quote:
Originally posted by T.Solo:
... Is there anyway to identify the "Heavy Duty" and "Australian" blocks ...
Hey Steve,
As best I've been able to determine, there were 3 heavy duty cast iron blocks commonly used in the US for 351C race engines between 1971 and 1984.
(1) The earliest blocks cast for NASCAR racing were cast and machined in the US. The block was usually referred to as “the 366 block", “Bud Moore's block” or “the SK block”. I believe the block has an SK number cast into it, SK56840. They had cylinder walls that were so thick there was no gap between adjacent cylinders in the water jacket (siamesed); they were made as thick as possible without inhibiting the flow of coolant through the water jacket. The thick cylinder walls allowed Bud Moore and others to bore the cylinders to 4.080" thereby achieving 366 cubic inches, which was the NASCAR limit for the smaller motors through 1973. The thick cylinder walls also allowed the engines to operate at high compression ratios without cracking cylinder walls. The bulkheads at mains #1 and #5 were thickened on their internal sides, but left "stock appearing" on their external sides; this gave the block the external appearance of a production block. The existence of this special racing block was intentionally hidden from the public. The 3 central bulkheads were thickened on both sides. It is rumored that approximately 200 "good" copies of this block had been cast between 1969 and 1972 (Bud Moore's first season in NASCAR was 1972). The need for cylinder walls that could be bored to 4.080" ended with the 1973 season, the displacement limit for 1974 was lowered to 358 cubic inches, which is still the limit today; thick cylinder walls were still needed however to prevent cylinder wall cracking due to high compression ratios and the stress of high rpm racing. The block was used by factory connected teams in both drag racing and NASCAR racing from 1971 through 1975.
US Ford rejected a proposal to cast more 366 blocks in 1973; they had been officially out of racing since the end of the 1970 racing season, and a corporate wide internal memo dated February 1973 forbad any financial participation in performance products, parts or events. Bud Moore was working with Don Tope and Don’s son Warren circa 1974, Don Tope was Vice-President of Ford Powertrain Operations, and an elected corporate officer of the Ford Motor Company. Powertrain Operations included the divisions which manufactured engines and engine parts! Bud was helping them with Warren's Trans Am Mustang, Warren was deeply involved in racing his former Ford sponsored Mustang Trans Am race car. Bud mentioned to Don that his supply of 366 blocks was almost exhausted and questioned if there was anything he could do to get some more blocks cast. US Ford had ceased manufacturing the 351C in mid-1974. So Don Tope approached Ford of Australia for assistance which they gladly provided. The 351C was already being manufactured in Australia; production there had begun in March 1972.
(2) The blocks cast via arrangements made by Don Tope were cast in late 1975 and early 1976 and were first employed during the 1976 racing season. The number of "good" blocks resulting from the 1975/1976 casting runs was about 200 blocks (the good blocks had minimal core shift and therefore uniformly thick cylinder walls). The blocks cast in Australia are commonly called NASCAR blocks today, but in 1976 they were still referred to as 366 blocks, or even as Tope blocks. They were considered by many as "continuations" of Bud Moore's original block. The new block had an XE192540 experimental engineering number cast into it. There is uncertainty whether or not the block had the "GF" Geelong Foundry symbol cast into it near the oil pressure port, perhaps some did and but others did not. The block had full thickness bulkheads and thicker cylinder walls, but the cylinder walls were not as thick as those of the 366 block. Whereas the 366 blocks had “siamesed” cylinder walls in the water jacket, the Australian NASCAR block had small gaps between the cylinder walls in the water jacket. The Australian block was equipped with four bolt main bearing caps cast in high nodularity iron.
Mario Rossi authored a story printed in Hot Rod Magazine which claimed the NASCAR blocks were cast in the US, shipped to Australia for machining, and then shipped back to the US, but that was in error. The mere existence of the 1975/1976 batch of Australian NASCAR blocks was kept hush-hush, their origin was unknown to most people, so rumors and stories surrounded the block. Ford was officially out of racing as of 1973, but Ford maintained a stock of racing parts hidden amongst their huge inventory of spare production automobile parts. There was no "catalog" for the racing parts; the stock numbers for the parts were only known by insiders, Ford race teams, dealers that supported race teams, etc. Ford's stock number for the NASCAR block was D1ZZ-6010-T according to Dan Jones. The NASCAR blocks were available via Gapp and Roush, Bud Moore, Holman and Moody and Bill Stroppe. The blocks were priced at about $1500 each; that was so expensive in 1976 grass roots racers couldn't afford them. The 1978 Holman Moody catalog lists the block as Holman/Moody stock number D6HM-6010-1, and refers to it as an Australian cylinder block.
There is also a NASCAR block with casting number XE182540 (one digit difference to the previous mentioned XE192540 number) mentioned a couple of times in old US magazine articles from the mid-1970s, one mention is in the Mario Rossi story. I've searched the Ford SK ledger documentation available to me looking for a reference to this block, but up until now I've never read or heard an explanation for the difference in numbers. I don't know anyone who can definitely say they've seen one.
(3) A second batch of Australian NASCAR blocks was needed because the supply of blocks cast in 1975/1976 ran out in 1980. The second batch was cast circa 1982. Both batches of blocks have the XE192540 experimental engineering number cast into them, and the second batch of blocks has the "GF" Geelong Foundry symbol cast into them near the oil pressure port (uncertain about that symbol being cast into the 1975/1976 batch of blocks). Like the first run of blocks this second run were also equipped with four bolt main bearing caps cast in high nodularity iron. Blocks from the first batch can be distinguished from the second batch cast in the 1982 by the surfaces of the sides of the block (the external surfaces of the water jackets). The sides of the blocks cast in 1975/1976 are "flat" like those of the production block. The sides of the blocks cast in 1982 were cast with bulges to improve coolant flow in the water jackets. The bulges in the sides of the blocks have earned those blocks the nick-name of “pillow blocks”. Five hundred NASCAR blocks were ordered in 1982, but a significant number were determined to have excessive core shift; only 200 blocks (approximate number) out of a casting run of approximately 500 were shipped to the US. The remaining blocks from that “batch” and possibly subsequently other batches cast in Australia were equipped with standard two bolt main bearing caps and were employed by Ford of Australia in motors assembled for production cars, fleet cars, trucks and marine applications. Ford of Australia phased the 351C from its production cars in 1982, but there was still demand for it from fleet (government) and marine customers, so it remained in production for at least another two years. Those 2 bolt Australian copies of the “pillow block” are good blocks but typical production core shift means the thickness of the cylinders walls is inconsistent making the block less desirable for heavy duty use unless a cylinder wall thickness check verifies the cylinder wall thickness in all 8 cylinders is good enough.
US Ford had re-entered the racing parts business by 1982, therefore there was no secrecy surrounding the existence of this second batch of racing blocks cast in Australia. They were advertised in Ford’s SVO parts catalog and sold via Ford’s network of SVO parts dealers for a short time (1982 - 1984) under catalog number M-6015-A3, priced at $1195 retail, which was less expensive than the price of a block from the first batch of NASCAR blocks, but it was still a whole lotta money in recession era 1982! The use of this block was phased out beginning 1984, it was replaced by a new heavy duty racing block based on the 351 Windsor. The heavy duty 351C block was dropped from the 1985 SVO catalog.
From time to time an unusual block will surface, originating from other small batches of experimental & SK blocks cast during the period of 1968 to late 1970, but none of these were commonly employed in racing as the 366 block and the two batches of Australian NASCAR blocks were.