I have a 520 wedge in my 69 GTX with the Trick Flow 270 heads. The heads came with springs that are rated to .700 lift before coil bind. My cam is a solid roller that was specked out with 1.6 rockers gives .696 theoretical lift. I am running the 1.5 Harland Sharp rockers that should give me .652 of theoretical lift. Both of these numbers are BEFORE the .020 lash.
My question is can I run the 1.6 rockers with only .024 before coil bind? How much horse power is the .040 added lift worth?
Motor has 12.5 compression, Intake duration is 266 and exhaust is 275 both @.050.
Currently running the Victor 4500 intake and the car has gone 9.88 @133.50 with a 1.33 60 ft.
Would a Indy 440-2 or 3 make more power?
Thanks for your input.

My street strip car has probably the next sized cam up from yours with 272/278@50, & 660 lift with 1.6 rocker arms. I use springs that are 230lb on the seat & have a spring rate of 555lbs. I'm installed at 1.95 & this engine revs out to 7000 rpm. I've just put the engine back in after I pulled it after 6 years of racing & the only things I changed were the valve locks & the roller lifters. And I only changed those parts coz I thort I should since its under a bit of stress.

You're screwing with fate, DON"T use THEM
I like to see a minimum of .055 clearance before coil bind between the springs (one or more springs) on the spring checker before coil bind at max lift at room temps.
Aluminum heads will grow when warmed up or hot which increases distance between the springs
As far as how much power increase with an additional.040 lift who knows I wouldn't hazard a guess: tsk: That will probably change from heads to a different head brand and valve job
I have seen increases and decreases at the track by tightening or loosening the lash by .004 to.015 tighter or looser when hot
Have you broken or bent a valve due to the valve spring failing? I have
Use a better set of springs for your motor

The Super Victor 4500 intake is very good so don't swap for an Indy intake. If you want to make more power then have Wilson Manifolds port your intake. You'll pick up 20 to 30 hp with a fully ported intake. You would need to test the rocker arm ratio to find out if it matters. If the engine needs faster valve action then it will pick up power with the 1.60 ratio rockers but don't assume that that is the case. The Trick Flow heads have such good airflow at low lifts that often times you do not need very fast valve action. If the valve action is faster than what the engine needs you can lose power. I've done a lot of camshaft and rocker arm testing with the Trick Flow heads and they have a narrow window where they are happy. Too much duration and too fast of valve action kills power in those heads. Just because something works with a different head doesn't mean it will work with a Trick Flow head.

Cab and Andy F. THANK YOU! You guys answered back exactly what I was looking for. I guess I will stay put with my engine combo and reduce some weight. I'm at 3500 lbs and have a set of spare doors I can gut and put lexan in. I think that will shed about 50 lbs or so.
Andy, My engine made peak power at 32 degrees of timing but goes down the track a whole lot quicker at 34. What have you found to be the magical number?

Trick Flow heads usually work best in the 34 to 36 range but your number could vary depending on fuel, weather, type of spark plug, etc. You also need to verify that TDC is actually TDC.

The density and actual altitude will dictate what timing works best that day with that density altitude at that track
Most BB Mopar engines will want more timing at 3500 Ft. above sea level that they will at 0 to 1000 F. above sea level
You're doing the right thing on testing and tuning at the track to find out exactly what your car and motor want to go as fast as it can
What works the best on an engine dyno may NOT be the best set up at the track when you're racing the car

Who built your engine? Couldn't you reengage them on what can and can't be done because it seems to me it's a winner! ESPECIALLY since it appears you're using a stock block. Like you have stated, much of the info you've provided is probably more theoretical than actual including the DA and applicable RPMs. In general, when you start squeezing more out of a given good package you really need to know more precisely every detail. Generally you can run about .060" from C/B in your application.

Your cam duration is the same as mine. What LSA is it ground on? mine is 110 degrees. Comp HXL lobes, so a hair over 0.700" lift with 1.6 rockers.
Springs I am using are the PAC-1326 (663 lb/in rate, and 275 seat pressure). Likely stiffer springs than I need, but I got a deal on them from the head porter.
Previous, used the PAC-1325 springs (644 lb/in rate, and 250 seat pressure.) Both rated for up to 0.800" lift when installed at 2.00"

Mine is also on 110 lobe sep.the 555 spring rate springs seem to survive well in my application. I bracket race in an 11.00 sec fixed dial in, street legal drag class on friday nights over summer, when the conditions are right & the fat lady is singing, my full factory trim e body will run 10.5 @127 on pump gas.

I'm attaching my cam cardto give you guys more info.
I built the engines in both GTXs in the picture. I never set my builds on kill as I'm lazy and hate to re do anything and like durabilty. Both cars are using stock blocks.
The car in the near lane has a 493 I built in 1999.
3900 lbs, pump gas, mufflers, air cleaner, drag radials, full auto valve body, power steering, power brakes, heater and CD player. 3.73 gears. 10.84 at 124 with a few 1.50 60 ft times. Girlfriend's race car.
Looking at the cam card and if I decide to go 1.6 rockers, what spring do you guys recommend?

Forgot attachment... Brain farts are happening way too often these days

On the valve spring pressures on a steel core solid roller cam your far better off with having a lot more spring pressures than suggested by your cam grinder, trust me on that from learning that the hard way
I would shoot for 235 to 250 lbs. on the seats and 630 to 700 lbs. opened with a minimum of .060 clearnce (max of .080) between at least on one spring coil on every valve spring at room temps
look at your cam lobes now while you have the motors apart and see if you have shiny lines on the back side of the cam lobes If you do you need to have a lot more valve spring pressure to keep the roller lifters rolling on the lobes, not flying off the tops of the lobes and slamming back down on the lobes 2/3 to 1/2 way down the back sides of the lobes
Good luck, stay safe