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By Jack Groat - 5 Years Ago
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I guess I need to buy rocker arm assemblies for my 292 rebuild. I see Mummert sells them for $950. His are 1.74 ratio. I have no problem with good used parts.
My Question: Are the used ones pretty much all the same? Are there different rocker ratios out there?
I found a set on ebay off a 239. Will these fit?
You guys are the best. I know I am going to get all kinds of info on rocker arms.
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By charliemccraney - 5 Years Ago
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John's 1.74 ratio are for aluminum heads only. That's why they are so expensive.
Factory rockers came in 1.43 and 1.54 ratio. Aftermarket are available in 1.6.
A set from a 239 will fit. They will be low ratio. Plan on a rebuild / refurbishing of used ones.
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By 2721955meteor - 5 Years Ago
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i have a set new rocker shafts re faced rockers 1,5s blocked off drain tubes. i want 250 for a pair . if you want to use spill tubes easy chang. my opinion feed to all rockers important for camshafts and eliminates sludge build up at end away frome tubes
i should use the classified but can't get any help removing items. frt won't be much. cliff ct1940@shaw.ca
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By Florida_Phil - 5 Years Ago
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You will get better performance with the high ratio rockers. They came on 1957 Fords and aren't hard to find. The casting number is ECG 6564. Check for wear. They can be refurbished. While you are at it, throw away the spaghetti push rods and buy a set of tubular rods. The stock rods tend to turn into pretzels.
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By Jack Groat - 5 Years Ago
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I have seen this time and time again where someone is selling high ratio rocker arms and claiming all kinds of performance improvements.
As an engineer working on a 3.8 liter V-6, we did a test with both 1.5 and 1.7 ratio rocker arms. The difference was zero.
Now this was just a stock engine so I don't know if it would be the same in all cases, but I don't get all giddy about having higher ratio rocker arms.
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By DryLakesRacer - 5 Years Ago
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We've used combination ratios on our 1/2 mile dirt engine for years finding a shorter ratios on the exhaust helps torque off the corners as the rpm is lower at that time.
The most important job of a cam and rocker is to move the valve fast right at the begining of valve opening when the suction from the pistons movement is the greatest. Performance cam grinders have told me the first .200" is the most important. An extra .100" at full opening isn't doing jack if the piston is stopped or barely in motion. Naturally aspirated torquey engines like a quick/early movement which is why a few degrees of advancing the cam helps a street engine or it sure has for me and my experiences. The cylinder head guru I use at times also works the inside of the intake runner/valve pocket to act as a venturi when he can to to add more low end at first valve movement.
99% of my driving has the RPM of my engine under 3000 probably closer to 2500 so I build them to perform there.
For our Y-Blocks I will agree the larger of the 2 stock ones are better, but having yours in good working order with minimal wear and good oiling is probably more important. Good luck
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By charliemccraney - 5 Years Ago
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On a stock engine, you may not realize any improvement but they certainly do increase potential when complimentary modifications have been made. They change the valve timing ever so slightly, increasing valve duration, lift and velocity.
The potential improvement probably is not worth the cost to most when it comes to aftermarket rockers, due to expense.
In this link, you can see a test comparing 1.4 and 1.6 ratio exhaust rockers. There is a difference and while it's not much, it is a difference, none the less.and as DryLakesRacer pointed our, the higher ratio favors higher rpm. For most, this difference is not worth it. For few, it is. And one test scenario probably doesn't tell the whole story, either.
http://forums.y-blocksforever.com/Topic48691.aspx
I remember something about mechanical advantages to using a higher ratio, I think something to do with pressure on the cam lobe, above my pay grade but still something that a stock motor would not be able to make much use of.
Ah, I found a link, an explanation from someone who knows.
http://forums.y-blocksforever.com/FindPost82749.aspx
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By Florida_Phil - 5 Years Ago
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Back in the day, we knew YBlocks out of 1957 cars performed much better than other Y Blocks. We were always on the look out for these motors and I bought a bunch of them. It wasn't until later that we understood the significance of 1957 distributor advance, heads, rockers, cam, intake, carb and exhaust. My 55 Tbird has it's original 292 cylinder block. It's about 300 cubes now. The rest of my engine was pirated from a rusted out 1957 Ford station wagon. My cam is a mild Isky grind. While it may not be the high ratio rockers alone, there is a world of difference in my motor and a bone stock pre 57 motor. If you are going to the trouble of rebuilding your rocker assembly, why not use readily available 1957 rockers? Those rockers alone are not going to make that much more power. With the right components, the difference will be noticeable.
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By Rusty_S85 - 5 Years Ago
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Yep rocker ratio changes can make an improvement to performance but not a by the seat of your pants feel. Im looking at 1.7 roller rockers for my build for my truck which isn't a Y-block, the pedestal roller rockers are only $230 for me for a set. I want roller rockers and the price between 1.6:1 and 1.7:1 didn't change so why not 1.7:1 I say.
But for your every day driver if you have something already running you really don't need to change the ratio as you wont feel a difference as at best you could see a few hp increase from all the reading Ive done.
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By Florida_Phil - 5 Years Ago
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I agree. Rocker arms are just one component. Change one part and you won't see much improvement. 1957 was the peak for YBlock performance. Back in the day we would take out a 1956 YBlock and swap in a '57 engine with no modifications other than Gunk and a hose.. The difference was incredible.
Ford made millions of these engines. Many are lying around in the back of barns and warehouses. Some are half buried in dirt. I bought a complete 1957 Ford 272 motor for $400. Not that hard to find if you look around. 3/4 of that engine is in my TBird now. If I had paid $1,000, I would have been worth the price.
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By Ted - 5 Years Ago
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Here’s an excerpt from an upcoming Y-Block Magazine article that may shed some light on the subject.
Ted Eaton (3/13/2019)
ROCKER ARMS
Rocker arm testing on the 312 dyno mule with ECZ-G heads showed that increasing the ratio from 1.4:1 to 1.54:1 was worth 3HP in peak values. Switching again from 1.54:1 to 1.6:1 was worth another 3HP. There were no measurable differences between the Dove, Harland Sharp, and Rocker Arm Specialist 1.6:1 roller rockers when all testing variables were kept constant. Rocker arm weight does not appear to be a variable that makes a performance difference in this particular testing instance. Had the valve springs been marginal in their setup pressures, then the rocker arm weights might have been an issue. The base peak HP was 267 with the 1.4:1 rockers, 270HP with the 1.54:1 rockers, and 273HP with the 1.6:1 roller rockers. This particular round of testing was performed on the 312 dyno mule with the Edelbrock #573 3X2 intake with Stromberg 97’s and a set of stock unported and unposted ‘small letter’ G heads. In this test, consider the 1.54 rockers being worth a 1.1% gain over stock while the 1.6 rockers would be a 2.2% gain over stock 1.4’s.
But what happens when the rocker arm ratio is changed up on the Mummert aluminum heads? Switching from the 1.54:1 rockers to the 1.6:1 roller rockers saw a gain of 12 HP. That’s pretty significant. If you are dealing with ported iron heads, then look for much more than a 3 HP gain as better breathing heads simply responds more favorably to rocker arm ratio increases.
And on the shaft mounted rocker arms, common hot rodding practice has been to replace the springs that hold the rockers in place with some form of machined bushings to maintain the rocker arms in their respective positions. Upon dyno testing two different engines on the dyno that had the springs replaced with machined bushings, both engines lost 2½ horsepower. Keeping the bounce or free movement minimal with rocker arm shaft springs does appear to be an advantage over using some form of machined bushings in their place. I would surmise that the springs act as a damper to keep ‘free’ rocker arm movement minimal on those camshafts that require a lash adjustment.
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By Ted - 5 Years Ago
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2721955meteor (3/11/2019)
I have a set new rocker shafts, refaced rockers, 1.5s, blocked off drain tubes. I want $250 for a pair . If you want to use spill tubes, easy change. My opinion feed to all rockers important for camshafts and eliminates sludge build up at end away frome tubes. I should use the classified but can't get any help removing items. Freight won't be much. cliff ct1940@shaw.ca
The ability to delete posts was removed as that activity was being abused. If an object sells or is being removed from a placed classified ad, then simply add a post to the thread that the object is ‘SOLD’ or whatever.
If wanting to sell those rocker arm assemblies, just post them in the Classifieds section. Putting that info within the middle of a non classifieds thread will not get the required exposure.
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