What's the general strength/RPM consensus on BBC rods with the 3/8" rod bolts. What kind of horsepower/RPM can a 3/8" rod handle, as long as it's got good rod bolts (ARP) and within factory specs? At what point do I need to consider upgrading to an aftermarket rod or a factory 7/16" rod?
3/8 or 7/16 rod bolt - BBC
middleagecrisis
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What's the general strength/RPM consensus on BBC rods with the 3/8" rod bolts. What kind of horsepower/RPM can a 3/8" rod handle, as long as it's got good rod bolts (ARP) and within factory specs? At what point do I need to consider upgrading to an aftermarket rod or a factory 7/16" rod?
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Depends on your usage, if its a street grocery car , then 3/8 is fine, but if you are looking for lots of spinning and hp in the future and dont have the rods, I would go for a set of cap screw design and be done with the worry about not having enough.
Sometimes you can get past just adding stronger bolts but usually I have this done and resize the big end and bush the little. Problem here is again is costs. Have to look at where you will be with the finished product ie. cheaper to keep the old or better to put that money in a decent new set already sized and bushed. Still have to look at the balance issue if not going with a new build.
I have gotten away with just adding the old new gm special bolts on a new LS7 bbc long ago but once I got the rod out of the rod vise, it did check the big end with snap guages to be sure nothing changed but that was long ago.
Sometimes you can get past just adding stronger bolts but usually I have this done and resize the big end and bush the little. Problem here is again is costs. Have to look at where you will be with the finished product ie. cheaper to keep the old or better to put that money in a decent new set already sized and bushed. Still have to look at the balance issue if not going with a new build.
I have gotten away with just adding the old new gm special bolts on a new LS7 bbc long ago but once I got the rod out of the rod vise, it did check the big end with snap guages to be sure nothing changed but that was long ago.
Tom, I ran factory 3/8 rods in my 427's for years without a single failure. I used the good ARP bolts, and had the rods done by a GOOD engine builder. I made enough power to run mid tens in a 3550 lb. car. I also made sure I didn't abuse them in the water, etc. I have upgraded to aftermarket rods in my newer engines, however.
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I appreciate the input guys. I was reading over on the Team Chevelle board about this same subject and the use of the "thumb" truck rods. My 454 is out of a motorhome, so I suspect I may have these rods in my motor. How can I tell if I have these HD "thumb" truck rods? Is there a visual mark like on the dimple rods? Thanks
Tom..the thumb rods at the big end layed on their side will look like they want to accept the thumb on your hand vs the pass rod that looks like a dog bone biscuit.Its the added material above the big end that makes the thumb rod more desireable.Equipped with 3/8ths arp bolts..they are a good piece with only a resizing reqd typically.
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Id do lots of the "thumb" rods with ARP bolts.They have more material in all areas then the dimple rods.I always recommend using good modern pistons if you are going to make big power with stock rods.Good pistons are lighter and put less stress on the rods,and the up side is they are factory designed to clear big roler cam,have smaller ring grooves for modern low drag rings,and piston domes are typically better designed then generic OEM type forged pistons.One more thing,you dont need to do anyhng to the small end of the rods,even if you have full floating pistons.Simply leave the rods alone,and all you will have to do is have the rods and pistons pressed together like any other stock engne.
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I found a post on Team Chevelle that had a picture of the thumb rod and a dogbone. A picture is worth a thousand words, lol. Since my motor was in a big honk'in '81 motorhome and had an engine oil cooler and Turbo 400, I'm crossing my fingers that it's got the HD stuff inside. I have'nt had a chance to pull the pan yet, hopefully this weekend. I appreciate all the input! Motor will be on a budget, but I don't want to grenade it either.
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