ok Ive posted up on the rocker subject a couple times and ive been stuck on 1.6 ratio, I'm trying to make all that i can out of a build that was less then impressive to me ... I'm wondering if i could run 1.7 rr with the springs i currently have and stock length pushrods. would it be worth doing (i have to get new rockers anyway) and would i have to put different valve covers on to fit them if i did go this route?

I talked to my engine builder when i was wanting to go to 1.6 ratio and he said something about the pushrods may not work with the bigger ratio? he said they might be to short but i dont see how pushrod length affects what size rockers you run?

 

The longer rocker arm geometry will change where the rocker tip sits on the valve stem so it directly will effect pr length. So you may have to go with a different length. Would have to measure with a length checker to be certain.
Then you have the issue of if the springs can handle the extra lift of the 1.7 rr.
Must know what height the current springs are installed at and the cam base lift usually provided with a 1.5 ratio, use that the recalculate the lift with a 1.7 ratio then determine if the springs can handle it at current install height.

 

well max cam lift with 1.7 rockers would be .567/.578
springs according to jegs:

beehive springs

Designed for hydraulic roller cams
.600" maximum lift, 1.290" O.D.
Originally designed for LS1, LS2, and LS6 engines

Specs
OD: Top 1.055" Bottom 1.290"
ID: Top .650" Bottom .885"
Seat Pressure: 105 lbs @ 1.800''
Open Pressure: 293 lbs @ 1.200''
Coil Bind: 1.100"
Spring Rate: 313 lbs/in

unfortunatly i cant just go to the builder because he seems to be totally unwilling to give me exact details so i cant get install hight from him is there a way to measure it?

I'll have to get a pushrod measuring tool

 

If a builder does not want to provide you with information for you to make decisions about down the road like that, I would get all of my items from him and go somewhere else is my first thought.
To check the height, you need a tool like this
JEGS Performance Products 80535 JEGS Valve Spring Height Micrometer
With the bind being at 1.1", then that means you need an install height of at least 1.678"...1.8" is about the norm and is why the open seat pressure is quoted at 1.8", but if you have an aggressive ramp on the cam, a little more seat pressure may be desired and hence a little shorter install height.
Different types of shims can be used under each spring or different types of retainer locks and tops can be used to obtain different install heights.
To be safe I would want at least a 1.77" install height with that cam if you are certain about your cam specs coming out to .578" max lift with 1.7 rrs.

 

well unfortunatly the car is put together and running atm ... the cam in the sig is the cam i have. The cam isnt very aggressive (.500/.510 max, 210/220 @ .050) as it is in the car currently with 1.5 ratio roller rockers and as stated with 1.7 it goes to 567/578 max ... is the @ .05 calculated the same way?

 

I run the 26918 spring with the stock seat and stock lock. This setup comes up to 1.740". However, actual coil bind is 1.080", still allowing to run a .600" cam, so I've been told. Comp lists the bind on the 26915 spring at 1.085", there should be room. It really depends on the seat and if any shims were used. I have used a dial caliper with the depth gauge to check the height also without removing the spring. Pull the valve cover and take a picture. If they used the Comp 648 lock, you could be around 1.770".

 

Well going back to your original question of "would it be worth it"..I would say no not to mention the hassle you may have to go through just to make sure if the springs will not bind. You could buy the measurement tool, but then you have to remove the spring first, then IF you find that the install height is not what is needed you have that to deal with. Stay with the preferred 1.6 rr, not many people run a 1.7 rr, it would seem to me that it would put additional stress on the valve train due to the added travel of the rocker tip.
But your calculations are correct for a .510 with a 1.5rr, then thats .578 with a 1.7rr.

 

well i guess in my head the worth it part isnt money its power haha, how much power is to be had over 1.5 if i went to 1.6? then to 1.7?

ill get a picture of it tomorrow (if its warm lol) and hopefully i can go get a pushrod measuring tool.

 

Depends where the head flow stalls. If they are stock heads, approaching 0.600" lift isn't going to do much for the top end, and may make it worse.

 

that does make sence that 1.7 would be pushing the heads, so if i do 1.6 rr then id be shooting more in the ballpark for stock heads flow? either way i'd like to step up the ratio of rocker so i can take more advantage of the cc304 or what there is to take advantage of...

im almost thinkin that i should just park the car and save up for a more agressive build like i really want.

 

https://www.camaroz28.com/forums/mem...img-0510-4608/

those arent beehives like what the build sheet says 0.o ... anyway thats what my valve springs are. Friday when i get back from college for the weekend im going to have a chat with my engine builder. I'll find out just what these springs are.

 

specs for springs in picture:

.595" max lift
coil bind: 1.140"
outside Diameter: 1.268"
inside Diameter: .880"
130lbs @ 1.790"
330lbs @ .500"
345lbs @ .550"
360lbs @ .595"

as far as the picture goes could someone tell me whether or not there shimmed or anything i have next to no experience with springs... im at a knowledge predicament. i need to find someone local that is willing to teach me this stuff :/

 

ok so it looks like the springs would handle the extra lift of a 1.6 ratio rocker right? is there a way to figure out pushrod length without the tool? i went into town to the local parts store and they had no idea what i was talking about so i looked on comps website and i'd have to pay more for shipping then i would for the tool. if i can get out of it i would like to wait to order the tool when im ordering other things along with it