replace the rocker arms
Grand Champion
Joined: Nov 2004
Posts: 6,099
Likes: 6
From: Colorado
That pic is from awhile ago. It certainly doesn't look that nice now, but I still keep it clean.
The rockers where one of the most noticeable performance items i've tried. They are really awesome for the price in my opinion.
The rockers where one of the most noticeable performance items i've tried. They are really awesome for the price in my opinion.
Last edited by Silver_Dodge; Feb 3, 2011 at 11:26 PM.
Champion
Joined: Feb 2009
Posts: 3,416
Likes: 4
From: Bay Area, CA
Simply put, the stock 1.6 moves the valve a distance that equals the lift measurement of the cam, times 1.6. So the 1.7 opens it a little bit farther.
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Veteran
Joined: Jan 2011
Posts: 304
Likes: 0
From: douglasville, ga
another rocker arm question. sorry.
i was just interested in what the ratio 1.7 on the harland roller rockers i have ordered meant. the stock ones are 1.6. so did some research and came across the following...........
The benefit of increased rocker arm ratio is the valve is opened a little further and faster, allowing more air in and out of the engine, thus creating more power. According to the guys at Crane Cams, changing from a rocker ratio of 1.5 to 1.6 generally adds about 3 degrees of valve duration, and changing from 1.6 to 1.7 rockers adds another 1-2 degrees. The net result is you are effectively changing your cam specs without changing your cam.
Traditionally, stock rocker ratios are right around 1.5, with a standard increase being a change to 1.6 rockers. The rockers found on Dodge’s Magnum motors are already 1.6 from the factory. If bigger is almost always better, why not swap in a 1.7? On the old LA engines, this swap created pushrod clearance problems, because the pushrod’s angle of attack was changed enough to make contact with its hole in the head, meaning that 1.7 rockers required machining the heads. Magnum engines have enough clearance for the pushrod (Fig. 3), but there is a possibility that you could run into piston-to-valve clearance problems because the valve is opening further and faster. If you’re building a motor from scratch, clay on the top of the piston will let you know if the pistons should be fly-cut. Crane tested 1.7 rockers on an engine and didn’t encounter any clearance problems. Usually, when you go from stock 1.5 rockers to 1.6, there is enough clearance that you can get away with it, so it would seem that going from a factory 1.6 to 1.7 would have the same result. But if the engine was in the vehicle, and it was our vehicle, we wouldn’t chance it.
i know many of yall have changed to 1.7 rockers and have no issues. have yall heard of any issues? i have the 5.2 motor.
The benefit of increased rocker arm ratio is the valve is opened a little further and faster, allowing more air in and out of the engine, thus creating more power. According to the guys at Crane Cams, changing from a rocker ratio of 1.5 to 1.6 generally adds about 3 degrees of valve duration, and changing from 1.6 to 1.7 rockers adds another 1-2 degrees. The net result is you are effectively changing your cam specs without changing your cam.
Traditionally, stock rocker ratios are right around 1.5, with a standard increase being a change to 1.6 rockers. The rockers found on Dodge’s Magnum motors are already 1.6 from the factory. If bigger is almost always better, why not swap in a 1.7? On the old LA engines, this swap created pushrod clearance problems, because the pushrod’s angle of attack was changed enough to make contact with its hole in the head, meaning that 1.7 rockers required machining the heads. Magnum engines have enough clearance for the pushrod (Fig. 3), but there is a possibility that you could run into piston-to-valve clearance problems because the valve is opening further and faster. If you’re building a motor from scratch, clay on the top of the piston will let you know if the pistons should be fly-cut. Crane tested 1.7 rockers on an engine and didn’t encounter any clearance problems. Usually, when you go from stock 1.5 rockers to 1.6, there is enough clearance that you can get away with it, so it would seem that going from a factory 1.6 to 1.7 would have the same result. But if the engine was in the vehicle, and it was our vehicle, we wouldn’t chance it.
i know many of yall have changed to 1.7 rockers and have no issues. have yall heard of any issues? i have the 5.2 motor.
Champion
Joined: Mar 2008
Posts: 3,363
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From: ohio
Champion
Joined: Aug 2010
Posts: 2,697
Likes: 3
From: Cape Carteret NC
I'm curious about your rig when it's done.. that 318 comes with a more aggressive cam than a 360.. (it doesn't take much to be more aggressive than the oe 5.9).. you'll likely gain a touch more than your average 5.9 does with this mod..
also, I may be wrong, but I think 96 and earlier rigs came w/ OE 1.5 rockers, and they bumped them to 1.6 in either '96 or '97.. If yours is running the 1.5's, and you bump to 1.7's, you're really going to see a difference!
keep us posted!
also, I may be wrong, but I think 96 and earlier rigs came w/ OE 1.5 rockers, and they bumped them to 1.6 in either '96 or '97.. If yours is running the 1.5's, and you bump to 1.7's, you're really going to see a difference!
keep us posted!
Champion
Joined: Aug 2010
Posts: 2,697
Likes: 3
From: Cape Carteret NC
from what I've read, he won't smack pistons- he'll be good..
but thinkin' it through tells me this: though it's a computer friendly mod, it's going to take his 'puter longer to adjust.. Once they are in, and once he turns his engine by hand to make certain nothing is going to collide, and ultimately fires it up: she's going to cough like a dragon.. for a little bit.. but it will adjust and he'll see some really good gains.. given, that is, that he is running 1.5 rockers now and not 1.6's.. if he's running 1.6's, there wouldn't be that huge an adjustment... <- this is ALL my supposition and has no basis in experience, just thoughts..
but thinkin' it through tells me this: though it's a computer friendly mod, it's going to take his 'puter longer to adjust.. Once they are in, and once he turns his engine by hand to make certain nothing is going to collide, and ultimately fires it up: she's going to cough like a dragon.. for a little bit.. but it will adjust and he'll see some really good gains.. given, that is, that he is running 1.5 rockers now and not 1.6's.. if he's running 1.6's, there wouldn't be that huge an adjustment... <- this is ALL my supposition and has no basis in experience, just thoughts..
Record Breaker
Joined: Jan 2010
Posts: 1,048
Likes: 1
From: Wisconsin
All dodge Magnum engines use the exact same rocker (1.6 ratio) as far as I know an this is the first thread I have ever heard different. I have have the HS 1.7 non adjustable rockers on a '94 318 and a '94 360 with zero starting or running or piston contact issues.