what ratio roller rockers to use

[my new 72]

I just bought a new set of sportsman II heads, and am wondering on what ratio rockers I should use. Should I go with 1.5, 1.6, or 1.7. And what diference do es the ratio make?

[Big69C20 Toy]

The ratio determines the total valve lift you have. You might have to go with a certain ratio to make sure you can clear your piston with the valve. The lift of the cam is multiplied by the lift of the rocker to give you the final lift which the valve has. Typically bigger ratio will provide more room for flow and easier to flow as well. Gotta check out those clearances. I'm not sure on your specific application but i'm sure someone can help. As always if i'm wrong someone will correct me !

[chevyhouse]

i used 1.6 roller rockers and the heads had to be clearanced around the pushrod because using a larger ratio slighty changes the angle of the pushrod. i used a small rattail file, it was only a very little bit but enough to raise havoc if not removed. also look at getting pushrod guides if you are using rollers. in fact, the august issue of chevy hi performance has an article on this for vortec heads to give you an idea of what needed to be done.

[hanssolo]

Whats your application? Street, street-strip? IIs will hurt lower torque. As they say, better flowing heads is like a bigger cam. For the street, I personally would'nt use much cam with IIs.
I lived in Mission Bend for 14 yrs. Trying to get back there. Where you at?

[my new 72]

Hanssolo,
I will pretty much be using my truck for everyday driving, with the occassional Mustang chewing, nothing radical, so the low end torque is not a big issue. My engine is going to be putting out a modest 475-500 horses anyway, and lowend loss will probably not be very noticeable to me or anyone else for that matter. My cam is a crane energizer 274. The exact specs are at the shop, so I do not have them handy, but I know it is lower than a .500 lift cam. When I get my money tree to start producing I will buy a roller cam and lifters, but for now I will have to settle with what I have. I will probably just go with the 1.5 ratio though. I live in the heart of Houston, just a few blocks away from the intersection of Montrose and Richmond. But I wouldn't tell anyone to move to Houston though, I hate it, and cannot wait to get out. I was born and raised here, but I am tired of it. Alot has changed in 14 years, it's not the same.

[Suicide-D]

Josh...

I thinks its the area of Houston you must hate... I live out in Katy and love it. I lived over off of west Alabama for a few years and it did suck. I applaud you for Mustang chewing efforts... there are enough of those to go around and their feelings do get hurt when a truck beats them... I have an even milder cam in mine crane energizer 272 it has .454 lift and I have 1.5 comp roller tip rockers.

[my new 72]

Dirt Dobber,

Do you have to run rod guides when using roller rockers? I have heard it is a good idea, but is it a necessity. Also should I buy stud girdles, or is that overkill? I have lived everywhere in Houston, and I like it here the best. No offence, but I really hate Katy. I am a city boy, no doubt about that. Even a few miles out of the city is too far for me. It's just the way people are raising their children now. I come from a home where if you misbehaved you were punished. Anymore people just tell ther kids that they were wrong and should try to be better next time, well that's a chickensh$t way to repremand your children. The kids now are getting the impression that they can do whatever they want as long as they say they are sorry. I am not saying to beat your child, but if he steals a candy bar or a pack of gum when they are little, then smack there asses, and maybe they will associate crime with punishment, not a slap on the wrist. Sorry for the rant, I just get a little worked up over pansy ass parents, and their brat children.

[Suicide-D]

Yes i have guide plates, and chrome moly pushrods. I was told by the professional that assembled my block that they were required... I didnt ask.. just did it. I have World S/R Torquer heads and thought it was something with the heads.

[batboy]

For a daily driver, I would use the stock ratio (1.5 for a small block). With the proper cam, you don't need a higher ratio rocker anyway, unless this is an all out racing motor. The problem with higher ratio rockers is that it slightly messes up your valve train geometry which potentially could create problems down the road. With that cam and those nice heads, using the stock ratio roller rockers will be perfectly fine. Guide plates are good, but you probably won't need a stud girdle for street use.

[my new 72]

Thanks bat boy, I appreciate the info. I am going to go with the 1.5 crane roller rockers and guide plates.

[bigjimzlll]

ever think of just using 1.6 on the exhaust valve? I have..except I dont want to buy a full set......maybe split a set with some one?

[mikep]

I also use sportsman 2's. Little reality check for you though. Unless you are running nitrous you won't see 475-500 horsepower with those heads and that cam. 400 on a good day with a really decent carb and manifold and about the same for torque is more like it. I'm running a similar cam with 234 duration/.492" lift and 10.2:1 compression with an air gap intake and 800 cfm edelbrock carb and I'll tell you for a fact I'm not pushing over 400 HP.

Even if you go with the 1.6's you wont need to enlarge the rocker slot with those heads. Theres plenty clearance and yes you need screw in rocker studs and guide plates but you know that. If you can clear the pistons with the 1.6 then go for it. More gross lift wont hurt you if your valvesprings will handle the stress and you can clear the pistons.

[my new 72]

Mike,

You are also running a 350, and I am not. with the extra stroke of the 400 crank, and the boring, I will reach my mark. A balanced,and blueprinted 383 stroker makes way more power than a 350. I used the best engine builder in Houston, and I told him what I wanted, and this is what he suggested. There are lots of little tricks to be done internally to make more power, all of which he did. I assure you my mark will be met.

[mikep]

Figure one horsepower per inch of displacement added. Barring significant porting work theres not much leeway and even then you are liited by your cam in this case the 272 H . All I am saying that having had engines on the dyno before you never know until you actually get it fired up on the dyno. I wouldnt realisticaly expect more than 425 hp unless you are going hi compression

[hanssolo]

'72- who was your engine builder? Just curios. I had Jeff's Perf. on 43rd? prep a rat for me several years ago. He's kinda aloof but a real pro. Whatever the racers use and machine shop cleanliness are the marks of a good shop as far as I'm concerned. I've used some that were real pigpens.

[Suicide-D]

Hanssolo,

I think I used the same guy to do all my machine work. The name of that company is Engines by Jeff. He is in the same area of town I cant remember the street name but I could drive to it. I was very happy with the work. and They didnt drag their feet on it... real quick

[my new 72]

I used Faerman Racing Engines on Pinemont. This guy is the best. If you have ever heard of Nickens Brothers Racing, he is ten times better than those two, and the shop is very clean, I was impressed with the knowledge this guy has. The winning racers around here use him too.