I am guided by whether it is a stock block formula. Formula B, Formula Atlantic, Formula Pacific and Formula Mondial all had limits on the type of engine you could use and the two key engines across them all were the Ford twin cam and the Ford BDA. They had to be Fords because it was Ford that had built them in sufficient numbers for them to be homologated. The twin cam was invented by Lotus and perfected by Cosworth but the only reason it was eligible was because it was standard equipment in many thousands of Ford cars. Similarly the BDA was initially a Cosworth project but it was only allowed into Formula Atlantic because Ford had homologated it in their cars.
So they are both Fords. Similarly a post-74 F3 Novamotor has to be a Toyota first and foremost.
In a 2-valve free formula or a 4-valve free formula, such as the post-76 FIA Formula 2 or early 1970s ANF2, then you can do your own thing and produce a Waggott or a Hart. Similarly Repco can start with an Oldsmobile but change whatever they want and the result can be a Repco.
I would offer the opinion that it has much to do with personal preference. Is a Hart 416S not really just a Ford, or a Novamotor 2T-G a Toyota? But a Repco-Brabham 620 is no longer an Oldsmobile, is it? Where do we draw the line? Personally, I go with the head design, in which case the Camlex is still a Ford... wait a minute: is a TC Ford not really a Lotus, or a Lotus-Ford at best???
What excellent alternative points of view! Here's my ha'penny's worth;
Ford acquired the rights to the Lotus (Mundy - designed) twin cam , which is why we've always called the twink a Ford. Repco used the Buick block to develop the engine for itself, which is why we call their engines Repcos. The same goes for the Waggots.
If you only finesse'd the engine (eg the Ford twin cam or the BDA family) - eg by Vegantune, Hart ,Holbay, Richardson, Swindon, Nicholson etc - than the engine is still considered a Ford.
It gets blurry when cylinder heads get redesigned. I suppose it eventually comes down to how much of the original total engine design still survives after "development" has been completed.
Strangely enough, the Americans never seemed to worry about this. A Ford V8 with Gurney-Westlake heads was always a Ford. No matter who developed a Chevy V8 (eg Traco, Bartz, Bolthoff etc), they were still Chevys. BTW, for those of you who are into American racing V8s, I'd recommend "Race Man : Jim Travers and the TRACO dynasty" and "Al Bartz - Engine Man"
Edited by skyphantom, 01 July 2014 - 08:53.