Discuss Head Work - LS1LT1 Forum : LT1, LS1, Camaro, Firebird, Trans Am, Engine Tech Forums

Welcome to LS1LT1.com/LS3forums.com - please click here to register...

 
LinkBack Thread Tools
post #1 of 12 (permalink) Old 11-04-2012, 10:26 PM Thread Starter
Regular Member
 
Join Date: May 2012
Location: USA
Posts: 40
 
Head Work

So i was thinking about doing some head work on my lt1 when i do the headers and ORY. I was thinking about 1.7" roller rockers, but I've heard that will need new springs, pushrods, valve covers and some additional mods. Has anyone had any expirience with this or know what exactly this upgrade will need? Also would there be any of this work for 1.6" roller rockers? Any help would be appreciative.

1993 Camaro Z28 M6. Yukon 3.73s, K&N CAI, Pacesetter Longtubes, Custom 3" ORX w/ moroso spiral flows, UMI LCAs, PHB, Strut Brace.
marcz2893 is offline  
Sponsored Links
Advertisement
 
post #2 of 12 (permalink) Old 11-05-2012, 03:25 AM
Regular Member
 
Viper's Avatar
 
Join Date: Jul 2010
Location: New Mexico
Posts: 1,052
 
Viper is offline  
post #3 of 12 (permalink) Old 11-05-2012, 11:17 AM Thread Starter
Regular Member
 
Join Date: May 2012
Location: USA
Posts: 40
 
Ok so the springs used in the aritcle are rated for .600 lift. with 1.7"RRs that will generate .595" of lift. So i would need even beefier springs. but this did help alot! thanks.

1993 Camaro Z28 M6. Yukon 3.73s, K&N CAI, Pacesetter Longtubes, Custom 3" ORX w/ moroso spiral flows, UMI LCAs, PHB, Strut Brace.
marcz2893 is offline  
post #4 of 12 (permalink) Old 11-05-2012, 01:22 PM
Regular Member
 
Dynamic396's Avatar
 
Join Date: Mar 2012
Location: Newman Lake, WA
Posts: 1,000
 
If you also change to springs that will support it, I'd run 1.7's, no problem. You'll pick up a decent little gain from it without affecting much else. The LT1 springs suck anyway, so you'll want better ones anyway. I would also switch to 7/16" rocker studs at the same time. Assuming you have a stock camshaft, you won't be anywhere near .595" lift with 1.7 rockers, so don't worry about that.

The one thing that I will also say is that if you plan on upgrading your camshaft later down the road (highly recommended), 1.7's would be extremely aggressive on most of the common grinds that guys are using in the LT1's. I say that to keep you from having to buy another set of lesser ratio rockers later on to make reliable use of a better cam later on.

1995 Camaro Z-28, M6, 396 stroker, Scat forged 3.875" crank, Scat Ultra Q-Lite 6" H-beams, Icon forged pistons (4.030"), splayed 4 bolt w/ARP studs, 12.25:1, AFR 210 heads (2.08"/1.6", 58cc), Comp Ultra Pro Magnum XD 1.7:1 rockers, GM847 cam (234/242 .611"/.632"), Edelbrock LT4 air-gap intake, Spec Stage 3+ clutch, Fidanza aluminum flywheel, 24x conversion, 0411 PCM, TPIS 58mm, Bosch III 42# injectors, Aeromotive 340, Kook's stepped LT's, Kook's custom stainless 3-1/2" merge ORY, Magnaflow
Dynamic396 is offline  
post #5 of 12 (permalink) Old 11-05-2012, 07:56 PM Thread Starter
Regular Member
 
Join Date: May 2012
Location: USA
Posts: 40
 
Quote:
Originally Posted by Dynamic396 View Post
If you also change to springs that will support it, I'd run 1.7's, no problem. You'll pick up a decent little gain from it without affecting much else. The LT1 springs suck anyway, so you'll want better ones anyway. I would also switch to 7/16" rocker studs at the same time. Assuming you have a stock camshaft, you won't be anywhere near .595" lift with 1.7 rockers, so don't worry about that.

The one thing that I will also say is that if you plan on upgrading your camshaft later down the road (highly recommended), 1.7's would be extremely aggressive on most of the common grinds that guys are using in the LT1's. I say that to keep you from having to buy another set of lesser ratio rockers later on to make reliable use of a better cam later on.
ok that helps alot. So just to be clear, 1.7" is too much for a bigger cam? (that i will be doing in the future), as of right now i just have time and money for a bolt on setup. Would 1.6" be better then? Also, would u recomend any specific manufacturer or site for the rockers and springs?

1993 Camaro Z28 M6. Yukon 3.73s, K&N CAI, Pacesetter Longtubes, Custom 3" ORX w/ moroso spiral flows, UMI LCAs, PHB, Strut Brace.
marcz2893 is offline  
post #6 of 12 (permalink) Old 11-05-2012, 08:00 PM
Whistles go Whoooooooooo
 
ShowNoMercy's Avatar
 
Join Date: Feb 2008
Posts: 16,472
 
I would stick with a 1.6 rocker unless you are 100% you won't get a cam later on. As pointed out, with a aftermarket cam you don't need the added lift from a 1.7 and it becomes overly aggresive.

I like comp cam pro mags, I believe they have been superseded by the new ultra pro mags, also great rockers. A steel full roller rocker will always be a little louder than a aluminum rocker, but I like steel. It makes me feel safer.

Lately I do quick google searches for cheapest price and then give it to Summit for them to match/beat.

Una salus victis nullam sperare salutem

If it ain't ARP, it ain't right.
Quote:
Originally Posted by sweetbmxrider View Post
I have a heavily modified lt1.


https://www.facebook.com/pages/The-U...30966313667982
ShowNoMercy is offline  
post #7 of 12 (permalink) Old 11-05-2012, 08:13 PM Thread Starter
Regular Member
 
Join Date: May 2012
Location: USA
Posts: 40
 
ok, and yea there will be an engine rebuild once i get out of school. thanks for the help

1993 Camaro Z28 M6. Yukon 3.73s, K&N CAI, Pacesetter Longtubes, Custom 3" ORX w/ moroso spiral flows, UMI LCAs, PHB, Strut Brace.
marcz2893 is offline  
post #8 of 12 (permalink) Old 11-06-2012, 09:59 AM
Regular Member
 
Dynamic396's Avatar
 
Join Date: Mar 2012
Location: Newman Lake, WA
Posts: 1,000
 
Most guys are using camshafts ground with the Comp XFI lobes, either off-the-shelf, or custom grinds, and I have nothing at all against them. They just have very aggressive ramp rates and are very "square" over the nose. It takes some careful valve train parts selection and setup to make them work well (and reliably). You would really be pushing things, in my opinion, to run a 1.7 rocker with an XFI lobe in a street application. They were designed around 1.6 rockers and beehive springs with their lighter retainers - and work very well with them.

The other thing that comes into play here is that you really don't NEED 1.7 rockers with stock heads and a decent camshaft. Even the best ported stock head is not going to make use of the additional lift of a 1.7, so at that point, you're just adding additional stress on your valve train, with little or no benefit from it.

I chose to use 1.7 rockers on my current 396 build, but it was carefully planned. I am intentionally using a camshaft (GM847) with slightly less aggressive lobes over the nose (duration at .200" tappet lift), but with a little more lift, as compared to a comparable XFI lobe. I am also using AFR 210 heads that continue to flow crazy numbers to well over .650" lift, so I wanted the extra lift that a 1.7 would provide to feed those extra cubes. Plus, I'm using $400 Pacaloy valve springs, titanium retainers and extremely lightweight valves to control those very fast opening rates.

Everything has to be a carefully planned package...

1995 Camaro Z-28, M6, 396 stroker, Scat forged 3.875" crank, Scat Ultra Q-Lite 6" H-beams, Icon forged pistons (4.030"), splayed 4 bolt w/ARP studs, 12.25:1, AFR 210 heads (2.08"/1.6", 58cc), Comp Ultra Pro Magnum XD 1.7:1 rockers, GM847 cam (234/242 .611"/.632"), Edelbrock LT4 air-gap intake, Spec Stage 3+ clutch, Fidanza aluminum flywheel, 24x conversion, 0411 PCM, TPIS 58mm, Bosch III 42# injectors, Aeromotive 340, Kook's stepped LT's, Kook's custom stainless 3-1/2" merge ORY, Magnaflow
Dynamic396 is offline  
post #9 of 12 (permalink) Old 11-06-2012, 03:22 PM
Regular Member
 
95 Firehawk's Avatar
 
Join Date: Dec 2011
Location: McDonough, GA
Posts: 562
 
I mostly agree with what was said about 1.7's, however a 1.7 can be used with aggressive lobes so long as you aren't planning to spin the motor so high. A 1.7 will lift the valve 6.25% higher in the same amount of time as a 1.6 (faster acceleration), and also apply 6.25% more force on the pushrod side of the rocker (F=MA), if they're both at the same rpm. If you slow the valve train down by the same amount that the rocker adds, you will get the same acceleration and force on the valve train. So if a said valve train can handle 1.6s at 6800 rpm, the same valve train will apply the same forces as 1.7s at 6400 rpm (6400 x 1.0625 = 6800). Like Dynamic said, everything has to be planned properly. If you choose a cam that needs higher rpms, you will be pushing it with 1.7s, but if you choose a cam that you will be shifting closer to 6200, you will be fine with 1.7s, even with aggressive lobes (with proper supporting components, of course).

As mentioned, this also goes hand in hand with the heads you are using. Makes no sense to have the additional lift (and stress) if your heads can't take advantage of it.


Sent from my iPhone using Autoguide.com App

1995 Firehawk #528 resto-mod underway

Planned 383 rebuild: 195cc competition LT4 AFR heads, custom cam grind (still debating specs), 6" or 5.85" rods, forged internals

Upgraded T56: Viper mainshaft and 2nd gear, steel 3/4 shift fork, Billet keys 1-4, bronze shifter cup, internals Cryo'd and REM'd
95 Firehawk is offline  
post #10 of 12 (permalink) Old 11-06-2012, 08:08 PM Thread Starter
Regular Member
 
Join Date: May 2012
Location: USA
Posts: 40
 
SO with the 1.7" RR i realize that it will limit my options. But for now with the stock cam, would 1.6" be worth it? Getting the 1.7"s, FOR NOW, i think is my best choice, in the future with a cam, i know it will take a specific cam/lobe type, but i'm prepared for that.

1993 Camaro Z28 M6. Yukon 3.73s, K&N CAI, Pacesetter Longtubes, Custom 3" ORX w/ moroso spiral flows, UMI LCAs, PHB, Strut Brace.
marcz2893 is offline  
post #11 of 12 (permalink) Old 11-07-2012, 09:37 AM
Regular Member
 
Dynamic396's Avatar
 
Join Date: Mar 2012
Location: Newman Lake, WA
Posts: 1,000
 
Quote:
Originally Posted by marcz2893 View Post
SO with the 1.7" RR i realize that it will limit my options. But for now with the stock cam, would 1.6" be worth it? Getting the 1.7"s, FOR NOW, i think is my best choice, in the future with a cam, i know it will take a specific cam/lobe type, but i'm prepared for that.
I wouldn't hesitate to run 1.7's on a stock camshaft if you put a good set of studs, springs and retainers on it, too. They'll put you at around .510"/.521" lift and you'll pick up a degree or two more effective duration at the valve. Not a bad mod for a couple of hours with the valve covers off, really. But, down the road, it will definitely limit your choices, especially if you intend to stay with stock heads.

Sure, you could limit rpm to keep valve train forces in check if you wanted to run an XFI-like lobe profile like Firehawk was saying, but why...? The reason you're putting the camshaft in there in the first place is so that you can spin it a bit and make some power up top. Plus, even with the 1.6 rockers that they were designed for, the XFI's, for the most part, are generating lift numbers that a stock head will never make full use of this side of hundreds of hours of porting, valve and flow bench work. And all for what...? Buy a set of good heads and move on.

Don't get me wrong. I'm not saying that 1.7's can't be run with a large camshaft. Heck, I'm doing it...! But, you'll just have to be very careful with valvetrain component selection to make sure you haven't created a ticking time bomb. Plus, evaluate what you will have in the end. If you take two of the middle-of-the-road XFI grinds for the LT1, the 268 and the 280, you'll see that with the recommended 1.6 rockers the 268 has lift specs of .570"/.565" and the 280 has lift specs of .576"/.570". To make even moderate use of these lift specs on a stock head, it will require some pretty extensive porting and valve work. Now you add the 1.7 rockers and your 268 is now .606"/.600" and your 280 is now .612"/.606". Even with a proper set of springs, retainers, valvetrain geometry and everything it will take to make it hold together, there's no way that a stock head will make use of these numbers, no matter what you do to it.

I'm not trying to beat up on the XFI grinds. They are good cams, and work well in the right setup. They are just very aggressive over the nose, making valve control a big issue when using them. Adding 1.7 rockers just makes things that much worse, and unnecessarily, I would argue.

Having said all of this, if you wanted to run 1.7's, you could simply have a camshaft custom ground to match your 1.7's when the time came for a cam swap. The cam grinder that I use has over 8500 cam profiles to choose from, so spec'ing out the perfect cam is not hard to do.

1995 Camaro Z-28, M6, 396 stroker, Scat forged 3.875" crank, Scat Ultra Q-Lite 6" H-beams, Icon forged pistons (4.030"), splayed 4 bolt w/ARP studs, 12.25:1, AFR 210 heads (2.08"/1.6", 58cc), Comp Ultra Pro Magnum XD 1.7:1 rockers, GM847 cam (234/242 .611"/.632"), Edelbrock LT4 air-gap intake, Spec Stage 3+ clutch, Fidanza aluminum flywheel, 24x conversion, 0411 PCM, TPIS 58mm, Bosch III 42# injectors, Aeromotive 340, Kook's stepped LT's, Kook's custom stainless 3-1/2" merge ORY, Magnaflow
Dynamic396 is offline  
post #12 of 12 (permalink) Old 11-08-2012, 12:25 AM Thread Starter
Regular Member
 
Join Date: May 2012
Location: USA
Posts: 40
 
maybe i'll hold back for now. get the cam heads and valve train as a package and do the entire top end as a unit. at least then i am not matching parts based on what i already have but a designed unit. thanks for all the help dudes, and hopefully faster times r in the near future.

1993 Camaro Z28 M6. Yukon 3.73s, K&N CAI, Pacesetter Longtubes, Custom 3" ORX w/ moroso spiral flows, UMI LCAs, PHB, Strut Brace.
marcz2893 is offline  
Sponsored Links
Advertisement
 
Reply

Bookmarks

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the LS1LT1 Forum : LT1, LS1, Camaro, Firebird, Trans Am, Engine Tech Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in









Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome