Roller Valve Spring vs FT Valve Spring

-
Jadaharabi

Jadaharabi

FABO Gold Member
FABO Gold Member
Joined
Jan 8, 2016
Messages
10,694
Reaction score
8,587
Location
Peoria, Illinois
My question is.
Will the valve springs on my heads that are 125 on the seat and 300 lb at .550 lift with a FT cam work with a roller cam with .480 lift?
What is the difference between a roller cam valve spring and a flat tappet valve spring?
 
The spring rate is usually less with a SFT spring and with that little on the seat and .480 lift you’ll have nothing over the nose.

That might be a bit sketchy at a pretty low RPM.

Just my .02
 
The main issue is..... the hyd roller lifters are pretty heavy, especially the retrofit style, so it takes more load to keep everything in control.

So, 125/280-ish will work up to some rpm point with a hyd roller cam, but unless the cam profile is rather tame...... there’s a good chance the valvetrain will start to get unhappy at a fairly modest rpm(low-5000’s).
Where it actually happens will be mostly dependent on the cam profile.
 
I'm wanting to put the roller in a 1990 roller motor. It will have 1.5 factory rockers and ported heads with edelbrock alum head valve springs(1.80? Installed height)

HR-286d-SBM Short Snout Magnum

Advertised Duration
In. 286
Ex. 298

Duration @ .050
In. .227
Ex. .234

Valve Lift 1.6
In. .512
Ex. .512

Lobe Lift
In. .320
Ex. .320

LSA
112

It's a Texas regrind.
 
Is that with the P/N 5767 springs, 9736 retainers, and 9611 locks? What type or diameter are the valve seals?
 
Usually roller cams have more spring pressure than a FT when comparing equivalent lifts/duration.
 
Do you know the inner spring seat height (the one with the .755 diameter) of the retainers? If you can come up with that, I can find out what a set of Melling VS-2203 springs (.745 I.D. .900 O.D. & 1.77 free length) or equivalent added as an inner spring would add to your seat and open pressures and what locator it would need to shim it up with. The downside is it’s about a $100 upgrade, and there’s possibly a set of springs available for less than that. But a different set of springs is probably going to require a different set of retainers, so it still may be the lowest cost option. Shimming would be the lowest cost option, by far.
 
Last edited:
The stock eddy valve springs were just on the edge of being adequate for the advertised limit to begin with, not a big safety margin.
 
Roller cams need more seat pressure than solid flat tappets....they need more spring pressure overall to control the weight, but in this particular case more seat pressure at a minimum. Main thing with rollers is you don't want them to bounce...and they are quite heavy, which is why they need more spring to control things.
 
flyfish said:
Roller cams need more seat pressure than solid flat tappets....they need more spring pressure overall to control the weight, but in this particular case more seat pressure at a minimum. Main thing with rollers is you don't want them to bounce...and they are quite heavy, which is why they need more spring to control things.
Click to expand...


Last lunati hyd roller I set up was 135 lbs @seat.
 
Garrett Ellison said:
Do you know the inner spring seat height (the one with the .755 diameter) of the retainers? If you can come up with that, I can find out what a set of Melling VS-2203 springs (.745 I.D. .900 O.D. & 1.77 free length) or equivalent added as an inner spring would add to your seat and open pressures and what locator it would need to shim it up with. The downside is it’s about a $100 upgrade, and there’s possibly a set of springs available for less than that. But a different set of springs is probably going to require a different set of retainers, so it still may be the lowest cost option. Shimming would be the lowest cost option, by far.
Click to expand...

What would be a good single spring with damper that I could put on these heads with my roller cam?
 
I'm looking for the inner step diameter of the 9736 retainers, and I will go from there with Mr. Wallace's spring calculator. Do your valve springs have a damper? We also need to confirm beyond a doubt those are the P/N's for the components.
 
Garrett Ellison said:
I'm looking for the inner step diameter of the 9736 retainers, and I will go from there with Mr. Wallace's spring calculator. Do your valve springs have a damper? We also need to confirm beyond a doubt those are the P/N's for the components.
Click to expand...

They are just a spring and damper. There is no innerspring.
I'll have to check on what the spring number is cuz I don't know off the top of my head.
 
Okay, I apologize, I misread your question and I caught where you ad said OTB magnum heads. My :realcrazy: Bad! I will get back to you once I get all the figures together from the Edelbrock spec sheet.
 
Garrett Ellison said:
Okay, I apologize, I misread your question and I caught where you ad said OTB magnum heads. My :realcrazy: Bad! I will get back to you once I get all the figures together from the Edelbrock spec sheet.
Click to expand...

Never said magnum heads. Said la roller motor. It has 308 heads. I want to put in a bigger cam.
 
Okay, I got you! The item we need to confirm is the Edelbrock 9736 retainers. If that's the case, you can go with a set of 5845 Edelbrock valve springs. These were what Edelbrock ran on the hydraulic roller version of these heads with the 9736 retainers with 150 closed at 1.800 installed height, 420 open at .580 open.
Edelbrock Sure Seat Valve Springs 5845
https://www.edelbrock.com/sure-seat-valve-springs-5845.htm
I'm looking over other options but it appears that Edelbrock went out of their way to design spring retainers for an outer spring inside diameter no one else manufactures.
 
That's true, but that 1.06 inch diameter on the retainer register is what bites you. Always good to have a valve spring positively located. I'm sure there's some allowance there, but I don't think that’s a good place for gambling! Now if you change retainers, you can do what you want, but the initial payout is exponentially higher.
 
Last edited:
You must log in or register to reply here.
-

Back
Top