There are the LS rods at 6.46" and 6.56" for 1.889 crank journal, 640 grams, 650 grams Eagle CRS6460H3D2000 Eagle CRS6560H3D2000 Under $500 Use them with the 1.850" bearing In case you missed this thread: http://www.v8buick.com/showthread.php?260666-curious-about-SBB&p=2153620#post2153620 Paul
I was thinking about those,but don't know exactly what the budget is,so I didn't mention them.(thanks for bringing those up for me) To bad they're so heavy,almost as much as a stock sbb 350 rod,will be a little lighter afer machining to narrow the big end to fit on the sbb 350 crank though. Hard to beat those nascar take outs if you can find close to the length you need,they are around 100 grams lighter some times more! But the nascar stuff price is usually over $2,000 for a new set and for that much they better be lighter! And a good looking used set of the take outs can go for less than $100 on ebay some times,even if they need to be reCONed,less than the new other ones.(buying new bolts for them is another story! OUCH!:shock Derek ---------- Post added at 03:43 PM ---------- Previous post was at 03:07 PM ---------- [/QUOTE] King Cranshafts willing to do what? I sent that link for the custom bearings to my machinist,I'll try to get him to open an account with them to get better pricing on custom bearings. Yeah,800 grams I would think is WAY to heavy,I like the lenght though.With that small of a rod journal,I think we need to make the rotating assembly a light as we can to try and give the cast crank a chance to live. A billet crank would be sweet for a stroker,could have it offset anywhere you wanted it with a 1.888" rod journal size. And still would be able to handle a hole bunch of boost.:eek2: Could get greedy and run a 4.250" stroke(as long as the rods could be made to clear the cam)with a 3.875" bore to make a sbb 401.:Brow: And run that external oil system finishline has for 455 like Andy mentioned to be able to make pan rail clearance if nessesary? Derek
The rod weight is not as important as the piston weight. The longer rod allows a shorter and lighter piston. All of the piston and pin weight reciprocates. Only part of the rod weight reciprocates. The longer rod also reduces the "G" forces at TDC. The LS rod comes with the SBC .927" pin and could be honed to .940" if needed Just something to consider. Paul
The minus for a longer rod in a cam clearance challenged engine like a sbb 350 is the rod will reciprocate less(less back and forth motion),thus staying closer to the cam.The chevy engineers got around this on a sbc 400 by making the rods shorter(5.565" vs the 5.700" rod lenght that is used on all other factory sbc engines) and giving it a really crappy rod ratio and a lot of side load,but no cam clearance issues. On a sbc 383 stroker with 6.00" rods with a 3.750" stroke either a small base circle cam is needed(with a cam that is .500" lift or higher with the standard 1.5:1 rocker ratio) or rods that are clearanced for the cam need to be used. A 4.00" stroke in a sbc is even more challenging for cam clearance with a 6.00" rod. Buick has the crank and cam even closer to each other on the sbb engines than a sbc,what helps Buick to barely stay away from the cam in stock form with the closer crank to cam center line is a even smaller base circle than a sbc cam and the use of a 2.00" rod journals which make the Buick rod a little narrower from bolt to bolt than a sbc rod that has a 2.100" rod journal.(1968 and newer sbc engines,older ones had a 2.00" rod journals) "All of the piston and pin weight reciprocates. Only part of the rod weight reciprocates." Don't the pistons go straight up and down in the cylinders,and the rods go back and forth on the pin?(except for the very slight rocking of the pistons in the bore from the piston to wall clearance from going up and down from the angle of the rod) The use of a custom piston with a forged side relief design(the style of piston nascar uses) and a shorter pin(and probably a smaller pin diameter if using a nascar take out rod) will really bring the weight of the piston and wrist pin assembly down,not to mention the extra stroke will require a shorter compression distance on the piston to help make it lighter. "The longer rod also reduces the "G" forces at TDC." Yes,a longer rod will have more dwell time at TDC and BDC,with a much better rod to stroke ratio. But with the sbb stroker this may not be a possibility because of clearance issues,but on the brite side(if its true) I have read that boosted applications engines like a shorter rod ratio? Plus with a rod that is 6.380" long will have a better rod ratio than a sbc stroker.(unless its an after market sbc block with a raised deck height with a raised cam) Derek
What Paul is getting at is the mass vs movement distance. By keeping the end with the most movement (piston and upper part of the rod and piston pin) as light as you can, it will cause less variance in balance and keep a closer centralized weight distribution around the crankshaft. This would permit higher RPM use and less vibration/easier balance.
What part of the rod has interference with the cam.? most of the time it is the big end of the rod and not the beam. Paul
I knew it was some kind of physics thing,I don't balance my own engines,I have a guy that does that for me. I just make everything fit without interference. I don't know it all,nor do I claim to,I learned something new today.:idea2: But With this being a cam to rod clearance challenged sbb 350 stroker,even though I would rather use longer rods,to much cam clearancing may have to be machined on the rods that it may be detrimental to the structual integity of the rod.o No: This is uncharted territory we're venturing in,hopefully we can map it out so if some one else wants to make the journey,there will be a map for them so they don't get lost.:TU: It would be great if the cam tunnel could be raised about 1.00" so the use of 6.800" rods could be used and a larger base circle cam,it can't so we can't. On a sbb 300 I can lower the crank about 1/4" by offset boring the main saddle for a 2.750" main journal and using International main bearings and some 1/4" spacers where the caps mount.(I may do this for my sbb 300 stroker build for the extra cam clearance:Brow But this can't be done to a sbb 350,so we have to make everything fit in the perimeters that the Buick gods set so many years ago.:rant: Derek
OK In this case the crankshaft is being stroked by moving the rod journal CENTER outward but the outward surface of the rod journal stays in the stock location. This does not move the rod closer to the cam. In most cases it is the big end of the rod that gets closer to the cam. Is that the case here? Paul
On an H-beam rod it would be where the bolt goes in the rod towards the end of the threaded side of the bolt. On this set of sbc 6.00" rods for the 434 sbc build I'm doing for a friend,the clearance is cut so far in the rod that the end of the bolt gets machined with the rod. Here is the sbc rod that I'm using for the sbc 434; http://www.ebay.com/itm/CRS6000BST-...05&rk=1&rkt=5&sd=200952427660&#ht_2418wt_1036 Only one picture!!!,you can see how the rod is machined into the bolt where the bolt end is on an angle on one side.(hard to see the unmachined side in the picture) And yes it is the big end is where the problem is on the one side closet to the cam,the rod will swing away from the cam more on the big end when its shorter,while a longer rod will have less swing staying closer to the cam when the crank rotates around. You don't want to cut to much of an angle on the bolt,or it will lose its too much of its holding power. (I hope I explained this clearly) Derek
Derek Thanks for the great explanation. We won't know for sure until a mock-up is done. Since the rod journals are being offset ground and not using a stroker crank with the same size rod journals there is a good chance that there will be very little rod to cam interference. Paul
Alles in Ordnung, Derek! We're all learning here. Anyone who says they're not learning anything just isn't paying attention. :grin: There's nothing to be ashamed of. Even us old men can learn things from each other, that's why this site is so wonderful. We all get to share ideas and information. :TU:
Yep, This is just like old times earlier this year. Need a SBB siamese cylinder wall block, cross bolted mains with raised cam location. 4.00" bore an steel stroker cranks. Please no one say LS Paul
Would be nice! Maybe one day... never say never and all that. I think we'll all be happy with aluminum heads, single plane intake, and shorty headers for now. :grin: Once the popularity of the Buick 350 increases with the help of aforementioned parts, we might see more stuff like forged steel stroker cranks and the like becoming more readily available. I'd like to see a block girdle designed for it too, for those super ridiculous forced induction 1200+ HP builds. :TU:
I think Finish Line makes a halo girdle for a sbb 350?(not sure) And yeah,those boost guys are nutz! Derek ---------- Post added at 10:33 PM ---------- Previous post was at 10:26 PM ---------- This is true if the big end decreases in size proportional to the stroke increase vs the stock setup. So with this theory,for every bearing size decrease,a rod big end decrease would be needed to compensate for the stroke increase.:eek2: And keeping the rod length the same will help give it the extra kick out also. Derek
Intake was ported a bit, but damn the exhaust was hogged out like a mofo... that's an 82.9% I/E ratio! That's new territory for my calculations...where 75% is the 'ideal' ratio. With numbers like that, I could see more intake lift and duration... I imagine it would react very positively to massive boost... With a smidge of overlap, just enough to help the boost evacuate any remaining exhaust gasses, a design like this would be pretty balls out.
Yeah,the kid did a great job for a first timer,as good as a pro.Figure that cam out(LOL)I'm sure a sbc generic straight pattern would work just fine with that ratio.:laugh:
And then some. I think with that ratio, it would benefit from more intake emphasis, just the opposite of the typical port jobs that net somewhere between 70%-75%, particularly with pro-charger boost. :TU: Providing you had the proper exhaust system setup of course. Certainly wouldn't go wrong with an off the shelf straight pattern cam though.
