89formula#1

Hey guys, just wanted to let everyone know that with the Edelbrock off and the new Holley on I went from 13.10 to 12.83 last night at 106mph, my best 60-foot all night was a 1.7. My dad said he would buy me new drag radials if i made it into the 12's and my first run i went 12.9 so I'm gonna get the new Mickeythompson ones, i've heard good things.. Ok but off that what else can I do to the car to get it down around the 12.3 range without taking the motor apart or using nitrous or any type of power adder?? thanks guys. Also would better springs and 1.6 roller rockers help at all?? thanks again

Chickenman35

I'd definately change the valve springs. The Z28 springs are borderline above 5,000 rpm with that cam. Isky makes some nice stuff. Their #8005A spring should be more than enough.

Changing to the 1.6 Ratio rockers on the exhaust side would probaly help. Comp cams sells mixed and half sets BTW. Just give their tech line a call. Their Pro-Magnum SS and Hi-Tech SS lines are very, very good. Well worth the investment. Note: Changing to a 1.6 ratio rocker will DEFINATELY require a spring change.

You might want to check out this site. Comp cams makes some comparisons on their different cams. The combo you have now is obviously working pretty good though.

http://www.compcams.com/information/...ts/DynoSheets/

BTW, is that a flat tappet cam or a Hydraulic Roller?

89formula#1

It is a Flat-tappet cam not a roller. I was thinking and I don't think the price of getting new springs and buying rockers is worth the tiny amount I will get from it. Is there anything else that anyone recomends I could do to get some more out of my combo without useing any type of power adder? Thanks

Damon

Wait- you were turning 1.7 60-foot times BEFORE you got drag radials? Like as in, on STREET tires? I assume you borrowed a set for track duty. If not, I'd love to pick your brain for suspension improvements to my similar 92 Camaro that likewise used to be a TBI car and now sports a carb'ed 350.

You won't know what you're missing on the valve springs until you have the right ones in there. You'll notice it'll make more power in the last 500 RPMs or so if the originals were getting "marginal" for your application. Might allow you to raise your shift point and go a little faster if you're leaving usable RPMs on the table due to marginal valve springs, not because the cam the cam is done making power. Below that point, there will be no difference.

BTW- I wouldn't use 1.6 rockers with that cam unless you first do 2 things:

1. Make sure the springs will take that much extra lift (requires checking the actual installed height and staying at least .050" from "flat stacking" the coils- subtract the 2 numbers from eachother and that'll give you a rough idea of the max lift they'll take AS ACTUALLY INSTALLED IN YOUR ENGINE). Having the spring's specs is very helpful but if you don't have them installed exactly at the spring's spec'ed installed height you'll either be limiting their maximum lift or reducing their spressure, depending on whether you have them installed at a height that is either greater or less than the recommended installed height. The Z-28 springs almost certainly won't take the extra lift. BTW- to calculate you max lift with the 1.6s just take the max lift from the cam card (which assumes 1.5s) then multipy it by 16 and divide the result by 15. For example, if your cam has .500" lift with 1.5s you'll have .533 max lift with 1.6s. (.500x16)/15=.533

2. Make sure you have adequate retainer-to-guide clearance (including any seals that may be installed on the valve guide). If your cam is gonna lift the valves to, say, .530" with 1.6 rockers and you've only got .500" clearance, guess what? Bent pushrods and broken valve train components.

Not sure how much more you've got in the combo just from tuning. Obviously, it's working pretty darned good already. Might play with the advance RATE to bring the centrifugal in MUCH faster than you would driving around on the street. Like 2200 RPMs at the track, vs. 2800 RPMs on the street. Play with the jetting on the new carb, too, as see if that gets you anything.

I think mainly, though, if you want to go faster at this point you need to get some weight out of the car- especially off the front end. You're not likely to tune another 50-60HP into that combo, which is about what you'd need to go bottom 12s.

89formula#1

No, my best 60-foot on street tires was a 1.9 the 1.7 was on really bald drag radials that amazing still work amazing, you can;t even see the tread anymore lol. I think I pretty much decided against the 1.6 rollers cause I think the gain would be so minimal for the price. Now I was thinking of putting in a little bigger cam down the road maybe even a roller cause I would liek to pull the motor and get the heads ported and what not. Now with that in mind is there a spring that Comp sells that would be find up to say a .560 lift that I coudl use for this cam I have now or do the springs need to be matched to the cam so I don't mess anything up in the valvetrain? Cause I definatly would hate to have to buy springs again when I do the cam change.. Thanks for all the information guys, oh yea and one more thing, would I just call comp to get the right springs for the cam or is there a way I can figure it out?? thanks again..

Damon

If you want to lift them up to .560 you're probably going to have to use a larger diameter spring (Z-28 springs are 1.25" diameter, as are most stock springs). Probably something like a 1.45" diameter or so.

Comp Cams (and all the others) will have springs specially designed to work with their various cams. You want to take their advice until you've set up more than just 1 or 2 vavetrains.

In fact, installing springs that hefty in a set of Vortec heads you should work with a pro. Somebody who will know how to get the spring pockets machined to proper size and depth, get the spring installed height at the same distance as the spec on the springs, and then can make sure you still end up with correct rocker arm geometry.

It's not THAT difficult once you see it done and explained a few times, but to try to explain how to do it over the internet could take VOLUMES. Might want to check out a thread I was involved in over on montecarloss.com. I walked somebody through setting up their valve springs for the first time..... it went on a LONG time with many posts and replies.

89formula#1

Ok well I was thinking and for what I want to do I don't think I need to get so serious, I just want to run an 11.9 on drag radials all motor without completly gutting the car. What things could I do to help me reach my goal? I know theres more left in the combo just the way it is cause the timing isn;t wut it should be I kinda just changed the springs and made sure it was past thirty and before 40 cause I didn't have time to mess with the stops and what not. Now can I get away with leaving my combo and doing little things to get to the 11.9 range or would I need to do some major stuff?? Also I was thinking about maybe going one step up with my cam in the extreme line and maybe the rollor one since mines a roller block. What do you think?? thanks Also I woudl change the springs for the cam.. thanks

KrisW

iTrader: (5)

One reason to change valve springs.......SCATTERED ENGINE!!!
You can even go on the cheap from PAW and get a set of singles that will let you run a high lift cam without mods to the head, just put 'em right on. No use dropping a valve over 5000 rpm. That'll happen with a good cam and stock used springs, even Z28 stuff. Been there, done that, got the scrap metal to prove it.

P.S. those springs are about 80 bucks and worked very well for me on a 400 small block 79 Z28 that ran 12.82s

89formula#1

Well I figure I'll just get the springs recomended by comp for my cam. Now do you think moving up a step or maybe two int he extreme energy cams would give me good results or not really?? thanks

KrisW

iTrader: (5)

I ran a Summit cam with .488/.510 lift and no chassis mods. With your car my engine would have been much faster. I would run a similar cam if you have big tube headers and free exhaust. Sounds like your chassis id dialed in. More cam than this and your intake starts to suffer at high rpm and hold you back. I ran the same intake as you with a 750 Carter AFB and 1 5/8 headers(400 c i d ). I sold the car before giving it more carb and bigger headers (1 3/4).