SBC 2.1 rods on 2.0 journal crank

[mgb260]

Lunati provides a rod bearing that allows the cheap, common SBC large journal forged rods to fit the small journal and Buick/Rover V8. Unfortunately it is available in standard size only. I just found out King Bearings has them in .001, .010, .020 and .030 undersize! Especially great news for the 300 builds to replace the cast stock rods.

http://www.rockstargarage.net/king-bearings/king-racing-rod-bearings-xp-trimetal/cr867xpn/i-1999611.aspx

[mgb260]

I priced reconditioned stock cast 300 rods at $320. Forged SBC 6" at $210. They would have to have the pin hole bored and the big end milled to same thickness as the stock rod. Keith Black pistons at $210. I also found 6.25" H beam rods that would be perfect for 305 SBC or 2.3 Ford pin height forged pistons.

https://www.speedwaymotors.com/Small-Block-Chevy-5140-Steel-I-Beam-Rods-6-0-Inch-Press-Pin,32646.html

https://www.summitracing.com/parts/uem-1749h-std/overview/make/buick

https://www.ebay.com/itm/Eagle-Rods-CRS6250B3D-Forged-H-Beam-Ford-351W-Chevy-SBC-350-400-Connecting-Rod/112198095737?epid=1836914772&hash=item1a1f871379:g:z04AAOSwal5YIeVs

[joe_padavano]

That is outstanding info, thanks.

[BlownMGB-V8]

Should work with the stock stroke but don't try it with a 350/340 crank as it is very likely to hit the cam. For those builds a better choice is a set of NASCAR takeouts with the Honda/Toyota bearing size which will require a regrind of about .100" to a standard bearing with tight clearance. You can pick those up all day long in various different lengths for under $300, sometimes $100. I recently scored a set of Carillo 6.2" long rods which IIRC I paid under $200 for. That makes the cost of custom forged pistons a LOT easier to justify.

Jim

[mgb260]

Also good for the 6" Chevy rod, 305 piston combo in the Rover V8. I'd stick with the 3/8" bolt I beam rods for most applications. The longer 6.25" rods only come in 7/16" so may be close. Not meant for stroker or 350 Buick where tolerances are already tight.

[mgb260]

deleted

[MGBV8]

How is this any better than using a small journal SBC rod, Jim?

[mgb260]

The 2.0(small journal) rods are getting scarce and are more expensive, may be getting discontinued. Speedway had those 6" 2.1 (large journal) rods on sale last week for $189. Mostly thinking of replacements for the cast 300 rods.

[Bland]

Can a 4.6 crank with the 2.1875 rod journal be safely ground to to use the 2.100 large journal Chevy rods?

Tim

[mgb260]

Yep, You would also have to match the width of the stock rods on the big end.

[Bland]

Perfect! I thought there would be no issues.

[roverman]

When modding SBC rods, WATCH the side/side offset of the small end to best be centered in the bore.  2" sbc rods getting scarce ?  I must be out of touch...

[joe_padavano]

Summit lists eight types of aftermarket SBC rods with 2.0" journals - both I-beam and H-beam.  Some are 6.000", some are 5.700".  They aren't cheap.

[mgb260]

Yeah, The last 2.0 (small journal) SBC came off the line in 1967. There were a few 68 327 small journal motors. Try to find a 6.125", 6.2" or 6.25" rod in the small journal size. There is even a 5.85" size in the large journal. Because of additional width with 7/16" bolts the longer than 6" in a Buick 300 would be a tight fit. I prefer the I beam with 3/8" capscrew bolts myself. The H beam are heavier and overkill unless for all out racing.

[mgb260]

Here is an example of 6.25" racing rods for $199!

https://www.ebay.com/itm/Suits-SB-Chevy-4340-Connecting-Rods-I-Beam-Race-6-250-2-100-0-927-Bronze-Bush/143090372393?hash=item2150d9cf29:g:SF0AAOSwnjZcPEql

[BlownMGB-V8]

For a cheap build it's hard to top something like this:

https://www.ebay.com/itm/NASCAR-Carrillo-6-125-1-976-x-787-Billet-Rods-Chevy-Ford-Dodge-13615/312024953201?hash=item48a622f171:g:z2IAAOSwh1haMy7q

$49 + $13 shipping BIN

Other sizes and such are available but with that journal size you can have the crank ground to your exact clearance with standard bearings. (possibly undersized on the mains). Check widths, and you'd need a piston to match, but it's a great start on a strong and light engine. The 0.1" or so undersize is not a concern. GSJohnny runs these in his 7500rpm drag car.

Jim

[mgb260]

Jim, Heck of a deal!. How much would it cost to turn down the rod journals to the Honda size though. Plus, add about $100-150 for new ARP rod bolts. Chris spent $450 to turn the mains of the 350 crank down to 300 size. For racing the smaller journal has lower bearing speed, which is why Nascar uses them. Plus, in the tight area of strokers and 350 Buicks the big end width is narrower. The more sources of parts for the Buick/Rover, the better.

[BlownMGB-V8]

If you're grinding .125" off the rod throws the cost should be about twice the standard regrind (.030 under x 4 minus extra on the mains) so not bad. The reason for the cost on the stroker was the removal of 0.500" of material, which doesn't apply here. You are right about the bolts, I didn't really look that close as I was just looking for an example. There are plenty of them though in the under $200 range with the rod bolts. Here's a set for $45 + $15 shipping, photo shows eight rods, bolts included.

https://www.ebay.com/itm/Racing-Nascar-Rods-Carrillo/132923894806?hash=item1ef2e1ac16:g:N9YAAOSwctJcHE6d

The seller of the set without the bolts is selling the bolts for $35 + $7. Another complete set is $99 OBO, etc. Lots for less than 200. Search "NASCAR rods" under Pistons, Rings, Rods & Parts.

Incidentally I lathe turned the mains of a 340 crank down to .030" over 300 size on a 15" LeBlond lathe. Not the easiest job but much easier than grinding it.

Jim

[roverman]

I narrow them on a lathe.   art.