Short Block Build
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,810
From: Cool Northern Michigan
Tks HeadsU.P.
Which would you suggest somewhere in the middle $$. Tks
https://www.summitracing.com/int/sea...d=1.6%20rocker
Which would you suggest somewhere in the middle $$. Tks
https://www.summitracing.com/int/sea...d=1.6%20rocker
Sometimes lack of research on your part causes the rocker to strike the valvespring retainer. But that's rare.
Sometimes the extra ratio can cause spring bind. But that's rare also.
The cam you selected is mild enough that the two above issues should be of no concern. However, I would rather not recommend rockers or cam brands.
Last edited by HeadsU.P.; Jan 8, 2020 at 04:43 PM.
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,810
From: Cool Northern Michigan
I 'm usually not a big fan of altered rocker ratios that make-up for lost lift from a incorrect cam. Its always better to order the correct dur / lift / LSA.
But in your case where a "top-end" kit has already been ordered, then by all means, get the 1.6s. The more I read on that kit, the better it looks. And you can trust Edelbrock has tested that combo a billzillion times with good results. And I believe those horsepower numbers are not exaggerated. Makes a nice street cruiser.
Last edited by HeadsU.P.; Jan 8, 2020 at 12:05 PM.
Burning Brakes
Joined: Nov 2012
Posts: 788
Likes: 100
From: Indianapolis IN
Always check for pushrod bind in the head/guide area when stepping up the ratio.
The pushrod moves closer toward the stud when the ratio is increased, unless the head was already machined for this clearance by the mfgr. "Better safe than sorry".
I think the 1.6's are a great recommendation with this cam, but only on the intake side, and it should equal 219* / .496" @ the intake valve w/1.6 on it. I'm sure the head passes more cfm @ .496" than .464" lift.
If you use a 1.6 on the exhaust also you may very well loose power over the original 1.5/ 1.5's !
And I would ask edelbrock if the added ratio would require a slight shim for the intake side to increase spring rate, and whether or not they tested with 1.6's also.
$.02
The pushrod moves closer toward the stud when the ratio is increased, unless the head was already machined for this clearance by the mfgr. "Better safe than sorry".
I think the 1.6's are a great recommendation with this cam, but only on the intake side, and it should equal 219* / .496" @ the intake valve w/1.6 on it. I'm sure the head passes more cfm @ .496" than .464" lift.
If you use a 1.6 on the exhaust also you may very well loose power over the original 1.5/ 1.5's !
And I would ask edelbrock if the added ratio would require a slight shim for the intake side to increase spring rate, and whether or not they tested with 1.6's also.
$.02
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,810
From: Cool Northern Michigan
Excellent point on the heads pushrod slot. I would hope Eddy figured that out long ago.
I will admit, I sat in the back of math class and nodded off on occasion. But this is how I came up with valve lift on the Exh side.
First I find the lobe lift by taking their data of .470" lift on the exhaust and dividing by the std rocker ratio of 1.5.
This establishes the cam lobe is 313.33".
Then I multiply that figure by the new rocker ratio of 1.6.
It came out to: 501.28 lift.
The reason the exhaust duration & lift is favored more than the intake is, that its been said that Chevys are terrible at exhausting gases. They have been that way for decades. This is regardless of what type of exhaust system is incorporated. But long tube headers helped.
So over the years, as the story goes, old Chevys ran better with dual pattern camshafts. Hold that Exh valve open a little longer. Maybe so, maybe not.
I will admit, I sat in the back of math class and nodded off on occasion. But this is how I came up with valve lift on the Exh side.
First I find the lobe lift by taking their data of .470" lift on the exhaust and dividing by the std rocker ratio of 1.5.
This establishes the cam lobe is 313.33".
Then I multiply that figure by the new rocker ratio of 1.6.
It came out to: 501.28 lift.
The reason the exhaust duration & lift is favored more than the intake is, that its been said that Chevys are terrible at exhausting gases. They have been that way for decades. This is regardless of what type of exhaust system is incorporated. But long tube headers helped.
So over the years, as the story goes, old Chevys ran better with dual pattern camshafts. Hold that Exh valve open a little longer. Maybe so, maybe not.
Last edited by HeadsU.P.; Jan 8, 2020 at 04:45 PM.
Thread Starter
Intermediate
Joined: Aug 2019
Posts: 39
Likes: 0
From: Lethbridge
Short Block Build
Always check for pushrod bind in the head/guide area when stepping up the ratio.
The pushrod moves closer toward the stud when the ratio is increased, unless the head was already machined for this clearance by the mfgr. "Better safe than sorry".
I think the 1.6's are a great recommendation with this cam, but only on the intake side, and it should equal 219* / .496" @ the intake valve w/1.6 on it. I'm sure the head passes more cfm @ .496" than .464" lift.
If you use a 1.6 on the exhaust also you may very well loose power over the original 1.5/ 1.5's !
And I would ask edelbrock if the added ratio would require a slight shim for the intake side to increase spring rate, and whether or not they tested with 1.6's also.
$.02
The pushrod moves closer toward the stud when the ratio is increased, unless the head was already machined for this clearance by the mfgr. "Better safe than sorry".
I think the 1.6's are a great recommendation with this cam, but only on the intake side, and it should equal 219* / .496" @ the intake valve w/1.6 on it. I'm sure the head passes more cfm @ .496" than .464" lift.
If you use a 1.6 on the exhaust also you may very well loose power over the original 1.5/ 1.5's !
And I would ask edelbrock if the added ratio would require a slight shim for the intake side to increase spring rate, and whether or not they tested with 1.6's also.
$.02
I'll let you guy's know what Edlebrock says in regards to the increased Rocker ratio shimming on the intake side & testing of this. Hopefully they did, and have an answer.
Tks,
Myles
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,063
From: altered state
St. Jude Donor '05
Ought to see 350 easy as heads up said
If you only have 1.5 run them, if you want more and score the 1.6 you can. Dont think it will make a big difference
You can run roller tips too and fit under the valve cover no need for full rockers. 1600 is cheap for what you get.
If you only have 1.5 run them, if you want more and score the 1.6 you can. Dont think it will make a big difference
You can run roller tips too and fit under the valve cover no need for full rockers. 1600 is cheap for what you get.
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,810
From: Cool Northern Michigan
What cuisinartvette is getting at is, another option to getting a little more valve lift is the popular Comps 1.52 ratio rockers. They have the roller tips, are very durable, not too tall, use the locking nuts and are fair priced. Then, with the 1.52 you are rest assured the pushrods will be well away from the slot in the cyl head.
This altered ratio concept brings up another point:
I am not an expert on Eddy heads, but normally when "Guide Plates" are involved and I repeat, normally, the pushrod slot is rounded out for pushrod clearance instead of oblong. If this is the case on those Eddy heads which HAVE the guide plates, then the 1.6 rockers will work fine w/o the pushrods rubbing the head.
How much more H.P. between 1.5 and the 1.6 rockers?
Easy, non debatable, hands-down, correct answer is:
Between 1 & 1,000
This altered ratio concept brings up another point:
I am not an expert on Eddy heads, but normally when "Guide Plates" are involved and I repeat, normally, the pushrod slot is rounded out for pushrod clearance instead of oblong. If this is the case on those Eddy heads which HAVE the guide plates, then the 1.6 rockers will work fine w/o the pushrods rubbing the head.
How much more H.P. between 1.5 and the 1.6 rockers?
Easy, non debatable, hands-down, correct answer is:
Between 1 & 1,000
Last edited by HeadsU.P.; Jan 8, 2020 at 04:52 PM.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
On edelbrock site's page for kit # 2038 ... scroll down to "installation notes" ... Do Not Exceed 5,500 RPM ... you've been tipped off
IMFB, routine blasts to 6K+ are just that; routine
Now that ya know how to back-calculate RAR & valve lift increase w/ 1.6:1 RAR ... perhaps ya can do likewise with duration @ 0.050" LL ?
https://www.edelbrock.com/e-street-t...hevy-2038.html
IMFB, routine blasts to 6K+ are just that; routine
Now that ya know how to back-calculate RAR & valve lift increase w/ 1.6:1 RAR ... perhaps ya can do likewise with duration @ 0.050" LL ?
https://www.edelbrock.com/e-street-t...hevy-2038.html
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,810
From: Cool Northern Michigan
The extra rocker ratio does effect duration too. The idea is the valve lift is increased, therefore it takes longer duration for the valve to close.
But I'm not getting into all that. Its not that important here.
But I'm not getting into all that. Its not that important here.
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
Thread Starter
Intermediate
Joined: Aug 2019
Posts: 39
Likes: 0
From: Lethbridge
Hi Guy's:
Here is Edlebrocks response to a shim on the intake side of the Heads in the 2038 kit.
Your Product Question:
Hi: Do you know if the heads in the 2038 Top end kit have been tested with 1.6 Ration Rocker Arms ? If so would the added ratio from 1.5 to 1.6 require a slight shim for the intake side to increase spring rate.
Tks Myles
Answer:
Myles, Yes you can use 1.6 ratio rocker arms on the Edelbrock E-Street cylinder heads, and you do not need to add any shims at all, no need to increase the spring pressures for using 1.6 ratio rocker arms, not sure why you want to use 1.6 ratio rocker arms, for no gain in performance....
Edelbrock - January 9, 2020
Myles
Here is Edlebrocks response to a shim on the intake side of the Heads in the 2038 kit.
Your Product Question:
Hi: Do you know if the heads in the 2038 Top end kit have been tested with 1.6 Ration Rocker Arms ? If so would the added ratio from 1.5 to 1.6 require a slight shim for the intake side to increase spring rate.
Tks Myles
Answer:
Myles, Yes you can use 1.6 ratio rocker arms on the Edelbrock E-Street cylinder heads, and you do not need to add any shims at all, no need to increase the spring pressures for using 1.6 ratio rocker arms, not sure why you want to use 1.6 ratio rocker arms, for no gain in performance....
Edelbrock - January 9, 2020
Myles
Last edited by Roentgen; Jan 10, 2020 at 09:06 AM.
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,810
From: Cool Northern Michigan
Interesting. Does not state minimal gain, or slight gain or 5 H.P. Just said NO gain.
I beg to differ, but I want David Freiburger standing next to me at the dyno.
I know those ads in performance catalogs claiming 20-25 horse gains by using their 1.6 roller tip rockers, is ridiculous.
However:
Anytime a Intake Valve is held open a little longer or opened a little bigger, that's just that much more CFM to enter the cylinder, more mixture to be compressed, which equals more power. But, whatever. He's the tech guy.
I still think the correct statement from him should have been a modest gain depending on application.
I beg to differ, but I want David Freiburger standing next to me at the dyno.
I know those ads in performance catalogs claiming 20-25 horse gains by using their 1.6 roller tip rockers, is ridiculous.
However:
Anytime a Intake Valve is held open a little longer or opened a little bigger, that's just that much more CFM to enter the cylinder, more mixture to be compressed, which equals more power. But, whatever. He's the tech guy.
I still think the correct statement from him should have been a modest gain depending on application.
Last edited by HeadsU.P.; Jan 10, 2020 at 10:23 AM.
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,810
From: Cool Northern Michigan
Yup. More of a opinion statement than a fact statement. Without opening a huge can of worms here, I would like to see dyno runs with 1.5, then 1.6 only.
And NO OTHER MODS. Most of those dyno test videos I have seen on YouTube include more than one alteration. Such as: after changing rocker ratio + a bigger carb, + more timing, bigger header tubes, etc. (Not a fair test assumption)
And NO OTHER MODS. Most of those dyno test videos I have seen on YouTube include more than one alteration. Such as: after changing rocker ratio + a bigger carb, + more timing, bigger header tubes, etc. (Not a fair test assumption)
Last edited by HeadsU.P.; Jan 10, 2020 at 10:41 AM.
Instructor
Joined: Oct 2016
Posts: 150
Likes: 25
From: Acton MA
but I want David Freiburger standing next to me at the dyno.
Anytime a Intake Valve is held open a little longer or opened a little bigger, that's just that much more CFM to enter the cylinder, more mixture to be compressed, which equals more power. But, whatever. He's the tech guy.
Anytime a Intake Valve is held open a little longer or opened a little bigger, that's just that much more CFM to enter the cylinder, more mixture to be compressed, which equals more power. But, whatever. He's the tech guy.
Last edited by Khibbs; Jan 10, 2020 at 11:20 AM.