2270 Engine Questions, Crank and Rods Options

[yeahmag]

I'm getting close to having all the parts for the 2270 build, but have a few questions:

• Crank brand: DPR, Scat, or AA? AA and Scat are new forgings but cost a bit more than the DPR crank. DPR is well respected in these parts.
• Crank size: Seem like a shame to leave it at a 2270 (78mm) when I could go up to a 2316 (80mm). Chevy journals.
• Rod length and type: Planning on 5.325" and Chevy journals for both clearance and the better bearing availability. Can I go longer for a better rod angle?
• Rod brand: Anyone have a preference? They all seem to be in the $400 range these days.

This will be primarily an autocross engine with some weekend drives. I also drive to events. The engine needs to be able to spin to at least 7500RPM even if it's not making power up there.

Here's the rest of the config (all of these parts are in hand):

• JE 96mm pistons with AA barrels
• Type 4 Store 9550 cam (86b/86c variant)
• Set of beautiful Finch heads I scored from Len Hoffman years ago
• Tangerine Racing 1.75" header
• 48 Dellorto Carbs with a 38mm vent (probably need to go to a 40mm vent)
• Dry sumped (either CB or ideally TP)

[yeahmag]

I think there were a few questions for me. I'll try and answer them here.

1. I don't believe the 9520 from Type 4 Store is a reduced BC cam, so I need to work within those confines. That makes me think I want a max of a 78mm, but I'll ask EMW and see what they say. The cam card makes it seem like a WebCam 86B/86C variant.
2. EMW has a nice selection of forged cranks and rods in 2L journal sizes.
3. I need to actually measure the heads myself, but I believe the are at 50cc.

[cgnj]

I think there were a few questions for me. I'll try and answer them here.

1. I don't believe the 9520 from Type 4 Store is a reduced BC cam, so I need to work within those confines. That makes me think I want a max of a 78mm, but I'll ask EMW and see what they say. The cam card makes it seem like a WebCam 86B/86C variant.
2. EMW has a nice selection of forged cranks and rods in 2L journal sizes.
3. I need to actually measure the heads myself, but I believe the are at 50cc.

@ 54 cc I needed base shims with 5.325 rods. I will check my receipts to see if I can tell you how big they were. At the time, I wasn't aware that I could have higher pin placement & that could have been the reason that I needed such a large shim. I ended up @ 10.2/1 compression. Valve lash checking and adjustment was an adventure.