Bewick:
gingerfold:
moomooland:
Here’s another mixed bag…
2
4
3
1
0The Robertson Dale Guy did not have an AEC 7.7 litre engine, but it had the AEC AV470 engine, which some journalists wrongly and erroneously referred to as the 7.7 litre engine. These engines were totally different designs, although of similar cubic capacity. Lazy and incorrect journalism.
So “GF” as I am not an AEC devotee could I ask did the AV470 engine supersede the 7:7 our did AEC continue manufacturing them both for a time ? Cheers Dennis.
No Dennis the dry liner 7.7 litre (actually 7.58 litres) and AV470 didn’t overlap. The first version of the 7.7 litre was introduced in 1934 and it was a relatively long stroke (146mm) engine relative to the cylinder bore (105mm). It produced between 95 - 105 bhp at 1,800 rpm. There were several variants with either indirect or direct fuel injection and it was AEC’s first reliable Diesel engine. It’s most common variants, designated A173 and A187 powered all types of AEC passenger and commercial vehicles from 4,6,8 wheelers and the Matador 4x4. The 7.7 was used by other manufacturers during WW2, including ERF and Atkinson when Gardner engines were given preference to military applications. Production ceased in 1953.
When its replacement in 1953 was the wet liner AV470 (actually 7.68 litres) 112mm bore by 130mm stroke. Power outputs ranged from 115 to 145 bhp at various rpms between 1,800 to 2,400. There was also a 4 cylinder version, the AV312. The AV470 was developed from a little used mid-1930’s AEC engine design of 6.6 litres which was the company’s first trial with wet liners. AEC switched between wet or dry liners for most of its existence. This 1930’s design was resurrected in WW2 when two of these engines powered the Valentine tank. The 1930’s design became the basis for the AV470, and the early 470s gained reputations for having tender cylinder heads, with failed head gaskets. Later AVU470s with unified threads, redesigned studs, redesigned stud patterns, and better head gasket material solved most of the problems, but it was always better to keep the revs high with the 470 and not let it slog. There were three different thicknesses of head gaskets for AV470 engines and skimmed heads needed different gaskets than original heads, something that undoubtedly caught out some mechanics.The AV470 was specifically developed for the AEC medium weight ranges of passenger and commercial vehicles, namely Reliance, Mercury and it was used in the Marshal 6-wheeler when that was introduced in 1960. The AV470 was a popular “loose engine”, being used by Dodge, Guy and Seddon in significant numbers. Production ceased in 1965 when it was replaced by the dry liner AV505.