Will my springs survive???
PAC 1218 springs good for .600 lift.
CC 4705 spring seats
CC 795 spring retainers
CC 611 10 degree locks

They are on my Stock, non machined lt1 aluminum heads. The machine shop was supp to install them at 1.80 height but they just slapped them on instead which would put them at 1.70-1.75 height??? My heads had .010 shaved off and i have the felpro 1074 gaskets on. Will my seat pressure be okay?? Cam has a lift of .533 on both intake and exhaust. See pic for spring specs, do i have room to avoid coil bind with my "low" lift cam?

Car has 100 miles on this setup without issue. And im using the gm 1.6 roller rockers thats why i used the 611 locks to keep space so the roller rockers dont hit the retainers.

 

in order to get a installed height of 1.800" on stock AL heads is to machine the spring pockets down some. Otherwise the springs are about 1.750" installed. Generally not a problem unless cam is very high lift

IDK the math to calculate what the new spring pressure for open and seat with the springs installed slightly shorter.

Is your .533 lift with 1:5 or 1:6 RR?

if the later than the lift is .568....I suspect that is still under what your lower install height coil bind would happen

 

.533 is the lift with my 1.6 rr's. Should be okay right. I heard some install heights could be as short as 1.70?? I could add 614 locks which add .050 spring height if its an issue. Not sure if the 1.6 gm rr's would hit the retainers with those locks???

 

.533 lift should be fine with current installed height. you just have more seat & open pressure than published specs for the springs now installed at the 1.7xx height

springs are a wear item, especially with higher lift than stock cams. you can pull a spring at 20k mi to check its spring pressure to see if has fatigued any and lost some pressure. Given the relative low lift of your cam I suspect you will be fine for some time

 

So your saying i should just run em as is? I read stock heads dont really benefit from higher than .525 lift so i had my cam speced at a lower lift that way they have a longer life. If the machine shop would of did what they were told i would be at 1.80, ohh well.

 

you can't get a 1.800" installed height on stock heads without machining down the spring pockets, or getting longer valves. My AL heads have been machined down for that height.

Your springs and installed height are fine for your cam. The shorter height basically just increases the seat and open pressure some and yes does lower the height before their spec coil bind...but your set up falls underneath all of that so you are good

some guys try thinner locators or retainers and 7 degree locks for other springs and do get a "little" more installed height but again your set up is within "safe" IMHO.

There are other springs spec for 1.750-1.780 installed height as drop in stock replacements. Your PAC were designed for LSx heads but are used by many on LT1 heads

Yes on stock unported heads no real need to go ape shiat on aggressive cam and lift as the heads won't support those kinds of cams

 

So if they are at 1.750 height im good. On another car forum someone is saying there is a possibility that my spring could be at 1.700 install height which would be too close to coil bind correct? Would it be wise to get my spring height measured to be sure im at 1.750 instead of 1.700? In that case adding the 614 locks would raise my springs up .050 and put me back in the safe zone.

 

Yes some of them "could" be at 1.700". IDK the math to figure out when coil bind would occur with your cam though.

You would have to pull each spring and locator to measure wtf they are...which means new valve stem seals as most have to come off to get locator off.

You could pull valve covers and rotate engine by hand and "look" at each spring...use a feeler gauge between coils to measure as a more crude way of doing it.

Ideally someone can chime in with the math formula to determine if a 1.700" (assumed height) is a coil bind problem for your cam. The seven degree retainers and locks would help raise it if it was a problem

 

Allright thanks for the advice!!! The idea of pulling the valve cover and using a feeler gauge is up my alley. And change locks if needed. Yeah def dont want to change out valve seals and all of that jazz. Like you said, chances are im closer to 1.750 and things are fine.

 

They say you need to run the 614-16 +.050 locks to get close to the 1.750" ht using the components you have. I would measure the height of a couple.

 

Do you think the gm 1.6 sa roller rockers would still clear the retainers with those 614 locks??

 

you need to use a retainer the same degree as locks. you can't run a 7 degree lock on a 10 degree retainer

350

This site describes measuring what coil bind would be given a particular installed height, cam lift, rocker ratio, pre-load - safety margin of (.060 for example)

http://www.hotrod.com/articles/how-m...rance-is-safe/

...but since you don't know what the installed height is other than something 1.700-1.7xx the math changes.

assuming at 1.700 and pre-load is .060 (IDK how many turns of pre-load are on yours) and safety margin of .060 (basically washing out the assumed .060 pre-load) I get .8472 before coil bind. But there are some assumptions here on installed height and pre-load

....so .8472 - .5330 cam lift you get .0314.....which is on the thin side of having enough "safety" room before coil bind, especially if there is any spring surge going on at high RPM's (making coils make contact as a result of the surge)

I could be wrong on how I calculated the formula noted in link. Since you did not do the install nor did the shop provide any specific installed height or pre-load (IIRC turns on 3/8" studs vs 7/16" = different amount of measurement also)

So to answer your initial ? I/we don't know because we are making assumptions on WTF the installed height is and how much pre-load was put on springs. We do know the spring specs and what coil bind is at 1.800" (1.140) but given your installed height could be .100 lower....can't say 100%

so if you use a feeler gauge to measure a few springs at full lift and get .060 +/- some you should be good

On another note, SA RR...for stock motors OK but spinning high RPM they can bounce off the valve which is why many switch to NSA and guide plates

 

I installed arp 3/8 studs on the heads. I have 3/4 of a turn on the rocker nuts. I feel the gm "lt4 SA roller rockers were more than enough capable of handling my 5800-6000rpm max pulls. Car will be kept under 5k 99% of the time.
Im betting my install height is prob a little higher than 1.70 so im probably fine like you said. I was thinking of using a feeler gauge between the spring coils with the valve cover off and engine running "lifters will be pumped up" to make sure i can at least get a .010 feeler gauge between them freely. I know its a rough measurement but if i can get .040 or more total using this method i would feel confident that the springs will survive for awhile. I will prob switch out springs and tear into stuff again once this next winter comes and the new top end has 7500-10000 miles on it. At least check things over.

 

I would not try and check with a feeler gauge with the engine running. Just use a 5/8" socket and rotate by hand

You likely are all good. Just when you don't do the work yourself or have confirmed 411 from whoever does do the work...just making assumptions on "if"...

5800-6000 rpm is on the high side for SA RR. I had my Crane 1:6 (same RR as your GMPP) SA RR jump off at the track running a VERY mild cam. This was shifting at 6000 RPM (cam was way done making power at that RPM). Fortunately no damage.

 

Well that sucks to hear that about the roller rockers. I was expecting 100% confidence in them under 6k. I mean if i was building a motor for 6300rpm and up i certainly would have gone nsa rr's and guideplates. But not for 6k and under. They seemed to work good on the lt4 motors spinning a little over 6k.

 

I run the same gm rockers and I shift at 6000, never had a problem.YMMV

 

The lt4 rocker was designed around the 6400 rpm redline, that should not be an issue. Others ran the s/a Promags to 6500-6700 with no problems. It becomes an issue when the springs aren't up to the task. In theory, your springs are tighter than Dick's hat band @ 1.700".

 

The GM (Crane) SA RA may have been "designed" for 6400 rpm, IDK. ....this being with a stock lift cam for the LT4. Certainly weak springs or springs seeing coil bind, SA tab to retainer contact or spring surge and SA RR "can" bounce off valve tip.

Do many use SA RR and shift 6k ish rpm, yes.

IMHO running NSA & guide plates, especially with higher lift cams than stock, and shifting at 6k and above the NSA takes the RR bouncing off valve out of the equation

Also for either SA or NSA, running the motor that high I would also use stronger PR than stock. A .080 thick wall one. PR flex can cause a SA RR to bounce off

 

Good point about the stock lt4 cam having lower lift and being less harsh on the rr's. I specifically went with the .533 lift cam over a .565 lift just for a little more reliability and less harshness on the valvetrain so i figured the gm rr's would be okay. I did get the trick flow hardened thicker pushrods and my cam is billet steel. Guess my weakpoint is my minimal clearance on my ill set up valve springs!

 

Yeah I think you are fine with the SA's given what your lift and rpm max intent is.....but given you are on the "tight" side of installed height for your springs ...it is that questionable installed height that throws your valve train off and if you do get close or at coil bind say on a miss shift high RPM OR you get cam surge/harmonics...something has to give and SA RR could be the part that jumps, or you break a valve spring, and your PAC's are single springs, than RR jumping off valve tip would happen...but that would be the least of your worries then (read valve to piston contact)

Valve train geometry is one area if not right severe consequences can happen. Worst case you are .100 lower on installed height.....1/10th of a inch (spoken as Baldwin doing Trump) HUUUUUUUGGGGEEEE in terms of valve train measurements go

Not trying to hit any panic button here just noting a "what if"....but since you did not do this spring install and the shop didn't bother measuring spring height none of us know anything other than a 1.800" install spec height spring was put in shorter. All may be perfectly fine....but the possibilities are there is a potential issue with your installed spring height, cam lift and less than what most would want to see as a "safety margin" before coil bind would happen

I had Comp 987 springs using 10 degere locks when I did have the Crane SA's. Did the 10 degree so the SA washers would clear retainers. Driving back from track I could hear a slight tick and when I got home pulled VC. RR was still on valve but the body side was. The tip of RR had jumped off and the PR made a recess in that RR. So it was still functioning albeit barely hanging on. Fortunately no damage at all and I just bought a new RR. When I went bigger cam and I was inspecting the Cranes I could see a ever so faint sign of RR body contact to retainers and then decided to go NSA Comp Pro Mags, 7/16" RR studs and ISKY adjustable guide plates with then 918 springs (918's big mistake but another story).