Rocker Arm Ratio - Summit Racing Quick Flicks

[@mbraun777]

Good video. What would make it great would be to include info on WHEN we would want to use different ratio rocker arms, and the down sides of changing that ratio with respect to parts longevity.

[@254967conwell]

I went from a stock 1.6 to a roller rocker 1.8 from yella terra and noticed considerable difference in the butt dyno. I have a Regal GS S/C, new long block from Summit Racing....With ZZP headers, 3in cat back, tuned PCM, CAI, and 3.3 pulley , ported S/C casing and ported throttle body....the biggest difference was the roller rockers..going from 60 MPH to 100 is scary

[@dennisrobinson8008]

On a .300 lobe the 1.6 is .480 lift and the 1.8 is .540 lift.

[@abrahamtorres4932]

AWESOME TEACHER! I ACTUALY UNDERSTAND WHEN YOU EXPLAIN THINGS! PROPS!!!

[@SummitRacing]

Thank you, *****! Please let us know if you have any questions.

[@tomassamuelsson6606]

Great explanetion! Thanx for you sharing your knowledge with us.

[@paulnichols943]

Hey norm , sorry to chime in again ,but after posting ,I read some of the others on this thread,while some are normal and understood and took away the info you talked about, the other oooh? 80% sound like the people I was talking about,it sounds like they didn't watch your video or most likely just don't comprehend it!!! You did make a VERY well explained video,thanks again ! You are a better man than I am ,I don't think I could deal with people asking questions that where just explained in detail ,not to mention asking about his rocker ratio when his motor is an overhead cam LOL BUT, it was very helpful to me and I'm sure quite a few others ,keep up the good work

[@grndragon2443]

can you folks make a video, on how rocker ratio's effect the power curve? And also mixed rocker ratio's ?

[@SummitRacing]

Thank you for watching!

[@madrabbit9007]

Good video, I had always wondered what those numbers meant.

[@SummitRacing]

Thank you for watching!

[@jmc1127]

Thanks for an excellent overview! Bravo!

[@LJC5865]

Being a 1st timer trying to learn before buying parts for 1st build. Place the rocker over the cam lobe in line and add a pushrod couldn't hurt. Visual set now able to hear and understand every word, not Distracted deaf with parts placed wherever.

[@blainsmith3097]

I know RR adds extra pound of pressure on the lifter lobe matting . I presume you can use same formula to calculate the force. so if seat is .100lb ..100 x 1.5 = 150 lb pressure on lifter , 1.6 = 160lb. ? something to consider when lobe pressure is a concern . this mathe may be wrong but seam legit ?

[@SummitRacing]

Due to the complexity and overwhelming possibilities when deciding push rod length, your best bet would be to contact our tech department. 1-330-630-0240. We will see if we can put this topic into a video.

[@Bigone250]

Yes very informational

[@gregg-wb8yys517]

Nice job Norm

[@SummitRacing]

Great! Let us know if you have any questions :)

[@VGHCX]

Is rocker arm ratio the same as mechanical advantage? If no, how are they different?

[@SummitRacing]

Thanks!

[@paulnichols943]

Thank you !!!! It took me a while to find this video,by wich i mean ,someone who answered the question that i was looking for !!! Also that explained it great !! Ford chevy mopar? Its all relative!! There are sooo many idiots that feel because they have a camera and a junk motor in their garage, ( probably because they destroyed it from not knowing how to build it) think they are professional engine builders and have absolutely no right giving others advise!! It's laughable to us that can tell the difference, but what about the poor saps that don't know any better and actually follow their advise blowing up there motors? All I wasted was time combing through all the morons til I found your video, rather than wasting time money and an engine from following retarded advise from idiots with a single digit I.Q and less mechanical abilities.

[@davidnuzzaci2459]

Thank you, very clear...

[@croatonTR]

Very good explanation. Thanks

[@ColdWarVet607]

I can not understand how you can just slap a higher ratio rocker in an engine. The push rod point is fixed by the head, the fulcrum point (where the rocker is bolted) is fixed by the head and the valve stem location is fixed by the head. To increase the ratio, one or more of those 3 points need to change. I always here about "put a higher ratio rocker in" but I sure dont see how just adding it can work, given the 3 points are fixed. The push rod needs to get closer to the fulcrum or the fulcrum needs to get closer to the push rod, or the valve stem needs to move away from the fulcrum point. So other than grinding out the push rod hole or getting a different head I sure dont see how this works. Pa-lese someone explain it to me!

[@kristopher2651]

I was reading something Crane Cams had put in a catalog that said for a good performance upgrade, leave your 1.5 rocker arms on the exhaust valves and change your intake rocker arms to 1.6 ratio. Would that affect overlap? with 1.5 rockers, my lift is .398 int./.442 exh. Putting 1.6 rockers on the intake valves would put it about .424. I'm not sure what the benefit would be. Any thoughts?

[@SummitRacing]

Kris Brickey, Swapping or staggering rocker arm ratios has been going on for a long time. Be careful though, not every motor(camshaft) responds positively to this. If you have a friend with a set you could “try before you buy”, that may keep you from spending money on a set of rockers that may not help you in the long run!

[@barrykilts4506]

Good info but I’ve been out of the game a while and just coming back do to a back injury.I have have most everything already for a 406 sbc chevy but since I bought the heads just before or as the aluminum heads were coming out,I found at the time what I thought was a good deal,new original bow tie heads with 205 instead of 202 valves for $800 and I worked them over.a few times when the weather was right and I hit it hard on the freeway it ran so good it nearly scared me.anyway since I already have all the old style parts I’m using them even though the new stuff is better it’s much more expensive to and my 406 will make 509 go all day but what I want is info I may not have about building better the bow tie heads and any info that will help me with low lift long duration cams but with 1.6 or anything you may know that’s better.one of the cams I have is an Elgin solid and I forget the spec.’s now but with the 1.6 r.r.’s it brought it to the neighborhood of the comp cam 230/280 magnum I also have but I expect good things from this little cam I am also starting at 4* adv..as I said I’ve been out of the game a while and you may and probably do know something I don’t. Oh this engine is just for the street and my amusement and I’ve had it built and altered several times and had the 509 block but it got damage so I now have a 511 that the machine shop screwed up and now after align boring had to buy iron caps and have to take the block somewhere 100 miles away to have the caps refitted to sit tight in the registers.sorry for the book but but description was needed .thanks for your video’s

[@cemakit123]

Good information sir

[@SummitRacing]

Thank you for watching!

[@eianwahgener7623]

But factory runs 1.5, aren't most modern cam lift profiles shown with a 1.5 ratio to begin with? (or whatever the stock ratio was, i know it's higher/lower on some engines)

[@slk4534god]

Ok I am installing a Ford 5.0 engine with a piston and cam change. It has the Ford E-303. I bought this used with 10,000 miles on a rebuild. My question is, why can't I adjust the valves on this using stock pushrods, lifters.an rocker arms? The 5.0 I took out to replace has zero lash when on the base of the cam. I can use a lifter and pushrod from the old motor and put it in the new motor and still have the same problem. To much slop in the pushrods! Do I need shims or different pushrods?

[@datsall4now]

How do I find what cam I have.I bought a 396 with a performanc cam but have no other info. I want to do roller rockers.

[@dennisfox4127]

How is the ratio changed? What do they do to the rocker arm?

[@BunnyBUNGALO]

I got a VW and I'm looking to get 1.4 ratio rockers. After I install dual carbs.

[@kristopher2651]

Should you use stock length pushrods if changing from 1.5 rockers to 1.6?

[@SummitRacing]

Hi Kris Brickey, Though it will be very close, due to a geometry change, the pushrod length should be checked!

[@kristopher2651]

Summit Racing Thanks for the info!

[@The_Bandit.1997]

I'm in the market for a 1984 trans am 305 stock engine, if I change the rockers to a 1.6 rocker ratio how much horsepower and/or torque would I possibly be looking at? I'm not looking to make it 1,000+ hp or anything, just rather curious

[@rotorblade9508]

stock is 204 hp, so you are going to need a ton of research to get to 1000hp. fist of all you need to know the transmission torque and rpm limit. For example 400lbft @5600rpm is 426Hp. This can probably be done. for higher rpm you need to tune the computer to accept higher rpms, and special components, probably an internally balanced engine block. Anyway, if you put Full Roller Rockers, 1.6 you will need new springs and rebuild and port the heads. then headers, a miniram intake, sport metallic CATs, new timing set probably, camshaft, throttle body, then tuning equipment or have someone to tune the ecm otherwise you can’t run the car anymore with so many mods. this way you can get to like 400 hp or more if the transmission allows more than 400lbft anything above 400 hp will be really quick.

[@AGuysGarage]

thanks for the info big ol hairy thumbs up

[@w0jwjohn680]

Great job.

[@85gbody97]

Is there a calculator or some way to put in your cam specs an see what would change if you would stick with a factory 1.5 ratio an then go to a 1.6 ratio. I grasp that it’s worth a Lil extra lift but it sounds like it also would change the event of the duration and not the actual duration as clearly ya can’t hood a valve open longer by simply opening its further but it seems like ya could cause the actual open sooner since it has more length on the front side of the rocker. Clearly I’m not sure of any of this thus why I’d like to know if any web site calculators exist that let you punch in your cam card specs and see what if any would change on it with the different rocker ratios.

[@SummitRacing]

Thank you for your question. There are a coupe points here and we will cover both. The opening and closing point at the seat will be the same whether it’s a 1.5 or 1.6 for instance, but the valve will open faster with a 1.6 and have more peak lift. Seat timing remains unaffected but .050 numbers will go up a couple degrees with a 1.6 for instance. It will do this more at the .200 lift range etc. and this is where the additional airflow comes from. At the same time, seat timing remains the same and idle quality or low end torque isn’t sacrificed. Just a potential for valve float to come in a little earlier than the smaller rocker ratio due to the quicker valve accelerations with “x” amount of spring pressure. For the people wondering about lift : If you know lobe lift, it’s simply a matter of taking that number time 1.5 or 1.6 to determine peak lift. If you know you have .500 lift with a 1.5 rocker for instance, the easiest way to see what a 1.6 would be is to take (.500 / 1.5) x 1.6 = .533

[@fadhilzulkafli4000]

hi i need help ..... what the bmw 328i rocker arm ratio and the dimension of the rocker arm

[@stephennolan3944]

Hello I am new to all of this, I assume you wouldn’t want to mess with rocker ratio unless you had an aftermarket cam, possibly change pushrods, valve springs and cylinder heads that have been throughly gone through is this correct? Also do you think you could shed some light on the different types of aftermarket rockers like full rocker arms and shaft rocker arms for instance what are each of there applications, would it be worth getting new? or if it’s mostly an aesthetic thing? I assume this wouldn’t have anything to do with the compression ratio but I am obviously a noob.

[@bradleylovej]

I know it's been 3 years, but I wanted to throw some info. I'm not the most expert at this, either btw. From what I understand, this is something you can do without changing cams. It's not like valvesprings where you have to change them with the cam. The rocker arms and the cam are part of the same system, but I think they can be changed independently of one another-you can just change your rocker arms and keep your cam stock. That being said, if you change your rocker arms, you'll likely have to measure your pushrods and get new ones. You also might want to check your springs since you'll have more lift. However, it's not likely the little bit of extra lift will make you have to upgrade springs. You might wonder why anyone would want to change their rockers to a higher ratio. Can't I just jam a big cam in and get on with it? It honestly seems like that's what lots of regular folks like you and I do. And that's totally fine. But there are reasons to change the rocker ratio (of course, we are talking about cars so there will be people who argue with this). 1. Maybe you don't want to change cams. Or you want to do a small cam package. This would likely be for a daily driver, or a car that wanted some extra power but also wanted to maintain street manners. Instead of going full-blown big cam where you get all of your lift from your cam lobes, you can get some lift from your rocker arms instead. 2. It makes it easier to push down the valve side. I am very interested in this. The lighter your valvetrain, the easier it is for your engine to do its work. That means an increase in horsepower, not a huge amount, but still noticeable. It also means that the engine will rev faster, and your engine will usually be capable of a higher redline (you have to also adjust your shift points with an automatic). I also think, though I don't have any direct evidence, that this will give you a really strong power curve where your engine makes good power all throughout its curve instead of just at the peak. That really makes you go fast!

[@jaiseholland6521]

@@bradleylovejhey man i know it’s a bit late but your comment has helped me a ton. thanks dude!

[@ethansmith9678]

I have a sbswith iron eagle head's intake rockerarm is 1.0 exhaust rockerarm 1.62 why that setup?

[@427_FE]

Thanks ! Does increasing the ratio have any effect on valve guide wear ?

[@SummitRacing]

Hello Jeff, As long as the rocker geometry is correct, there should not be a problem. In general, a roller tip rocker will reduce valve guide wear because it lessons friction at the valve's tip. A full-roller rocker will minimize friction at the valve tip and at the fulcrum or trunnion. Upgrading to rockers should be considered with a performance cam upgrade or when increasing the rocker ratio.

[@rotorblade9508]

you need to do a careful research before because you may need new springs, or the lift may be higher than the heads/engine can accept. also the timing set may need upgrade. For higher rate springs then you may need even spring cups if the heads are aluminum. but probably the stock new springs would be just fine with stock cam.

[@EL-gu1oy]

I need help I blew the gasket on my 350. and bought some aluminum heads to swap in with a cam and I need to buy rocker arms and pushrods and idk what size pushrods or rockers I should get plz help its my first time opening up a sbc. so I need some help

[@anthonyhewgley5543]

i have a mostly stock 1994 gmc sierra 1500 with a 305 sbc, swirl port heads 1500-5500rmp range, 4l60e. ive installed a jet performance powershift chip, fuel injector spacer, high flow exhaust. ive also removed my pcv valves and installed breathers instead... what kind of power difference could i expect from switching from 1.5 ratio rockers to 1.6 or 1.7? om making right about 210hp right know

[@SummitRacing]

Hi Anthony Hewgley, Every motor reacts differently to rocker ratio changes. The only true way to figure this out is to dyno test before and after the installation of the new rockers.

[@billwilk1591]

I have edelbrock Victor jr heads, on my sbc and a set of 1.6 comp cams ultra roller rockers, they are very close to the valve spring retainer will I have grind on the rocker arms to make sure that they are not going to hit the spring retainers?

[@SummitRacing]

Hi Bill, Try to never modify a rocker arm unless absolutely necessary, you may actually hurt more than help! It would be best to install a set of checking springs in place of the valves springs, install the pushrods , adjust the lash and roll the motor over by hand inspecting for any clearance issues. This is the best time to check and make sure your pushrod length is correct as well. Never assume the so-called stock length is what you need!

[@FromThe3PointLine]

nice video

[@sam111880]

good but if you had your x different then 1.0 you couldn't just multiply rocker arm ratio by lobe lift ... you need to just uses y * lobe lift in that cases. Unless this does n't have the same meaning as I am thing of it as more torque number or it could be just a ratio / formula that you equate to your cam/follower performance when testing as a short hand way of remembering

[@racerrr9080]

Does a 1,6 rocker change the valve lash?

[@SummitRacing]

While varying valve lash is an old racers tuning trick to try and squeeze out that last little bit of power, just changing to a different rocker arm ratio doesn't necessarily require a different valve lash setting!

[@coyote5.02]

So if my duration is 230 with a 1.5 rocker, what will it be with a 1.6

[@SummitRacing]

The duration will remain the same, however the lift at the valve will increase.

[@coyote5.02]

Summit Racing thank you.

[@pututadhikomarakertadikara454]

Roller rocker arm Suzuki gsx-rr1000

[@knightridersofgreece]

in a stock 350 chevy motor with all factory parts....if i change from 1.5 to 1.6 am i going to see any difference?

[@SummitRacing]

+steliosz28 , By changing a rocker ratio you are adding some valve lift. Since we don’t have the factory camshaft numbers, a general rule of thumb is you will get approximately .030-.035” of additional lift at the valve. On a completely original motor such as yours, you will probably not see much seat of the pants gain.

[@daleolson3506]

You'll see rocker studs pulled out,worn out valves and valve guides ,bent push rods.and if you don't check valve to piston clearance,a possible blown motor.

[@leadfootandy]

So, changing the ratio can increase power, but if a cams rpm range is 1500-5000, does the ratio affect that at all? If so, buy how much? Also, by changing the ratio, does it make the valve drop down into the combustion chamber farther than with a stock ratio?

[@SummitRacing]

+Andrew Swensen, While increasing the rocker arm ratio will in fact increase power, it generally is not by a substantial amount; though it varies per motor. The increase is realized by simply pushing the valve open into to the cylinder a little further allowing a little more cylinder filling. Feel free to call and we can help you choose the right components for your build. 1-330-630-0240. Thanks for watching.

[@leadfootandy]

Thank you! But, does it affect the RPM range at all?

[@jonnywilson9117]

I believe only changing the camshaft will affect rpm range. Changing rocker arm ratio will only affect valve lift.

[@hectorortega9131]

Thanks Norm. 👍👍

[@SummitRacing]

Thank you for watching, Hector!

[@hectorortega9131]

+Summit Racing no Problem, I Like Your Old School Kwnolage. 👍 I Always Follow you Post Bud. keep up the good work. 👍

[@SummitRacing]

Hi Elias, we have a few questions before we can make a recommendation for you. Give our tech line a call so we can discuss your build further. 1-330-630-0240. Thanks!

[@davidgragg7036]

1.5 rocker and a .300 lift gets .450 okay but how did he get 1.6 rocker and a .300 lift and cam up with a .480 .??

[@NubsWithGuns]

lift X ratio .300 X 1.5 = .450 .300 X 1.6 = .480 Not sure why they felt the need to drag it out and make it sound 100x more complicated that it has to be, probably to make you feel small so you will call them on the phone and buy stuff you don't even understand.

[@SummitRacing]

Hi Steve, There is a lot of information to discuss here, can you give our tech line a call at 1-330-630-0240? Thanks for watching!

[@Ls3guy]

great info now how about push rod info

[@djbaar3301]

Lewis Tool? from dynodon100 comment.

[@dynodon100]

Don't forget to use your Lewis tool when going to 1.6 on stock heads or you will be very sorry!

[@darrendavis5336]

dynodon100 what do you mean by Lewis tool? I got a 350 and I'm running an extreme energy Comp Cam Kit I think my Max lift was like 510 I remember her right. And I've decided to put roller rockers but I put 1.6 on my exhaust and 1.5 on my intakes. should I be worried about something LOL

[@NubsWithGuns]

If you had simply said "lift mutiplied by the ratio" maybe that part wouldn't have confused like 10 people in the comments. Was no rerason for all that babble explaining how to do the math.

[@SummitRacing]

Thank you for watching!