pros/cons to 1.7 RRs
10-28-2008, 04:59 PM
#1
pros/cons to 1.7 RRs Heard a few things about 1.7 RRs. Would just like to see what people think the pros and cons of selling my 1.6s and getting 1.7s would be. Just curious about it. I know it changes the lift and duration of the cam. Also, I've heard of running 1.6s AND 1.7s, splitting them on the intake/exhaust sides.
10-28-2008, 05:34 PM
#2
It seems that guys with stock cams are running them, but not many are goin over 1.6's with a aftermarket cam. I read where a few were having issues witht the valve events at high rpms running the 1.7's. Im no expert hopefully someone else can chime in.
10-28-2008, 07:35 PM
#4
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I went from 1.6s to 1.7s in my bolt on LT1 and picked almost 2 tenths and over 2 mph. I changed my shift points from 5900 to 6200 as well. I changed my valve springs and seals when i did the swap. Don't be discouraged to try it. I heard all the negative feedback about the 1.7s when I swapped, but it didn't deter me from doing it. Now 1.8s are available and people are still skeptical about stepping up. If extra lift and duration doesn't help, cam only LT1s wouldn't be any faster than stock cam LT1s...LOL
10-28-2008, 07:36 PM
#5
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i think that if you go with 1.7's you will want a bigger diameter valve stem... especially with an aftermarlet cam and using the correct pushrods to reach midlift...
1.7's will put you close to the edge of the stem...
1.7's will put you close to the edge of the stem...
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10-29-2008, 05:18 PM
#11
I went from 1.6s to 1.7s in my bolt on LT1 and picked almost 2 tenths and over 2 mph. I changed my shift points from 5900 to 6200 as well. I changed my valve springs and seals when i did the swap. Don't be discouraged to try it. I heard all the negative feedback about the 1.7s when I swapped, but it didn't deter me from doing it. Now 1.8s are available and people are still skeptical about stepping up. If extra lift and duration doesn't help, cam only LT1s wouldn't be any faster than stock cam LT1s...LOL
What did you end up with for a pushrod length, only problem I've ever heard of having with 1.7's was making sure you get the PR-length correct. I have a set of brand new Comp cams 1.7 RR that have been setting in the box for almost 4 years. Never got around to doing the swap from my 1.6 RR comp cams. I would assume you changed the valve springs to something in the .550 range. I think the numbers work out to be .521 lift on a 96 6 spd LT1 stock cam with 1.7 RR. Now I want to put them in the car if your saying you picked up 2mph and 2 tenths, WOW !
10-29-2008, 07:31 PM
#12
Had the scorpian 1.7's on my LT1 for over 2.5 years not problem. Cleared the stock valve covers and used the stock pushrod length. My car ran better than any other bolt-on LT1 car I came across.
IMO you have to swap out the valvesprings and stuff for the 1.6's might as well upgrade to the 1.7's, this is my opinion for the stock camshaft only.
Lift on my stock 96 cam with the 1.7's was .510/.521.
IMO you have to swap out the valvesprings and stuff for the 1.6's might as well upgrade to the 1.7's, this is my opinion for the stock camshaft only.
Lift on my stock 96 cam with the 1.7's was .510/.521.
10-29-2008, 10:49 PM
#13
All these threads lately about 1.7's are really making me want to put mine on. I just have to wait until some online store has the valve spring kit in stock that I'm going to get. 
Also, T/A KID. Did you run stock lifters and pushrods when you put your 1.7's in, or did you swap them out for different ones. I've been wondering if I should or not.
Also, T/A KID. Did you run stock lifters and pushrods when you put your 1.7's in, or did you swap them out for different ones. I've been wondering if I should or not.
10-29-2008, 11:51 PM
#14
I ran the stock 110,000 mile lifters, and the pushrods I spent $35.00 for some hardened stock length pushrods since mine did not come with hardened pushrods from the factory (mine is a 96).
10-30-2008, 05:43 AM
#15
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What did you end up with for a pushrod length, only problem I've ever heard of having with 1.7's was making sure you get the PR-length correct. I have a set of brand new Comp cams 1.7 RR that have been setting in the box for almost 4 years. Never got around to doing the swap from my 1.6 RR comp cams. I would assume you changed the valve springs to something in the .550 range. I think the numbers work out to be .521 lift on a 96 6 spd LT1 stock cam with 1.7 RR. Now I want to put them in the car if your saying you picked up 2mph and 2 tenths, WOW !
I maintained stock stock pushrod length, but just made sure I went hardened. I bought GM replacement valve springs good for .560. I found the part number in a search and got the springs, seals, etc all at one time. Hope this helps.
10-30-2008, 12:34 PM
#18
i would not use SA rockers at all!!!!!!
1.6 or 1.7 roller rockers(alum.for mild and chromoly for racing)
7/16 studs
flat guide plates
hardened .080 wall pushrods
titanium retainers
10* locks
pac 918s(new style) springs
larger rockers ONLY change valve lift which Lt1/4s seem to really respond well to........
1.6 or 1.7 roller rockers(alum.for mild and chromoly for racing)
7/16 studs
flat guide plates
hardened .080 wall pushrods
titanium retainers
10* locks
pac 918s(new style) springs
larger rockers ONLY change valve lift which Lt1/4s seem to really respond well to........
10-30-2008, 02:07 PM
#19
Yes, I agree on using only NSA 1.7 RR's. I already have the GMPP guideplates, GMPP 7/16 screw in studs, Hardened comp cams push-rods, LT-4 springs (.525 lift) and the 1.6 RR's from comp. So (LT14life JT), your suggesting that a (.550 or a little better spring) and a stock length pushrod (hardened, of course 
) will work fine ? I would think you would want to put a push-rod length checker on the setup. Factory length of stock pushrod is ( 7.20 ? I can't remember ). I have a set of Comp EX-614 springs new in the box ( I believe they are good for .600 lift ) would this be to much spring for the 1.7 RR comp upgrade on my current bolt-on setup ? If this will really add 2mph and 2 tenths to my current time, I like the sound of running a 12.40 @ 111 mph with a stock cam & stock heads full bolt-on car !
) will work fine ? I would think you would want to put a push-rod length checker on the setup. Factory length of stock pushrod is ( 7.20 ? I can't remember ). I have a set of Comp EX-614 springs new in the box ( I believe they are good for .600 lift ) would this be to much spring for the 1.7 RR comp upgrade on my current bolt-on setup ? If this will really add 2mph and 2 tenths to my current time, I like the sound of running a 12.40 @ 111 mph with a stock cam & stock heads full bolt-on car !
10-30-2008, 02:49 PM
#20
i would not recommend the Lt4 valve springs at all unless you are running the sodium filled Lt4 valves....
besides they dont really have enough seat pressure (105lbs.)you should be looking at a spring with atleast 125lbs on the seat,set up at 1.75-1.80 installed height.
besides they dont really have enough seat pressure (105lbs.)you should be looking at a spring with atleast 125lbs on the seat,set up at 1.75-1.80 installed height.