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Re: Is the 1.57:1 Rocker Arm Ratio another Corvair Myth?
Posted by: strangecars ()
Date: May 05, 2015 06:05PM

I was under the impression that Vair ratios were 1.57 not 1.5. I have 6 sets of sbc roller rockers that could be used with a mod or 2 if we can agree 1.5's will work.

Steve Morton
1961 Rampside,
63 vert,
64 coupe,
65 EO vert,
67,
#0003 1969

Morton's Classic Garage
Parts and Service
Nampa, Idaho 83686
60+ Corvairs and 4 semi trailers full
of parts

Mortonsclassicgarage@gmail.com
[www.facebook.com]



Edited 1 time(s). Last edit at 05/05/2015 06:06PM by strangecars.

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Re: Is the 1.57:1 Rocker Arm Ratio another Corvair Myth?
Posted by: MattNall ()
Date: May 05, 2015 07:26PM

1.5 will work

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Re: Is the 1.57:1 Rocker Arm Ratio another Corvair Myth?
Posted by: kdrolt ()
Date: July 09, 2017 02:28PM

Somewhere in the bowels of the "modifications" chapter in a tattered copy of Ocee Rich's book on Corvairs, circa 1963, I saw a suggestion to use W-head (348, 409) Chevy v8 rocker arms for the (?memory?) 1.76 higher lift ratio. I went looking to see if anyone had done that, or stumbled across it as I had, here on CC as well on thr web but no joy. Not that I have plans to do that, but there is nothing like breathing life into an existing thread with a very-much-older "hop up" trick. The engineer in me thinks this would demand closer action of the pushrod to the ball rotation axis, so as not to upset the rocker tip -to- valve stem relationship, and that makes me wonder how much room there is in the upper reaches of the pushrod tube to allow that kind of tweak. FWIW, YMMV.

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Re: Is the 1.57:1 Rocker Arm Ratio another Corvair Myth?
Posted by: gnvair ()
Date: July 09, 2017 06:00PM

kdrolt Wrote:
-------------------------------------------------------
> Somewhere in the bowels of the "modifications"
> chapter in a tattered copy of Ocee Rich's book on
> Corvairs, circa 1963, I saw a suggestion to use
> W-head (348, 409) Chevy v8 rocker arms for the
> (?memory?) 1.76 higher lift ratio. I went looking
> to see if anyone had done that, or stumbled across
> it as I had, here on CC as well on thr web but no
> joy. Not that I have plans to do that, but there
> is nothing like breathing life into an existing
> thread with a very-much-older "hop up" trick. The
> engineer in me thinks this would demand closer
> action of the pushrod to the ball rotation axis,
> so as not to upset the rocker tip -to- valve stem
> relationship, and that makes me wonder how much
> room there is in the upper reaches of the pushrod
> tube to allow that kind of tweak. FWIW, YMMV.

Some of us use the Competition Cams Magnum tip roller rockers
in the 1.6 ratio for the non rail style Ford Windsor series small blocks.
I have never heard of anyone using the W motor rockers.......probably because the ratio is way too high and because the popular bearing trunion style have the wrong angle.

Lee J

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Re: Is the 1.57:1 Rocker Arm Ratio another Corvair Myth?
Posted by: 66vairman ()
Date: July 09, 2017 07:43PM

Maybe I missed it - but the "ratio" is the distance of each side of the rocker from the pivot center and geometrically varies as the valve opens.

The pushrod side is alway fixed as the rocker moves to open the valve, BUT the distance from the pivot point to the valve tip CHANGES. This gets back to the geometry often discussed when a head is cut and changes the geometry valve tip to rocker relation.

So at full valve opening the "ratio" will increase. How much - time to get out the dial indicator and compare a small movement near the valve fully open position. Or get the drawing numbers and load into a CAD-CAM program.

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Re: Is the 1.57:1 Rocker Arm Ratio another Corvair Myth?
Posted by: kdrolt ()
Date: May 27, 2018 05:30AM

Answering my own comment, Bill Thomas did the 409 rocker arm mod on his 1960 95 hp 140 cid engine, along with larger valves from the Corvette. He also, not surprisingly changed the intake valve axis angle as well as tilted the exh stub for better flow. The Rich book didn't include this detail, but I found it in a reprint of a Thomas hop-up article for Corvair mills, so I thought I would follow up. HTH

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Re: Is the 1.57:1 Rocker Arm Ratio another Corvair Myth?
Posted by: erco ()
Date: January 14, 2023 10:47AM

Old thread, but very interesting to me. I measured only 0.374 actual valve lift from my low-mileage GM 2304 cam during my current 140 rebuild. I tried several different rockers I have accumulated in the 40 years I have owned my '67, all with the same result. I bought my cam from Clark's many moons ago based on Bob Helt's article (CC Oct '78), excerpts attached.

The attached valve lift chart clearly shows 0.374 lift for a 1965 2304 and 0.392 for the same cam in 1966. These numbers correspond to 1.5 and 1.57 times my measured lobe lift of 0.249. If the fabled 1.57-ratio rocker never actually existed, where did that 0.392 spec come from? Just some guy with a calculator? Definitely a bummer, that extra .018 lift would improve performance.

I agree with a previous poster that the most direct way to get a higher rocker ratio is moving the pushrod socket closer to the ball pivot. It would only take a few thousandths to get to 1.57 or 1.6. I wouldn't worry about pushrod tube clearance but instead the stamped steel pushrod guides, which have pretty tight clearances. Anyone who has ever installed one upside down knows that the pushrod holes in the stamping are tilted to match the pushrod angle and it won't assemble.

During my rebuild I modified several pushrod guides to center the rocker tip on the valve tip. The guides are thick but soft metal, it was a matter of slitting, bending sideways & welding. #4 exhaust shown. A little tweak here equals 1.5 times on the tip end.

Attachments:


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Re: Is the 1.57:1 Rocker Arm Ratio another Corvair Myth?
Posted by: v8vair ()
Date: January 14, 2023 11:02AM

Every shop manual from 1960 to 69 says 1.5.
How to Hot Rod Corvairs say 1.5 , every stock rocker I checked was 1.5 or less
Go figure , most cam cards say 1.55 or 1.57

1964 Bill Thomas Monza Replica Racer
1964 Spyder Street Car
1998 Honda Prelude Dirt track car
1967 Crown V8 under construction
Mike Levine
Cumming Georgia
North of Atlanta

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Re: Is the 1.57:1 Rocker Arm Ratio another Corvair Myth?
Posted by: wittsend ()
Date: January 14, 2023 01:37PM

In the past 7 years since this thread started no one qualified/equipped has actually measured the ratio thenselves? It seems those who have assembled their engines want to believe the 1.56 ratio and those who are ready to assemble their engines are concern the ratio is only 1.50.

This same phenomena exists in the Ford 2.3 (Lima engine) world. Many of us have gone to the Ranger roller cam. At some point Ford changed the roller rocker. Some say it increases lift and others not. Yet there too no one has ever done more than "bench raced" the concept. In both cases the actual testing never seems to get done. Perplexing because it seems rather important to many. IF..., I had the necessary parts I don't thing my inquisitive mind would rest until I did.

Could it be as someone noted earlier the arcing rocker to the stationary valve isn't a constant LIFT ratio. And as such the 1.50 might be the "average" lift and 1.56 being the gross lift???

On another note, I find the 348/409 1.76 rockers a point of interest. While they might be rather rare today (and expensive) the more readily available big block Chevy rockers are reported to have a 1.70 ratio. Given the lowly lift of the 80HP cam, I = .314 E =.344 and the fact that self serve yards sell rockers for about $1 ea. it might garner more than $12 in performance increase. The nice thing about increasing the ratio is that at any given comparative point the lift is higher, it is not just a total lift number that is effective. The other factory cams have a .050 to .075+ more lift and the ratio might be too high but the low lifting 80hp cam was always a wonder to how effective the 1.70 ratio might be.

------------------------------------------------------------------------------

***'61 Lakewood, a "Freebie" in hibernation for 27 years - In the process of applying CPR.***

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Re: Is the 1.57:1 Rocker Arm Ratio another Corvair Myth?
Posted by: v8vair ()
Date: January 14, 2023 01:58PM

wittsend Wrote:
-------------------------------------------------------
> In the past 7 years since this thread started no one qualified/equipped has actually measured the ratio thenselves? It seems those who have assembled their engines want to believe the 1.56 ratio and those who are ready to assemble their engines are concern the ratio is only 1.50.
>
> This same phenomena exists in the Ford 2.3 (Lima engine) world. Many of us have gone to the Ranger roller cam. At some point Ford changed the roller rocker. Some say it increases lift and others not. Yet there too no one has ever done more than "bench raced" the concept. In both cases the actual testing never seems to get done. Perplexing because it seems rather important to many. IF..., I had the necessary parts I don't thing my inquisitive mind would rest until I did.
>
> Could it be as someone noted earlier the arcing rocker to the stationary valve isn't a constant LIFT ratio. And as such the 1.50 might be the "average" lift and 1.56 being the gross lift???
>
> On another note, I find the 348/409 1.76 rockers a point of interest. While they might be rather rare today (and expensive) the more readily available big block Chevy rockers are reported to have a 1.70 ratio. Given the lowly lift of the 80HP cam, I = .314 E =.344 and the fact that self serve yards sell rockers for about $1 ea. it might garner more than $12 in performance increase. The nice thing about increasing the ratio is that at any given comparative point the lift is higher, it is not just a total lift number that is effective. The other factory cams have a .050 to .075+ more lift and the ratio might be too high but the low lifting 80hp cam was always a wonder to how effective the 1.70 ratio might be.

I’ve checked every Rocker I’ve owned , stock and Roller. The Fords don’t work unless you like the roller running off the tip of the valve

1964 Bill Thomas Monza Replica Racer
1964 Spyder Street Car
1998 Honda Prelude Dirt track car
1967 Crown V8 under construction
Mike Levine
Cumming Georgia
North of Atlanta

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Re: Is the 1.57:1 Rocker Arm Ratio another Corvair Myth?
Posted by: vairmech ()
Date: January 14, 2023 03:55PM

v8vair Wrote:
Snip>>>>>>>>>>>
>
> I’ve checked every Rocker I’ve owned , stock and Roller. The Fords don’t work unless you like the roller running off the tip of the valve
>>>>>>>>>>>>>>>>>>>>>>>>>

I find that strange. Here is one of the Ford roller tip rockers with the wrong pushrod, I forget the lift though. While the pattern on the stem is off it isn't off the tip. Like I said wrong length pushrod.




Here is a stock rocker with the same setup.



Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com

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Re: Is the 1.57:1 Rocker Arm Ratio another Corvair Myth?
Posted by: v8vair ()
Date: January 14, 2023 04:02PM

I bet that rocker is not 1.6 , did you measure valve lift ?
The push rod will bind on the guide plate if it’s much past 1.55 from what I’ve seen
But if you say they work good luck smiling smiley

1964 Bill Thomas Monza Replica Racer
1964 Spyder Street Car
1998 Honda Prelude Dirt track car
1967 Crown V8 under construction
Mike Levine
Cumming Georgia
North of Atlanta

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Re: Is the 1.57:1 Rocker Arm Ratio another Corvair Myth?
Posted by: JimBrandberg ()
Date: January 15, 2023 07:04AM

I have to go back and look at my calculations.
I did a measurement of distance to coil bind of stock valve springs and determined that a 280 or 270 Isky cam was too close for comfort so I installed Isky springs and retainers at large expense in a few jobs.
My close to comfort was probably based on running both 1.5 and 1.57 multiplications.
I probably also factored in people's stories regarding 280 Isky with stock spring troubles.
I suppose "stock spring" is a misnomer since flat damper springs may vary.

Jim Brandberg
Isanti, MN
CorvairRepair.com



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Re: Is the 1.57:1 Rocker Arm Ratio another Corvair Myth?
Posted by: erco ()
Date: January 15, 2023 02:44PM

I just ordered some 1.6 rockers to test fit to my 2304 cam. Will advise.

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Re: Is the 1.57:1 Rocker Arm Ratio another Corvair Myth?
Posted by: v8vair ()
Date: January 15, 2023 03:57PM

Measure your lobe lift then measure with a dial indicator valve lift . See if the math works, very simple smiling smiley

1964 Bill Thomas Monza Replica Racer
1964 Spyder Street Car
1998 Honda Prelude Dirt track car
1967 Crown V8 under construction
Mike Levine
Cumming Georgia
North of Atlanta

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Re: Is the 1.57:1 Rocker Arm Ratio another Corvair Myth?
Posted by: JimBrandberg ()
Date: January 16, 2023 05:13AM

How about the hydraulic lifter squish or travel when simply measuring valve lift?
I do have some solid lifters I've used for checking things occasionally. I wonder if the height on them is about what 1/2 travel on a hydraulic lifter is.

So absolutely positively 1.5 is the number for stock Corvair rocker arms and 1.57 is indeed a myth?

Jim Brandberg
Isanti, MN
CorvairRepair.com



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Re: Is the 1.57:1 Rocker Arm Ratio another Corvair Myth?
Posted by: v8vair ()
Date: January 16, 2023 02:25PM

JimBrandberg Wrote:
-------------------------------------------------------
> How about the hydraulic lifter squish or travel when simply measuring valve lift?
> I do have some solid lifters I've used for checking things occasionally. I wonder if the height on them is about what 1/2 travel on a hydraulic lifter is.
>
> So absolutely positively 1.5 is the number for stock Corvair rocker arms and 1.57 is indeed a myth?


I use a solid lifter for degreeing the cam and checking lift at the valve

1964 Bill Thomas Monza Replica Racer
1964 Spyder Street Car
1998 Honda Prelude Dirt track car
1967 Crown V8 under construction
Mike Levine
Cumming Georgia
North of Atlanta

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Re: Is the 1.57:1 Rocker Arm Ratio another Corvair Myth?
Posted by: wittsend ()
Date: January 16, 2023 03:31PM

I was looking on the Isky site today for other reasons..., but came across this Isky Cam Install Instructions (scroll down to "checking at the valve"):

"Another reason for never checking at the valve is that a rocker arm's theoretical ratio, usually 1.5:1, is true only at approximately mid (1/2) valve lift. The ratio varies from slightly more to slightly less than 1.5:1 through the lifting cycle, because the rocker arm continually varies its point of contact on the valve stem."

A number of posts above I asked the question: "Could it be as someone noted earlier the arcing rocker to the stationary valve isn't a constant LIFT ratio. And as such the 1.50 might be the "average" lift and 1.56 being the gross lift???"

Perhaps this is the answer to that question.

------------------------------------------------------------------------------

***'61 Lakewood, a "Freebie" in hibernation for 27 years - In the process of applying CPR.***

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Re: Is the 1.57:1 Rocker Arm Ratio another Corvair Myth?
Posted by: 63turbo ()
Date: January 16, 2023 04:11PM

A bigger source of inconsistency is probably from lash vs a zero lash solid checking lifter. This comes about from the pushrod end being possibly down farther at zero lift and will move the pushrod end closer to the pivot. Geometry be damned! there was a large number of different recommended lash settings in the manual over the years also. I have never measured lift at the valve, but I have noticed a difference in the way the engine runs going from 3/4 turns down to 1 turn down. Kind of subtle but certainly wasnt expecting that.

------------------------------------

Kevin Nash
Friday Harbor Washington
63 Spyder, Daily driver, EFI read about my project here: [corvaircenter.com]
first test start on EFI here:[www.youtube.com]
first official EFI boost test here:[www.youtube.com]
My new fan! [corvaircenter.com]
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Canadian 64 Monza Parts car
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Re: Is the 1.57:1 Rocker Arm Ratio another Corvair Myth?
Posted by: v8vair ()
Date: January 16, 2023 05:02PM

I had 1.57 Crane Roller Rockers on my 383, the math worked.
My 434 had 1.55 Jessels , the math worked.
Most of my Corvair cam cards say 1.57 and the math doesn’t work, it gets close with the Harlem Sharp Rocker

1964 Bill Thomas Monza Replica Racer
1964 Spyder Street Car
1998 Honda Prelude Dirt track car
1967 Crown V8 under construction
Mike Levine
Cumming Georgia
North of Atlanta



Edited 1 time(s). Last edit at 01/16/2023 05:11PM by v8vair.

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