7/16" Chevy Big Block Rods (Question for Joe Lucia?)

[Rob V.]

Re: 7/16" Chevy Big Block Rods (Question for Joe Lucia?) UPDATED WITH PHOTOS

Duke--

Thank you very much for your response. I will check and see what I can find with respect to non GM connecting rods before I take the plunge. Perhaps Eagle makes a set of connecting rods for big blocks, as you have found their small block rods to be so exceptional. And wisely saving money is always a good thing!

Hope you have a great Friday and weekend!

Rob

[Duke W.]

Re: 7/16" Chevy Big Block Rods (Question for Joe Lucia?) UPDATED WITH PHOTOS

Back when I was developing the "327 LT-1" configuration, I needed a rod that would safely rev to 7500, and there wasn't much choice in small bearing rods. Crower offered a small bearing rod in their Sportsman line, which were more than satisfactory, but only available on special order, so Scott Marzahl did a group purchase over on the Corvette Forum and several guys bought-in who later did "327 LT-1" and "Special 300 HP" configurations. The group price was about 500 bucks a set.

Later, Eagle came out with small bearing SIR5700 rods with 3/8" bolts and from inspecting the design I concluded that this rod is also acceptable, and it's bargain priced. My understanding is that Eagle rods are forged in Asia and finish machined in the USA. Both the small and big bearing rods appear to be machined from the same forging (as is the case with the Crower Sportsman), which means the small bearing rods actually have more material on the bottom end than the big bearing version.

Check Eagle, Scat, Manley, and Crower... all should have online catalogs, which should have enough information about their products for you to make a decision on what you need for your application.

Maybe others can offer additional guidance.

Duke

[Rob V.]

Re: 7/16" Chevy Big Block Rods (Question for Joe Lucia?) UPDATED WITH PHOTOS

Hi Duke--

I have seen your recommendation for the use of the Eagle SIR5700 small block Chevy connecting rods several times, and was fascinated to read your post providing the background on why you made this decision. Thank you! Also, thank you for providing some vendors for me to research in my pursuit of big block connecting rods. As you also point out, perhaps there are others that can provide their insight/experience with non GM connecting rods--it does not hurt to hear about them. One thing is for sure, Mr. Joe Lucia once again saved me from making a potentially big mistake with regard to the used, 7/16" connecting rods that I have. This morning I mentioned to my co-worker about Joe's thoughts on my rods, and my co-worker was glad that Joe provided the information he did. I will find a nice dark corner in the basement for the rods to reside.

Happy Friday,
Rob

[Domenic T.]

Re: 7/16" Chevy Big Block Rods (Question for Joe Lucia?) UPDATED WITH PHOTOS

Rob,
Somehow I don't remember dot rods having bushings on the top end, not saying that they don't but don't remember seeing them. The other thing is that the pistons also have to be fot the full floater with clips to keep the rod from hitting the cylinder.
A tid bit: All aircraft rods are full floaters. They have snubbers pressed into the pins that rub the cylinder. The cause of failure was usually the small end of the rod. Those engines only did about 2700 RPM, and some 3400 RPM. The cause of failure would usually be at the top end of the rod and not always RPM related. The fuel mixture when to lean would cause the aluminum piston to expand faster than the steel cylinder and the piston would stick at the top of the cylinder. That can also happen in auto engines in some cases. It's hard to spot because when everything cools down the piston shrinks Bach and all you see is scratch marks. Point being is that It may not be a problem using full floaters for street use when properly done.

Dom


QUOTE=Rob Vanderhoeven (38355);740899]Good Evening Joe--

Well, my daughter took photos of my 7/16" connecting rods, but the photos are probably as worthless as my description. We were unable to loosen the rod bolt nuts and take the rod caps off. I will not tell you all the things I did to try and remove the rod nuts; however, suffice it to say, I wondered if I was going to be a potential "Darwin Award Nominee." I suppose the connecting rods need to be clamped in a specialized vice to remove the nuts. More to follow, I hope...

Rob,
Somehow I don't remember the dot rod full floater being bushed. That is a point of failure and I would not want to reduce the strength if it was a mod. Also a thing to check is that the pistons also have to have the clips to keep the pins from hitting the cylinder walls.
A tid bit: All aircraft rods are bushed full floaters. They do not use the clips in the pistons but use a aluminum snubber that is pressed in the pin. The aluminum snubber will rub the cylinder. The auto version that I used had the clips. The aircraft version of the standard full floaters had to only put up with 2700 RPM and some as high as 3400 RPM. Their cause of failure was the top end of the rod.
Just saw one that left the piston at the top of the cylinder, it stuck there because of a lean fuel mixture that expanded the aluminum piston from excess heat faster than the steel cylinder could expand


Hope you have a great evening and weekend!


Rob[/QUOTE]

[Rob V.]

Re: 7/16" Chevy Big Block Rods (Question for Joe Lucia?) UPDATED WITH PHOTOS

Hi Dom--

Thank you for the information that you provided concerning the full floating rod pins. Since I am a retired USAF pilot, currently working in an aviation related field, I am always interested in the mechanical aspects of aircraft; and I find it very interesting that the piston driven aircraft engines use full-floating rod pins. After reading last night why these pins are used in automotive racing applications, I can understand why they are used in aircraft engines. As for me, I am convinced while the rods I have might work, I better use the connecting rods with the press in pins as Joe suggested. Thank you very much Dom for continuing my mechanical education! I love this site...

Rob

[David B.]

Re: 7/16" Chevy Big Block Rods (Question for Joe Lucia?) UPDATED WITH PHOTOS

Happened to notice your thread along with corresponding responses. If interested, I might have a set of the 3963552 rods. They were acquired when I purchased the sprint car operation of Grant King (Indy car builder) shortly after his untimely accident. I noticed one rod still in the box the others stacked together. They all appear to be in good condition but do have some shelf rust. Will double check to verify there is a full set if you have an interest .

[Rob V.]

Re: 7/16" Chevy Big Block Rods (Question for Joe Lucia?) UPDATED WITH PHOTOS

Hi David--

Yes, I am interested. Thank you for your kindness! If you do not wish to post your findings here, our home email address is: robdianev@yahoo.com

Rob

[David B.]

Re: 7/16" Chevy Big Block Rods (Question for Joe Lucia?) UPDATED WITH PHOTOS

Since this forum is for tech stuff you read my mind. Will get in touch.

[Jim C.]

Re: 7/16" Chevy Big Block Rods (Question for Joe Lucia?) UPDATED WITH PHOTOS

This brings back a lot of memories. I raced super late model dirt cars in the early seventies and we used the 7/16 bolt rods in a .125 over 454 with Chevy aluminum heads. They were all balanced and also floated the wrist pin. I would run that engine 7000 RPMs all season and never had a rod problem. I had two of those engines. I wish I still had them.