1.7 rr with a cc305
Thread Starter
On The Tree
Joined: Jan 2004
Posts: 188
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From: Houston/ Austin, TX
1.7 rr with a cc305 Im thinkin about replacing my stock rockers with some better RR, but im unsure of what to get. I currently have a 96 forumul with a cc305, ported heads, and a valve job. Would it be a good idea to go with 1.7 rr or would 1.6 be better? Why dont more people use 1.7 rockers?
How would they affect my gas mileage? And what kinda power increase would i most likely get?
The engine has 3k miles on it.
How would they affect my gas mileage? And what kinda power increase would i most likely get?
The engine has 3k miles on it.
Thread Starter
On The Tree
Joined: Jan 2004
Posts: 188
Likes: 0
From: Houston/ Austin, TX
I thought that was true, but i saw some listed for the LT1 at www.thunderracing.com so i was curious.
Originally Posted by LT1TECH2003
you cant buy 1.7 rockers for a small block except for ls1
Also www.flatlanderracing.com 1.7 RR are available.
With that cam though it's already kinda big I would aim for under .600 lift to be safe if you can stay under that you should be ok. Anything over that may require a "clay" testing procedure to check it clearing the pistions like MM said.
The only other thing is I don't understand why it isn't run commonly but I don't really care either I plan on buying them also. I figure swapping those chits out are a bitch with all those damm threads why go 1.6?? when I can go 1.7 for the same price.
There is a difference in how it stress the studs though. So to resolve that and add some extra protection I plan on changing our "stock" rocker studs. Which are inside the heads 3/8 th but uptop where you screw on your Rockers it's 7/16th thread which is a bit weaker. I'm gonna upgrade to 3/8th below and up top. Those studs should give some prevention to the added stress of the lift.
WWW.racenet.net has 1.8s!!!!! but I cram to run those without seeing them more commonly, the rockers studs breaking or ripping out would not make for a pretty site while blasting through a 5000 rpm romp.
Calculate your lift example shown using .525 lift w/1.5 rockers.
.525 / 1.5 = .350 so if you ran 1.7's it would be .350 x 1.7= .595 lift.
if your cam is advertised with .526 lift using 1.6 then you have to divide .525 by 1.6=.343 which would would change your 1.7 lift.
Look into those studs if you wanna play it safe. But even then I haven't ran it YET so I can't gaurantee it or give you mileage with them on.
With that cam though it's already kinda big I would aim for under .600 lift to be safe if you can stay under that you should be ok. Anything over that may require a "clay" testing procedure to check it clearing the pistions like MM said.
The only other thing is I don't understand why it isn't run commonly but I don't really care either I plan on buying them also. I figure swapping those chits out are a bitch with all those damm threads why go 1.6?? when I can go 1.7 for the same price.
There is a difference in how it stress the studs though. So to resolve that and add some extra protection I plan on changing our "stock" rocker studs. Which are inside the heads 3/8 th but uptop where you screw on your Rockers it's 7/16th thread which is a bit weaker. I'm gonna upgrade to 3/8th below and up top. Those studs should give some prevention to the added stress of the lift.
WWW.racenet.net has 1.8s!!!!! but I cram to run those without seeing them more commonly, the rockers studs breaking or ripping out would not make for a pretty site while blasting through a 5000 rpm romp.
Calculate your lift example shown using .525 lift w/1.5 rockers.
.525 / 1.5 = .350 so if you ran 1.7's it would be .350 x 1.7= .595 lift.
if your cam is advertised with .526 lift using 1.6 then you have to divide .525 by 1.6=.343 which would would change your 1.7 lift.
Look into those studs if you wanna play it safe. But even then I haven't ran it YET so I can't gaurantee it or give you mileage with them on.
With the CC305 and 1.7's you'll be looking at .578 lift. Plenty of piston to valve clearance, as that's not a huge player on an LT1 until you get up closer to .600 or so. Depending on the flowing characteristics of the ported heads, that should put your valve transition into the meat of the flow. Most ported LT1 castings I see usually peak at about .550 or .600, so the more trasition time you see there the better. Either way, you'll see a gain as the 1.6 ratio on a CC305 is only a .544 lift, in which case you wouldn't even see your peak flow. I'm just being general here.
I was thinking along the lines you are, and I already have a set of 1.7's waiting to go on my 224/230 setup, just working bugs out on the car first.
Don't forget you're going to need hardened pushrods (if you don't already have them) and the LT1 guideplates. Thunderracing sells those.
I was thinking along the lines you are, and I already have a set of 1.7's waiting to go on my 224/230 setup, just working bugs out on the car first.
Don't forget you're going to need hardened pushrods (if you don't already have them) and the LT1 guideplates. Thunderracing sells those.
