Rusty Bowtie
General Category => GM Tech Questions and Answers => Topic started by: Cool53 on January 31, 2014, 11:30:58 AM
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If you are doing a rebuild and your old connecting rods need to be rebuilt, and you need new pistons, AND your crank needs to be turned, consider buying a kit that offers a longer connecting rod than stock. Unless you are building a Mopar 440 or Hemi that already has rods that can reach the moon, then an engine like a small block Chevy likes to make more torque with a 6" rod as opposed to a 5.7" rod, you get a lot more bang for your money. The reason for this is that the piston stays stationary during the sweep longer and allows more pressure to build before the piston starts moving again, which gives it a lot more push. There is no downside to running a longer rod, except on some engines you may have a clearance problem. The longer rod makes cam tiing a lot less important, and if you draw a diagram of what happens with a longer rod you'll see why. If you have to buy parts, go for the better part. In this case they are not even that much more.
For those that load their own ammunition for shooting, you know how important the crimp is on the bullet. If the bullet sits loose in the case then when the primer is lit then the nitrocellulose starts to burn and almost immediately the bullet starts to move, and you end up burning a lot of the powder in the barrel. this causes a really slow bullet. But if the bullet is held as long as possible with a tight crimp then the whole charge is burned just as the bullet is released. More speed, more power. Instead of the powder fizzing it explodes. this all gets us to ignition timing. That's next.
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Jef
I agree with everything your saying but it begs the question of why didn't the factory engineers design the engine that way in the first place?
Moose
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Another plus for those of us who run the old inline engines i that longer(sometimes a lot longer) rods give us a choice of cheaper easier to find modern design pistons. One example is a guy who replaced 7" GMC rods in his 302 with 8" Hudson rods using Cjevy V8 4" bore pistons and saved 1.25 lbs per cylinder. The problem is the rods we need are expensive or not made.
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We will be able to make rods affordable I would say, in the next year. And Moose, the factory ran the longest rods they could but didn't feel the shorter pistons needed would give enough support for longevity. Now with better alloys and lighter, thinner rings it is more possible.
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Some old race cars actually used welded rods when welding technology was not near what it is today. But neither was compression and RPMs.
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As soon as we make the first set of rods, which are for the 292 straight six running 283 pistons, we will have most of the info we need to make rods for almost anything. With SolidWorks it's not all that hard to make changes. I'll post pictures as soon as Leigh finishes the first set.
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That is good news. The guys over on the Inliner site will rejoice. ;D Will they be steel or aluminum? I think the small block V8 rods would work in the 250s if you could get the forgings before they machine the bottom end width.
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we are going to concentrate on the inline 6's first. We are building a 292 for Leigh for his '46 Chevy pickup so he'll be making his rods first. they will be steel, and unless other wise requested they will all be H Beam. I will have Leigh write a note for us. He was going to build a new shop for his new machining center but realized how long it would take so he's going to rent space. He's in Concord, NH. But he is the best machinist you will meet. I actually have two friends who are exceptional machinists in that they can both make it manually or automatically. I'll get Leigh to leave some info.
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Wow, That is really interesting. There are lots of people out there making some great stuff it's just hard to find them sometimes.
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Hello everyone. In response to the long connecting rods I will be making with Jef for my 292. This is going to be one of the first projects I will be working on in my new shop. I am sure I will have some space soon for the new shop. A lot of my work will be prototypes, and short run production. As far as the rods for my 292 I am planing on going with a 7.250 center to center distance. I have already been talking to J and E pistons about a custom piston for this application or possibly a modified 283 piston, and the prices have been very reasonable. I hope to supply this as a kit for the inline guys keeping the costs down to make this affordable for the hot rodder in his garage. For the first set of rods i am making I plan on using 4140 steel in an H-Beam style with an emphasis on grain structure (direction), while also trying to keep the weight down as much as possible with a short light piston and new modern rings. Jef and I will be documenting this as we go and will keep everyone posted. If anyone has any questions feel free to contact me and I will do my best to answer your questions.
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If you and Jeff put this information on the Inliner site you will get a lot of interest. There are guys over there who are making a lot of stuff but as you know longer rods that fit are rare. http://www.inliners.org/
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This is music to my ears. Have you considered using a more modern piston. For instance the Ls1. They are available from Diamond Without valve pockets and any pin size you want. They are a light piston. Just a thought.
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jef and I have been looking into other pistons both modified and custom. Naturally we will be going with the lightest piston as possible for this application along with the rods and rings to keep the rotating mass to a minimum. The rods that I am designing will more than likely use a small block chevy ARP bolt. This should be another cost savings due to them being readily available, but very high quality.
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Any info on the rods. How is the project going.
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I signed the lease on the new building this week. Looking at a CNC machining center Friday. Things are moving forward. I will keep you posted as we go.
Thanks
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How about an update on the rods.
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Any news on the new rods.
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I take it this is a dead forum.
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I take it this is a dead forum.
Subject might be dead...did you send Cool53 an email....I just did.
Ed
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Yeah, What happend? We should be up to our ears in long rods by now. >:( ;D
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I don't think this is for us,but who knows.If i wanted to turn the tires,i would get a used 5.3 with harness a L85e and a turbo with a cooler probably not cost as much as all this hot rod 6..On the other hand i have seen a fellow that cut two double hump chevy heads and made them fit a six . Crazy machine also had two 4 barrels on it.Now that would shake the timbers out of our old chevy's now wouldn't it
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Once you try to apply logical thinking to hot rodding the whole thing falls apart. There is nothing logical about it. We do it because we can. In 1940 aBob Ruffi made a one way pass on a California lake bed of 146mph. His engine was a 1925 Chevrolet 4 cylinder. The rest of the hot rod world chased that for years mostly with V8s. 4,6,or 8 cylinder it's all just a game we play and in the end none of us here are going to be the fastest man on earth. So how we choose to go relatively fast doesn't really matter and is our own choice. ::)
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Well sixball to each his own.My biggest pet peeve today is my friends that live on lakes and they don't even fish EVER. I have to ask why, I guess its different strokes for different folks,who am i to criticize wayner. If i lives next to the salt flats I think i would be in the 200 mile an hour club.OH sorry i am already there, OK then 250 mph
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The interest in the long rods is for the guys in the SDRA. We run inline motors and are always looking for some help with these things. I would like to find a good source for 6" to 6.3" rods for 250"chevy's. Also something in the 7" to 7.5" for the 292" chevy's.
Thanks
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Well sixball to each his own.My biggest pet peeve today is my friends that live on lakes and they don't even fish EVER. I have to ask why, I guess its different strokes for different folks,who am i to criticize wayner. If i lives next to the salt flats I think i would be in the 200 mile an hour club.OH sorry i am already there, OK then 250 mph
My biggest pet peeve is people with pet peeves. ;D But yes, a Red Hat garners respect no matter what. They are not easy to come by. Different strokes, different bores, and different number of cylinders and different anything else as long as it's not different just to be different. Just being different is not logical. Is his where I came in? :-\ ::)
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I ran across this old topic about long rods for 292 Chevy sixes. I don't know what happened to the original guy and his plans but Tom Lowe does offer longer than stock rods for 292 also forged Ross pistons and a lot more.http://www.12bolt.com (http://www.12bolt.com)
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Sixball that is a great site thanks again vette59jdwl
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what happened, did this just die?