stevil

ThunderRacing carries the GM guideplates, I got them with my 1.6 ProMags. PN# 14011051

I've never heard of the 1.7RR, wish I would have known about them in the spring. I love my 1.6RR, I gained 20rwhp with those and an electric waterpump. Stepping up to the 1.7 sounds very tempting.

You should hit the track, and get better times than the Tazzo.

I did it with 1.6RR, why not? There are some other factors that affect my times I'm sure, like weight and weather. But the best I did before the rockers was 13.4 and almost 103 mph. Now I'm running alot faster, gained over 3mph.

05/10/2002 @ Norwalk
Cool spring weather, around 50°
K&N, MACs, !cat, cutout, CSI, and other misc
13.456 @ 102.52 w/ 1.999 sixty

05/19/2003 @ Norwalk
Warmer, around 65°
above mods, with 1.6RR
13.369 @ 103.94 w/ 1.994 sixty

10/18/2003 @ Norwalk
Cool fall weather, around 40°
same mods, !FSB, !STB
13.021 @105.59 w/ 1.916 sixty

All those are with drag radials. I tried my street tires today, since I stay even or pull LS1 F-bods and Vettes up to 130+ on the freeway. I ended up with a nice 107.1 trap.

Spartus

MattysTA, why did you go with the GM guideplates and not ones from Crane, Comp, or even the ones FlatLander racing carries? I know the spacing of the valves is greater on the Lt1 heads, but the studs should still have the same spacing as any SBC head.... So then if using SBC guide plates on LT1 heads, technically the area between the slots for the pushrods should be wider too. That way things will line up. If not I would think that one rocker would be hanging off the edge of the valve..

Did you need to rotate the guide plates a whole bunch to help line things up? Also, did you check geometry after installing these rocker arms? I'm curious if a shorter pushrod is needed.

-Tom

94bird

When going with a higher rocker ratio, you'll need a longer pushrod than stock, if the stock one doesn't work. You're moving the pushrod closer to the stud, which is further away than the original 1.5 ratio location. Understand?

I agree though, I've seen noone mention checking their rocker arm geometry after going to a 1.7 ratio. It's very possible a .050" or so longer pushrod should be used.

SAR2K

I've been running 1.7s for well over a year now with stock length push rods. The main factor in the geometery with this set up for me was guide plates. For that the GM plates were the answer to my slight alignment issue.
Steve...

stevil

Here is a pic of the good 'ol flat GM guideplates.

MattysTA

The studs were one of the main reasons i went with the gmpp guideplates. the studs are also spaced farther apart than the regular small blocks. the diffrence between lt1s and regular smallblocks is the location of the pushrods are the same. the location of the valves are .50 further apart. to retain correct alighnment of the valves to pushrods, the studs also had to be moved slightly to now give the rockers an angled set-up to retain correct pushrod to valve stem alignment.Yes i did take a look at how my goemetry is and it is working out well. although it may not work for everyone with the stock length pushrods due to slight casting differences maybe, but mine are working out well...

MattysTA

That was the only real problem i was having also, then i switch out the manley ones for the gmpp's and voila! problems solved

billygoat

from the looks of it im going to add these to mine also, i
was just wondering if there is any change in gas milage with the 1.7 s , and maby i missed it but is a re tune recommended with these installed, i got shortys, underdrive pullys, no cat, three inch cat back, cai, thanks or does any one think i should have had a retune already wiht what i got now,

MattysTA

well i havent gone down on the gas milege much while driving normally(which isnt often lol) but im always on it when i drive my car so i go through gas like an eithopian with a slushy....

yes i would get a retune with this mod along with the other mods you have. i didnt get a retune because i have amaft+ and do my own tuning with that and a hypertech scanner cartridge.

Fastbird93

Just an FYI for people, I just ordered a set of the GMPP guideplates from Thunder Racing. They have them in stock still.

I decided to give these a shot on my 224/230 car. I'm kinda interested to see what they do for me.

drewstealth

Yeah, let us know how they do for you with that cam. I am gonna be getting that cam more and likely and wanted to know how the 1.7's would do with it.

Fastbird93

Well, it's probably going to be a little while, maybe a month or more depending on how things go.

If the guy with the hotcam picked up 15, I'm pretty sure that I should see that if not more because of the capacity of my heads. I'd venture to say that if they work as advertised 390 at the wheels isn't out of the question.

RealQuick

I should be getting mine today and hitting the dyno Saturday. However, I should have a new tune by then as well, so the hp gain wont be exact, but hopefully bewteen the two I see a good gain.

RallyRed701/2

have you double checked yet to see if they are rubbing or not???

MattysTA

sorry with all the questions i forgot to post up my results. I pulled my valve covers to re-adjust the rockers and i did not find any rub marks at all from these rockers!