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Tom Molnar rod response |
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kidgrem
AMC Apprentice Joined: Dec/24/2007 Location: Missouri Status: Offline Points: 116 |
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Posted: Jun/13/2014 at 6:40pm |
Since I am flipping the rods and they will be on center I should be good to. These rods are tiny compared to the scats. Twenty one Quarters (money) lighter. Hi Gary, I'm not worried about our rod
handling the power in a Chevy engine but this being in an AMC engine
puts a whole different set of variables into the mix. The beam offset
requirements for a Chevy rod is completely different than what is needed
in an AMC block. To get the beam of the rod centered in the cylinder
bore on a Chevy, the beam is moved away from the cheek of the crank and
to get it centered in an AMC block it needs to be moved closer to the
cheek of the crank. While a Chevy rod will fit in your application and
if you read on the internet it will be fine (there are lots of people
who think they are "experts" on the forums), what really happens is the
beam of the rod ends up not being under the center of the piston. The
way I explain this to people is you can balance a dinner plate on a
wooden dowel but if you move the dowel off center, the plate falls off.
If the rod is not centered in the bore, the piston wants to tilt
slightly on the power stroke which not only side loads the rod and over
time can cause fatigue fail of the rod, it also upsets the ring seal and
will cause a lower power output. I have had people tell me when they
replaced Chevy rods in their Ford blocks with a Ford correct rod that we
build, they picked up as much as 30 HP.
Thank you, Tom Molnar Molnar Technologies On Thu, Jun 12, 2014 at 11:56 kidgrem> wrote: CH6000LLB8-A Chevy Small Journal 6.000 606 7/16 2.125 0.927 0.940 1.010 I have a AMC With small journal SBC 6.00" Scat rods with a 3.850 stroke and a 778 gram piston, ring and pin combo. 10.7 compression. The scat rods weigh 734 grams. The engine makes 620 HP. Will the CH6000LLB8-A handle the HP if I switch to your lighter rod. How about if I use a 200 HP shot of nitrous. Thank`s Gary |
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tsanchez
AMC Addicted Joined: Jul/09/2007 Location: Arizona Status: Offline Points: 4302 |
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Great then he should make a stroker rod for us then. Until then this is what we do.
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dbomb
AMC Addicted Joined: Jul/22/2012 Location: new jersey Status: Offline Points: 705 |
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good post both ways
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rebuiling 73 amx need parts
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SKeown
AMC Addicted Joined: Jul/30/2009 Location: Texas Status: Offline Points: 3085 |
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First off, I'm a firm believer in the need to center the rod on the wrist pin. Personally I use Carrillo Chevy LS 6" rods for 2" journals with an offset ground 3.925" stroke. With the LS rods that are center beam instead of being offset in either direction, I just have .010 removed from the chamfered side of the rods. That does a pretty good job of centering them. There's a member on this forum that was breaking I-beam Lunati rods due to not having the rods centered, they were breaking just below the piston pin bore. I saw evidence of the piston canting at the top of the stroke as well as the power stroke. I was running very tight piston to head clearance and the pistons were touching on the least supported side only. If you have no choice other than resorting to std Chevy rods you can remove .010 from the non chamfered side, then have that side chamfered and reverse them. Power isn't what brakes rods, power will bend them (as in my Jr fuel dragster, back when we ran nitro instead of alcohol like today) RPM, piston weight and stroke length is what brakes rods/bolts on the exhaust stroke when there isn't any resistance to keep the piston from heading north. With good 7/16" bolts you should be okay. I have 3/8" SPS Carr bolts and my engine has seen over 7500 RPM with 515 gm pistons and a 3.925" stroke. Edited by SKeown - Jun/13/2014 at 11:02pm |
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stickshifter
AMC Addicted Joined: Jan/17/2008 Location: Bed Rock Status: Offline Points: 573 |
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7.03 @ 196 mph
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kidgrem
AMC Apprentice Joined: Dec/24/2007 Location: Missouri Status: Offline Points: 116 |
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Gary, Yes flipping the rod puts the beam very close to where it needs to be. I am not sure what bearing you would use to clear. The new bearings from Clevite are narrow and unchamfered but they are still close to the non chamfered side of the rod. If the crank has a fillet radius in the corner it may hit the bearing unless it is modified with a chamfer. If the crank does not have a fillet radius, it will not be as strong as one with a radius. If you are willing to go through the extra work (or pay someone else to do it) our rod will work. I would not recommend the 500 gram lightweight version. Thank you, Tom |
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SKeown
AMC Addicted Joined: Jul/30/2009 Location: Texas Status: Offline Points: 3085 |
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Tom Molnar was originally the designer for Oliver rods. 30 HP, maybe that's how I overcame you're dual carb setup? SKeown
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tsanchez
AMC Addicted Joined: Jul/09/2007 Location: Arizona Status: Offline Points: 4302 |
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My pistons are full skirted, no issues there. My issue is converter
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Hurst390
AMC Addicted Joined: Apr/20/2008 Location: secret Status: Offline Points: 5752 |
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Kidgrem..have you balanced that assy yet and is it internally balanced?
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SC/Hurst Rambler
11.62 120 100% Street Legal |
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BassBoat
AMC Addicted Joined: Aug/29/2008 Status: Offline Points: 1713 |
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When I reversed the SBC rods, had the big end chamferred to make sure they didn't get into the radius to the crank, also chamfered the rod bearings as well. When Tom Molnar worked for K1 I bought stroker rods from him, which as far as I know are still available from K1 in 6.000 and 6.125 length, with correct offset for AMC and for use with 2.100 rod journal and 0.927 piston pin.
BB
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