Are Stud Rockers inherently a flawed design?

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cjperformance
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Re: Are Stud Rockers inherently a flawed design?

Post by cjperformance »

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.
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.
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 !
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Re: Are Stud Rockers inherently a flawed design?

Post by Truckedup »

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.
Here in America a 318 in the reasonable light weight 62 model had a top speed of 110 and a blistering 17.2 1/4 mile.....Actually not bad for the time period.

http://wildaboutcarsonline.com/members/ ... st_1-4.pdf
Motorcycle land speed racing... wearing animal hides and clinging to vibrating oily machines propelled by fire
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Re: Are Stud Rockers inherently a flawed design?

Post by Truckedup »

Truckedup wrote: Mon Oct 15, 2018 8:20 am
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.

Here in America a 318 in the reasonable light weight 62 model had an estimated top speed of 110. It took nearly 30 seconds to hit 100 mph and a 17.2 1/4 mile @77 mph....Actually quite typical for the time period.

http://wildaboutcarsonline.com/members/ ... st_1-4.pdf
Motorcycle land speed racing... wearing animal hides and clinging to vibrating oily machines propelled by fire
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Re: Are Stud Rockers inherently a flawed design?

Post by Geoff2 »

CJ,
If it was an American 57 Plymouth [ there were some Aussie bodied Chrysler cars around that time in the mid 50s, such as the Chrys Royal ] then no way did it have smaller brakes than a Fiat.

Starting in 57 & continuing to 1961, Chrysler cars had twin leading shoe front brakes [ two wheel cyl on each front wheel ], were 11" diam & front shoes were at least 2.5" wide [ could have been wider ]. They were called 'centerplane' brakes. Another little known fact is that Chrysler Imperials for 1949 could be ordered with optional disc brakes...4 wheel discs. So far out for the time, they did not sell well & were dropped a couple of years later.


Trucked,
All the Chrysler cars sold here from about 1957 on had 3.23 diffs, non-posi. All the engines were in the lower performance range for that engine family. All 313/318 Poly's were 9:1 CR, 2 bbl. None ever came with 4bbl. In 58, the BB 350 engines were low compression, blocks were stamped LC. Same in 59, when the 361 appeared. They had a huge dish in the piston, must have been about 7.5-8:1 CR; came with 2bbls, were pretty gutless in the heavy cars.
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