[Nacs Fab]

I’m going solid roller and looking for the most durable roller lifter set to accompany my 312/316 Duration .660” lift, 110LS camshaft. I want to drive this rig and sometimes distances over 90 miles one way. Could I lighten up on the valve springs a little as in 354 Open and 153 on the seat vs recommended 580 open/236 seat or would this be a disaster?

Heads I’m purchasing from an Individual are new with the Comp 930 spring and I’ll change out springs before installation

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[tom s]

I would no go under 200 on the seats.You wont have the shock absorber of hyd rollers and you dont want to get into a issue of lofting the lifters and pounding out the bearings.Is it a tight lash street roller cam?Tom

[Nacs Fab]

.026” lash on Intake and Exhaust


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[PunchT37]

Solid roller + weak springs = disaster.

[tom s]

You would have been better off if you bought a tight lash street roller IMO.Tom

[Steve C.]

Crower SEVERE DUTY roller lifters, P/N 66294

>>>>>>>>> Order them with the HIPPO Pin Oiler option.

https://www.crower.com/severe-duty-r...-straight.html

Always subject to debate, they can also be ordered with the needleless bearing option if interested


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[slowbird]

Originally Posted by tom s

You would have been better off if you bought a tight lash street roller IMO.Tom

Agree, tighter the better

[Nacs Fab]

Originally Posted by slowbird

Agree, tighter the better

What lash should I be looking for?


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[Steve C.]

More to it than the lash.

Example, I'm using a UltraDyne lobe with my valvetrain mass I was told by Tim at Bullet Racing I could go as little as 180-190 lbs seat pressure.

Mine happens to have 255/259 at .050"
288/292 at .020"
176/179 at .200"
0.4176" lobe lift w/ 1.65/1.6 rocker ratio

I run it with .022" lash
But my peak power rpm is under 6000 rpm. Street only.


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[Steve C.]

Of interest, and to follow up on my comment regarding more to it than lash......

"If you're looking at a cam designed for .022" cold lash, you're looking at a 30 year old cam design. There's no correlation between the lash the cam was designed for, and the aggressiveness of the profile. A cam designed for .022" lash, can be easier, the same, or harder on the valvetrain then a cam designed for .004" lash. It's irrelevant."

"We design the lift from the lash point up, then go back and design a matching ramp from the lash point down to the base circle. The lift we decide on for the lash ramp, has nothing to do with valvetrain stability, or aggressiveness. On most of our cams, we use a .012" lash ramp, and the only reason we use that height, is because it's just a little bit above the growth you would see on an aluminum block/head engine, and you want to be able to set the lash cold to a point where when it gets hot, you're lash point is right at the end of your lash ramp."

"The tighter lash designs are no easier on the valvetrain. The reason they make them, is for marketing. If you design the same exact valve lift curve with both a .020" lash ramp, and a .010" lash ramp, even though they both give you the same exact valve action, the one with the tighter lash ramp looks more aggressive when looking at "Major Intensity"(difference between .020" & .050" duration)."

Mike Jones
Jones Cam Designs

https://www.speed-talk.com/forum/viewtopic.php?t=29717


Valvetrain Tech: Lash Is Much More Than Just A Little Gap

https://www.enginelabs.com/engine-te...-a-little-gap/





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[68WarDog]

[QUOTE=Steve C.;6295556]More to it than the lash.

Example, I'm using a UltraDyne lobe with my valvetrain mass I was told by Tim at Bullet Racing I could go as little as 180-190 lbs seat pressure.

Mine happens to have 255/259 at .050"
288/292 at .020"
176/179 at .200"
0.4176" lobe lift w/ 1.65/1.6 rocker ratio

I run it with .022" lash
But my peak power rpm is under 6000 rpm. Street only.


I too have been running a UD solid roller cam 254/262@.050 with .640 lift/ 1.65 HS / crower lifters on the street for > 10 years without any difficulties. However I would highly recommend a lifter bore brace. My lash is .026 . As already mentioned, spring pressure is paramount, I'm 220/ about 600 off the seat . And since I do ALOT of spirited driving with periodic visits to the 660, I have replaced springs every 4/5 years, although my head porter ( Marty Warden)tells me that may not be necessary since we changed over to pacaloy .I check lash during yearly maintenance and nothing has changed. Steve is spot on about adding the additional oiling hole. Good oil is also important, I'm running amsoil 10-40. Good luck with your build.

[Steve C.]

Never trust catalog specs on valve springs, they can vary more or less than what is published.

We check new valve springs at their actual verified installed height with a Rimac machine before they are installed. Then use that as a baseline.

Once the baseline pressure is known we monitor the valve springs with a LSM brand on the head valve spring pressure checker, there are other brands but that is a good one. Just be aware these types of testers can vary considerably compared to a bench tester. In all instances our LSM checker measures less with installed springs vs the springs tested prior to installation with the Rimac tester. It can be as much as 10-20 pounds less !

Therefore for our use the on the head spring tester is used only to monitor the springs with use over time. We check the valve springs once a year when the lash is checked.


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[Jay S]

Originally Posted by Nacs Fab

I’m going solid roller and looking for the most durable roller lifter set to accompany my 312/316 Duration .660” lift, 110LS camshaft. I want to drive this rig and sometimes distances over 90 miles one way. Could I lighten up on the valve springs a little as in 354 Open and 153 on the seat vs recommended 580 open/236 seat or would this be a disaster?

Heads I’m purchasing from an Individual are new with the Comp 930 spring and I’ll change out springs before installation

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What is the .050” rating for your cam? Who ground it?

Looks similar to a cam I have. 312/316 with .440” lobe lift. The one I have is a compcams grind, and it would be pretty insane to drive it 90 miles on the highway. 284* 288* @.050”, pretty hard on the valve terrain.

[Steve C.]

As Jay pointed out. They could be Comp Hi-Torque .440" lobes.

lobe 4214
312
284
205
.4400"
.660" w/1.5

lobe 4254
316
288
210
.4400"
.660" w/1.5

Page 88
https://www.compcams.com/lobe-catalog

These designs are very aggressive. Years ago Andy Mitchell used these lobes in a 505 Pontiac build called the Road Warrior featured in Hot Rod magazine.
He used the 304/312 lobes with a 1.65 rocker ratio. Dyno'd at 742 hp at 6200-6400 rpm.

He used large 2.180 intake valves in Edelbrock heads rated 315 at .700" lift. In order control his valvetrain mass he used Comp 26099 valve springs.
Today they are rated 250 lbs at 2.050" with a 563 rate. However at the time he set them up at 1.950" for about 306 lbs on the seat.

This is a lot of spring for the street !


.

[Nacs Fab]

Here’s the cam card.


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[Steve C.]

Old camshaft, probably about 13 years. Interestingly the lobe numbers don't correlate with the .020" duration numbers listed in my old Comp catalog nor today's online data.
The additional 0.001" lobe lift is the result of the lobe number "B" suffix code.

Make sure you use lifter bore bracing if it's a factory block.


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[Nacs Fab]

Planning on using the billet full brace kit from Rusolfsson. I will go with new Crower lifters in that Hippo part number you listed. I’m waiting on a reply from Butler about what spring they recommend along with whether I should go bushed or needle bearing. No need in going with less spring it sounds like. Thank you guys for the info.

[Steve C.]

Here is a conversation on a MOPAR board regarding the use of a single pattern cam with the High-Torque .440" lobe number 4213 with 308 at .020".

Note the valve springs mentioned. 275 - 325 lbs seat pressure from some. I would highly suggest you take a measurement of the actual installed height on your cylinder heads.

However keep in mind this is involving a MOPAR valve spring mass, I have no clue how that might correlate to a Pontiac.

https://board.moparts.org/ubbthreads...-pressure.html

Another interesting related conversation, but due note this involves a BB Chevy valvetrain mass !
https://www.speed-talk.com/forum/viewtopic.php?t=16847


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["QUICK-SILVER"]

Originally Posted by Nacs Fab

No need in going with less spring it sounds like.

If a person was to run that cam with softer springs... What RPM would you set the rev limiter?

I suspect it would be well below where the engine made peak torque.

Trying to figure out what RPM "lifter toss" happened, and things went south, could be nerve wrecking.

Clay

[Nacs Fab]

Originally Posted by "QUICK-SILVER"

If a person was to run that cam with softer springs... What RPM would you set the rev limiter?

I suspect it would be well below where the engine made peak torque.

Trying to figure out what RPM "lifter toss" happened, and things went south, could be nerve wrecking.

Clay

I agree, not a gamble I want to take.


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