Big Block Valve Spring Help Please

I need solid recommendations for new valve springs. I have a 440 with a MP Purpleshaft .484 lift cam but I am about to install 1.6 roller rockers. These new 1.6 rockers will put the lift to .516. Based on what I've learned so far I should limit seat pressure to about 120 lbs and open pressure to 300 lbs. I currently have MP 933 springs with a max lift suggesting of .510. I'm sure a spring suitable will be single but with a damper. Suggestions with real world experience needed please. Thanks! Greg

Do you know what the current cam spring pressure ratings are for the 484 cam?

Going from 1.5 to 1.6 rockers may require a little more spring pressure, so having the original spring pressure specs would help.

Do you know what the current installed heights are? This would also help to find a spring rated at your same IH.

The WOT rpm would help too. Once you can get this info, the engine guru's will be able to estimate the spring pressures for you.

Thanks! The Mopar Performance 933's have an installed height of 1.83/1.86. Spring pressures are 310 lbs open and 115 lbs closed. The spring diameter is 1.532 OD and wire diameter is .224. I'm shifting at 6000 rpm's.

Two things on valve springs and installed height, never assume that the specs. are correct
Do you have the tools needed to verify the installed height and the installed pressures and coil bind height? If not either buy a height mike or inside calipers and a decent spring pressure gauge or take the heads to a good machine shop that can set them up properly for you
I can't believe that any Mopar after market valve spring set for a BB won't work up to .550 lift with at least .080 clearances from coil bind and have more than 360 lbs. open
another thing to check is the accuracy of the rocker arm ratio, get a light weight checking spring and make a old hydraulic lifter into a solid so it won't loose lift and see how much lift you have at the retainers(both intake and exhaust) with zero lash and do the math on the true rocker arm ratio
I've seen a bunch of ductile iron rocker arms of all brands have a lot less ratio than advertised
Good luck on your project, there are a lots of ways to make more power

I don't have these tools and I just need a solid recommendation for a set of valve springs that my machinist can work with. Any recommendations? Thanks!

Isky 8005A

This is the Comp #911 single/damper (OD=1.524") spring chart. Once you know your recommended seat pressure, then reference the installed heights to see if this spring will work or not. This spring is real close to your existing OD of 1.532".

Thanks Y07! That one is much closer to my budget and it has been confirmed by a tech at Comp Cams to be the one for the job.

The 933 will work. The measured pressure is usually a bit higher than advertised. They just "say" 0.510" because of the 509 cam. Have someone put them on a tester, verify pressures and coil bind.

Thats a great suggestion but I've been running these 933's for almost 20 years and I'm thinking fresh springs for peace of mind if nothing else.

I'm running Crane #99839-16 springs on a cam with .520 lift. Outside diameter is 1.500, inside diameter is 1.086. I have them installed at 1.800 and seat pressure is 121, open they are 310. Spring rate is 354. They are supposed to be good to .660 max lift at which point they are 360 open. The price from Summit was reasonable as well. If I remember correctly, they were under $100. Been running them for 3 years now and they work great to 6000 rpm. I don't spin it any more than that.

I don't know what pistons you are running, but it's probably worth checking piston-to-valve clearances

Bunk,
What installed height did Comp tell you to use for the 911's?

I ran a set of Comp single springs with the dampner on a 383 with the MP .484 cam for years and they worked good. Ron

Comp 911 16 spring installation height is 1.90 but I have found a new set of Edelbrock RPM springs with retainers and locks that I'm going to use. I will get my machinist to set them up properly for me. Thanks again for you help Y07!

Wiseco Pro Tru's with 6 cc valve reliefs and they sit in the hole .034.

Bunk,
Your welcome!

But please keep in mind that you may need to raise the seat/open pressures of what ever spring you end up using to keep up with the new 1.6 rocker arms and 6000rpms.

Did you receive an answer to how much spring pressure to use with the 1.6 rocker arm swap?
If not, here are a few contacts that you can use to confirm that you are using enough spring pressure for your new 1.6/6000rpm swap. Just get them the details of what you are doing and ask for their spring pressure recommendations.

sales@manleyperformance.com
gwarner@cranecams.com
techsupport@lunatipower.com
thomas.Fleegle@pspring.com (PAC)