What valve springs with 218-212 roller cam

[quickturbo]

I'm wondering what valve springs I should use with a 87 GN motor with a 218-212 roller cam with 1.65 roller rockers and GN1 aluminum heads. The receipts I have from the motor build say I have K-750 springs installed. My motor gets to the 5200-5300rpm area and falls on its face. I eliminated all the electronics as a issue and in 90% sure my intake valves are floating at that rpm. My boost gauge will bounce around quickly in the 12-15 psi range at 5200rpm+ area. If I go to 18psi it will just fall on its face.
Thanks

 

[jpwalt1987]

What lifters?

 

[quickturbo]

What lifters?

Morel hydraulic roller lifters

 

[bison]

What installed height and pressure are the current springs?


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[turbo nasty]

I just went through this with a set of TA SI heads. TA 1160 springs just raised teh issue a few hundred rpms. Im having to get a spring thats 165ish on teh seta and 450 over the nose. Kenny D, Bobby at RPE and others say this is what you need to get. Granted you will need the proper locater, retainers, shims and locks for them. Maybe your current stuff will swap over.

 

[quickturbo]

What installed height and pressure are the current springs?


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It looks like the installed height it's around 1.755". I don't have my hands on a spring pressure checker at the moment. I should be able to borrow one this week.

 

[bison]

It looks like the installed height it's around 1.755". I don't have my hands on a spring pressure checker at the moment. I should be able to borrow one this week.

This installed height is likely a problem. Those springs are around 130lbs @ 1.700" iirc


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[turbo nasty]

Yep advertised is 130# on the seat at 1.70

 

[quickturbo]

With the 1.65 roller rockers I'm around .545 intake lift on my 218-212 cam. Is that a little tall for those springs?

 

[turbo nasty]

Your going to have to check for coil bind at peak lift some shoot for .050 clearance as the bare minimum I prefer .060 because Im paranoid lol.
I had to take some shims out from under the locators due to the high lb inner springs bigger wire size only having .040ish clearance at peak lift. If you do have to add or remove shims keep in mind that the valve guide seals need to be pulled to lift the locators in order to put the shims in. So there is the possibility of them getting nicked, etc and want to grab some new ones and have them ready. Its time consuming and a bit tedious.

 

[bison]

With the 1.65 roller rockers I'm around .545 intake lift on my 218-212 cam. Is that a little tall for those springs?

Order a set of PAC 1201 and set them at 155-160 on the seat. You will be fine on clearance. At around .060" from bind you should be right there on seat pressure


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[quickturbo]

I finally got around to measuring my installed height and pressure
My k-750 springs were installed at 1.753" and with the pressure checker I borrowed that is about 115lbs.

 

[quickturbo]

I finally got around to measuring my installed height and pressure
It looks like the installed height is 1.753 at 115lbs. I think that sounds soft. I will order a set of PAC 1201

 

[turbo nasty]

I wouldnt want less than 140 on the seat

 

[bison]

I wouldnt want less than 140 on the seat

I wouldn't want less than 150 with the 1.65 rocker. Unless he plans on keeping it under 5700


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[turbo nasty]

.

 

[forcefed3.8's]

I ran to 6200 with an aggressive 224 roller with only 140 on the seat, 340 on the nose. It was floating the valves like crazy, this cam needed 500 open. My point, just because it will hit an rpm, doesnt mean it is doing it cleanly. Listen to Bison. Valve springs are part of the reason most of these cars are much slower than they should be.

 

[gunzandgearz]

Valve springs are of huge importance, probably as much as valve timing events especially in blown or boosted applications where the boost pressure is trying push intake valve off the seat. Far better to run too much spring then not enough or just enough.

 

[gunzandgearz]

A little more info, if you happen to be running solid rollers, and you think youre getting into valve float, try tightening up the lash a little and see if it fixes it. tighter lash will help control valve bounce and save youre valve seats which are also of major league importance to low lift flow.

 

[TurboTdr3.8]

Yep advertised is 130# on the seat at 1.70

Just cause it says that on the box does not mean that in real life testing , only the tester will tell the truth