Just curious....trying to figure out if I can do a bigger cam without upgrading my valve springs...which would make it more $$$ than it's worth.

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Stock springs are pushing it around .500. Adding 1.6 rockers tend to get near or over the spring rate. All springs wear out. Racers are know to change springs a couple of times a year. Factory springs should be changed at least every 5 years or so depending on your driving habits. When installing a new cam you should always install the recommended springs also. If the old springs are worn out then the new cam isn't giving the best performance it can and you risk getting valve float with the higher lift and old springs.

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87 IROC-Z Pro ET Bracket Race Car and knocking on the SuperPro ET class
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Yeah..I was thinking the lift would be around .460 and I might be able to get away with it. I was just now doing some checking, and I'd definatly end up with over .500 lift..not even close. Oh well.

I'm still thinking about it though

 

I've seen .480" on a set of 140k mile springs on an L69. Ran suprisingly well too, shifted with the needle buried on his 6k tach.
...ed
ps...what do you mean upgrading valve springs would be more $$$ than it's worth. You can get a decent set of valve springs for pretty cheap. Of course, if you have stock springs you must be talking stock heads, which probably won't benefit from really high lift anyway.
...ed

[This message has been edited by Ed Maher (edited September 15, 2000).]

 

I knew you'd do the cam, JESTER!!! You should ne able to get away with a .420/.442 cam easily but a .442/.465 might be a stretch. Either way, new springs are pretty cheap (35-60) and worth it. By the Summit cheapo cams ($79, I think) and the money you save on the cam you can use on springs/gaskets/beer to get friends to help.

Thought you had too many miles???

 

I do have too many miles. Evil temptation just reared it's ugly head on me once agian...that 224/234 summit cam started looking good. Especially since I already have a set of lifters, and you can get that cam seperate from PAW for $45. It started out just thinking about putting in these 1.6RR's I have sitting here from a trade. Then I got to thinking how I should use guidleplates and screw in studs with them. All good so far..cause I could reuse them on my 350. Then I got to thinking how I'd need hardened pushrods, but I'd need to get a new set for the 350 (longer for flat tapet lifters). Then I thought maybe I should just get a bigger flat tappet cam for this one.....it just snowballed. Such a powerful addiction

As it is I decided to just throw the rockers on without guideplates. F%$k it. I bend something...then I'll worry about upgrading.

[This message has been edited by Jester (edited September 15, 2000).]

 

I hope they are self-aligning RR's... If not, you'll be in for a hurt of a repair bill.

Please tell me that those are not the original valve springs, man!!! If they are not, get new ones ASAP as they will be so sacked-out, it's not funny...

 

nope, they're not self aligning. But I think I'll be fine..the tolerances in the pushrod slots on these heads seems to be fairly tight.

Upgrade springs that work just fine? not unless I was going with a bigger cam

 

You are nuts to use those RR's, man...

I'm telling you , you think your springs are fine but you'll pick-up 5-15hp with a spring change alone if you have 250k mile springs, man... No joke. I'm sure others will agree... Plus, your cam is probably worn to heck, by now, too, and you are not getting much lift. 1.6 rockers will get you back to stock (exaggerating...)

 

Oh no I believe you about the springs. I know it too..but I'm not bothering yet, not on this engine. The cam though is newer, and roller, so I doubt it's lost much at all.

You have to realize I'm starving student with alot of bills a new set of springs would be about 2 weeks take home pay, it's not worth it. yet

[This message has been edited by Jester (edited September 15, 2000).]

 

Oh, didn't know you had roller cam. Yeah, I'd just put on the rockers, I guess... Hope you don't do some high rpm damage... Have fun.

 

Yeah..thats why this cam really isn't all that bad. only 202/207, but roller makes a big diff. The LSA is WAY too high though..I have 9.3:1 CR and still have to use 92 octane. Sucks.


Bpout the rockers...yeah I know it's a bit risky..but I know of 2 cars with these heads not running self aligning rockers or guideplates. One was stock that way....go figure. So I think I can rick it.

[This message has been edited by Jester (edited September 15, 2000).]

 

Yeah, you have a terribly mismatched motor... That cam has MELLOW lift numbers for a roller cam... What gives???

 

Have you ever seen flowbench data for 187 305TBI heads? Even fully ported (which mine are) with larger valves (which mine do not have) They flow as much a .3 lift as they do at .5" lift. They suck. More lift would do me little good. More duration..definatly. Besides..like I said I'm only using this cam cause it was almost free, and I'm not sinking much money into this motor. So..I prefer the low lift. it MATCHES my tired a$$ valve springs better

[This message has been edited by Jester (edited September 15, 2000).]

 

enough said... have fun, but didn't you start this post about putting ina bigger cam???

[This message has been edited by FastBroker (edited September 15, 2000).]

 

Yeah I did..but when I got to counting up all cost of the things I'd have to get to do it (like valve springs), I decided it wasn't worth it. I'll just put it toward saving for my new motor.

 

Jester, FWIW, I am running the .420/.442 cam w/ 1.6's, which gives around .450/.470 lift (approx). I am using stock SBC springs (80# seat pressure) that are relatively fresh (~30k miles), and I'm having no problems. I only shift at 5200 rpm though.

 

Nova., how does your combo pull and how is your idle stability and idle vacuum, if you know it??? How is your idle and off-idle throttle response, while I am asking?

 

do the damn springs Jason!

they are not hard on a thirdgen you got all that room!

Midwest Motorsport (Bill may have the # still) sells some for 25 bucks

 

Phew, a voice of reason.

 

Fastbroker...

Engine is a 350 w/ 8:1 comp, RPM intake, and Q-jet

Pulls great from idle-5200

Idle is pretty smooth

IIRC, idle vaccum is 18 in-hg @ 900 rpm

Off-idle is fine... very good throttle response.