Rules for 1.5 or 1.6 rockers... - Chevelle Tech
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  #1  
Old Feb 16th, 11, 7:48 AM
Aaron Aaron is offline
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Default Rules for 1.5 or 1.6 rockers...

Anyone care to share the pros and cons of the using either....my limited understanding is that 1.6's will benefit the intakes....increase lift by .030....BUT there is are some reasons that I dont fully understand and know that 1.6's could harm you in some cases. What are those cases?
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67 chevelle
3485 lbs without driver before cage
383 SBC / TH 350 with 3400 stall / 4:10 gears

Best time on motor: 11.811
Best mph: 116.44 mph
Currently undergoing a metal work to remove all rust.
Goal is to have a 10.99 or faster run
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  #2  
Old Feb 16th, 11, 8:17 AM
1967ragtop138674speed 1967ragtop138674speed is offline
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Robert
 
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Default Re: Rules for 1.5 or 1.6 rockers...

1.6 will put more pressure in the motor and torque
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  #3  
Old Feb 16th, 11, 8:36 AM
bracketchev1221 bracketchev1221 is offline
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Default Re: Rules for 1.5 or 1.6 rockers...

If the cam is too big to start with. The rocker swap is great if the cam is undersized, but if the cam is too large, it will make it worse and kill bottom end.
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  #4  
Old Feb 16th, 11, 8:46 AM
Aaron Aaron is offline
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Default Re: Rules for 1.5 or 1.6 rockers...

Quote:
Originally Posted by bracketchev1221 View Post
If the cam is too big to start with. The rocker swap is great if the cam is undersized, but if the cam is too large, it will make it worse and kill bottom end.
OK..then by rule a 1.6 rocker benefit mild cams...such as..the GM "Hot Cam" in a 350.

Ok..then would a higher rocker ratio benefit a cam that has been degreed at say straight up or just one to two degrees vs say 4 or 5?

The other post mentioned bring in pressure...so if you have the cam advance not alot then a 1.6 will benefit more pressure into the motor?
__________________
67 chevelle
3485 lbs without driver before cage
383 SBC / TH 350 with 3400 stall / 4:10 gears

Best time on motor: 11.811
Best mph: 116.44 mph
Currently undergoing a metal work to remove all rust.
Goal is to have a 10.99 or faster run

Last edited by Aaron; Feb 16th, 11 at 9:06 AM.
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  #5  
Old Feb 16th, 11, 9:16 AM
lun40119 lun40119 is offline
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Jake
 
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Default Re: Rules for 1.5 or 1.6 rockers...

Rocker arms are like levers.........the higher the ratio of arm, the harder it is to turn over. Now the difference between a 1.5 and a 1.6 in your normal everyday street stuff, I doubt you will see much of a difference as far as being hard on parts.

But when you start getting into big lift stuff you need to find a balance of base circle, lobe lift, and rocker arm ratio. When we started working on my stuff, we ran into this. do I want a .433 lobe with a 2:1 ratio, or a .468 lobe with a 1.85:1 ratio or a .541 lobe with a 1.6:1 rocker. We ended up with a 1.85 ratio arm, and it has proven to have worked, at least in testing. (No road time yet) 75+ dyno pulls, and hours on the spintron.

I hope my rambling is making a little sense Aaron, here is a video of Richard Maskin(owner of Dart)talking about valvetrains and rocker arm ratio. He also focuses on how everyone uses too much spring pressure . It is a good deal to watch. This guy doesn't read the book and learn....................HE WRITES THE BOOK!!!

http://www.dartheadstv.com/video/13363
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1967 Chevelle
1.321 60'
6.143 @ 110.46
9.754 @ 136.30
3V Performance 23 Pumpgas 402
http://www.youtube.com/user/excedrin67?feature=mhum#p/u/4/v1Tff2or1oY
1st Place Drag Week 2012 SB/NA
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Jan 2012 HotRod
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Last edited by lun40119; Feb 16th, 11 at 9:49 AM.
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  #6  
Old Feb 16th, 11, 10:20 AM
Aaron Aaron is offline
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Default Re: Rules for 1.5 or 1.6 rockers...

Quote:
Originally Posted by lun40119 View Post
Rocker arms are like levers.........the higher the ratio of arm, the harder it is to turn over. Now the difference between a 1.5 and a 1.6 in your normal everyday street stuff, I doubt you will see much of a difference as far as being hard on parts.

But when you start getting into big lift stuff you need to find a balance of base circle, lobe lift, and rocker arm ratio. When we started working on my stuff, we ran into this. do I want a .433 lobe with a 2:1 ratio, or a .468 lobe with a 1.85:1 ratio or a .541 lobe with a 1.6:1 rocker. We ended up with a 1.85 ratio arm, and it has proven to have worked, at least in testing. (No road time yet) 75+ dyno pulls, and hours on the spintron.

I hope my rambling is making a little sense Aaron, here is a video of Richard Maskin(owner of Dart)talking about valvetrains and rocker arm ratio. He also focuses on how everyone uses too much spring pressure . It is a good deal to watch. This guy doesn't read the book and learn....................HE WRITES THE BOOK!!!

http://www.dartheadstv.com/video/13363
Interesting comment on everyone using to much spring pressure.....
__________________
67 chevelle
3485 lbs without driver before cage
383 SBC / TH 350 with 3400 stall / 4:10 gears

Best time on motor: 11.811
Best mph: 116.44 mph
Currently undergoing a metal work to remove all rust.
Goal is to have a 10.99 or faster run
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  #7  
Old Feb 16th, 11, 10:31 AM
lun40119 lun40119 is offline
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Jake
 
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Default Re: Rules for 1.5 or 1.6 rockers...

Quote:
Originally Posted by Aaron View Post
Interesting comment on everyone using to much spring pressure.....
Why is it interesting??? It can be done........no doubt in my mind. Here is my lobe. .866 lift at the valve. ~140/~580 seat and open. 272/286 dur at .050.
Peak HPish.....
__________________
Jake
1967 Chevelle
1.321 60'
6.143 @ 110.46
9.754 @ 136.30
3V Performance 23 Pumpgas 402
http://www.youtube.com/user/excedrin67?feature=mhum#p/u/4/v1Tff2or1oY
1st Place Drag Week 2012 SB/NA
2nd Place Drag Week 2011 SB/NA
Jan 2012 HotRod
http://www.hotrod.com/featuredvehicles/hrdp_1201_1967_chevy_chevelle_its_big_to_be_small/
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  #8  
Old Feb 16th, 11, 10:35 AM
lun40119 lun40119 is offline
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Jake
 
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Default Re: Rules for 1.5 or 1.6 rockers...

Aaron, just so I am clear. I am not saying that everyone should cut there spring pressure in half. I am saying that it can be done, but you need to take everything into consideration when doing this.
__________________
Jake
1967 Chevelle
1.321 60'
6.143 @ 110.46
9.754 @ 136.30
3V Performance 23 Pumpgas 402
http://www.youtube.com/user/excedrin67?feature=mhum#p/u/4/v1Tff2or1oY
1st Place Drag Week 2012 SB/NA
2nd Place Drag Week 2011 SB/NA
Jan 2012 HotRod
http://www.hotrod.com/featuredvehicles/hrdp_1201_1967_chevy_chevelle_its_big_to_be_small/
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  #9  
Old Feb 16th, 11, 9:27 PM
Aaron Aaron is offline
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Posts: 6,335
Default Re: Rules for 1.5 or 1.6 rockers...

OK Jake I think I follow you....very technical... on the information...I somewhat a novice compared to that reply.

Here are the flow numbers on my heads after porting.

LIFT/After
.200/ 141.1
.300/ 194.3
.350/ 216.0
.400/ 236.6
.450/ 254.8
.500/ 269.4
.550/ 279.8
.600/ 285.2
.650/ 288.2
.700/ 290.3
.750/ 291.2

My compression is right at 10.7 in a 383.

Cam is a solid roller with 288/296 and 255/263 for 626/.626 lift on a 109 lsa.

Im using 1.5 rockers at this time.

My piston to valve will be ok with 1.6's according to my engine builder.

My question is will I see positive effects from 1.6.

My seat pressure is 240 lbs at 1.9 install height....per Luanit.

The cam card called for 210 lbs at 1.95....

Not sure why the call to the cam company told me to use 40 more lbs.
__________________
67 chevelle
3485 lbs without driver before cage
383 SBC / TH 350 with 3400 stall / 4:10 gears

Best time on motor: 11.811
Best mph: 116.44 mph
Currently undergoing a metal work to remove all rust.
Goal is to have a 10.99 or faster run
Reply With Quote Quick reply to this message
  #10  
Old Feb 16th, 11, 9:46 PM
lun40119 lun40119 is offline
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Jake
 
Join Date: Jan 2010
Location: Appleton, WI
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Default Re: Rules for 1.5 or 1.6 rockers...

You are going to need more information. I "think" you will be ok, but I wouldn't bank on what I say anymore, especially after working with Tom. I ran a SR with 276/286 @ .050 and .640/.645 with 250/650 for 5000 miles with no problems, but your cam and my old cam could be very different. It is all in the lobe intensity and the weight of the parts you are using.
__________________
Jake
1967 Chevelle
1.321 60'
6.143 @ 110.46
9.754 @ 136.30
3V Performance 23 Pumpgas 402
http://www.youtube.com/user/excedrin67?feature=mhum#p/u/4/v1Tff2or1oY
1st Place Drag Week 2012 SB/NA
2nd Place Drag Week 2011 SB/NA
Jan 2012 HotRod
http://www.hotrod.com/featuredvehicles/hrdp_1201_1967_chevy_chevelle_its_big_to_be_small/
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