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Author Topic:   cam install
racer17j
Dirt Forum Champ
Total posts: 1565
posted April 04, 2003 12:25 PM UIN: 54865418
ok guys gonna try a new cam this year wanted to make sure i install her right before i have always just lined the dots up but wanted some opinions here i have a 3 setting timing chain so would i want to run it straight up like before or +or- on my gear. here is what i have hydorlic speed pro cs -187r
intake .050dur 244,sae dur318,lift 340, valve lift 510 107 center
exaust is the same except 109 center. car is 3000# small 1/2 mile run 62-6700rpm. rochester 2g flat top 9:1 350 882 heads z-28 springs and have either 1.5 or 1.6 long slots i could put on it what do you think my best bet would be i don't have any access to a degree wheel of money to have somebody to do it for me so i gotta get the best i can with what i have got

dirtbuster
Dirt Freak

Total posts: 353
posted April 04, 2003 12:47 PM
With 107 intake and 109 exhaust that means your lobe seperation angle is 108 which also means there is 1 degree advance built into the cam. Although it seems strange to me that the cam would only have 1 degree advance built into it, I would prob put it in advanced 4 degrees with the appropriate crank keyway. The reason I say advance is because when your timing chain stretches a little and wears in you will prob end up around 3 advanced plus it should help your bottom end a little. Or put it in straight up and try it then move it from there if you need to.

You are pretty much limited to the 1.5 rockers because if you have true z-28 springs they are really only reccomended to about 4.80-4.90 lift and you are already over that.


UFnARacing
Dirt Full Roller

Total posts: 68
posted April 04, 2003 01:14 PM
17j, I know you've been racing for awhile, but I must add to what dirtbuster hinted on about the Z-28 springs. I read on here Steve Hendren saying those springs are junk. So, I did some research. Here's what I found out about the Z-28 springs:

Pressure set @ 1.7" height is 110 pounds. Not "too" bad for open pressure.

Pressure set @ 1.21" height is 280 pounds. Not good at all if you run any decent cam profile.

Coil bind is at 1.16" height.

Using those figures, that would mean the most spring pressure you could get is at 1.15" height. And you would only have about 300 pounds there. That's way too close to coil bind. And again, no where near the amount of spring pressure needed for a decent cam profile.

Just wanted to throw out that info for you. I just got done putting new cam and heads on my motor to move up a class. So I went from .460" lift to .520" from Camcraft. Charles told me to use 345 over the top spring pressure. Hope this info helps.

By the way, I have a brand new set of Z-28 valve springs that just have 20 minutes of cam break in time on them!!!

Randy

racer17j
Dirt Forum Champ
Total posts: 1565
posted April 04, 2003 01:39 PM UIN: 54865418
i've been race'n for a while but never realy messed with the motor end of it mostly just freshen up junkers and run um that worked good about 5 years ago but the cubic $$ is ruleing my class now and i'm tired of running 5th lol i haven't put the springs on yet i also have a set that came off my uncles mod i could look into but that might be to much tho and not sure if they would be the right size for my stock heads. i've always ran the stock springs with my 480 lift cam with 1/6 rockers so that came out to be 512. what is a decent set of springs then if you guys don't like the z-28's

rico 08
Dirt Freak

Total posts: 372
posted April 04, 2003 01:56 PM
You need to be real careful that's putting those springs to the limit definitely,510 lift would be fair with a solid lift but a hyd will be close to coil bind,i've seen z-28 springs do alot and have faith in them just keep in mind at 6700 rpm you're reaching the limit and it may float before then you'll just have to see.

UFnARacing
Dirt Full Roller

Total posts: 68
posted April 04, 2003 02:12 PM
I have a Summit right here in my home town. So most of my engine parts are from there. I bought part #KMO-K-700 springs. $43 for the set. For my cam, I set the valve closed height at 1.675" and that gives me about #345 at .520" lift. These springs are made of H-11 material, which is supposed to last all season long. We'll see on that one.

Randy

racer17j
Dirt Forum Champ
Total posts: 1565
posted April 11, 2003 05:17 PM UIN: 54865418
ok guys here's the deal i put her in on the + with bolth marks at 12 o clock. i can't for the life of me get it to run it will either blow flames out the pipes or back fire thru the carb but will not start i've tried to change the distributer 180* incase it needed to be on 6 that didn't work any ideas i'm gonna try to change out to another dist see if that might help but other than that i'm lost i already have to sit tonite out don't want to sit another

rico 08
Dirt Freak

Total posts: 372
posted April 11, 2003 05:22 PM
If i'm getting what you're saying right you are putting the marks BOTH at 12 o'clock?You need the big cam gear at 6 o'clock and the crank gear at 12.

racer17j
Dirt Forum Champ
Total posts: 1565
posted April 11, 2003 05:42 PM UIN: 54865418
wouldn't that be to fire on 6 tho i changed the dist 180 shouldn't that do the same thing as lining then up and dropping it in on #1

66jj
Dirt Freak

Total posts: 352
posted April 11, 2003 06:57 PM
RACER17J put your cam in straight up, not advanced or retarded.

also run 1.5 rockers like it was designed.

thats the way it was designed to be installed. i would think the manufacturer would know best...

jeff

rico 08
Dirt Freak

Total posts: 372
posted April 11, 2003 07:36 PM
Here's how i do it i line up the marks,top gear with dot down at 6 o'clock and the bottom at 12 o'clock,then after assembling everything rotate the engine clockwise until the intake valve closes and the compression stroke ends,when the mark comes up on the balancer to tdc stab the dist on #1(you may want to go ahead and dial in you're timing now by putting the mark on say 8-10 or more degrees to keep you from not having enuf timing on startup)and go.Sometimes trying to find the compression stroke by putting you're finger over the plug hole will get you off,that's why i like to do it that way,another benifit is not loosing any assembly lube 'cause you are turning it over by hand.BEWARE turning the engine over backwards will gaurantee you will be 180 out.Good luck!

Eljojo
Dirt Freak

Total posts: 273
posted April 11, 2003 08:53 PM
I'm confused! (That doesn't take a whole lot anymore) If the crank turns twice for every turn on the cam, wouldn't the top mark be down and the crank dot be up after one revolution? At this point wouldn't the distrubutor rotor be pointing at the right rear tail light? I may have to take something APART!

rico 08
Dirt Freak

Total posts: 372
posted April 11, 2003 09:10 PM
After you set the marks on cam/crank put on the timing cover,forget those marks,then move onto the balancer/timing tab and dist timing.

racer17j
Dirt Forum Champ
Total posts: 1565
posted April 11, 2003 11:54 PM UIN: 54865418
66 you read my mind lol thats the way i have always done it before but with this new cam wasn't sure i just wish i didn't have to fight this ****g cover now

rico 08
Dirt Freak

Total posts: 372
posted April 12, 2003 10:25 PM
After i slept on this one i think i figured out you're problem,when you line up the marks with the top at 6 and bottom at 12 the engine is at tdc overlap and not at firing so if you go 12 o'clock with the cam gear you should be at firing on #1,but i'd just do it the way i described earlier that way you will be less likely to get 180 out.

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