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Valve Spring Pressure #1155692 01/13/12 01:21 AM 01/13/12 01:21 AM
Joined: Sep 2007 Posts: 426 Cascade, CO reknapp52 OP mopar
reknapp52 OP mopar Joined: Sep 2007 Posts: 426 Cascade, CO	I will be installing some new heads and a roller cam in my race car for the 2012 season. The cam has a duration of 308 @ .020 and .704 lift at the valve with 1.6 rockers. The motor will not go over 7500 RPM. What is a good conservative seat pressure to use? 7015881-5851burnoutinPhoenix.JPG (96 downloads)

Re: Valve Spring Pressure [Re: reknapp52] #1155693 01/13/12 02:09 AM 01/13/12 02:09 AM
Joined: Jul 2010 Posts: 2,091 Delray beach, Florida P Performance Only top fuel
Performance Only top fuel P Joined: Jul 2010 Posts: 2,091 Delray beach, Florida	Quote: I will be installing some new heads and a roller cam in my race car for the 2012 season. The cam has a duration of 308 @ .020 and .704 lift at the valve with 1.6 rockers. The motor will not go over 7500 RPM. What is a good conservative seat pressure to use? 275 lbs. machine shop owner and engine builder

Re: Valve Spring Pressure [Re: reknapp52] #1155694 01/13/12 02:24 AM 01/13/12 02:24 AM
Joined: Jun 2003 Posts: 52,972 Romeo MI MR_P_BODY Master
MR_P_BODY Master Joined: Jun 2003 Posts: 52,972 Romeo MI	I run the same lift and use 320# seat... PAC springs and turn 8200 all the time

Re: Valve Spring Pressure [Re: reknapp52] #1155695 01/13/12 02:45 AM 01/13/12 02:45 AM
Joined: May 2008 Posts: 5,399 Aurora, Colorado 451Mopar master
451Mopar master Joined: May 2008 Posts: 5,399 Aurora, Colorado	I'm running PAC 1325 springs at 1.950" which is about #275 on the seat with a 0.714" lift cam, but have only taken it to 7,000 rpm.

Re: Valve Spring Pressure [Re: reknapp52] #1155696 01/13/12 01:09 PM 01/13/12 01:09 PM
Joined: Aug 2005 Posts: 760 Southington Ct. T turbobitt super stock
turbobitt super stock T Joined: Aug 2005 Posts: 760 Southington Ct.	Quote: I will be installing some new heads and a roller cam in my race car for the 2012 season. The cam has a duration of 308 @ .020 and .704 lift at the valve with 1.6 rockers. The motor will not go over 7500 RPM. What is a good conservative seat pressure to use? Not enough information. The lift and duration don't tell you much. the type of ramp profile would be more helpful. Allan G. 1970 Challenger w/572 Hemi street car and my pride and joy. 1986 T-Type with 272 Stage 2 Buick V6 engine - True 8 second street car. Just updated the engine and put down 928 HP @ 35# boost to the ground on chasis dyno. 1976 Cee Bee Avenger Jet Boat - 460 Ford powered.

Re: Valve Spring Pressure [Re: turbobitt] #1155697 01/13/12 01:28 PM 01/13/12 01:28 PM
Joined: Feb 2003 Posts: 3,456 Out West 4 408strokerdart master
408strokerdart master 4 Joined: Feb 2003 Posts: 3,456 Out West	Quote: Quote: I will be installing some new heads and a roller cam in my race car for the 2012 season. The cam has a duration of 308 @ .020 and .704 lift at the valve with 1.6 rockers. The motor will not go over 7500 RPM. What is a good conservative seat pressure to use? Not enough information. The lift and duration don't tell you much. the type of ramp profile would be more helpful. Allan G. Also, what size and material valve?

Re: Valve Spring Pressure [Re: turbobitt] #1155698 01/13/12 04:25 PM 01/13/12 04:25 PM
Joined: Jul 2010 Posts: 2,091 Delray beach, Florida P Performance Only top fuel
Performance Only top fuel P Joined: Jul 2010 Posts: 2,091 Delray beach, Florida	Quote: Quote: I will be installing some new heads and a roller cam in my race car for the 2012 season. The cam has a duration of 308 @ .020 and .704 lift at the valve with 1.6 rockers. The motor will not go over 7500 RPM. What is a good conservative seat pressure to use? Not enough information. The lift and duration don't tell you much. the type of ramp profile would be more helpful. Allan G. Allen, that cam shouldn't be a spring killer. .440 lobe and only .704 gross lift with a 1.6 rocker and only .660 lift at 1.5 i wouldn't call it a slouch, but ramp velocity should be very "moderate". machine shop owner and engine builder

Re: Valve Spring Pressure [Re: Performance Only] #1155699 01/13/12 06:32 PM 01/13/12 06:32 PM
Joined: Aug 2005 Posts: 760 Southington Ct. T turbobitt super stock
turbobitt super stock T Joined: Aug 2005 Posts: 760 Southington Ct.	Quote: Quote: Quote: I will be installing some new heads and a roller cam in my race car for the 2012 season. The cam has a duration of 308 @ .020 and .704 lift at the valve with 1.6 rockers. The motor will not go over 7500 RPM. What is a good conservative seat pressure to use? Not enough information. The lift and duration don't tell you much. the type of ramp profile would be more helpful. Allan G. Allen, that cam shouldn't be a spring killer. .440 lobe and only .704 gross lift with a 1.6 rocker and only .660 lift at 1.5 i wouldn't call it a slouch, but ramp velocity should be very "moderate". I commented like this because general lift numbers can be deceiving. A lot of people fall in the trap of thinking that there is a general lift = "X" amount of spring load number. Example, Some of the Comp "TK", and "RT" rollers are really aggressive even though they have some smaller lift and duration profiles. For one of my more recent cams I just spec'd for myself, I'm using the High Tech .420 lobes or "-5". These would require a different spring than a TK or RT profile of the same lift. For this, I'm using 275 seat load but also have boost pressures to consider. Allan G. 1970 Challenger w/572 Hemi street car and my pride and joy. 1986 T-Type with 272 Stage 2 Buick V6 engine - True 8 second street car. Just updated the engine and put down 928 HP @ 35# boost to the ground on chasis dyno. 1976 Cee Bee Avenger Jet Boat - 460 Ford powered.

Re: Valve Spring Pressure [Re: turbobitt] #1155700 01/13/12 07:51 PM 01/13/12 07:51 PM
Joined: May 2008 Posts: 5,399 Aurora, Colorado 451Mopar master
451Mopar master Joined: May 2008 Posts: 5,399 Aurora, Colorado	Good point on the lobe profiles. I'm using the comp cams HXL 264/264 @ 0.050" with 1.6:1 rockers so my lift is 0.714"/0.714" with the #275 seat pressure.

Re: Valve Spring Pressure [Re: turbobitt] #1155701 01/15/12 02:28 AM 01/15/12 02:28 AM
Joined: Sep 2007 Posts: 426 Cascade, CO reknapp52 OP mopar
reknapp52 OP mopar Joined: Sep 2007 Posts: 426 Cascade, CO	I have attached the spec card for the cam that I have. I can't find any info on the Comp Cams website, as far as what springs to use, or any info for that matter. It may be an older grind--any thoughts on how it will work in a Super Gas application? Mine is a 447 low-deck motor, will be using the Edelbrock Victor heads. 7019410-CompCamSpecs.jpg (140 downloads)

Re: Valve Spring Pressure [Re: reknapp52] #1155702 01/15/12 09:35 AM 01/15/12 09:35 AM
Joined: Jul 2010 Posts: 2,091 Delray beach, Florida P Performance Only top fuel
Performance Only top fuel P Joined: Jul 2010 Posts: 2,091 Delray beach, Florida	HI-TORQUE .440" ROLLERS These designs are very aggressive and can be used with a variety of rocker ratios. Smaller designs work well in oval track motors and larger designs work in drag racing applications. The Hi-Torque .440� designs are stable to 8200+ rpm. 8200+ rpm. LOBE RATED DURATION IN LOBE TAPPET LIFT @ THEORETICAL VALVE LIFT NUMBER DURATION DEGREES LIFT TDC @ �0� LASH ROCKER ARM RATIO CAMSHAFT TYPE @ .050� @ .200� 106� 110� 1.5 1.6 1.7 4217 278-8 250 174 .440 .115 .099 .660 .704 .748 4216 280-8 252 176 .440 .119 .102 .660 .704 .748 4240 284-8 256 178 .440 .122 .105 .660 .704 .748 4241 288-8 260 182 .440 .131 .114 .660 .704 .748 4243 292-8 264 186 .440 .140 .123 .660 .704 .748 4245 296-8 268 190 .440 .149 .131 .660 .704 .748 4252 300-8 272 194 .440 .157 .139 .660 .704 .748 4253 304-8 276 197 .440 .177 .160 .660 .704 .748 4213 308-8 280 201 .440 .185 .167 .660 .704 .748 4214 312-8 284 205 .440 .191 .174 .660 .704 .748 4254 316-8 288 210 .440 .198 .180 .660 .704 .748 Last edited by Performance Only; 01/15/12 09:38 AM. machine shop owner and engine builder

Re: Valve Spring Pressure [Re: Performance Only] #1155703 01/15/12 10:46 AM 01/15/12 10:46 AM
Joined: Jan 2003 Posts: 16,928 NC 440Jim I Live Here
440Jim I Live Here Joined: Jan 2003 Posts: 16,928 NC	Quote: HI-TORQUE .440" ROLLERS These designs are very aggressive and can be used with a variety of rocker ratios. Smaller designs work well in oval track motors and larger designs work in drag racing applications. The Hi-Torque .440� designs are stable to 8200+ rpm. 8200+ rpm. LOBE RATED DURATION IN LOBE TAPPET LIFT @ THEORETICAL VALVE LIFT NUMBER DURATION DEGREES LIFT TDC @ �0� LASH ROCKER ARM RATIO CAMSHAFT TYPE @ .050� @ .200� 106� 110� 1.5 1.6 1.7 4217 278-8 250 174 .440 .115 .099 .660 .704 .748 4216 280-8 252 176 .440 .119 .102 .660 .704 .748 4240 284-8 256 178 .440 .122 .105 .660 .704 .748 4241 288-8 260 182 .440 .131 .114 .660 .704 .748 4243 292-8 264 186 .440 .140 .123 .660 .704 .748 4245 296-8 268 190 .440 .149 .131 .660 .704 .748 4252 300-8 272 194 .440 .157 .139 .660 .704 .748 4253 304-8 276 197 .440 .177 .160 .660 .704 .748 4213 308-8 280 201 .440 .185 .167 .660 .704 .748 4214 312-8 284 205 .440 .191 .174 .660 .704 .748 4254 316-8 288 210 .440 .198 .180 .660 .704 .748 Good info for evaluating the cam. Lobe intensity from 0.020" to 0.050" is 308-280=28 Lobe intensity from 0.050" to 0.200" is 280-201=79 It does goes easy near max as it limits lift to .440" So the quick action initially matches the description "high torque"

Re: Valve Spring Pressure [Re: 440Jim] #1155704 01/15/12 11:09 AM 01/15/12 11:09 AM
Joined: Jul 2010 Posts: 2,091 Delray beach, Florida P Performance Only top fuel
Performance Only top fuel P Joined: Jul 2010 Posts: 2,091 Delray beach, Florida	Quote: Quote: HI-TORQUE .440" ROLLERS These designs are very aggressive and can be used with a variety of rocker ratios. Smaller designs work well in oval track motors and larger designs work in drag racing applications. The Hi-Torque .440� designs are stable to 8200+ rpm. 8200+ rpm. LOBE RATED DURATION IN LOBE TAPPET LIFT @ THEORETICAL VALVE LIFT NUMBER DURATION DEGREES LIFT TDC @ �0� LASH ROCKER ARM RATIO CAMSHAFT TYPE @ .050� @ .200� 106� 110� 1.5 1.6 1.7 4217 278-8 250 174 .440 .115 .099 .660 .704 .748 4216 280-8 252 176 .440 .119 .102 .660 .704 .748 4240 284-8 256 178 .440 .122 .105 .660 .704 .748 4241 288-8 260 182 .440 .131 .114 .660 .704 .748 4243 292-8 264 186 .440 .140 .123 .660 .704 .748 4245 296-8 268 190 .440 .149 .131 .660 .704 .748 4252 300-8 272 194 .440 .157 .139 .660 .704 .748 4253 304-8 276 197 .440 .177 .160 .660 .704 .748 4213 308-8 280 201 .440 .185 .167 .660 .704 .748 4214 312-8 284 205 .440 .191 .174 .660 .704 .748 4254 316-8 288 210 .440 .198 .180 .660 .704 .748 Good info for evaluating the cam. Lobe intensity from 0.020" to 0.050" is 308-280=28 Lobe intensity from 0.050" to 0.200" is 280-201=79 It does goes easy near max as it limits lift to .440" So the quick action initially matches the description "high torque" since the OP is limiting the rpm to 7500, i still think 275-280 seat and 700 lbs over the nose will get the job done. more spring won't hurt anything though. it's listed as "very aggressive", but this is an older design and there are other lobes that make this one look pretty tame comparatively speaking. a simple phone call to comp cams will give him the answer he's looking for. machine shop owner and engine builder

Re: Valve Spring Pressure [Re: 440Jim] #1155705 01/15/12 11:17 AM 01/15/12 11:17 AM
Joined: Feb 2005 Posts: 4,315 Prospect, PA BSB67 master
BSB67 master Joined: Feb 2005 Posts: 4,315 Prospect, PA	Jim - If you have not done so, you should graph the advertised, 0.050, and 0.200 numbers for lobes-of-interest. It is clear that you would appreciate this. It paints a very clear picture of the agressiveness of the lobes, and is a great way of making the comparisons between different lobes, as the slope of the line is the rate. I've done this for most of the comp lobes from the realitvely slow -5 to the TKs, and some other bands as well. I did it by hand on 11x17 in multiple colors. Let me know and I'll send you what I have if you're interested.

Re: Valve Spring Pressure [Re: BSB67] #1155706 01/15/12 12:35 PM 01/15/12 12:35 PM
Joined: Jan 2003 Posts: 16,928 NC 440Jim I Live Here
440Jim I Live Here Joined: Jan 2003 Posts: 16,928 NC	Quote: Jim - If you have not done so, you should graph the advertised, 0.050, and 0.200 numbers for lobes-of-interest. Do you mean like the attached? I all those lobes are of the same family, so they look similar in slope/intensity below 0.200". I will make another comparison with a lobe from another family. Quote: I still think 275-280 seat and 700 lbs over the nose will get the job done Dan, I don't know the right spring pressures. But what you are saying sounds like plenty to me for that cam. Some guys are running 0.660" rollers with only 220ish on the seat. But I am thinking the lobe intensity from 0.020" to 0.050" would be a factor in the seat pressure. And this is more agressive in that range than some other 0.660" rollers. And rpm limit is a key factor as you pointed out. 7019733-Lobe_Intensity.pdf (159 downloads)

Re: Valve Spring Pressure [Re: 440Jim] #1155707 01/15/12 01:04 PM 01/15/12 01:04 PM
Joined: Feb 2005 Posts: 4,315 Prospect, PA BSB67 master
BSB67 master Joined: Feb 2005 Posts: 4,315 Prospect, PA	Quote: Do you mean like the attached? I all those lobes are of the same family, so they look similar in slope/intensity below 0.200". I will make another comparison with a lobe from another family. Not exactly. I use the change of cam shaft degrees (technically crank) on one axis, not actual degrees. This way the size of the cam does not effect the comparison - it is strictly compares the lobe rate. Said differently, all of the RT lobes irrespective of the duration will draw the exact same line. Also, in the electronic spreadsheets that I used did not work well for me when comparing similar lobe rates, specifically, the NC vs HT406 vs the RX, or the RC vs HT440 vs RT as they end up on top of one another. The fine lines on a large page really make a difference for me. Last edited by BSB67; 01/15/12 01:07 PM.

Re: Valve Spring Pressure [Re: BSB67] #1155708 01/15/12 01:09 PM 01/15/12 01:09 PM
Joined: Aug 2005 Posts: 760 Southington Ct. T turbobitt super stock
turbobitt super stock T Joined: Aug 2005 Posts: 760 Southington Ct.	Quote: Quote: Do you mean like the attached? I all those lobes are of the same family, so they look similar in slope/intensity below 0.200". I will make another comparison with a lobe from another family. Not exactly. I use the change of cam shaft degrees (technically crank) on one axis, not actual degrees. This way the size of the cam does not effect the comparison - it is strictly compares the lobe rate. Said differently, all of the RT lobes irrespective of the duration will draw the exact same line. Also, in the electronic spreadsheets that I used did not work well for me when comparing similar lobe rates, specifically, the NC vs HT406 vs the RX, or the RC vs HT440 vs RT as they end up on top of one another. Keep in mind that some of the newer profiles have TK or RT opening profiles with softer closing. This makes direct comparisons using the cam intensity numbers difficult. Allan G. 1970 Challenger w/572 Hemi street car and my pride and joy. 1986 T-Type with 272 Stage 2 Buick V6 engine - True 8 second street car. Just updated the engine and put down 928 HP @ 35# boost to the ground on chasis dyno. 1976 Cee Bee Avenger Jet Boat - 460 Ford powered.

Re: Valve Spring Pressure [Re: 440Jim] #1155709 01/15/12 01:23 PM 01/15/12 01:23 PM
Joined: Jan 2003 Posts: 16,928 NC 440Jim I Live Here
440Jim I Live Here Joined: Jan 2003 Posts: 16,928 NC	OK, I dug out some numbers and made some comparisons. Attached is the table of numbers. 1) The MM305 flat tappet actually has a more agressive (more intensity) from 0.020-0.050 than many rollers. So it makes good torque. 2) Comparing two 0.660" rollers, the Hi-Torque 0.440" has more intensity than the RZ series which is designed for higher rpm, stability, endurance, etc. So if both were being used at moderate rpm (7000ish), the RZ could use less spring pressure, IMO. 3)The street roller is less intense from 0.020-0.050 to allow less seat pressure (from their catalog statement). And it is mild from 0.050-0.200 as well. 7019789-Lobe_Intensity2a.jpg (103 downloads)

Re: Valve Spring Pressure [Re: 440Jim] #1155710 01/15/12 01:24 PM 01/15/12 01:24 PM
Joined: Jan 2003 Posts: 16,928 NC 440Jim I Live Here
440Jim I Live Here Joined: Jan 2003 Posts: 16,928 NC	And attached is the graph to go with that table. 7019795-Lobe_Intensity2.pdf (149 downloads)

Re: Valve Spring Pressure [Re: BSB67] #1155711 01/15/12 01:27 PM 01/15/12 01:27 PM
Joined: Jan 2003 Posts: 16,928 NC 440Jim I Live Here
440Jim I Live Here Joined: Jan 2003 Posts: 16,928 NC	Quote: Not exactly. I use the change of cam shaft degrees (technically crank) on one axis, not actual degrees. OK, that is the intensity I was talking about. Time to replot... see attached. The y-axis (vertical/side) is the duration change from 0.020-0.050" plotted at the 0.050" position on the x-axis (bottom) 7019800-Lobe_Intensity3.pdf (148 downloads)

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