel rod. None of it would be shelf parts,but if you are at the point where you are having a billet crank made,you shouldn’t be using any shelf parts anyway. Sounds like a raised-cam block would do wonders.
That's cutting it close! I believe Ivan in Canada used 6.400" rods, maybe 6.450, his needed corner treatment. Biggest bang is $2,300 Carrillo rods on the cheep! Just abt the price of new ARP rod bolts! The rod bearings are pricey tho. Jim, so your using those snowmobile wrist pins too huh?
Honda size jrnl without offset stroke would gain you some room. Enough to not cut corners with a huge duration roller lobe profile? Who knows...
Perfect. That’s what I need to see. I would run some type of solid cam. Flat or roller. No power adders here. The 1.88 and 2.00 are pretty common. I haven’t had any issues getting bearings. I run 2.00 in my big blocks. There are some LS Carrillo rods that are 6.450”,but then you are committing to that wrist pin. I would just have something made. Oliver has been pretty good for me in the past,but any of those rods will be fine in there,unless I find a way to make enough power.
Dan, the motor in car now has Pankl's. Those Carrillos are going in next one, in case I blow it up! I have everything, except blk bore & crank offset grind. I mean everything. Roller cam, pistons, rings, bearings, rods, cam bearings, wrist pins, roller rockers, TA SP3, beehive valve springs, sfi flexplate, etc. Glad I bought all that extra stuff.... I think these are standard size, got a decent price on them. The bearings in car are -.001 and Calico coated, but were pricey.
