If I upgrade to ARP rod bolts, do I need to resize the big ends?: Grassroots Motorsports forum: Grassroots Motorsports Magazine

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Jan. 15, 2012 8:24 p.m. Sonic Dork

The title says it all, really. I'm thinking about putting in a set of ARP rod bolts in our Lemons Civic to address one of the shortcomings of the D16 engine for this sort of use.

While reading around, I see references all over the place that some people say you have to have the big ends resized if you switch to ARP rod bolts. I've never heard of this before, and can't really see that it would change the shape of the big end, but I've never done this bit of it before.

Has anyone else heard of this? Is it something I need to address?
Jan. 15, 2012 8:58 p.m. novaderrik Dork

yes, you are supposed to do it.. the new fasteners can distort the rod compared to the stock hardware.
Jan. 15, 2012 9:02 p.m. DrBoost SuperDork

Do what I do. Rebuild the engine as you drive. Tighten the crap out of the rods and mains. When you drive it'll scrape material off the crank and shells. That's why I pour raw babbit in the crankcase. I figure it'll work it's way into the low spots and make new bearings as you drive!!!
Jan. 16, 2012 7:29 a.m. wheels777 Dork

If they are pressed in - YES.
Jan. 16, 2012 9:27 a.m. erohslc HalfDork

DrBoost wrote:

Do what I do. Rebuild the engine as you drive. Tighten the crap out of the rods and mains. When you drive it'll scrape material off the crank and shells. That's why I pour raw babbit in the crankcase. I figure it'll work it's way into the low spots and make new bearings as you drive!!!

Naw, you're doing it wrong!
1) make sure the babbit is in small balls, like lead shot fishing sinkers.
2) with the motor running, slowly pour the babbit down the intake, sort of like SeaFoam, ie you may have to goose the throttle a bit to keep it running.

The babbit will be vaporized, and migrate past the rings into the crankcase. Then, as you said, it will '...work it's way into the low spots and make new bearings as you drive'
Jan. 16, 2012 9:40 a.m. kb58 HalfDork

This reminds me of an Internet story that made the rounds not long ago. The scary thing is that it's written just well enough that it might even be true :
I was recommended to port and polish the intake and exhaust. We found out they used abrasive material to do it like gritty sand. So I got with my friend that tunes Hondas and we decided to try it ourselves. We got a bag of sandblasting sand and hooked up into the intake and started the car. We had to hold the gas so it would run. He wanted to let the engine suck in the sand through the intake so it would port it out and then push it out the ehxaust so it would port the exhaust manifold. I was worried that it might cause problems but he figured it'd be OK as long as we didn't make boost and it get sucked in the turbo. After running the car and letting it suck in sand we got about half way through a 25 lb bag. The check engine light was on and the engine was bucking and kicking and sounding really weird. We stopped and hooked the car back up normal and took off the sand supply. We tried to start it again and it was really hard. Once started it couldn't idle and kept making weird noises. We took it out and drove it and it started to make scraping and knocking noises.
Jan. 16, 2012 10:59 a.m. iceracer SuperDork

Changing rod bolts should not require any rod resizing as long as the they are the same dimensions and the correct torque is used.
Jan. 16, 2012 11:55 a.m. tpwalsh New Reader

If the rods are used then I would have them resized even if I was using stock hardware. Rods go egg shaped over time, but especially under abuse. Ya its $200 but it's piece of mind for an already stressed part.
Jan. 16, 2012 3:49 p.m. 16vCorey SuperDork

On a VW at least (and probably other brands too) the rod can slightly distort when you remove the clamping force from it. I've had good luck with replacing them one at a time. Remove one bolt, put in new bolt, torque to spec. Remove the other bolt, put in new bolt, torque to spec.
Jan. 16, 2012 5:03 p.m. oldeskewltoy HalfDork

actually it is advisable to have ever rod checked when ANY new rod bolt is pressed in.

Higher end rods will have bolts, which are easier to replace without worrying about resizing