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

[Rob V.]

Hi--

Does Chevrolet still sell as new 7/16" dimple big block rods?? (I believe that some of the applications were L-88 427 and LS-6 454). If they are still available, what is the current part number??

Thanks in advance.
Rob

[Joe L.]

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

Hi--

Does Chevrolet still sell as new 7/16" dimple big block rods?? (I believe that some of the applications were L-88 427 and LS-6 454). If they are still available, what is the current part number??

Thanks in advance.
Rob

Rob------

7/16" pushrods were originally used on L-88's and all ZL-1 but were not used on LS-6. Originally, they were GM #3942416, intake, and GM #3942415, exhaust. These were discontinued in 1988.

There were other 7/16" big block pushrods available in SERVICE only. Those manufactured of 1010 steel were GM #10134304, intake, and 10134303, exhaust. Those manufactured of 4130 steel were GM #10134306, intake, and 10134305, exhaust. All of these are now discontinued.

The use of any 7/16" pushrod requires the use of GM #3879620 guideplates.

[Rob V.]

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

Hi Joe--

Thank you very much as always for your response. I must apologize for my inexact/poor wording of my question. My question concerned big block Chevy 7/16" dimple connecting rods; sorry. However, the information that you provided on pushrods is not wasted--I need to get pushrods as well. Once again, thank you for your kindness and great information!

Red in the face with embarrassment, Rob

[Joe L.]

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

Hi Joe--

Thank you very much as always for your response. I must apologize for my inexact/poor wording of my question. My question concerned big block Chevy 7/16" dimple connecting rods; sorry. However, the information that you provided on pushrods is not wasted--I need to get pushrods as well. Once again, thank you for your kindness and great information!

Red in the face with embarrassment, Rob

Rob------


Actually, your question was not all that badly written. As I re-read it, I should have interpreted it as referring to connecting rods. So, here's the deal on connecting rods.

There were two 7/16" rod bolt connecting rods. The first was GM #3969804. These were used only on later 1969 L-88's and all ZL-1's. These rods used a boron steel rod bolt. These rods were the strongest rods GM ever offered for a big block. These rods were discontinued without supercession about 10 years ago.

The 2nd 7/16" rod bolt connecting rod was originally GM #3963552. This rod was used for 1971 LS-6 (and 1970 LS-6 for Chevelle). It used a knurled shank rod bolt. This rod was almost as strong as the above-referenced, It was replaced by GM #14096151 in August, 1986 and the latter was replaced by GM #10198922 in March, 1992. Finally, the latter was replaced a few months ago by GM #19170198. It carries a GM list price of about 130 bucks.

[Richard F.]

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

I thought that the 552 rod was for a pressed-in pin, and the 804 was a floater. Also, was the 552 magnafluxed like th 804?

[Joe L.]

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

I thought that the 552 rod was for a pressed-in pin, and the 804 was a floater. Also, was the 552 magnafluxed like th 804?

Richard------

The GM #3969804 was designed for floating pistons pins and the GM #3963552 was designed for pressed pistons pins. Both were magnaflux inspected.

[Rob V.]

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

Hi Again Joe--

Your information is perfect--just what I needed. Apart from the used, "seasoned" block; intake manifold; and my 7/16" dimple connecting rods, all the other big block engine parts I have accumulated are new/unused. I got my connecting rods from my friend, and all I know is that they were resized and set up for floating piston pins. I do not know, nor does my friend, for what prior application these connecting rods might have been used; nor do I even know if they were a matched, balanced set--or just eight rods thrown together and sold as a set. Finally, the rod bolt nuts look like they have had a socket on them several times as the finish is worn pretty well on the edges. Bob, my friend, thought the rod bolts were the "good GM boron bolts" but you couldn't prove it by me. Guess I better have the rods magnafluxed, as well as the rod bolts/nuts; verify balance; and have the rods resized again (if necessary). The other option, which might be more palatable, is bite the bullet and buy new rods. I respectfully request your thoughts/comments on this issue, as your sage guidance has already saved me several times from making costly errors in my build acquisition process.


Best Wishes,

Rob

[Joe L.]

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

Hi Again Joe--

Your information is perfect--just what I needed. Apart from the used, "seasoned" block; intake manifold; and my 7/16" dimple connecting rods, all the other big block engine parts I have accumulated are new/unused. I got my connecting rods from my friend, and all I know is that they were resized and set up for floating piston pins. I do not know, nor does my friend, for what prior application these connecting rods might have been used; nor do I even know if they were a matched, balanced set--or just eight rods thrown together and sold as a set. Finally, the rod bolt nuts look like they have had a socket on them several times as the finish is worn pretty well on the edges. Bob, my friend, thought the rod bolts were the "good GM boron bolts" but you couldn't prove it by me. Guess I better have the rods magnafluxed, as well as the rod bolts/nuts; verify balance; and have the rods resized again (if necessary). The other option, which might be more palatable, is bite the bullet and buy new rods. I respectfully request your thoughts/comments on this issue, as your sage guidance has already saved me several times from making costly errors in my build acquisition process.


Best Wishes,

Rob

Rob------


Post a photo of one of the rods and one of the rod bolts and I may be able to tell you what they are.

In any event, I would replace all the rod bolts with ARP bolts. I used a brand new set of the GM #10198922 and I still replaced the rod bolts with ARP. Any of the "LS-6" rods I mentioned above used knurled shank rod bolts, so they are easy to identify.

[Rob V.]

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

Thanks Joe! I will have to beg my wife or daughter to take photos and help me post them (as you suggest), so it might be this weekend. I did examine the connecting rods last evening, and there were no part numbers on them; and there appeared to be differences in the shape of the balancing pads. Anyway, I will get you pictures. Once again, thank you for helping me.

Rob

[Rob V.]

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

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...


Hope you have a great evening and weekend!


Rob

[Joe L.]

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

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...


Hope you have a great evening and weekend!


Rob

Rob------


These could be the GM #3969804. However, they've definitely been re-worked. Any vestige of the green dye on the big end is gone as is the babbit coating on the small end. Also, my recollection is that the small end on original 804 rods was not bronze-bushed (I have a bunch of NOS examples of this rod but I can't bear the thought of going through a bunch of super-heavy group 0 tote bins to find them).

It should not be all that difficult to remove the rod bolt nuts. Just put the rod in a vice, preferably with soft jaws, and twist away on the nuts. They don't appear corroded in any way. Even assuming they were torqued to spec (and, I don't know why they would be), they should not be all that difficult to remove.

[Rob V.]

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

Joe--

Great information again! I do not have a vice, so I guess it is off to the machine shop I go. I will have the shop manaflux the rods, and if ok, will install the ARP bolts that you recommend. I must admit, I am not wild about the connecting rods. One of my co-workers who has built a lot of engines for dirt and asphalt modified and sprint cars, basically inferred that I was stupid to use rods of unknown/dubious/questionable history in my engine. I sort of agree, but without any rational basis. Are there any newly manufactured connecting rods that you would recommend?? (You previously mentioned what is currently available from Chevrolet/GM; anything else?? For example, another NCRS TDB member recommends the use of Eagle connecting rods for small blocks.)

I don't blame you for not wanting to dig through your parts bins to find examples of your NOS connecting rods--that is heavy, exhausting work. Besides, your excellent descriptions, and analysis of my rods was just what I needed. Additionally, I now know that my 13 year old daughter can be drafted into servitude to photograph and post stuff on-line for me! Major score!

Thanks Again!
Rob

[Joe L.]

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

Joe--

Great information again! I do not have a vice, so I guess it is off to the machine shop I go. I will have the shop manaflux the rods, and if ok, will install the ARP bolts that you recommend. I must admit, I am not wild about the connecting rods. One of my co-workers who has built a lot of engines for dirt and asphalt modified and sprint cars, basically inferred that I was stupid to use rods of unknown/dubious/questionable history in my engine. I sort of agree, but without any rational basis. Are there any newly manufactured connecting rods that you would recommend?? (You previously mentioned what is currently available from Chevrolet/GM; anything else?? For example, another NCRS TDB member recommends the use of Eagle connecting rods for small blocks.)

I don't blame you for not wanting to dig through your parts bins to find examples of your NOS connecting rods--that is heavy, exhausting work. Besides, your excellent descriptions, and analysis of my rods was just what I needed. Additionally, I now know that my 13 year old daughter can be drafted into servitude to photograph and post stuff on-line for me! Major score!

Thanks Again!
Rob

Rob------

You might be able to hold the rod with vice grip pliers (using pads on the jaws to protect the rod).

However, whether or not these rods were originally designed for floating pins, they're set-up for floating pins now with the bronze bushings. I do not recommend the use of floating pin rods for street applications.

As far as whether these rods are otherwise suitable for re-use, it's hard to say. However, if they are carefully magnaflux inspected, re-sized, and, if the rod bolts are not the boron steel type, refitted with ARP-2000 rod bolts, they should be OK for any street application. Of course, all this will cost a good piece of the cost of a set of new rods. The GM #19170198 would be an excellent rod to use. But, these rods GM list for about 130 bucks each, meaning a set is going to set you back over a thousand bucks. Aftermarket rods are not going to be cheap, either, especially if they're a quality rod.

Keep in mind that most original big blocks were only fitted with 3/8" rod bolt rods and did just fine for street operation. The 7/16" rod bolt types are "extra insurance", though.

[Rob V.]

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

Hi Joe--

You get an air rescue save again! After re-reading your posts, I decided to forget about using my current connecting rods, and instead get new GM rods. Also, I was curious why you recommended that I not use full-floating pins, so I found my well used copy of How to HOTROD Big-Block CHEVYS, pages 104-105, and that provided an excellent explanation why pressed-in pins are the recommended application for the street. I hope you are keeping score how many times you have prevented me from making foolish and expensive mistakes on this big block engine build for my '67 Coupe. I cannot thank you enough for sharing your knowledge and expertise with "us."


Rob

[Duke W.]

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

Although I don't have any specific recommendation, you can probably find aftermarket rods today that are as good or better than the GM rods, but a lot cheaper.

The Eagle SIR5700 rods that I recommend for small blocks only cost about $250 for a complete set.

Duke