Hey folks, I have big block iron heads but my valve springs need to be shimmed...and quite a bit. How much useful spring pocket do I need to leave? Before shimming, clockwise, I have 12:00 = 0.141", 3:00= 0.148", 6:00= 0.162", 9:00= 0.147".
I'd like to have from 0.075" to 0.100" of shims. That doesn't leave much pocket for the springs.
Cam has .512 lift in and out. I'm not an RPM fiend but things can happen, yeah? Up until now, I've never gone past 5500.
Thoughts?

 

You have several options. One is to get other springs that give the correct tensions closed and open at the installed height you have now. Or, you can get different retainers and/or split locks that change installed height--locks usually by .050" either way, and retainers .060" in the case of Isky chrome moly 507ST vs. 507STA. You can also use hardened shims--very important because the flat spring dampers chew into soft steel shims. Hardened shims can be bought from Comp etc. with an inner locator or with a outer cup type locator.

 

Thanks Rund, I just messaged Mark (CutlassEFI) about springs that might fit my needs. I've also looked at the shim cups but I'd have to measure to see if I have room in the pocket. Would locks also give me more clearance between the rocker and the retainer? Sound like they might. I'll look into it.

 

Also, my current springs are rated for max lift of .530 (I have .512) and a coil bind height of 1.125, giving me 0.043 clearance at max lift (assuming the 1.680 installed height is achieved). Is that enough clearance?

 

These look interesting. What's the downside to using lowering locks? Retainer to guide clearance?
https://www.speedwaymotors.com/11-32...ght,23693.html

 

I ordered springs from Mark (Cutlassefi) with the same specs but with a 1.8" installed height. A shim under a spring or two on each bank and I should be right on. Thanks for the advice @Run to Rund !

 

Stepped to same problem- valve rotators in my opinion make the difference- i have no sample of different heads to prove this. Took few moments to realise wheres the problem when machinist called that springs your supplied are too short.
But alas, they sell the correct springs for these, both for flat tappet and roller cams. I was also in a situation of needing approx. .150" of shimming due to selecting springs from catalog listing them compatible to Oldsmobile, and not actually measuring them.

 

There's no "opinion" about it. The heads that used valve rotators also had deeper spring pockets so the installed spring height remained the same. The rotators are thicker than the normal retainers.

 

You are thinking about the right questions. You have to check retainer to guide clearance, with the valve seal installed. I found that some umbrella seals are thicker than others, and the Howard's has some that worked better for me. Sure, the locks affect retainer to guide clearance as well as retainer to rocker. The rule of thumb for coil clearance from binding height is a minimum of .050". Mark can help you after you get some actual measurements.

 

Hmm, I hadn't thought about the rotators. They are pretty thick. However, I ordered these springs as a kit and told them that these heads originally used rotators and to consider that before making a recommendation. I guess they didn't. But to be fair, I hadn't measured the needed installed height either.
The latest challenge is that my spring compressor won't fit on the intake of the #7 cylinder, and maybe not the exhaust, because of the brake booster. I already removed the AC box so I could remove the pushrods from the passenger side. Luckily I have some 1/4" steel plate so I can rig something. Kicking myself for not dealing with this when the engine was on the stand. Live and learn.

 

If you are breaking in a new hydraulic or solid flat tappet cam, remember to use the outer springs only for the first 20-30 minutes. Then you have the hassle of installing the inner springs while the engine is in the car.

 

@Run to Rund Actually, this all started because my witness mark on the valve tips was off-center, towards the exhaust. I did the best I could with my knowledge at the time (engine on stand) but the rockers would bind on the studs with shorter pushrods. Joe P. found me studs that the rockers wouldn't bind on and I've been working backward ever since. Just don't ask me why I didn't check the installed height when I built the engine. I simply didn't know how critical it would be. Embarrassing but true. I order the springs from Howards to match my cam for a 455 with no rotators and thought that's all I needed to do. For a long time I thought my valves were too short, because of the binding issue. I know that a lot of folks run the comp cams roller tips, studs, and guide plates without milling the pads with no issues. So a question I have is what is a typical starting install height for most big block iron headed Olds? And do most folks run the rotators?
Like I said, live and learn. As long as I'm still kickin', I'll be learnin', lol.

 

Factory installed height with no valve jobs is 1.67" or with rotators removed, 1.88". I have heard that the rotators are a bad idea with increased spring pressure because they won't work properly. Additionally, they don't have a second, inner spring perch . The springs themselves usually have some variability in pressures. I generally get an installed height that is close to desired, use only hardened shims or cups and retainers. You don't want the springs to dance around so use well-fitting retainers and bottom seats/cups, etc.

 

So I'm in the ballpark. Yet, I'm pretty sure these valve tips were surfaced. I suppose a valve job (which these heads had) would put the valve head a little deeper into the combustion chamber, making the valves taller, so they need dressed. Is that how it works?

 

Well, if using same valves- at best they sit at same height, or then they sunk some down the head.
Installing bigger valves or inserts results usually on a tad shorter installed height- really depends how your machinist choses to do his job.
Then, atleast SI valves, list valves with a tad different stem lenghts, so even that goes to equation.

 

Well that brings up an interesting fact. Stock valve stem diameter is 11/32", yes? Which is .3437". However my valve stems measure .355 just above the keeper slot and .360 just below. There was talk in another thread about maybe these being oversized valves to compensate for the guides being reamed. But these heads have new guides so that doesn't add up.
What this comes down to is that I bought some machined heads; J, ported, polished, Teflon seals, etc. But there were some details left out and I don't have the ability to contact the seller anymore. I'm no too worried about it at this point. They seem to flow well, I don't have any head-to-block leaks, and mostly, I can't afford anything else at this time. I've started a "go fund myself" savings account so that down the road I can upgrade to aluminum.
Today I'm going to make a plate-style spring compressor so I can get that last, cylinder # 7, spring replaced.

 

Those are most likely plus .015 valves. That’s very common in cheap rebuilds, sorry.

 

Meh, don't be sorry. They should run fine with the springs you sent me, Mark. They'll get me by for a few more seasons, I would think.