400/470 motor with Eddy RPM heads and Howard's 574" lift solid flat tappet cam. The Eddy heads came with springs that only have 120 lbs. seat pressure. What would you suggest I get for replacement springs with this combo?

Until someone chimes in with an exact recommendation in the meantime I would measure the open/closed heights and psi when open and coil bind/wipe pattern & the rest of the std checks to help with a baseline.

Why don't u call Howard's & tell them what cam u have, they should tell u what springs r needed.

Marsh uses a spring made by Isky that is PERFECT for that application call Moparts Connection and get hooked up
Or you could just buy a set of Comp inners --drop them on and keep rolling--yea which one--well I can't remember the number but they only sell three and two won't fit so do the research and get your problem solved for like $38

I did that. First, I called Edelbrock. They said I needed to talk to the cam manufacturer. So I called Howard's and they said I needed to talk to Edelbrock.

Call Dwayne Porter.

I use the Comp 925 springs on those heads with a Mopar Performance .590 solid lift cam. I would also suggest that you go to a 10* retainer with those springs.


Brian

Been using Isky forever...........

I also would recomend you to contakt Duane Porter at Porters Racing Heads ! You probably can buy al the stuff you need of him to

I have shimmed more than one set of stock springs on both the RPM heads and Stealth heads to use them on cams with less than .600 net lift to get 140 to 160 lbs. on the seat sand between 325 to 375 lbs. open pressures. I shoot for at least .060 to coil bind also when I'm done with setting them up
I do have a older mechanical Rimac 1000 valve spring tester and a drawer full of valve spring shims so I use it and them to get all of the springs within 5 lbs. of each other on the seats
On your deal you should probably be able to get the same good results if you can find a shop that has both of those tools in stock

I run Eddy's and think the base springs are a bit weak for that cam lift. It does depend on ramp speed and I suggest you call Howard's and talk to somebody else... they should be able to give a recommendation.

When I started pushing my fast rate .55" lift cam on the track I upgraded to a Comp double spring. Under 6000 RPM I was probably OK with the single Eddy spring but I occasionally ran it up to 6,500 and did not want to find out the hard way I needed more spring.

I agree as I bought my EZ heads from Dwayne which he set up and I believe he said he used Comp springs. My cam is a solid flat tappet thats .585 & .592 lift and they are not beehive springs. Dwayne is as good as you can get on heads and valvetrains so yes I would call him. 802-951-1955. Good luck , Ron

Cam manufacturer should spec this for you based on ramp profiles, but just based on the lift dimension the OP gave and my rudimentary knowledge, something in the 150-175 seat and 350-375 open range should be about right.

It looks like I should be looking for a seat pressure of 150-160 lbs. for the cam I have. According to the spec sheet that came with my heads, the pre-installed springs are rated at 120 lbs. I looked on Summit's website at inner springs and they sell Comp inners in various pressures, heights, diameters, etc. What I noticed though is that all of the installed heights are less than the installed height of the springs on my heads (1.88") except for one that is 1.90" tall. Should the inner spring be the same height as the outer or are the inners typically a little shorter than the outers? How do I go about choosing an inner that is the correct height?

The inners are always installed shorter than the outer due to the step on the retainers Measure the difference on the steps and go from there
Do you have access to a valve spring tester? If so see about using shims on the ones you have first, take nothing for granite

Comp Cams 930-16 springs should work for your setup.

I'd rather not spend another $160 if I don't have to. If I can add inner springs for $40 I'd rather do that. Something like this. https://www.summitracing.com/parts/cca-973-16/applications

It looks like the Comp inner springs that I posted the link for in my last post should work based on the measurements I have taken of the pre-installed springs on my heads but I do have a couple more questions. The springs that came on my heads have a smaller flat metal spring inside them. If I buy the Comp inner springs, should the flat inner springs come out or should they be left and the new inners installed inside of them? Also, do you think I should replace the valve locks (7 degree) with 10 degree locks? I called Edelbrock and they told me it wouldn't be necessary but it seems like it would be a good idea.