The nailhead and the new 400/430 engines(long)

My dad and gramps were both mostly Buick guys. I liked them, but also other marques-mainly Pontiac. My dad traded his '65 Catalina when he took delivery of the '67 Wildcat coupe he'd ordered. It was a good car for some time-a leaky rear main seal and engine mount breakage where the fan then took out the radiator shroud were the only maint items other then PM that I recall. I was driving a '65 Pontiac GP and at a point dad and I traded cars back and forth a few times. At the last time my family lived in Minneapolis while I was in Denver.

One day in 1971 when the cat had about 75k miles as I was driving out of the mountains I noticed the 430 had developed an engine knock. Troubleshooting, including disabling spark to cylinders one at a time, indicated that #7 was not happy. Teardown found a spun rod bearing and a complete rebuild followed. Dad got the car back from me and drove it a few more years without issue.

I was always a bit puzzled a by all this as the car had good maint and was not a car that was 'beat on'. Now, as we move to more modern times and can look back, we know this experience wasn't uncommon and we know why.

Some years ago a group of Twin Cities area 'Buick guys' had a chance to meet and chat with retired Buick engine engineer, Cliff Studdecker. He, like engine designer Dennis Manner, was a Minnesota native and had long careers with Buick. Cliff talked about testing and results of the new 'lightweight' 400/430 engines being developed to replace the nailhead 401/425. While the nailhead had a forged 2 1/2" main crankshaft, the new engines were to have a casting. I don't recall if this first included the 3" mains or were originally smaller, but Cliff stated that there were breakage problems until this dimension increased to the 3 1/4" that the 400/430/455 all used thru their production life. He explained that under full power runs, the lightweight block flexed. I recall asking him-"So the block was stabilized by the rotating assembly. That sounds nuts!!??" He kinda smiled nodding. Anyway, the increased bearing surface area thus now had more oiling needs that the 'divorced' oil pump design was able to handle as miles and years added up.(and by the oil distribution path, #7 was often the first failure location). Cliff also talked about 'real world' testing with instrumented cars driving between Michigan and the Desert Proving Grounds. Full power blasts up Colorado's Ute Pass were mentioned-it was an interesting and worthwhile day.

So...for some years now I've had a Calif '67 cat like dad's and as time went by (many more years than ours but at about 80k miles)I began to notice a slight drop in hot idle oil pressure (ALWAYS run gauges since 1971)and the slightest lower knocking under load. I built a 455 (with the oiling fixes) did a swap and all is better. A look at the original 430 showed the rod bearings about ready to do more than complain as they plastigauged around .0038.

So that's my story with the new, improved 430 and while the head design is fine, I prefer the nail. Dan Mpls. Mn.

Great post, as usual, Dan. Using the crank as a structural member of the block is what enabled the 430/455 to be light weight. As I recall the 455 was very close in weight to a 350 Chevy? Awesome...with a price,

Tom

PS I appreciate you lending your winter weather to us for a while but I`d like to give it back...please?

Good post Dan - now we can appreciate your preference for the nail !

Here's a link to a chart showing different engine stats - height, width, and weight.

http://carnut.com/specs/engdim.html

The Buick big block is a "lightweight" when compared to some of it's competition.

Ed

So, as an owner of a 67 Riv/ 430 , with 68,000 original miles, logging about 1000 per year, is there anything I can do to prevent an engine failure? Engine seems to run fine.

Oil pump was rebuilt when the timing chain and water pump were replaced.

Sam from Jersey

So, as an owner of a 67 Riv/ 430 , with 68,000 original miles, logging about 1000 per year, is there anything I can do to prevent an engine failure? Engine seems to run fine.

Oil pump was rebuilt when the timing chain and water pump were replaced.

Sam from Jersey

Just my data point, I bought a new 1969 Electra with the 430 engine. I drove it a 175,000 miles and had no engine problems. I ran good oil and changed it often. I knew about the redesign in 1970 because of the oiling problem but didn't experience any problem.