Re: 454 heads and blocks
Seems that you are still curious.
I am "that someone" mentioned here, post #1
Those blocks, in that order...all are very good just the 512 and 289 are preferred for casting and machining accuracy. 959 and 445 are plenty good, just not as good. Unlike some brands....there are none to avoid! Just if I had a stack of blocks to pick from, a 512 or 289 would be preferred. I built a 959 the other week for my 70 Elky, no problems at all.
Please consult any of the numerous BBC books.
Refer to the BBC INFO thread, top of the ENGINE area, pictures there that I posted, added to what was there to square away those seeking basic BBC Knowledge.....
There are three size / configuration intake ports on heads and intake manifold runners
Rectangular port HUGE PORT
Oval port Good-sized port
Peanut/truck port Small port
The 781 and 049 are OPEN CHAMBER OVAL PORT
The 236 and 360 are OPEN CHAMBER Peanut Port (PP)
I have not seen an 045 head.... I do have my suspicions that it is an OPEN CHAMBER OVAL PORT HEAD with small valves for a HD truck application...
In a nutshell....the BBC heads are famous for their free-flowing intake configuration.
The 236 and 360 heads have the Peanut Port (PP), smallest of the bunch. As this is mostly a PERFORMANCE-oriented group, plus the heads made for the Chevelles back in the day were either oval or rect port from the factory, the PP heads are looked-at as boat anchors by most here. The bottom line here is that for a cruiser with 3.08 gearing, the guy who seldom goes to the strip, someone looking to destroy tires at the burger joint....the PP heads are certainly viable.
Anyway, back to your question
In the mid 70s, BBCs got discontinued as car engines. Chevy re-designed the heads to work better for their only purpose...truck engines. Truck engines need low rpm torque. So, long story short, will simply state that a small runner has high velocity and keeps the fuel air mix suspended...great for power and somewhat better economy in an engine that will seldom see north of 3500 pm. Lots and lots of PP headed engines in Pickups, Suburbans, motor homes....
The problem is that guys with their souped up 454 cars and 4.11 gears.....the 236 and 360 PP heads...the intake ports more or less give up the ghost at around 5000 rpm....regular oval port heads run good to 6000+ and the rect port heads shine above 3000 rpm.
I do understand that typical improvements like big valves, bowl blending under the valves also work well for Peanut Port heads. VortecPro can get these puppies to hum. I also think a small BBC like a 396 or 402 would like the smaller intake runners....plan to experiment some day.
Last edited by kettbo; Dec 13th, 08 at 12:39 AM.