The Ford Barn

Ol' Ron · 09-28-2018, 09:30 PM

Recently there has been several threads on valve spring pressure. Yes there is a very good reason for this pressure, but it's not a guessing game. I hope Pete jumps in here and explains why hi spring pressure is nor necessary for a street engine. For he lat 20 years I'v been using 50/60 Lbs on all my cams and nobody had floated a valve yet. The L-100 cam runs very well up to 5k with 50 lbs. Maybe not in a race but for the time it takes to put the pedal to the metal, Used 65 lba on a 400jr for several yr\eats and the same springs on the Sig Erson D410, For many laps. Just remember you must have a reason for making a modification. It's pretty hard to float a Chevy valve in a flathead.

Tinker · 09-28-2018, 09:41 PM

I have zephyr springs on my rebuild, most likely over kill (60lbs). Mild lumpy reground cam, punched .60 over ( it was .40 over and wanted some life out of the block, and not just go right to max out). Worry the long terms effects on the fiber timing gear (yes I have one) and cam. They were available.

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Yoyodyne · 09-29-2018, 09:41 AM

Quote:

Originally Posted by Ol' Ron

For he lat 20 years I'v been using 50/60 Lbs on all my cams and nobody had floated a valve yet. The L-100 cam runs very well up to 5k with 50 lbs.

What spring at what installed length do you use to get that 50 lbs?

Ol' Ron · 09-29-2018, 11:24 AM

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OK we have to set some parameters: What is the application is the engine? what lift does the cam have? Street engine spends 90% of it time in cruise. Lift determines the base circle. Small base circle means the lifter must be longer, back in the day you could get different adjusting screws for the lifters that had longer heads. Today we use Chevy valves. Now check installed height. Installed height is determined by the valve and retainer, installed in the block.
Measure the distance between then. Now at thet measurement you need 50 lbs of pressure on most camshafts, i got this by adding 2 060" shims on stock valves springs with the L-100 cam and Chevy valves. At present my friend Robs 294 has this in his truck and every time we go to lunch we have to "Clean the engine out" on the way there. When Uncle max's tipple Stromburg 48 open up, the tack hits 5K in the blink of an eye. No valve float.

09-28-2018, 09:30 PM	#1
Ol' Ron Senior Member Join Date: May 2010 Location: Chester Vt Posts: 8,857	I think we need a discussion on camshafts and valve springs Recently there has been several threads on valve spring pressure. Yes there is a very good reason for this pressure, but it's not a guessing game. I hope Pete jumps in here and explains why hi spring pressure is nor necessary for a street engine. For he lat 20 years I'v been using 50/60 Lbs on all my cams and nobody had floated a valve yet. The L-100 cam runs very well up to 5k with 50 lbs. Maybe not in a race but for the time it takes to put the pedal to the metal, Used 65 lba on a 400jr for several yr\eats and the same springs on the Sig Erson D410, For many laps. Just remember you must have a reason for making a modification. It's pretty hard to float a Chevy valve in a flathead.

09-28-2018, 09:41 PM	#2
Tinker Senior Member Join Date: May 2010 Location: MN Posts: 7,053	Re: I think we need a discussion on camshafts and valve springs I have zephyr springs on my rebuild, most likely over kill (60lbs). Mild lumpy reground cam, punched .60 over ( it was .40 over and wanted some life out of the block, and not just go right to max out). Worry the long terms effects on the fiber timing gear (yes I have one) and cam. They were available. . Last edited by Tinker; 09-28-2018 at 10:35 PM.

09-29-2018, 11:24 AM	#4
Ol' Ron Senior Member Join Date: May 2010 Location: Chester Vt Posts: 8,857	Re: I think we need a discussion on camshafts and valve springs Sponsored Links (Register now to hide all advertisements) OK we have to set some parameters: What is the application is the engine? what lift does the cam have? Street engine spends 90% of it time in cruise. Lift determines the base circle. Small base circle means the lifter must be longer, back in the day you could get different adjusting screws for the lifters that had longer heads. Today we use Chevy valves. Now check installed height. Installed height is determined by the valve and retainer, installed in the block. Measure the distance between then. Now at thet measurement you need 50 lbs of pressure on most camshafts, i got this by adding 2 060" shims on stock valves springs with the L-100 cam and Chevy valves. At present my friend Robs 294 has this in his truck and every time we go to lunch we have to "Clean the engine out" on the way there. When Uncle max's tipple Stromburg 48 open up, the tack hits 5K in the blink of an eye. No valve float.