Help. I think my valve springs are gay

[66FAIRLANE]

My 390 has a Cam Research solid 590/590 240/244 on 110 sep. For some time its been hitting a wall just after 6000rpm. If I persist it bends pushrods. It used to spin over 6500 with no problems. The other day I made a valve spring checker
http://fepower.net/simplemachinesforum/index.php?topic=424.0
I used it tonight and only checked one bank (the one that usually bends pushrods). It was quite easy to use to check seat pressures but open was a little more difficult so I only checked 2. I also realised I was doing something I probably shouldn't, opening valves to full lift without knowing where the piston was!

Anyway, cam card calls for 125 on the seat and 325 open. All the left bank checked between 90 and 100 on the seat and the 2 I checked at full lift were 280ish. Personally I would like to see 130 to 140 at the seat as I like rpm. The springs are doubles supplied by CR when I bought the cam. The springs are a few years old.

I am pretty sure this is my missing rpm issue but would value the opinions of those more experienced than myself.

[ToddK]

Those measured pressures are a bit light, sounds like it might be time for some new springs. Even the springs I'm using with my bubby Comp 270S are stiffer, at 110/350lbs.

[jayb]

Wow, "gay" valve springs is a whole new concept LOL!  The seat pressure is definitely too low for that cam.  You might be able to shim the springs up to get the seat pressure you need, but watch out for coil bind if you do that.

[drdano]

What is the brand on the springs?  I went through two boxes of Comp Cams springs a few months ago and BOTH boxes had 10+ springs in each that were over 20% light on the seat.  Needless to say, I'll never install springs without checking them ever again.

[66FAIRLANE]

Thanks for the responses guys. The springs are unknown brand and were supplied by Cam Research with the cam. The installed height is correct but I have no idea if that actually acheived the seat pressure required when they were new as I had no way of checking then and just trusted the shop.

I will check for coil bind and then may shim up as I am still tossing around long term plans for this engine.

[Joe M]

They are not gay, they just prefer an alternative lifestyle.  Not that there is anything wrong with that!

[manofmerc]

I had something similar happen with my 67 comet dragcra with 460 power .My last time to the dragstrip about 100' from the finish line my car started breaking up .It didnt sound ignition or fuel related .I remembered my stubborn machinist telling me he set my spring pressures at 125 closed even after i told him I wanted 145 which is the spec on the lunati 73121 springs I have .I bought myself a pro form spring checker from summit .Well some of my exhaust were at 110 closed and the intake were in the 120 range .The installed height was anywhere from 2.005 to 1.976 .I had to shim these spring to 1.336-1.405 to get them to 140 .I dont think my machinist really checked the spring height .I hate this he is a neighbor and a good guy I am going back to the track to verify the results .If no breakup at higher rpms he has some questions to answer .It was a two day job shimming the springs with the motor installed in my comet .By the way my mph went down almost 2 mph .From 118.69 to 116.90 .I  will see Doug

[66FAIRLANE]

Please school me on coil bind. I realise they can't bind but what is the accepted limit? How do you measure on the engine? Can you feeler gauge between coils?

I had a little play with feeler gauges last night and I think I am going to be out of luck shimming these as the coil spaces weren't even with the largest gap at around .065.

[jayb]

Coil bind is when the coils are stacked solid.  If you can get a feeler gauge between any two of the coils, you are not at coil bind yet.  A lot of guys run so close to coil bind that they are within .015" or so of having the coils stacked solid.  If you can get a 0.065" feeler gauge between two adjacent coils, you have a long way to go.

[66FAIRLANE]

Thanks Jay. Most info I could find was unclear on wether it was .060 between all coils or .060 in one spot. I will have to shim these puppies up a fair bit so I will see how I go.

Thanks for the info.