Self adjust rockers or not?
Thread Starter
Instructor
Joined: Jan 2009
Posts: 170
Likes: 1
From: Crofton MD
Self adjust rockers or not?
Ok I know this topic is talked about A LOT but please bear with me, I did a serch and after an hour of reading was still confused.
I own a stock 90 6-spd. It has just over 100k on the odometer and runs good. I just want to add a little more power so I can at least hang with the newer mustangs. Ive read roller rockers and exhaust are the easiest way to get some quick HP. I use this car daily by the way.
My questions are why do some recommend going with the 1.5 for intake and others the 1.6?
Also, ive heard that the self aligning are the way to go when others say to use the guide plates and hardened pushrods, which is best for a stock car?
I own a stock 90 6-spd. It has just over 100k on the odometer and runs good. I just want to add a little more power so I can at least hang with the newer mustangs. Ive read roller rockers and exhaust are the easiest way to get some quick HP. I use this car daily by the way.
My questions are why do some recommend going with the 1.5 for intake and others the 1.6?
Also, ive heard that the self aligning are the way to go when others say to use the guide plates and hardened pushrods, which is best for a stock car?
Last edited by Alex Annapolis; Sep 15, 2009 at 11:23 PM.
Race Director
Joined: Sep 2003
Posts: 16,838
Likes: 341
From: Database Error Indiana
You need self aligning for a 90. No such thing as self adjusting. I would do intake and exhaust. I see no point in changing guide plates and all that. You may want to install new springs while you are at it but even that is optional. The increase in lift will get you some easy horsepower but its not enough to just automatically kill the springs. This is really one of the easy mods that work. 
Burning Brakes
Joined: Aug 2006
Posts: 1,061
Likes: 99
From: Seattle WA
1.6's just give you about 7% more lift from the same cam and a touch more duration, too. It's a lot easier to change rockers than a cam; that's why 1.6 rockers are a popular mod.
Le Mans Master
Joined: Aug 2000
Posts: 8,838
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From: Australia
If you run self aligning rockers you keep the factory plates.
If you go to non self aligning rockers you need to install "proper" guide plates and harderened pushrods
Thread Starter
Instructor
Joined: Jan 2009
Posts: 170
Likes: 1
From: Crofton MD
what do you guys think of the summit racing aluminum rockers? They are self aliging, narrow width and not too expensive. However, I will spend more if their going to last much longer
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Race Director
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From: The Top of Utah
They don't. Hydraulic lifters automatically, hydraulically, maintain zero lash, once the installer sets the preload, properly. The preload is set by moving the fulcrum of the rocker arm. The same as adjusting the valve lash for a mechanical lifter cam.
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Former Vendor
Joined: Nov 2006
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From: Carmichael ca
I believe these are the blue made in China ones, don't buy them. I tried installing a set once and the machining was off on some of them and they cocked the push rods off to one side, rubbing against the guide plates. If you want a set I can sell them to you real cheap. Spend a little more and get a quality product.
Thread Starter
Instructor
Joined: Jan 2009
Posts: 170
Likes: 1
From: Crofton MD
thanks guys
I think im going to go with the comp cams pro mag. just not looking forward to grinding down the bolt sleeves. Im thiking of just buying new valve covers but their not as cheap as i thought.
Hey still never got an answer on 1.5 vs 1.6 for the intake?
I think im going to go with the comp cams pro mag. just not looking forward to grinding down the bolt sleeves. Im thiking of just buying new valve covers but their not as cheap as i thought.
Hey still never got an answer on 1.5 vs 1.6 for the intake?
Race Director
Joined: Sep 2000
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From: The Top of Utah
The change in rocker ratio will increase the valve lift at any point the valve is off seat. Valve lift equals cam lift multiplied by the rocker ratio. To determine the change in valve lift, divide the present valve lift by 1.5 to determine the cam lift and then multiple as above. Typically, changing to 1.6:1 rockers from 1.5:1 will result in an increase of valve lift somewhere around .030". The seat to seat duration will not change one ounce. The rollers will add little to no additional power, over the stock ball fulcrum. All told, the rocker arm swap could give you a power increase of 10 - 15 HP.
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Le Mans Master
Joined: Jul 2007
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From: Tampa Florida
The "guide" plates you see on your engine are not true guide plates; only there to help assembly at the factory.
If you run self aligning rockers you keep the factory plates.
If you go to non self aligning rockers you need to install "proper" guide plates and harderened pushrods
If you run self aligning rockers you keep the factory plates.
If you go to non self aligning rockers you need to install "proper" guide plates and harderened pushrods
with non self aligning....you will need "hardened" pushrods.
Last edited by engle1147; Sep 17, 2009 at 08:50 PM. Reason: speeling
Instructor
Joined: Jul 2009
Posts: 223
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From: Timisoara, Romania
I felt these things were just assembly plates too but Summit sell and adversites these: http://www.summitracing.com/parts/NAL-3973418/I ordered a set of these awhile back since they are advertised as "hardened" guide plates and I was going to run non self aligning rockers. These thing are identical (shape/size, stamp marks & and hardened coating material)to what came on my '89 from the factory. with non self aligning with you will need "hardened" pushrods.
with non self aligning with you will need "hardened" pushrods.
Pro
Joined: Jul 2006
Posts: 635
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I always thought 1:5 rockers were the same as stock and you only got the horse power increase by going to the 1:6's. I've heard of people using 1:6 on the intake side and 1:5's on the exhaust but I thought that was only on aluminum heads with pressed in rather than screwed in rocker studs.I think most corvettes are the screwed in type . If I were you I wouldn't do this without also replacing the springs, to close to the edge of what stock springs can handle.Best springs are the comp 26918 beehive springs. time you buy a kit with 26918 springs,retainers,locks you'll have 260.00 into it.the comp pro mag. rockers are apx. 285.00. I really want to do this too but wonder if the over 500.00 cost is worth it for 15- 20 horse power.After all putting about this same money into a gear change for rear would make car much better than just rockers. Do a gear change first! Good Luck Tim
Le Mans Master
Joined: Aug 2004
Posts: 5,141
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From: Metairie Louisiana
time you buy a kit with 26918 springs,retainers,locks you'll have 260.00 into it.the comp pro mag. rockers are apx. 285.00. I really want to do this too but wonder if the over 500.00 cost is worth it for 15- 20 horse power.After all putting about this same money into a gear change for rear would make car much better than just rockers. Do a gear change first! Good Luck Tim
After adding up the costs like you just did my rocker swap became a cam swap. I figured if I was going to spend all this money why not do the valve train correctly and get a hp increase I could actually feel with the cam swap.
Pro
Joined: Jul 2006
Posts: 635
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With most cams better than stock you come right back to needing better gears and a torque converter to better get car rpm's to where the cam makes power.Buy too big a cam and not do these you are just wasting your money and you might end up with a car not very streetable or one that doesn't make near the power it should. Comp cams has a few cams that don't require gears and converter change but then you don't get as much h.p. increase either. The comp cams 502 is I beleive one of these. It requires headers, Intake flow improvements,and computer reprograming.Everything is interconected when it comes to real performance,you have to pay to play. That's why everyone does the 1:6 rockers, not too huge a expense and it's a pretty quick 15-20 h.p. change. I just think I'd spend my money where it will make the best improvement to the car. Better gears will transform the car give you a much better seat of the pants improvement and give a better platform for later improvements. I myself would still like to do the 1:6 rockers but I'm looking for used parts where I don't have as much into it.