coil bind clearance of .055 and .059?
 

The above is what I will have is this acceptable? The springs are Comp 914-16 and the cam is a Comp special order hydraulic roller 112lsa with .230/.236 duration and .641/.645 valve lift using 1.65 rockers. I have the cam and lifters and the heads are done so I'm hoping I don't have to buy anything else. This is a street car not a race car.

Do you know what the seat pressure is now, and which valve is at .055” a exh or intake?

Installed height is 1.800 and seat pressure is 165 lbs. Valve lift with the 1.65 rockers is .641 and .645 which results in compressed heights of 1.159 and 1.155. Coil bind is 1.100. Spring rate is
367 thus open pressure is right at 400 lbs. both valves. As I said the heads are done. Jim Robertson did them and they have T&D shaft rockers in them. I have checked this board and others on the net re coil bind clearance and as usual answers from the worlds experts are all over the place. Hence my asking here. I'm hoping some people like Tom S., Cliff Ruggles, and Tom Vaught, and a few others, will see this and respond to it. I would call Jim Robertson but hate to bother him. Jim Robertson built the heads for a cam with only .026 and .023 less valve lift than the cam I am going to use now so I would think I'm OK, but I'm a carb guy not an engine guy so appreciate hearing from those who know these things.

Exhaust is .055.

You will be ok , but I would check your seat pressure after about 500 miles just to get base line on the rate that they may be dropping off pressure.
Do you have the type of checker to do it with the heads on?

Thanks for the response re coil bind clearance. Yes I have a spring checker like that. DK how accurate it is. I will never race this thing. Of course I will stick my foot in it sometimes.

I hope you stick your foot in it more then just sometimes, as that should be a fun motor!

I posted this in another thread but it might apply here. We monitor the valve springs with a LSM brand on the head valvespring pressure checker, there are other brands but that is a good one.
Just be aware these types type of testers can vary considerably compared to a bench tester like a Rimac machine.

In all instances our LSM checker measures less with installed springs vs the springs tested when new prior to installation with the Rimac tester. It can be as much as 10-20 pounds less !

My suggestion if using this type of spring tester. After the new springs are installed take a reading of their pressure. Use that as a base line. Then later you can check them to see if the have changed.
So for us the on the head spring tester is used only for us to monitor the springs with use over time. I use a solid roller cam set up and we check the valve springs once a year when the lash is checked.


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You do have valve seal clearance at your lifts right,?

I ask this because your at upper lift limits of the springs themselves other clearances are possibly in play as well

Thank you both for the help. The .059/.055 numbers do not take the seals into account just spring height/valve lift/coil bind. I will also take these numbers to my machinist he's been at it 49 years and has built lots of engines, done race heads, etc.

.050"-.060" from bind is perfectly fine and preferred. Between .050" and .100" is ok. Over .100" and that spring wants to do the chicken dance and things start to get wonky.
Springs always lose pressure after they heat cycle and run, typically up to 20lbs-ish. Setting them up with more when new is always a good idea. As pointed out, retainer to seal clearance is also something you need to check. Hope this helps.

Good article and it might be of interest:

How Much Valvespring Coil-Bind Clearance Is Safe?

https://www.motortrend.com/how-to/ho...rance-is-safe/

"Depending on the intended use and the spring and cam-lobe design, coil-bind safety margins can now vary from 0.015 to 0.120 inch, with tighter numbers predominating on very stiff valvetrains. Anything more than 0.150 inch may cause spring surge, which can greatly reduce the available spring load needed to close the valve."

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THIS IS A KEY SENTENCE: "This is a street car not a race car."
You also have a fairly mild camshaft but with decent valve lift.

A few good points: You have T&D shaft rockers and Mr Robertson did them.

a) I am not sure how much deflection, if any, those rocker arms have.
So we assume that they are true 1.65 rockers and the cam lobes were ground correctly. A soft checking spring would give you the max valve travel
towards the piston. That check would allow you to determine valve guide to retainer clearance. Something to check but we are talking actual springs installed on the heads and the spring reserve before solid coil bind.

Coil springs today are designed with "Surge Dampening" built into them.
Some coils will actually touch occasionally. Spring surge kills valve springs.

All that being said, have you actually assembled everything on the engine and now are checking things like Retainer to Valve Seal clearance, Valve Spring Clearance before solid coil bind, actual Rocker Arm Ratio for the rockers and found the rocker arm with the greatest valve lift for that shaft specific head assembly?

How much of this checking was done by Mr Robertson?

Tom V.

Also, are your coil bind numbers taken off the box or is that measured? I usually find about .006 to .010 more forgiveness when checking. While it's nice to mention that spring pressures decrease, if they really loosen on this build there won't be room to toss in another shim. Beside, he's nicely on the high side for a HR setup so will only be dropping down to a normal spring load when they drop a bit.