SStrokerAce

yeah and I think what they are saying is that BOTH don't have enough.

Go to www.compcams.com and look thru the catalog for spring spec charts and go from there........

Bret

vette40th

978 seat pressure at installed height=127#s, max lift is 655 without .050 buffer,
987 seat pressure at installed height =121#'s max lift is 650 without .050 buffer.

I think the buffer is a safe zone from max lfit so you have a little room left over in coil bind.
http://www.compcams.com/Technical/Cu...ML/340-349.asp

SStrokerAce

120 something and 165 is a far way from the right spring

vette40th

165#'s is way more than you need, I am sorry , your are just askiing for valve train related problems. I ran Comp R's with 140# seat pressure springs, 1.6 Stainless steel Crower Rollers, ARP studs, and springs were just to much, broke several of them.
Now before you all go into geometry, and any other thing about improper this and that, these springs were COMP Cams 941's, and have 443# spring rate, and these 2 springs JustNo is looking at are weaker, at 344 and 400. All I had was a Hot Cam, and they were recommended by CNC heads, and they were used in the C5R before they went 427(according to Katech motors).. Pete there knows allot about heads, but sometimes too much spring pressure is just a waist of HP etc.
The manufactureers of these cams have to know something to recommend the springs they do, dont you think.

JustNO

The problem is, #8000 AFR springs came with my 210cc AFR Heads. (220lbs on the seat and .670" ) But these springs are for solid roller cams! My cam is hydrolic roller..! AFR change these springs without paying extra money ,but I still couldn't find 160lbs AFR springs.

Mindgame

Vette, I think you're missing something....

A "recommendation" is just that... it is not specific to every application. If you are just looking for springs based on "max lift" capabilities then you are really out to lunch.
If I were to take two cams, one with 210º @.050, the other with 230º, both on the same LSA and both with the same .575 of lift with a 1.5:1 rocker. Based on the "max lift" basis, they'd both need the same spring. That is hardly the case though and it is the arguement against going with what the catalog "recommends". On that note... if you're talking to a builder, cylinder head shop, whatever, about spring rates and they don't ask you what the camshaft profile is.... then they shouldn't be giving recommendations.

I have never run anything less than 150 lbs with a good hydraulic roller and I have never (except once with a bad set of springs) had a spring or roller breakage problem. So... who knows what your problem was, but I'd bet my house that it was something other than the fact that you were running 140 lbs.

You can take advice from experience or you can leave it but I've been playing with engines as a hobby and as a competetive racer for what seems to have been a real long time now.

Bret builds the things for a living.

-Mindgame

97Z-M6

if you run a spring with a 120 on the seat you will destroy that motor, unless you dont plan on going over 3000 rpms, those spring pressure are more suited for the cc 306. and if you will look at the cam profile of the cams you will see why.

and heres a true life example, my buddy has a 230 236 wiht a 544 and 555 lift, the machine shop put in the recomended spring and it was a double spring, my buddy called comp and told him what he needed. but they recomended what was on the spec card a dual spring with a 130 on the seat. well the car ran good for about 3weeks. then it didnt have anything on the top end. well before we got into the heads he spun a bearing, so we pulled the motor well we took the cam out and set it aside and took a break well i was siting and i noticed on the cam that the top of the back side if the lobe there was a spot where the lifter hadnt been thouching the cam then we looked at the heads and the the inner spring was broke on every spring, and the spot where the lifter slamed back down on the cam was a slight dent in the cam. not enough to hurt anything. but he fixed the motor put the cam in there and went with a little stronger spring and hasnt had a bit of problems.

the ex grind cams are alot different aniaml than the standard cc306 and 847. you need more spring pressure. the ex grind cam throw the valve open real fast so it you dont use the right spring for your application (not your cam) but the whole application. you will have similar problems make worse. and if his motor would have been built with close piston to valve clearances, say .040 and not the stock .070 it would have had a different out come. like brok pistons and broke heads and valvels.

go alitlle over kill on the spring selection.

SStrokerAce

Spring pressure is usually a plus.... problem is what comes with the extra pressure is extra deflection. Extra deflection is time for upgraded parts, like rockers, studs(stud girdles or shaft mounts) and pushrods.

When you have less mass to control you can use less spring pressure, or the lobe is not as aggressive. .200 duration numbers tell you a lot about that... more .200 duration for the same .050 and max lift is the key here.

Bret

JustNO

I definitely will not use cc 987 or 978 springs. Maybe I will go with 145lbs AFR's springs,if I can't find 160lbs of AFR's.

vette40th

I see where you guys are coming from, but I have been running motors for 20 years, and always run what the manufacturer recommends, or a proven combo, ie a LPE motor from a mag artcile lets say where they have all parts written .
The only time I have ever broken something was with the 941's.
But another thing is I never run motors past 6500 rpm. I have always had "streetable" motors, then once i got into FI cars, I was always towards the conservative side, as electronically tuneing and driveability was a concern.
But overkil on spring pressure seems to me to be Overkill, but in keeping the valvetrain in sync is important. I agree.
I use the 918 springs for my 230/236 cam. Lets see how they work, so far so good.

SStrokerAce

918 = less mass.... so you can use less pressure.

Bret

JustNO

Hey guys, I found two good ones;

cc 933:1.550 2 spring assembly >> .730 I.D. 176@1.950 seat, 494@1.300 open

cc 985:1.430 2 spring assembly >> .700 I.D. 164@1.750 seat, 331@1.250 open

Which one is better for my 236/245 dur. 575/575 lifts 114lsa cam ??

Another question is; My heads will come with valvetrain ,so I will change springs with which parts?? Titanium retainers,shims,cup seat thats all? The rest will be stay same??

thanks so much
Deniz

JustNO

Any suggestion??

vette40th

Wether one if these is good, you also have to ensure the machinist installs them at the correct height. Most GM/AFR LT1 heads are installed around 1.8", + - .05 inches.
Since everyone thinks High Spring pressure is correct, use the 985 as it is closer to factory OD size. Clearance could be an issue with the other.

JustNO

My heads are 210cc and came with full valvetrain.. (It was already clearanced for its valvetrain) I agree with you valve train is very important,and should be perfect!