Engine 1.6 vs 1.7 steel vs alum.

[nickyb]

where do I start? the comp cam stage 3+ I got has 544/544 lift with 1.7 rockers , I got comps 1.6 alum. rockers.
these will give me (I belive) 513/513 lift. soooo do I sell these and get 1.7? if I do im thinking steel not alum. for daily driving.(yes and cost)
I don't know if the alum. ones i have will hold up in a daily. any experience or problems, any suggestions?

 

[Bullitt347]

Considering the 93/94/95 5.0 Cobra's came from the factory with aluminum roller rocker arms (Crane) and thousands of other 5.0's have had them installed with no issues, then there should be no concern over using aluminum rocker arms, assuming that you are using a quality piece.
My race engine has aluminum rocker arms, cam has over .700 lift and the engine sees over 8k rpm. No, they are not cheap china knockoffs, the "Sportsman" series is over $1,400. Get into the "Pro" series and you can spend a lot more.
You do get what you pay for..

 

[General karthief]

That is an interesting question. Longevity, durability is important to me too, not just a weekend, every once in a while go to the car show driver, or a full song trip down the 1/4 mile, do they still run 1/4 mile? I want to jump in it and roll anytime, anyplace. I do drive, I guess you could say, aggressively.
I have a set of 1.7 Ford roller rockers I'm planning to use, unlike Nicky, I've got a stock cam.
So how does longevity/durability compare between aluminium and stamped steel rockers in everyday use?
And why did Ford use Crane rockers and not their own?

 

[nickyb]

Considering the 93/94/95 5.0 Cobra's came from the factory with aluminum roller rocker arms (Crane) and thousands of other 5.0's have had them installed with no issues, then there should be no concern over using aluminum rocker arms, assuming that you are using a quality piece.
My race engine has aluminum rocker arms, cam has over .700 lift and the engine sees over 8k rpm. No, they are not cheap china knockoffs, the "Sportsman" series is over $1,400. Get into the "Pro" series and you can spend a lot more.
You do get what you pay for..

Thanks I looked into crane energizes (they look like ones on cobras) and for just a little more then I paid for comp ones they seem the way to go.

 

[Bullitt347]

That is an interesting question. Longevity, durability is important to me too, not just a weekend, every once in a while go to the car show driver, or a full song trip down the 1/4 mile, do they still run 1/4 mile? I want to jump in it and roll anytime, anyplace. I do drive, I guess you could say, aggressively.
I have a set of 1.7 Ford roller rockers I'm planning to use, unlike Nicky, I've got a stock cam.
So how does longevity/durability compare between aluminium and stamped steel rockers in everyday use?
And why did Ford use Crane rockers and not their own?

You would be surprised how much is outsourced at auto manufacturers. Every electric power window motor/regulator, power seat motors, ect ect are all outsourced. Most of a new car is not made by the manufacturer. Outside of engine/trans/body panels a huge amount of content is through 2nd/3rd party suppliers.
Almost every AC Delco part is made in China. I doubt Ford and Fiat are much different.

 

[KRUISR]

I would bet you can't FEEL the difference if you keep your existing 1.6s vs changing to 1.7s.

 

[General karthief]

I would bet you can't FEEL the difference if you keep your existing 1.6s vs changing to 1.7s.

I think you would be surprised at the low end torque feel.

 

[KRUISR]

Better torque with which one?

 

[nickyb]

Well the heads(nkb's) are not available and they are 62cc 's which would yield 10.5 to 1 . The enforcers are 64cc's that's 10.0 to 1 So I am trying to keep the planned power of my build close as possible.
But maybe the universe is stepping in to take my build to a more street able one????

 

[General karthief]

Better torque with which one?

1.7, of course it's relative to other mods.
93 GT advertised 275 @3000 rpms
93 cobra advertised 285 @ 4000 rpms

 

[KRUISR]

93 GT advertised 275 @3000 rpms
93 cobra advertised 285 @ 4000 rpms

Is that difference the rockers or the GT40 heads vs E7's?

 

[Bullitt347]

Is that difference the rockers or the GT40 heads vs E7's?

The Cobra has better heads, better rocker arms, better intake manifold, larger MAF, larger throttle body. Not sure if the camshaft was the same or not. All of those things are why it has more torque/hp.
With a bit of work, (camshaft/exhaust/porting) you can get over 300 hp to the wheels. You are not going to do that with the GT without getting better heads/intake/throttle body/MAF /rocker arms, all of the stuff the Cobra already has. Although, you may get there with the E7 heads, it would just take a lot more work on the heads compared to the GT40's

 

[General karthief]

Is that difference the rockers or the GT40 heads vs E7's?

Ahhhh, like I said, it's a combination, the 1.7 rockers on a E7 head would likely do nothing by them selves,
bullitt was faster on the keyboard.
My combination: long tube headers, GT40p heads, 1.7rr, stock cam, tubular intake, the usual throttle body/maf, #24's, 355 gears.
If I find a deal on some aluminium heads before the heads go on I'll grab them but not a build stopper. I'm thinking I may not be able to use the I.7 rr with a bigger valve, that will also change the rpm where the torque number comes in, I want it down low
the p heads, besides the bigger valve, a little better flow, plug angle, will bump the compression up a little. I'm going for the low end torque,

 

[KRUISR]

Ahhhh, like I said, it's a combination,

I agree its the combination. My point was that since the OP has heads, cam and intake already in the package, whether he used 1.6 or 1.7 rockers, there will not likely be much difference in how the car feels. Sure it might be a few HP, but in the overall combination what are we talking is 5 HP on a combination that probably will make 320-350+ at the crank.

Your post above showed 10 ft-lbs advertised difference between 93 GT torque and 93 Cobra toque. I would account the difference more to the heads than the rocker arms.

In all my statements regarding not too much difference, I am making the assumption that the OPs 1.6 rockers are roller rockers. If they are stock stamped rockers, he definitively should change them to roller rockers of either ratio.

I'm thinking I may not be able to use the I.7 rr with a bigger valve,

To me, the cam is the biggest factor on this one. When are intake and exhaust valves starting to open and close vs the piston. For example GK, your stock cam will start to open on intake 20 deg BTDC vs the OPs cam (XE270HR) will start 27 deg BTDC. Obviously the more before TDC the valve starts to move the more of a worry it could be.

GK, I have the same set of parts kicking around the garage for one of the extra blocks I have and will likely assemble for whatever the next project car is.

 

[General karthief]

Totally agree with you Kruisr, my butt dyno is fairly sensitive.
the ego dyno is very inaccurate.