Just off seat it measures approx 230 lbs with my LSM spring checker. The spec is 250. I am purchasing a bench LSM spring checker to verify the new springs.

 

Are your valves light weight AFR small stem and isn't your max rpm 7500? You don't need much over 200 pounds closed to operate fine. What you want is taller springs with higher max lift. The springs I have been using the last few years are the Comp Cams 26115's. They are made for .800 lift so my .685/.714 lift doesn't even heat them up. Spring loose seat pressure with time. So the installed height is 2.05 for 225# seat. I've messed with less shim on springs to get closer to 205 - 210# seat pressure and never have had valve float with my 7500 rev limiter. I use Manley proflow light weight SS valves. I reshim them after they loose about 20 pounds and they kinda get replaced about every year when I was really into racing. During the winter down time you have to remove all the rocker arms to relax the springs for storage

COMP Cams Valve Spring Chart Then page forward to 306

COMP Cams 26115-16: Dual Valve Springs Outer Spring O.D.: 1.560 in. | JEGS

 

Heat is what really kills springs. Real drag race motors have glowing springs because of the rpm. We were winter testing road racing years ago in Florida and at the same time a bunch of the NHRA ProStock guys had rented the 1/4 for preseason testing. We had a break in the action and went over to talk to them. They break lots of springs with 1.00 inch lift and 10,000 rpm. They use tilton oil pumps to basically flood the valve covers with oil to cool the glowing springs.

I have always been running high vol oil pumps for the heat reason. I modded my AFR head for oil return. On the outside of the springs I machined a trench, drilled out the return holes, and blended/contoured the end returns for superior oil return. I also started using the biggest diameter springs that I could. 1.55 or 1.56 . If I was lifting a valve .640 I was using springs for .750 max lift now I use springs for over .800 lift. as set up. In a 30 minute sprint race my poor motor is at WOT and into the rev limiter or near it in on every gear shift. Never run things near coil bind. You have to watch a sprintron test of spring surge and harmonic distortion and it will scare you. Oh and it isn't babied around town!

tighter lash just adds to longevity of all the parts. I've replaced sets of my Comp cams Pro magnum steel RR's because they loosened up over the years and yes going down on rocker ratio is a good thing if you don't need those extra few HP.

 

The power curve flattens out at about 6800 rpm. Even though the engine is supposed to b a 7000 rpm engine, based on the issues I have had with it, I don't have the confidence in the engine to spin it up that high. I have sent an oil sample out for testing. My guess is it will likely indicate problems. The valves are 8mm and overall length is 5" for intake and 5.02 for exhaust. The 1225 spring spec is 0.800" max lift. Changing valve length, rocker ratios etc. are all great recommendations but require $$$. I also am not crazy about the idea of pulling my heads..... I like the idea of pulling the rocker arms during extended non-use but living in Atlanta I pretty much drive it year around but it can go for 4 to 6 weeks without use, perhaps I should at least turn it over at least once a week when not using to mix it up a bit. I do have a couple of questions:
1) I am running 3/8" Tend pushrods, are they required? The builder used 5/16 with .080 wall. They are cheaper for sure.
2) The coil bind numbers are based on gross lift not taking into account lost lift due to lash. I think the lash I was using was too tight. I think it should be .016/.018 for a hot lash spec of .018/.020. That will help a little.
3) Is a bench spring tester worth the money? The LSM unit is about 400.00. Would use to verify springs before I install them but not sure how much I would use after that. I currently have an LSM tester to check off-seat pressure of an installed spring. I use that every time I check lash.

I will keep this tread updated regarding my oil test and what PAC has to say about my broken spring that I shipped to them yesterday. I am also planning and double checking my leak down numbers. At the end of the day this engine may be heading for a complete rebuild which this time..... I will do mostly myself. I wouldn't trust any engine builder here in Atlanta working on my lawnmower anymore.

 

What cam and heads do you have again. If you are sub 7000 and light weight valve train. I would set it up with 205 210 seats.

Your broken spring wasn't. 800 max lift

 

See my sig below.... what do you mean regarding 205 210 seats? I also don't understand you you mean regarding your comment "Your broken spring wasn't. 800 max lift"

 

Max recommended lift is different than recommended installed height to coil bind distance.

AFR should have stated the max lift. But you didn't have very much distance between the coils at max lift. Let's just say that your spring makes 5 revolutions from top to bottom. You had 1.233 minus 1.150 equals. 0833 inches divided by 5 equals about. 017 between your individual coils. Way tight and caused failure

Only run about 205 to 210 seats and something around 550 # at maximum lift

 

I understand what you are saying not sure I agree with your approach regarding coil clearance.
AFR states Gross Max Lift General Guidline at 0.800"
This is off the Racing Springs web site:

• Part#PAC-1225
• NamePAC-1225 Drag Race Dual
• SKUPAC-1225
• Alt Part#PAC-1225-16
• DescriptionDrag Race 1200 Series Valve Spring 1.550 - 0.800 lift
• Outside Diameter1.550
• Outer Spring ID1.100
• Middle Spring IDN/A
• Damperno
• Inner Spring ID0.788
• Install Height2.000
• Load at Installed Height250
• Spring Open Height1.200
• Spring Open Load765
• Recommended Valve Lift0.800
• Spring Rate (lbs/in)644
• Coil Bind (max)1.150

Based on the numbers above the max lift of 0.800" at an installed height of 2" results in a spring open height 1.2".
Coil bind spec is 1.15". This results in a spec difference of 0.05". My spring open height is 1.265 resulting in a difference of 0.115" which 2X greater than the specified minimum....which is good.
I also am able to place a 0.060" feeler gauge between the coils at max lift which AFR said would be the minimum it should be.

 

I've never run anything that high of spring rate in my vette motors. That would be just brutal on all the valves, seats, rollers, and bearings. 644 # I have always run @500 #.

Those are for 8800 rpm type motors.

Tony always wanted me to get the AFR 245 heads. I was trying to figure out why I have power into red line. My valve events are 4 degrees retarded. This rebuild I put it back to straight up. Out of all your build what do you think the restriction is? Like the manifold

 

Shoot, it ain't the 80s anymore. There's a lot of street driven cars today running .700+ with rockers in the 1.65 -1.8 range

 

i am sure I am running higher springs pressures than needed. It was originally supposed to a 7000+ rpm engine. Turns out the power band was a bit lower than expected but suspect I have a fuel delivery issue with foaming in the carb bowls at WOT and mixture going lean. I have installed a return line from the carb and reconfigured the plumbing to hopefully fix that. I think the engine can do better than 573 at wheels. The engine dyno had it at 700 hp. I don’t know where the restriction would be with my combo.
my best pull ever was 573 Hp at 6350 rpm and 514 ftlbs at 4820 rpm.

 

I don't have access to dyno simulation software anymore, but maybe someone on here has access and could run one with your CFM at. 050 lift increments, valve events, CI, carb cfm, and C/R.

 

Not for long.

 

As a follow up I decided to post the same question on several other forums as well to get some additional feedback. I still need to discuss with PAC but did get some feedback from Comp Cams and AFR as well as other people on Yellow Bullet, Phantom Bullet and Hot Rod Forum. What have leaned overall is that spring selection and installation is one of the topics where there is not definitive answer. At the end of the day ya got to go with the one that seems to be best suited to how you use the car and your budget. Some said I have too much coil bind but most said I didn't have enough. Comp Cam recommended a spring that had a lift pressure of 810 and seat of 285lbs. Unfortunately the only spring they could come up with was to large in diameter (1.66" at 285 seat and 810 lift) for my heads so unless I want to machine the head, I cannot use......but I am not sure I want to use it. AFR recommended I add 0.045" of shim to be within their recommended coil bind spec. So, I am going to stick with PAC 1325 springs. I may try and get in touch with PAC again but they already said that spring is right for my application. The trouble is when you look at all the criteria for selecting a spring such as installed height, coil bind, full lift and seat pressures, spring rate, inside and outside diameters, retainer selection etc.... there is always a compromise regarding what is the best spring selection. I received surprisingly few responses to my question which also demonstrates the fact this is not a black or white issue.

 

Update: Changing to Manly polished NexTek Oval track springs. These are about 260 on the seat and 650 open. Almost a 100 lb difference between open pressures. Also found the AFR spring seat (That came with the head) was not a good fit. There was plenty of slop which allowed the spring the dance around. The new Manly machined spring seat and retainers appear to be of higher quality. Also discovered the cause of the silver flecks in my oil filter that never seem to go away....the sharp edges on the PAC springs were eating into my titanium retainers. I know this is not uncommon. Going to chamfer the new springs as recommended by Manly but they are actually already so much smoother than the PACs. Anyway..... they were not cheap. Also, this notion of maintaining 0.060" gap in between each coil does not work if you follow the manufacturers coil bind recommendations. They will even recommend the same and then go on to say you should aim to be in the area of 0.060" to 0.10" of the coil bind spec for best spring control. If you do this, there is no way to maintain 0.06" between each coil.... comes out closer to 0.030". I think that whole 0.06" between each coil may be before they realized being too far away from coil bind is not good either.

 

Ah you're on the Bullet too?

I've had decent luck with PAC springs, but it sounds like the ones you have aren't right for the application.

 

I am on Yellow Bullet and Phantom Bullet. HotRod Forum has been most helpful. Yes, PAC springs are considered top of the line and the people there were very helpful but I think the Manly springs are better for my application. I guess I will find out soon enough.