I will message Tom Molnar and let him know about the issue with the Molnar rods needing to be ground to clear the cam... The Molnar rods cannot be used with a stroker engine unless you use a Billet crank. The crank has to be offset ground to a smaller bearing to make a stroker with a stock modified crank. I have Hershe rods in all my engines and no cam issues, but I am using stock stroke...
Yes, that is an option...probably cost just as much to regrind this one, as to get another one. Would it be easy to sell though? The cams are relatively cheap compared to the required roller lifters. Already got an extra stroked crank sitting here...don't really want an extra roller cam taking up space. Also, the tightest spots between the crank counter weights, and the cam lobes, only have about 0.025" to 0.027" clearance. So word to the wise...go with a smaller base circle cam if stroking a Buick 350.
Mart, Juze86 has a standard stroke in his sbb 350 with the new Molnar rods. He has pictures in his thread with the rods and mentions the cam clearance issues there as well. It would seem that Molnar used an off the shelf design without looking at a stock sbb 350 rod. IIRC the Molnar rods didn't have the proper offset either so the wristpin end wasn't centered in the piston either, they were probably machined on center from an off the shelf design. They should of used the Scat pro comp series style design type rod for a sbb 350 for extra cam clearance. Like these; Notice how they are slightly shorter on the rod side for extra clearance in that area more like a sbb 350 cap screw rod is. This is the style I would of had made if there were more than couple of people interested when I was able to have them made. See how the Molnar rod below is slightly longer where the bolt threads in the rod side of the parting line vs. the above style rod. Derek
If costs are similar for you I wouldn't even consider modifying yours, you'll eventually sell it. (I suppose that's why I have a small whse full of 'someday' or 'not this time' parts, but they do get used or turned over) It's normal with any stroker build to use mock up parts before any custom ordered parts are made. Stock cams and various donor parts can be helpful, along with some forethought and planning. Not busting your chops here, I think you already figured out that the cam could have been ordered after you mocked up the short block. (I know you stroked the crank late in the game. This is more to the benefit of the next person contemplating) I suppose if you had some wood shop tools, a temp rod could have been made up. I prefer trimming C-weights, esp when going so much lighter, piston skirts can hit and not the same in every position. Order 9 or 10 valves when possible instead of 8...maybe a handful of singles at different lengths when working with a new to you platform. (or have your vendor do that for you, prior to machining) It's less $$ in the long run than paying a shop to modify new parts the second time around. Don't put rings in until final assembly. You may need to deepen valve reliefs, etc. Don't balance until the end, grind cranks until the main line is done and rods are in hand, etc. etc. These things are completely normal for this kind of build and shouldn't induce panic. I definitely know the feeling of being undersupplied or equipped. Hang in there, handle one step at a time. Think about how the next thing might not work before you get to that point. Read more about stroker builds before embarking, etc. etc. You'll be a pro by the time your finished with this one [as far as your extra crank, that's on you to handle the accountability of it and deal with shipping or the sale of it. Same with any extra parts you collect making your way through new territory]
Shame I didn't took any pics from modified rods, but not much, maybe something like red line in picture below, you have to grind little and check clearence and grind more if needed. About bolts, only corner because that sticked out from rod after grinding. I chamfered whole bolt end so they fit in any position. Like Derek already said my engine has standard stroke. I got my rods almost year ago and they were some of the firts ever made, piston offset was not the best and rods were little shorter than stock, 6.380" (stock 6.385"?). I don't know has Molnar made any changes after that.
Rod & piston installed, only torqued to 30ft# and the bolt still cleared the lobe. (Not completely flush with rod.)
Cool, but looks like its a bit more than you actually need there, looks like by guessing, around .075" of clearance now? .025" would of been enough and you may of kept the full circle for the stretch gauge but if there is more than half of the circle left the gauge still may work and be repeatable? Derek
He won't need the gauge again, just get it to visually line up to the rod (at similar torque) Think about using a degree gauge (torque angle) on a stretch to fit bolt. Hopefully they were torque cycled a few times and burnished in.
It may be just the way it looks. There was only 0.010" clearance before I stretched the bolts, and took an average. I stretched them to 0.0055" and that equalled 54 ft lbs of torque. (Max torque on 3/8" Carrillo bolts with S-6 mark on heads is 58ft lbs.) So once the rod bolts were torqued up, I took it back to the belt sander, and made the bolt flush with the rod. Blended into the shape of the rod, so there were no bumps/stress risers, and hand sanded the edges to remove the razor edge.
Nice work Ivan! I have to say, very nice job with the pictures you took with the little spy mirror as well! So, does this mean that you're not going to get the base circle reduced? And there is another set of the same rods for sale on eBay if you still wanted to know?; http://www.ebay.com/itm/181969787105?_trksid=p2055119.m1438.l2649&ssPageName=STRK:MEBIDX:IT Derek
I'm already watching those. Lol I'm waiting to talk to Mike tomorrow about the cam. I talked to my son, and he doesn't want to buy another cam. ($$$) But I said I could ship it out, and while they are balancing the engine, they could be regrinding the cam to the spec's we asked for. We shall see what Mike says. There are also two of the crank counter weights that get to within 0.025"-0.027" of the cam lobes...should we leave it alone, or add some clearance on them? (Balancing guy will have his work cut out for this one.)
I think Mart answered that one already in a previous post because he had a lobe that actually did hit the crank. Derek
You're right, I went back and looked. He said Mike said 0.020" was enough clearance between the lobes and the crank counter weights.
Something I have been thinking about, I don't see any kind of lube mentioned or in the pictures when you torqued the rod bolts here. Without thread lube a whole lot more torque would need to be applied to get the stretch the bolt needs than it would with it lubed. Even using oil, torque would need to be increased over using the proper thread lube like this ARP Ultra Torque Assembly lubricant; https://www.summitracing.com/search...KeywordMatch&SortOrder=Ascending&keyword=lube You want this lube on the threads AND under the bolt's head where it meets the cap! With lube you should be able to get the .0065 of bolt stretch with less torque applied needed for 3/8"-24 Carr bolts.(if that is the kind of bolts you have) So before you start torqueing and grinding, get the proper lubricant so your torque values will be more consistant to get the stretch you need if you haven't already done that. Derek
I have a bottle of the ARP Ultra-Torque fastener assembly lubricant. Yes, I cleaned all threads & bolts before applying the lube to the threads and shoulders.
Wow, lots going on in this thread! I haven't looked here in a while, sorry. I'll plug your cam details into the sim when I get the time, probably this weekend. Since I'm pressed for time and feeling a bit lazy right now (otherwise I'd have to sift back through 25 pages in this thread), give me the head specs and other relevant engine details so I can plug those into the sim too. The more info you can give the better, though there is no provision in the sim for CSA numbers on the heads. I'll need valve sizes, CFM flow @ varying lifts, intake to be used, headers, compression ratio (if not known yet, combustion chamber head size, piston dish displacement (including valve notches), head gasket to be used, piston placement relative to deck, etc.), bore, stroke, etc. then I'll try to see if I can come up with a cam install point this combination might like best. I can also post the sim's 'guestimation' on power output @varying RPMs too, if you're interested.
