1.6 rockers with this combo?

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Brandt Fonda

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My engine builder says I have the clearance, and I have a set of 1.6 roller rockers laying around. So is there any downside in going with 1.6 ratio with my combination? Car is street/strip with emphasis towards strip. Also if you have any predictions on this combo love to hear them!

360 La, performer rpm intake mainifold, Eddy rpm heads ported w/ 1.6/2.02 SS valves, Comp hydraulic roller cam: Dur. @050: 236 / 242, Lobe sep. 110 deg, valve lift: 544/541, Eagle forged rotating assembly, internally balanced, light weight flywheel, 9:7:1 comp., rings gapped for nitrous, 100-150 NOS, 7qt kevko oilpan, Oiling mods

also does anybody have any input on staggering ratio's of rockers : 1.6 on intake and 1.5 on exhaust?
 
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The valve lift and rocker ratio are limited (I believe) by the flow of the intake/exhaust runners.
On the iron j heads I wanna say the experts here said lift after .45?? Was a waste on stock heads.

I don’t know what the limit is edelbrock heads.
You have given engine specs, but
Everyone here needs to know:
Vehicle:

Weight
Transmission (stall converter)
Expected driving usage/purpose
(Circle track, drag strip, street or combination there of)
Type of tires (slicks, etc.), size
Differential gear ratio

There are brilliant people here, but they need as much info as possible to really help you out.

Many reference the B3 rocker geometry setup.
I don’t think that you need 1.6 rockers, but obviously if you have them and they work alright, run them. It is possible that much lift might create slower/lazy air flow at some point-experts would have to confirm that guess. Best wishes!
 
Thank you for your reply! Sorry yeah I did say emphasis on strip use and I thought my avatar gave vehicle away lol, but for sure as you said: that was my worry is over camming my heads. Maybe the 2.02 valves prove to be the choke point.

Here are some more specifics
1967 Barracuda approx. 3060 pounds full tank
A833 trans w/ standard ratio
Street/strip emphasis on strip
8.75 nodular rear w/ eaton tru trac 3.90 gears
28 x 11.50 MT et streets
 
My engine builder says I have the clearance, and I have a set of 1.6 roller rockers laying around. So is there any downside in going with 1.6 ratio with my combination? Car is street/strip with emphasis towards strip. Also if you have any predictions on this combo love to hear them!

360 La, performer rpm intake mainifold, Eddy rpm heads ported w/ 1.6/2.02 SS valves, Comp hydraulic roller cam: Dur. @050: 236 / 242, Lobe sep. 110 deg, valve lift: 544/541, Eagle forged rotating assembly, internally balanced, light weight flywheel, 9:7:1 comp., 7qt kevko oilpan, Oiling mods

also does anybody have any input on staggering ratio's of rockers : 1.6 on intake and 1.5 on exhaust?
I’d say that is a really good combo you have there.
Adding rocker ratio does a few positive things.
A small narrowing of the LSA
Quicker lifting valves which is great for the intake charge. Quicker is always better on street cams.
Adds minor duration. The general consensus is 2*’s.
The added lift to .580/.577 is probably lifting the valve up into a higher and more favorable flow rate. IMO, I have often stated, while not needed, why not lift the valve as high as the heads flow well? It’s grabbing all the head has to offer in terms of flow which equals power.

Staggering rocker ratios can help. This is mainly a try it out and see and the dyno is a quick place to get that answer but less fun, though much more accurate over the drag strip. The power you’ll find will probably be small in terms of “The Seat of the Pants” feel, but might, just maybe, be a nice number on the report.

Overall, the cam is the one thing I’d change. But, everyone here will have their own cam to state is a great cam. The thing with camshafts is, ask 10 people there idea of a “BEST CAM” and you’ll get 10 different answers from idiots to pros.

One can argue that adding rocker ratio is introducing possible but easily (kind of, skill level dependent) avoidable problems with rocker geometry and wearing out valve springs. Ignore this and take the time to look if you need an upgraded spring and take the time to get the rockers where they need to be placed along with the right length pushrod. All of those problems go away when you do it right.

For help on rocker geometry, contact member B3, his name is Mike. He is a geometry freak and loves getting this stuff right.
(Not my word, his. He loves this stuff!)
He is also a really really cool guy.
I have used his services before and will again.

@B3RE

Run what ya got and enjoy. It’ll be good!
 
You say you have ported heads, do you have a flow sheet with them? There are several members here who port heads that open the valves beyond the max lift the heads flow to keep the valve open longer at peak flow. Once on the way open, and once on the way back closed. If the port isn't just all to crap turbulent at the new fully open point of .588/.577 (and the average porting job on a set of Edelbrocks should flow pretty well up to the .600 mark, maybe even beyond...) it should be of some improvement. Rob is dead on, the quicker that you get the valves off the seat to .200 lift and beyond, the snappier it's going to be. I think higher ratio would work pretty well with the big Comp XE/XHR cam, especially if you spray it, but I'm pretty sure that cam calls for more cylinder pressure than what you'd have with it installed on the recommended intake centerline. As far as staggering the rocker ratios, it's pretty common to run less exhaust ratio in the world of SBC's with a lot of claims made that most SBC's see zero improvement on the dyno with higher exhaust ratios dependent on the majority of cylinder heads, so it's mostly left at 1.5 to improve piston to exhaust valve clearance while running higher intake ratios (according to IIRC Joe Sherman and maybe Steve Brul'e, anyway). I've not come across any LA Chrysler testing, but I imagine @Rat Bastid and @PRH would probably have some hands on knowledge in the field.
 
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I’d say that is a really good combo you have there.
Adding rocker ratio does a few positive things.
A small narrowing of the LSA
Quicker lifting valves which is great for the intake charge. Quicker is always better on street cams.
Adds minor duration. The general consensus is 2*’s.
The added lift to .580/.577 is probably lifting the valve up into a higher and more favorable flow rate. IMO, I have often stated, while not needed, why not lift the valve as high as the heads flow well? It’s grabbing all the head has to offer in terms of flow which equals power.

Staggering rocker ratios can help. This is mainly a try it out and see and the dyno is a quick place to get that answer but less fun, though much more accurate over the drag strip. The power you’ll find will probably be small in terms of “The Seat of the Pants” feel, but might, just maybe, be a nice number on the report.

Overall, the cam is the one thing I’d change. But, everyone here will have their own cam to state is a great cam. The thing with camshafts is, ask 10 people there idea of a “BEST CAM” and you’ll get 10 different answers from idiots to pros.

One can argue that adding rocker ratio is introducing possible but easily (kind of, skill level dependent) avoidable problems with rocker geometry and wearing out valve springs. Ignore this and take the time to look if you need an upgraded spring and take the time to get the rockers where they need to be placed along with the right length pushrod. All of those problems go away when you do it right.

For help on rocker geometry, contact member B3, his name is Mike. He is a geometry freak and loves getting this stuff right.
(Not my word, his. He loves this stuff!)
He is also a really really cool guy.
I have used his services before and will again.

@B3RE

Run what ya got and enjoy. It’ll be good!
Thank you for your reply! I had thought I should see a better midrange? The added duration might affect low speed drivablility but perhaps increase top end HP? I could not make up my mind about the cam and finally got this one because it closely matched the specs of a Hughes engines flat tappet cam I had in the past and I really liked it. My builder suggested staggering the rocker ratios says it's very effective for..... Chevy motors yikes!... Love to hear from Mike and what his insight is.
You say you have ported heads, do you have a flow sheet with them? There are several members here who port heads that open the valves beyond the max lift the heads flow to keep the valve open longer at peak flow. Once on the way open, and once on the way back closed. If the port isn't just all to crap turbulent at the new fully open point of .588/.577 (and the average porting job on a set of Edelbrocks should flow pretty well up to the .600 mark, maybe even beyond...) it should be of some improvement. Rob is dead on, the quicker that you get the valves off the seat to .200 lift and beyond, the snappier it's going to be. I think higher ratio would work pretty well with the big Comp XE/XHR cam, especially if you spray it, but I'm pretty sure that cam calls for more cylinder pressure than what you'd have with it installed on the recommended intake centerline. As far as staggering the rocker ratios, it's pretty common to run less exhaust ratio in the world of SBC's with a lot of claims made that most SBC's see zero improvement on the dyno with higher exhaust ratios dependent on the majority of cylinder heads, so it's mostly left at 1.5 to improve piston to exhaust valve clearance while running higher intake ratios (according to IIRC Joe Sherman and maybe Steve Brul'e, anyway). I've not come across any LA Chrysler testing, but I imagine @Rat Bastid and @PRH would probably have some hands on knowledge in the field.
Thank you for your Reply, that is some great analysis. I don't have a flow sheet, my builder did the porting and I'm sure he didn't go all out, just hit the highspots. Do you have any knowledge of staggering the rocker ratios: 1.6 on intake and 1.5 on exhaust?
 
Thank you for your reply! I had thought I should see a better midrange?
Against what cam?
The added duration might affect low speed drivablility but perhaps increase top end HP?
Yes and yes
I could not make up my mind about the cam and finally got this one because it closely matched the specs of a Hughes engines flat tappet cam I had in the past and I really liked it.
What is missing is the amount of overlap the cam has and what it is being compared to.
My builder suggested staggering the rocker ratios says it's very effective for..... Chevy motors yikes!... Love to hear from Mike and what his insight is.
Well, Chevy, Ford or Dodge, an engine is an engine. With that said, outside of there basic engineering differences, generally speaking, there still V8 engines that work the same way.

Here is the key to a few things, what ever trick works on one may indeed work on another. What ever gains you power is the winner. Where ever you can find an edge, use it.

Some guys will pound their chest and say “I’ll only use mother MoPar parts! I’ll never use another brands part, screw that!”
This is IMO, a can be huge mistake. It also depends on the thickness of your wallet among other things.
 
Against what cam?

Yes and yes

What is missing is the amount of overlap the cam has and what it is being compared to.

Well, Chevy, Ford or Dodge, an engine is an engine. With that said, outside of there basic engineering differences, generally speaking, there still V8 engines that work the same way.

Here is the key to a few things, what ever trick works on one may indeed work on another. What ever gains you power is the winner. Where ever you can find an edge, use it.

Some guys will pound their chest and say “I’ll only use mother MoPar parts! I’ll never use another brands part, screw that!”
This is IMO, a can be huge mistake. It also depends on the thickness of your wallet among other things.
Guess what I was trying to do was compare the same cam with or without 1.6 rockers, I thought maybe the 1.6 rockers might give me more midrange on that same cam vs 1.5?
Those were my thoughts as well engines are engines should work similarly.
Got chevy valves in the heads shhh.... lol. I am def. willing to use whatever is available to make the performance better.
 
I don’t think you’ll get more mid range in any meaningful amount to jump and shout about but you should gain some top end. This amount is completely dependent on the head flow numbers to even guess about. Plain and simple, if the head supports more air and fuel flow, you’ll make more power up top.

Personally, if you dyno this engine, I got $5 that it’ll make 430+HP. Might see 450.

What are you doing for header pipe size? 1-3/4?
That’s where I’d go.
 
Don't the Edelbrock heads use long 11/32 stem single groove chevy valves anyway, lolol? Stock flow with Eddy heads is 240-243 between .600 to .700 according to the contributors here who have listed them on the small block head flow chart pages here.
Small Block Head Flow Chart
Something would have to be redone beyond mild cleanup to change the peak flow characteristics. So 3.90 gears and 28X11.50 et's. Mike at B3 will also have some input on the stagggered ratios, but I'm somewhat confident it mostly applies to the SB Chev world. Speaking of Hughes, I imagine Dave probably has tried staggered rocker ratios, too, being they sale roller rockers. What I have noticed is I haven't came across staggered rocker sets for LA engines like with some other engines.
 
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You would have to try the rockers to see. May add something...or nothing...or stay the same.
They will add 2-3* of effective duration & a little more lift.
 
I don’t think you’ll get more mid range in any meaningful amount to jump and shout about but you should gain some top end. This amount is completely dependent on the head flow numbers to even guess about. Plain and simple, if the head supports more air and fuel flow, you’ll make more power up top.

Personally, if you dyno this engine, I got $5 that it’ll make 430+HP. Might see 450.

What are you doing for header pipe size? 1-3/4?
That’s where I’d go.
Yeah, kinda seems like it will probably just shift the cam operating RPM range to the right.
I would be very happy with anything in 430-450 range. I'm putting in a light weight flywheel from Brewers and a McLeod twin disc. I'm planning on spinning it 6500rpm maybe a little more if cam and heads are still producing.
I have the TTI 3/4 step headers, the 3" TTI x pipe, straight into 2 super 44's and dumped in front of rear axle.
Don't the Edelbrock heads use long 11/32 stem single groove chevy valves anyway, lolol? Stock flow with Eddy heads is 240-243 between .600 to .700 according to the contributors here who have listed them on the small block head flow chart pages here.
Small Block Head Flow Chart
Something would have to be redone beyond mild cleanup to change the peak flow characteristics. So 3.90 gears and 28X11.50 et's. Mike at B3 will also have some input on the stagggered ratios, but I'm somewhat confident it mostly applies to the SB Chev world. Speaking of Hughes, I imagine Dave probably has tried staggered rocker ratios, too, being they sale roller rockers. What I have noticed is I haven't came across staggered rocker sets for LA engines like with some other engines.
Yes they are the 11/32 so little lighter.
I agree I don't think the port work is going to be a game changer and maybe in the future I should go with a port matched Victor intake.
Yeah I might give Dave a call and ask him about rocker stagger thats a good idea.
You would have to try the rockers to see. May add something...or nothing...or stay the same.
They will add 2-3* of effective duration & a little more lift.
Sounds like the 1.6's are going on, only question now is whether or not to stagger? I wonder what effect staggering will have on the duration.
 
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If you have 16 rockers, very easy to try the stagger idea.....
As I said 1.6 over 1.5 adds about 2-3* of effective duration & 6.7% more lift. By effective I mean the duration at the 050 lift point. Bear in mind the seat duration does not change. The higher rocker ratio has the effect of putting in a cam that has faster rate lobes.
 
Done deal 1.6 intake and 1.5 exhaust it is! Thank you all for your input! After I get it broke in I'll post some dyno content on and off NOS.
 
Try swapping them around and around for all the combinations.
1.5 both side, 1.6 both side then 1.6 / 1.5 on the intake /exhaust, then swap them. I think you’ll find the results interesting.
 
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