how is everone doing, i just recently bought a 1965 olds dynamic 88, all orig.
this is my first question i know my super rocket can with about 370 hourses but it feel like much more...so how much horses does it really have?
Additionally, my 425 is being rebuilt and i putting a 750 holly four barrel on it (with duals, new ehaust manifold, and intake manifold), in stead of the two barrel Rochester carb that on it that is already on it and i just wanted to know what would that do the horse power?

Thanks yall

 

One word. TORQUE

You are feeling the torque when you step on it. It isn't all about horespower...

 

A single exhausted 2bbl 425 I believe was factory rated at 310 HP....the Sfire Engine was rated at 370 HP in 65. It had a 4bbl, bigger cam and a 4bbl carb. The 425 has lots of torque as said. I have compared/driven a 68 Delta with 455 and a 66 Delta with the 425 and the 425 had more get-up and go than the 455 in my opinion. I believe the factory HP ratings back in the 60's were sort of a numbers game and not necessarily true output numbers when it comes to actual HP.

 

If your 425 is an original 2 bbl, it is not a 370 HP motor, but a 310 HP version. Check the serial number to see if it starts with an M or N. Olds offered three varieties in 1965 310 HP ( 2 BBL ) standard in most models, 360 HP ( 4 BBL ) in all other models as an option and 370 HP in the Starfire and Jetstar 1 only, but optional in other models ( very rare in other models ). The 370 HP moptor actuially puts out 385 HP , but was down rated for insurance purposes. In later years, the Actual HP was listed at 385 HP when it was used in the Toronado.
The 370 HP motor has higher compression, ( 10.75 ), much bigger cam, and dual exhausts. Olds claimed all of this only added 10 HP to their 360 HP. I ordered a 65 Delta 88 in 1965 with the 370 HP motor and drag raced it for several seasons. In stock trim from the factory, after a distributor curve and carb jetting it was pulling 330 HP at the rear wheels with a TH400 and 3:91 gears. It consistently ran 13.90's on street tires and open exhaust at Irwindale raceway in AA/SA and with cheater slicks on the street, it ran even quicker. Not bad for 4200 LBS on an old 4GC carb.