lift VS springs

[victorfb]

does anyone know what the max cam lift my valve springs can handle safely? the heads are the aluminium BBC large oval port # 12363390 with 2.25 int. and 1.88 ex. stainless valves with 11/32 stems. all i can find on the springs is that they are hi performance. what does that mean? i have 2 differant cams i can use on the 502. one is a solid roller, lift = .661 int. .668 ex. dur @ .050 = 254 int. 260 ex. with 112 sep. the other is a hyd roller, lift =.521 int. .540 ex. dur @ .050 = 236 int. 242 ex. with 110 lobe sep. both are comp cams. the solid roller obviously has a much higher lift but it scares me with the springs. the other seems like a pretty mild cam compared, and would hate to use it and find i should have went with the solid roller cam. any help and/or advice would be appreciated. thanks. oh yea. the heads are stock with just a port match. not sure if porting will help on these heads, or if it is recommended.

[Fiat48]

1st I need to know:
Is either of these cams in the motor now?
Is the motor apart or together?
High performance is like "universal." Means nothing.
What is the application? Blown, unblown, jet, v drive? RPM wanted?

[victorfb]

sorry for the lack of info...
no, niether of the cams are in yet.
the motor is a 502 truck crate with iron heads still in its original form, but should start removing the top end soon. i just want to get all info and parts together first so i dont have an open motor laying around. it will be going into an 18' rogers with Berk JG. ill match impeller when i know what the motor will be. i allready have and will probably use an edelbrock "air gap" RPM performer with 1 inch spacer to give it a little more of an open plenium. topped with an 850 vac sec demon carb with lighter spring. im still unsure of what RPM im shooting for as i dont know what a safe RPM this motor will handle. though around 6000 max seems safe. i will be running OT headers.
the solid roller cam is identicle to what "cyclone" was running last season but he ran the AFR heads.
oh, and i am also using comp cams roller rockers.

[Fiat48]

You'll have to look at Compcams and find the spring pressure requirement for which ever particular cam. It's also listed on the cam card. Then remove a valve spring and measure it's installed height. That's the distance between the retainer and the head where the spring fits. Record that measurement (probably around 1.950). Take the spring to someone who has a valve spring tester (machine shop) and see what the spring pressure is at that installed height. While them spring is in the valve spring tester, compress the spring to .100 before the coils stack (coil bind). Read that pressure. Compare that with the spring requirement for either camshaft.
http://www.holley.com/HiOctn/TechServ/TechInfo/IECVTTech2.html
Also check that the bottom of the retainer doesn't hit the valve guide(or seal) with the valve fully opened (again, whichever cam).
And you'll also need to check piston to valve clearance.
As far as cam selection, I think you should talk to comp cams and tell them your application. In my thinking the 112 L/s is too wide for an unblown jet, but opinions vary. I'm sure others will join in with their opinion or experience.

[victorfb]

thanks Fiat48. checking the springs myself i know is a great idea, and will have to do just that. i was just wondering if anyone had allready done the testing on these springs. im pretty sure they are the same ones that came with the heads originally. all the parts mentioned came from a guy that had them on the same bottom end as mine and dyno tested the combo with both cams. i still have not recieved the dyno sheets. i looked at what comp cams offers for marine hydrolic roller cams, and all three came with a lobe sep of 112, and are designed for jets.
like i said. the solid roller cam was run on mikes boat "cyclone" last season. and he did run water through the headers but it was controlled at certian RPMs.

[razor1115]

Victor
I had the same engine and measured the springs myself. I can't recall the numbers but you can find the spring part number in the crate motor build sheet. Then you can reference the parts handbook to find the specs on the springs such as installed height, open spring pressure, closed spring pressure, coil bind... You will need to know all these factors for the your cam selection.
I know without a doubt, the stock crate motor springs will NOT handle your .600+ lift cam. They WILL coil bind. The other cam selection may be OK but double check. As previous posts indicated, check the clearance to the unbrella seal on the valves whatever cam you choose. I was setting up my 540 and found I actually would have contacted the seals if I had not checked them. Saved me a lot of work / destruction. I pulled the head back off and ground the clearance on the valve guides to let the seals seat closer to the head. If you have this issue, and you probably will, I just ground mine in the garage, then deburred them so there were no valve hanging issues. Then, just THOROUGHLY clean all the grinding dust from the heads...
Also, be sure to leave 0.060" clearance to coil bind in the issue of spring growth/ safety factor.
Zack

[flat broke]

Vic,
You will want to measure those springs out as per Fiat's suggestion. Regardless of what a book says the spring weighs in at, you should always double check and the pressures at installed height and just before coil bind. The last thing you want is an out of spec spring in your brand new motor. If you need a spring mic to measure the installed height, or a good quality stud mount spring compressor to get the springs out to have em tested, let me know and I can let you borrow em. Out of curiosity, are the aluminum heads you're using used? If so, all the more reason to test the springs even if the book says they will work.
Chris

[victorfb]

wow, thats awsome Chris. thanks for the offer.
here what i found out... the heads are used, but for only a few pulls on a dyno, and the valve springs that are installed now, are from a comp cams kit for the Hydrolic roller cam i mentioned earlier. if i wanted to go with the solid roller cam i would need a new set of comp cams springs # 991-16 (advise from comp cams tech). ive made the decision to go with the Hydrolic roller cam and use the springs i have now, but will still have them tested. like you said, dont want to mess up a new motor. i was told by the guy that had this combo dynoed that it pulled nice and hard, and the carb is allready tuned to this exact combo. so i am hopeing there will only be a small amount of fine tuning when assembled and fired up. since i will be removing the springs for testing anyhow, i will also remove the vlaves (and clean of course) so i can inspect all the ports and possibly do a little mild porting. nothing serious, just remove any obstructions. ive found in the past that most heads can use a little work on the bottom of the runners right before the valve seats. (shortest and smoothest flow area). that way i can also relap the valves to the seats and see what kind of contact surface i have.
i still dont have the dyno sheets, but i am told this combo ran around 570 HP. and with the solid cam its about an estemated 30 HP gain. but of course a little more to maintian, and more wear on the valve train.
with the hydrolic cam, comp cams suggested to intall the cam with a 108 to 110 center line which should allow for a bit more top end. does anyone know who makes and sells a timing set for this 502, that will allow me to degree the cam? i know the selection is very limited on these blocks because of the differant timing cover and such.

[flat broke]

Vic,
Just let me know if/when you need the tools and I'll get em out to you. In regard to the timing set, you should be able to find a 9 keyway crank gear set pretty much anywhere. If you can't source em though the catalogs like Summit or Jegs, give George at Clay Smith a call as he has some under the Clay Smith name (not sure who really makes them). I would opt for the 9 keyway crank gear over the offset bushings as I feel the bushings are a unreliable way to go (but thats just my opinion after installing that type of kit)
Good luck with her and keep us posted.
Chris

[Fiat48]

Comps 991 spring is 1.650 diameter. measure the diameter of the springs you have. If they are 1.550 diameter, then we already know no need for testing as they won't work. And you'll have to cut the seat pockets.
The spring Comp recommended is a dual spring 1.650 outer with a .783 inner. 222 Lbs at 1.950 installed height with 670 lbs @ 1.250. Coil bind at 1.125.
Things may have changed but I have had better luck with K motions K-1000H. They have held up better for me. Specs are close.