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Discussion Starter #1 (Edited)
Hey,
1.5 or 1.6? I have a 355 with 10:1 Sportsman 11 heads and a 270 dur 465 lift cam in a 62 Chevy 2. I don't have manifold or carb picked out yet. I am thinking of an RPM manifold and a 600 EdeIbrock carb. It will be driven daily and I only live 5 miles from work. Any help with rockers and carb/mani combo would be great!
Thanks
 

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rebuild it yourself. Holleys are not that difficult to teardown clean and put in new gaskets. I'd run it with an RPM air gap too. with your set up I doubt you'd feel a difference between the 1.5 or the 1.6 rockers. You have to make sure that the pushrod holes on the heads are big enough because with 1.6's it puts the pushrod in a different location. Be sure you check pushrod length too.
 

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Last 350 i had i tried the 1.5 and 1.6, it liked the 1.5 alot more, I too had 10.5 cr sportsman2 heads and a .465 lift cam. As for intake/carb, mine ran nice with a rpm intake and 750vs carb, i recommended a 670 street avenger, should be good out of the box. My 750 holley was a pain to dial in.
 

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Discussion Starter #6 (Edited)
rebuild it yourself. Holleys are not that difficult to teardown clean and put in new gaskets. I'd run it with an RPM air gap too. with your set up I doubt you'd feel a difference between the 1.5 or the 1.6 rockers. You have to make sure that the pushrod holes on the heads are big enough because with 1.6's it puts the pushrod in a different location. Be sure you check pushrod length too.
I know the 1.6's will work-I ran them before on these same heads. I was just wondering if the extra gain in lift would be beneficial for this application. Would there be a substantial loss to the bottom end? Thanks for clearing that up.
 

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I know the 1.6's will work-I ran them before on these same heads. I was just wondering if the extra gain in lift would be beneficial for this application. Would there be a substantial loss to the bottom end? Thanks for clearing that up.
using 1.6 ratio will kill bottom end and throttle responce with your combo, i tried both and it was a night and day difference in drivability. Go with 1.5's
 

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using 1.6 ratio will kill bottom end and throttle responce with your combo, i tried both and it was a night and day difference in drivability
I find that EXTREMELY hard to believe. I've gone from 1.5's to 1.6's to 1.7's and it's such a small change you would need a dyno or one VERY consistent car to tell a difference. If I was going to buy new rocker arms, (Oh yeah, I am!) I'd go with 1.6's if I knew for sure they wouldn't cause any clearance issues. I'd run 1.7's on my 410" if it had more piston to valve clearance.
John Lingenfelter used to run 1.9 rockers and he didn't seem to lose any bottom end or throttle response...but then, he knew what he was doing.
 

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I find that EXTREMELY hard to believe. I've gone from 1.5's to 1.6's to 1.7's and it's such a small change you would need a dyno or one VERY consistent car to tell a difference. If I was going to buy new rocker arms, (Oh yeah, I am!) I'd go with 1.6's if I knew for sure they wouldn't cause any clearance issues. I'd run 1.7's on my 410" if it had more piston to valve clearance.
John Lingenfelter used to run 1.9 rockers and he didn't seem to lose any bottom end or throttle response...but then, he knew what he was doing.
Im simply going off of personal experience, ive driven my car thousands of miles and at the strip too and felt the difference on the street not strip. The sets ive used were comp cams 1.6 and cam dynamics (crane) 1.5 with 3 different combos and my 355 had the most grunt and throttle using 1.5's, ive spent hours and days on end fooling with every little adjustment with trial and error on many engine parts on my 350's. sometimes a dyno doesn't work like the real world, everything always looks good on paper until you judge it by the seat of your pants. Anyway how come every guy with a street question always gets schooled by a strip guy? He felt the same way. Just remember the signature and believe!
 

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Im simply going off of personal experience, ive driven my car thousands of miles and at the strip too and felt the difference on the street not strip. The sets ive used were comp cams 1.6 and cam dynamics (crane) 1.5 with 3 different combos and my 355 had the most grunt and throttle using 1.5's, ive spent hours and days on end fooling with every little adjustment with trial and error on many engine parts on my 350's. sometimes a dyno doesn't work like the real world, everything always looks good on paper until you judge it by the seat of your pants. Anyway how come every guy with a street question always gets schooled by a strip guy? He felt the same way. Just remember the signature and believe!
The only problem with this is, more lift with the same duration should yield more torque. Not loosing it. You essentially have a more aggressive cam profile which means the valves are opening and closing quicker allowing heads to get in the high flow areas quicker. However, if you just install the rockers without changing push rods, your geometry will be way off and you will probably loose power. The geometry effects the way the valve is opened and closed. You want a pattern that is center so it wont side load the valves and a pattern that stays in one area on the valve stem. Otherwise, your rockers are effecting your camshaft profile. That could be the reason you had bad luck with them and lost power. Might be worth another try.

-dan
 

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I have RPM heads on a 355. Flat hydraulic lifters (I know, but I just couldnt afford rollers in 1995), roller rockers in 1.6 ratio. And correct push rods. Thing is snap on off the throttle and pulls as well as the rear will hook up, ford 9in with posi, 285/40 tires. Oh, the EFI (eddy unit) helps, and the 700-r4 gearing matches up great to the 3.73 rear gear. I dont have any complaints.

And personally, I would see it as going backwards to put some 1.5 ratio rockers in my setup at this point. Like why?? All the data shows you are just gaining some advantage with the 1.6 ratio.. Oh, and my cam is an off the shelf eddy RPM performer, run of the mill parts that work good together. JR

Oh, and my car is all street, no track. I cant afford racing.
 

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The only problem with this is, more lift with the same duration should yield more torque. Not loosing it. You essentially have a more aggressive cam profile which means the valves are opening and closing quicker allowing heads to get in the high flow areas quicker. However, if you just install the rockers without changing push rods, your geometry will be way off and you will probably loose power. The geometry effects the way the valve is opened and closed. You want a pattern that is center so it wont side load the valves and a pattern that stays in one area on the valve stem. Otherwise, your rockers are effecting your camshaft profile. That could be the reason you had bad luck with them and lost power. Might be worth another try.

-dan
You could be right but i have a BBC now and will never go back to sbc., this setup was years ago when i was into street/strip 350's, as for the question of rocker ratio and geometry, with 1.6 i know you get .031 more lift and 2 degrees of duration so maybe its duration related and not lift, as for power and geometry i would have to say that the negative power difference would be minimal but would greatly affect valvetrain durability without longer pushrods to correct geometry. Sorry, dont want to debate this or pee anyone off, just wanted to defend my personal experianced answer to his rocker arm question 1.5 vs 1.6 for the street on which he agreed.
 

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Discussion Starter #16 (Edited)
I must have gotten lucky in the past. I have ran 1.5's and 1.6's always using the rod length the parts shop gave me. The last motor was 400sb with 1.6 rockers and hardened pushrods. It had about .600 liftwith the 1.6's. All I did was rotate the motor to make sure nothing was hitting. A good thing I was so lucky because I was having a lot of fun with that set up. I'll better pay attention to geometry this time. Is it necessary to watch geometry even with a 1.5 rocker?
Thanks for everyone's input.
 

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Is it necessary to watch geometry even with a 1.5 rocker?
Thanks for everyone's input.
I think so. If its a stock build, nah. But if its any type of performance motor that has a good amount of lift or will see high rpm, I think its very important no matter what rocker you use.

One other thing, if you go with a 1.6 rocker, you must make sure your valve springs will work. You are adding 6-7% more lift and increasing the speed that the valve opens. You should choose springs as if you are installing a little more aggressive camshaft. You will also want to check piston to valve clearance.

-Dan
 

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Anyway how come every guy with a street question always gets schooled by a strip guy? He felt the same way. Just remember the signature and believe!
My car is driven everywhere, I don't own a trailer. And anytime you want to put your King Torque 454 up against my poor limp wristed small block (only 574ft.lbs.) I'll let you see who is really Queen. Hell, I could run 3.08's and all you would ever see is tail lights.
 

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My car is driven everywhere, I don't own a trailer. And anytime you want to put your King Torque 454 up against my poor limp wristed small block (only 574ft.lbs.) I'll let you see who is really Queen. Hell, I could run 3.08's and all you would ever see is tail lights.
:popcorn::popcorn::poke::stir::popcorn::popcorn:
 

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I know the 1.6's will work-I ran them before on these same heads. I was just wondering if the extra gain in lift would be beneficial for this application. Would there be a substantial loss to the bottom end? Thanks for clearing that up.
well if ya got 'em....use 'em. I used 1.6's on a 268 duration cam, overall the engine was very responsive and made good power....lots of torque. I just don't know if it would have done the same thing with 1.5's I was trying an experiment about high lift/short duration cams=more torque. I didn't want a lumpy cam like a 480/280 but I had really good set of heads so I wanted to take advantage of the head flow. Cam was a camgrinder custom 454/268 duration, forget the [email protected]" on a 108LSA and with the 1.6's made it a 483 lift cam. It idled like a stock engine and passed smong with flying colors.
 
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