For sake if reference to a rocker shaft the poly is no magic beast, the poly has a set if inline intake valves and a set of inline exhaust valves, this just puts the valve tip on opposite sides of the shaft, rocker and pushrod positioning does the rest. But no its not a traditional 'inline valve' head like a gen1 chev or windsor or later 318/340/360 etc.Geoff2 wrote: ↑Mon Oct 15, 2018 5:11 am CJ,
An in-line valve head is a head where all the valves are inline, not some of them.
As for numbers..., I can give you two examples. Wheels magazine tested a 1958 318 Poly Powered Plymouth Belvedere with 3.23 axle. It ran a top speed of 118 mph, almost unheard of that time in Oz. Oh, & it had a two bbl carb. If you don't believe it, I have the magazine & you can come & look at it...
Mate had a 64 Plym with 318 Poly, 2bbl. Beat his mate's GT Phase 3 HO Falcon from a standing start.
What 64 plymouth was it ? Different models range from being heavier to lighter than a Ph3 HO, regardless there were a ton of cars back in the day that would dust a HO from a standing start, particularly a 3.5 or 3.25 diff model, they were not fast off the line full stop, they were not designed to be, they were a touring car, with close ratio box, crap tyres, tight suspension, light flywheel, big duration cam, the HO was designed to be fast once moving, and it was.
I read a great old magazine article on the 57 Plymouth sport fury. Apparantly it had less brake surface area than one of the smallest Fiats of the day and more hp than the most powerful road going (just quoting magazine figures here) ferarri of the day, the auto model as tested was fast (cant remember figures) for the day for sure but one hard stop from 100mph toasted the brakes and the car would not come to a full stop until they took it out of drive!
Yes in 1958 in Australia 118 mph was a pipe dream for most! Certainly far out of reach of the average aussie car at the time !