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08-29-2014, 05:45 AM | #1 |
Member
Join Date: Jan 2014
Location: Belmont, Western Australia
Posts: 71
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Y block Rocker arms
I have a freshly built y block and was wondering if anyone has tried or know the performance effect of using stock 1.54 high ratio rocker arms on the the intake valve and stock 1.43 low ratio on the exhaust valve? The idea would be to increase intake flow and duration on the intake but limit the overall overlap for a smooth idle.... Addition info
Engine specs -heads have 1.9 intake valves -mild cam -piston / bore are 312 -4bbl intake with 575 Holley (vac secondaries) -after market exhaust manifold Any feed back appreciated Cheers Norm |
08-29-2014, 08:16 AM | #2 |
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Join Date: May 2014
Location: Tulsa, Oklahoma
Posts: 151
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Re: Y block Rocker arms
I've read about and heard this discussed before and can't remember the actual outcome but the net effect wasn't worth the trouble as I recall. Much better to go with the higher lift rockers overall if you have them. jmho.
Ted Eaton may have results on this. From what you have stated above your engine should still have a reasonable idle? |
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08-29-2014, 08:23 AM | #3 |
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Join Date: May 2010
Location: St. Michael, Minnesota
Posts: 1,713
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Re: Y block Rocker arms
I agree with Y's Guys. If the car has a stick transmission, give it as much as it will take. If the motor will have an automatic, or is going in a work truck, then back off a bit. Try to look up pictures on how to pressurize the rocker shafts.
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08-29-2014, 08:28 AM | #4 |
Member
Join Date: Jan 2014
Location: Belmont, Western Australia
Posts: 71
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Re: Y block Rocker arms
I have both sets, later model engines ( not y blocks) have this set up as was curious to see if it was worth doing to the y block, my idle is ok and was just interested in a combination of torque and economy the low ratio rockers give and the power the high ratio give! Thought someone may have done it already...
Cheers |
08-29-2014, 08:33 AM | #5 |
Member
Join Date: Jan 2014
Location: Belmont, Western Australia
Posts: 71
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Re: Y block Rocker arms
It's has a ford o matic so starts in 2nd...and I run the partly pressurised rocker shaft set up, so you think the 1.43 rockers are the go for this set up??
Cheers guys |
08-29-2014, 10:09 AM | #6 | |
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Join Date: Jun 2010
Location: Detroit suburb, MI
Posts: 3,706
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Re: Y block Rocker arms
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Quote:
Changing rocker ratios will not increase/decrease camshaft duration or overlap. It will just change the total valve lift and the speed that the valves open and close. Increasing valve lash would do it a little bit, but would not be a recommended way to go. If you don't like the lope, you need to change the camshaft. |
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08-30-2014, 06:18 AM | #7 |
Member
Join Date: Jan 2014
Location: Belmont, Western Australia
Posts: 71
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Re: Y block Rocker arms
So I have just installed a set of high ratio rockers and set the valve lash to .18 and am getting a strange back fire through the carb when you stab the accelerator ...... Any ideas??
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08-30-2014, 08:13 AM | #8 |
Senior Member
Join Date: May 2010
Location: St. Michael, Minnesota
Posts: 1,713
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Re: Y block Rocker arms
Causes; vacuum leak, one valve tight in the guide, it needs some miles to loosen up.
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08-30-2014, 09:33 PM | #9 |
Member
Join Date: Jan 2014
Location: Belmont, Western Australia
Posts: 71
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Re: Y block Rocker arms
Righto, makes sense given the valves are now opening a little further, I'll go for a burn.
Cheers |
08-29-2019, 04:39 PM | #10 | |
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Join Date: Jul 2011
Location: South Carolina
Posts: 316
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Re: Y block Rocker arms
Quote:
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