Horsepower & torque

[Guest bigconnector]

I need some help from you guys that are a lot smarter than me. I'm in the process of rebuilding (hopefully enhancing) a 425 for my '39 street rod. After completing the overhaul (.030 over, new stock cam, rebuilt rocker arms shafts, hardened valve seats, etc., etc., I excitedly bolted on my new Offy intake with its three 36DCNVH Webber carbs.

It is my belief that the "stock" 425 is rated at 340 Hp and 465 ft-lbs torque. The best I could get on the dyno with the Webbers/Offy intake was 232 Hp and 367 ft-lbs. (We re-jetted to even get these numbers.) Just to compare, I replaced the new set-up with the old (non-machined nor polished) stock 4 barrel intake and the stock, old, tired carburetor. Now we read 263 Hp and 393 ft-lbs. One more try with the stock intake and a new 500 cfm Edlebrock resulted in 265 Hp and402 ft-lbs.

I'm getting pretty frustrated at this point. Did the spec sheets showing 340 Hp tell the truth? What can I expect to get with a fresh engine and "stock" carburetion? Would a dual-four set-up give me a whole lot more?

Your thoughts and comments would be greatly appreciated.

Thanks,

Jim

chambers@iserv.net <img src="http://www.aaca.org/ubbthreads/images/graemlins/confused.gif" alt="" />

[Sgt Art]

Are your HP figures at the wheel or flywheel when you dyno'd it? In the 60's ,most engines were rated at the flywheel with no accessories.

Did you compression ratio drop any?

The 360 HP engines were two four bbls. Here's a site with the specs:

http://www.greatoldcars.com/Engine%20Statistics/1930-1939_buick_engine.htm

[Guest bigconnector]

At the flywheel (using engine dyno). Compression is 10.25:1

Jim