1.75 rockerarms
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Category: Other Topics
Forum Name: Pulling Forum
Forum Description: Forum dedicated to Tractor and Garden Pulling
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=161550
Printed Date: 22 Nov 2024 at 11:20pm
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Topic: 1.75 rockerarms
Posted By: Big Orange
Subject: 1.75 rockerarms
Date Posted: 02 Jun 2019 at 3:11pm
| Will 1.75 rockerarms work in a 426 with stock camshaft? |
Replies:
Posted By: concretepumper
Date Posted: 03 Jun 2019 at 7:33am
| I have them in 2 3500's. Both stock cam. One has M&W pistons the other has Agco pistons and neither hit. Both running 3000 rpm. |
Posted By: NEVER green
Date Posted: 03 Jun 2019 at 4:45pm
|
Better get the thicker pushrods, bent several in my engine. ------------- 2-8050 1-7080 6080 D-19 modelE & A 7040 R50 |
Posted By: SteveM C/IL
Date Posted: 04 Jun 2019 at 10:05am
| Wouldn't that rocker help a stock field tractor? Are there any modifications needed to add them? If it would help one run better I wouldn't mind putting them in my 220 & 8070. Where do you buy such things. I am not a puller,just a farmer. |
Posted By: CAL(KS)
Date Posted: 04 Jun 2019 at 10:16am
|
http://www.murphysmotorservice.com" rel="nofollow - http://www.murphysmotorservice.com
------------- Me -C,U,UC,WC,WD45,190XT,TL-12,145T,HD6G,HD16,HD20 Dad- WD, D17D, D19D, RT100A, 7020, 7080,7580, 2-8550's, 2-S77, HD15 |
Posted By: concretepumper
Date Posted: 04 Jun 2019 at 12:01pm
| The two I put them in have all stock engine components with the fuel turned up and set to 3000 rpms. I noticed a more crisp and responsive acceleration. I had a cam cut for a different 426 by Vogal Cam in IL and Chuck Vogal told me that by not changing the duration of the cam that those 1.75 rocker arms would reverse flow the head. Maybe it does, I haven't be able to find out, but Chuck is a flat tapper guy |
Posted By: injpumpEd
Date Posted: 04 Jun 2019 at 12:34pm
They would not last too long in field use since they are aluminum, and ride right on the steel rocker shaft. ------------- 210 "too hot to farm" puller, part of the "insane pumpkin posse". Owner of Guenther Heritage Diesel, specializing in fuel injection systems on heritage era tractors. stock rebuilds to all out pullers! |
SteveM C/IL wrote:Posted By: SteveM C/IL
Date Posted: 04 Jun 2019 at 12:54pm
| Ok. been this long....what's a few more years? |
Posted By: O.P.S. Heads
Date Posted: 04 Jun 2019 at 2:21pm
| Please explain how changing only the rocker arm ratio will reverse flow a cylinder head - whatever that means. |
Posted By: injpumpEd
Date Posted: 04 Jun 2019 at 6:39pm
|
Opening the valves so far up to a point they no longer increase air flow. Keep increasing lift, the air goes in to reversion. Those poor old heads just don't flow a lot of intake air. Steve, a field tractor that gets a few hundred hours a year will last a long time I'm sure. I just wouldn't expect 5000 hours without premature wear, and needing re-adjusted. They are pressure lubricated, so....lol! ------------- 210 "too hot to farm" puller, part of the "insane pumpkin posse". Owner of Guenther Heritage Diesel, specializing in fuel injection systems on heritage era tractors. stock rebuilds to all out pullers! |
Posted By: O.P.S. Heads
Date Posted: 04 Jun 2019 at 7:55pm
|
Thanks Ed. I knew what that was, just didn't know that was what it was called. So, a stock cam would have a lift of (I'm guessing here) .275 inches at the cam. Multiply that by 1.75 and you get .481 inches of valve opening. A reground cam is between .350 and .370 inches at the cam typically (max). Using a stock rocker ratio of 1.5 to 1 you would get .525 inches lift at the valve. My point here is the valve will open further with most reground cams and a stock rocker than it will with a stock cam and faster rockers. So if someone is trying to sell you a reground camshaft which will most likely open the valves farther, and then saying faster rockers are bad because they might open the valves too far, they might be talking out of both sides of their mouth. The exception would be if he is going to grind a cam with a lower amount of lift. It's always best to flow your head and see where it quits flowing at - no doubt about that. Boost pressure may also change that some, but I will admit I wouldn't begin to undertstand the science behind it.
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Posted By: concretepumper
Date Posted: 04 Jun 2019 at 8:10pm
| From what I understood after talking with Vogal was that the exhaust side of the cam is very inefficient on a 426 and by using greater ratio rocker arms that there is no gain in flow but would "reverse flow" the head. He said a reground cam changing the duration and advancing the cam degree with factory rockers would be the best. I'm no expert, just one that ask way too many questions |
Posted By: concretepumper
Date Posted: 04 Jun 2019 at 8:22pm
| Before going the route of a cam regrind on a different 426, I was looking for a easy way to add power and I had ran across the 1.75 roller rockers Murphys Motor sold. When I had talked to them years ago they had told me they had built a D21 pulling motor for a guy and had designed these rockers for him and decided to sell them to the public. They didn't have any spec on them at the time, just to check valve to piston clearance. I put them in all stock 426, spun the engine by hand than ran it. Both with these rockers are still running with more fuel and higher rpm since original install with no problem yet... (knock on wood) |
Posted By: Big Orange
Date Posted: 14 Jun 2019 at 12:26am
| The speed the valves open & close is very important. |