Hemi Roller Lifter Springs!!!

I'm having a ***** of a time trying to come up with roller lifter springs for my DeSoto Hemi! I need 150lbs on the seat, 350lbs opened, 1.04 coil bind. The Stock diameter (outer spring) is 1.33 and the inner is .915...free height is 2.00. Valve lift is .375. ANY suggestios, at ALL, would be greatly appreciated. Thanks, guys...

 

I would be surprised if you can find any with that od. All the stuff that I used was 1.45, 1.55, or 1.625. I think you will have to machine the recess on the head for larger od springs. Your valve lift figure is at the cam or at the valve?

 

I'm resigned to the fact that I'll need to cut the seats some. That's the valve lift...

 

Typically, these engines use 1.2" open and 1.7" closed +/-...where does the 1.04" come from and what dia wire are you playing with??
With only .375" valve lift the 1.2/1.7 should be adequate. Did I miss part of the conversation?


.

 

That sure doesn't sound like much spring pressure for a roller. Is it hydralic?

 

I hope that .375 lift isn't X 1.5 = .562....

 

73RR - 1.04 is height where the coil(s) binds. Outer spring wire diameter is .162 and inner spring diameter is .106. I've got no problem with installed/open spring height, its FINDING adequite springs of that size and necessary open/closed pressure.

KROOSER - Thats valve lift...including the 1.5 rocker ratio...

 

Have you called all the major cam companies and asked what they had?

If not, I think your going to have o have them custom made. There is a spring company here in STL that will engineer any spring you need. But I bet that machining the head will be cheaper than have 1 set of springs made.

 

Sorry Tony, I should have worded the question differently...Is 1.04 a measured number (your old springs?) or something found in a catalogue/spec sheet??

It looks like your best bet is the MoparPerformance spring: P3412068; 1.46 OD; outer wire 0.191 dia; inner wire 0.135 dia; free length 2.05; solid 0.98; 139 lbs closed and 370 lbs open, (based on 1.2/1.7)

I am really curious about the apparent 'low-lift' of the cam. What can you tell all of us with inquiring minds?

Gary.

.

 

73RR - 1.04 bind is measured on my springs. Cam is a Chet Herbert #7 DeSoto Roller. Duration is 268, lobe center is 112. Intake opens @6 BTDC, closes @ 50 ABDC...Exhaust opens @ 50 BBDC, closes @ 6 ATDC. The reason for the low lift of the cam is due to the low installed height of the Stock DeSoto springs. I have been advised that the cam will be fine for a Street Blower, and my intended limit of 5,500 occasional RPM. This is only a low deck 291 engine, not a whoop *** 392...

 

Theres the conumdrum, if Herbert specs low cam lift due to stock spring ht then why do they require 150# seat, seems to me if you have a spring to satisfy the seat pressure then you'd have a spring for a reasonable lift (say, .460 or more) for a cam of that much duration.

 

The high spring pressure is to keep the roller down on the lobe, plus the blower adds to the need for a beefier spring...

 

You can use longer valves and/or you can get keepers(locks) and retainers that are +0.050" (each)...... The retainer and keeper trick alone can buy you alot of installed height and get you more spring choices. Another trick you can do is install "heavy wall" bronze guides that'll allow you to run valves with smaller 11/32" valve stems (stockers ar 3/8").....that opens even more choices for various stem length and head diameter choices as well.

"Rebuilder" companies such as VSI have great cross-reference charts that you can use to look up valves by different dimensions. These are very helpful with working with motors where you have to play games due to valvetrain limitations.

...or course, in any case you'll be machining the head for the spring OD and you'll be looking into different puchrods (and/or an adjustable valvetrain).

-Bigchief.

 

Does anyone know what the seat pressure is for Magnum engines,,,they have hyd. roller cams.
Since your upper rpm limit is only 5500,,,maybe you could get away with a little less pressure?
.375 lift would not be too hard on springs,,,,the blower would require a little more pressure though.
How much boost you plan to run?

Tommy

 

I also hope you have invested in a nice set of 1 piece stainless valves,,that much open pressure (350 #) will kill stock valves.
Good luck with the build.

Tommy